Articoli di riviste: "Moments de flexion des vagues"

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Pollard, Jonisha P., William L. Porter e Mark S. Redfern. "Forces and Moments on the Knee During Kneeling and Squatting". Journal of Applied Biomechanics 27, n. 3 (agosto 2011): 233–41. http://dx.doi.org/10.1123/jab.27.3.233.

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Abstract (sommario):

Euler angle decomposition and inverse dynamics were used to determine the knee angles and net forces and moments applied to the tibia during kneeling and squatting with and without kneepads for 10 subjects in four postures: squatting (Squat), kneeling on the right knee (One Knee), bilateral kneeling near full flexion (Near Full) and bilateral kneeling near 90° flexion (Near 90). Kneepads affected the knee flexion (p= .002), medial forces (p= .035), and internal rotation moments (p= .006). Squat created loading conditions that had higher varus (p< .001) and resultant moments (p= .027) than kneeling. One Knee resulted in the highest force magnitudes and net moments (p< .001) of the kneeling postures. Thigh-calf and heel-gluteus contact forces decreased the flexion moment on average by 48% during Squat and Near Full.

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Gál, J. M. "Mammalian spinal biomechanics. I. Static and dynamic mechanical properties of intact intervertebral joints." Journal of Experimental Biology 174, n. 1 (1 gennaio 1993): 247–80. http://dx.doi.org/10.1242/jeb.174.1.247.

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Four-point bending was used to apply pure extension and flexion moments to the ligamentous lumbosacral spine and pelvic girdle of monkey (Macaca fascicularis), rabbit (domestic and wild, Oryctolagus cuniculus), badger (Meles meles), wallaby (Wallabia rufogrisea frutica), sheep (Ovis aries), seal (Phoca vitulina) and tiger (Panthera tigris). The absolute ranges of angular change in lumbar-lumbar joints (from X-radiographs) were considerable and similar in monkey and wallaby (greater in flexion) and in rabbit and badger (symmetrical in extension and flexion). Mass-specific bending comparisons showed that monkey and seal joints were the most and least resistant, respectively, to these moments. The patterns of mobility showed no clear scaling effects. Subsequently, additional ligamentous joint complexes (three vertebrae and two intervertebral discs) of monkey, wallaby, tiger, jaguar (Panthera onca) and seal (Halichoerus grypus) were subjected to cyclic extension and flexion moments. Changes in intervertebral angle (y, from X-radiographs) were modelled as functions of applied specific bending moments (x):y=A(1-e-Bx). A and B values represented bending capacities and joint compliances respectively. Homologous monkey and wallaby joints had considerable flexion capacities, with low compliances. Homologous jaguar and tiger joints had limited flexion capacities, but greater compliances. The data suggest that flexion resistance may be controlled by different mechanisms in different species.

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Dall, P. M., B. Müller, I. Stallard, J. Edwards e M. H. Granat. "The functional use of the reciprocal hip mechanism during gait for paraplegic patients walking in the Louisiana State University reciprocating gait orthosis". Prosthetics and Orthotics International 23, n. 2 (agosto 1999): 152–62. http://dx.doi.org/10.3109/03093649909071627.

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Abstract (sommario):

Reciprocally linked orthoses used for paraplegic walking have some form of linkage between the two hip joints. It has been assumed that flexion of the swinging leg is driven by extension of the stance leg. The aims of this study were to investigate the moments generated around the hip joint by the two cables in a Louisiana State University Reciprocating Gait Orthosis (LSU-RGO). Six (6) subjects were recruited from the Regional Spinal Injuries Centre at Southport, who were experienced RGO users. The cables were fitted with strain gauged transducers to measure cable tension. Foot switches were used to divide the gait into swing and stance phases. A minimum of 20 steps were analysed for each subject. Moments about the hip joint for each phase of gait were calculated. There were no moments generated by the front cable in 4 of the subjects. In only 2 subjects did the cable generate a moment that could assist hip flexion during the swing phase. These moments were very low and at best could only have made a small contribution to limb flexion. The back cable generated moments that clearly prevented bilateral flexion. It was concluded that the front cable, as used by these experienced RGO users, did not aid flexion of the swinging limb.

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Gillette, Jason C., Catherine A. Stevermer, Stacey A. Meardon, Timothy R. Derrick e Charles V. Schwab. "Upper Extremity and Lower Back Moments during Carrying Tasks in Farm Children". Journal of Applied Biomechanics 25, n. 2 (maggio 2009): 149–55. http://dx.doi.org/10.1123/jab.25.2.149.

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Farm youth commonly perform animal care tasks such as feeding and watering. The purpose of this study was to determine the effects of age, bucket size, loading symmetry, and amount of load on upper body moments during carrying tasks. Fifty-four male and female participants in four age groups (8–10 years, 12–14 years, 15–17 years, and adults, 20–26 years) participated in the study. Conditions included combinations of large or small bucket sizes, unilateral or bilateral loading, and load levels of 10% or 20% of body weight (BW). During bucket carrying, elbow flexion, shoulder flexion, shoulder abduction, shoulder external rotation, L5/S1 extension, L5/S1 lateral bending, and L5/S1 axial rotation moments were estimated using video data. The 8–10 year-old group did not display higher proportional joint moments as compared with adults. Decreasing the load from 20% BW to 10% BW significantly decreased maximum normalized elbow flexion, shoulder flexion, shoulder abduction, shoulder external rotation, L5/S1 lateral bending, and L5/S1 axial rotation moments. Carrying the load bilaterally instead of unilaterally also significantly reduced these six maximum normalized joint moments. In addition, modifying the carrying task by using smaller one-gallon buckets produced significant reductions in maximum L5/S1 lateral bending moments.

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Kaur, Mandeep, Daniel Cury Ribeiro, Kate E. Webster e Gisela Sole. "Association Between Knee Moments During Stair Navigation and Participant-Related Factors in Individuals With Anterior Cruciate Ligament Reconstruction: A Cross-Sectional Study". Journal of Sport Rehabilitation 31, n. 2 (1 febbraio 2022): 174–80. http://dx.doi.org/10.1123/jsr.2021-0104.

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Context: Altered knee joint mechanics may be related to quadriceps muscle strength, time since surgery, and sex following anterior cruciate ligament reconstruction (ACLR). The aim of this study was to investigate the association between knee moments, with participant-related factors during stair navigation post-ACLR. Design: Cross-sectional study. Methods: A total of 30 participants (14 women) with ACLR, on average 7.0 (SD 4.4) years postsurgery were tested during stair ascent and descent in a gait laboratory. Motion capture was conducted using a floor-embedded force plate and 11 infrared cameras. Quadriceps concentric and eccentric muscle strength was measured with an isokinetic dynamometer at 60°/s, and peak torques recorded. Multiple regression analyses were performed between external knee flexion and adduction moments, respectively, and quadriceps peak torque, sex, and time since ACLR. Results: Higher concentric quadriceps strength and female sex accounted for 55.7% of the total variance for peak knee flexion moment during stair ascent (P < .001). None of the independent variables accounted for variance in knee adduction moment (P = .698). No significant associations were found for knee flexion and adduction moments during for stair descent. Conclusion: Higher quadriceps concentric strength and sex explains major variance in knee flexion moments during stair ascent. The strong association between muscle strength and external knee flexion moments during stair ascent indicate rehabilitation tailored for quadriceps may optimize knee mechanics, particularly for women.

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Andrysek, Jan, Susan Klejman e John Kooy. "Examination of Knee Joint Moments on the Function of Knee-Ankle-Foot Orthoses During Walking". Journal of Applied Biomechanics 29, n. 4 (agosto 2013): 474–80. http://dx.doi.org/10.1123/jab.29.4.474.

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The goal of this study was to investigate clinically relevant biomechanical conditions relating to the setup and alignment of knee-ankle-foot orthoses and the influence of these conditions on knee extension moments and orthotic stance control during gait. Knee moments were collected using an instrumented gait laboratory and concurrently a load transducer embedded at the knee-ankle-foot orthosis knee joint of four individuals with poliomyelitis. We found that knee extension moments were not typically produced in late stance-phase of gait. Adding a dorsiflexion stop at the orthotic ankle significantly decreased the knee flexion moments in late stance-phase, while slightly flexing the knee in stance-phase had a variable effect. The findings suggest that where users of orthoses have problems initiating swing-phase flexion with stance control orthoses, an ankle dorsiflexion stop may be used to enhance function. Furthermore, the use of stance control knee joints that lock while under flexion may contribute to more inconsistent unlocking of the stance control orthosis during gait.

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Weir, Gillian, Jacqueline Alderson, Natalie Smailes, Bruce Elliott e Cyril Donnelly. "A Reliable Video-based ACL Injury Screening Tool for Female Team Sport Athletes". International Journal of Sports Medicine 40, n. 03 (10 gennaio 2019): 191–99. http://dx.doi.org/10.1055/a-0756-9659.

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AbstractThis study aimed to develop a 2-dimensional (2D) video screening tool capable of predicting an athlete’s peak 3-dimensional (3D) knee moments during unplanned sidestepping. 2D video-based kinematic measures were simultaneously captured with 3D peak knee moments for 30 female field hockey players (15 junior, 15 senior). Intra- and intertester repeatability of 2D kinematic measures was performed. Then, linear regression models were used to model 3D knee moments from 2D kinematic variables utilizing 80% of the sample (n=24). Regression equations were then validated on the remaining 20% of the sample (n=6). Angular 2D measures had good-excellent intra- (ICC=0.936–0.998) and intertester (ICC=0.662–0.949) reliability. Displacement measures had poor-excellent intra- (ICC=0.377–0.539) and inter-tester (ICC=0.219–0.869) reliability. Significant independent predictors of peak knee moments were dynamic knee valgus, knee flexion angle at foot strike, trunk flexion range of motion (ROM), trunk lateral flexion, hip abduction and knee flexion ROM (P<0.05). Regression equations generated from these models effectively predicted peak knee extension, valgus and internal rotation moments (i. e., were not different from measured values P>0.05, ES<0.4) in the 20% subsample. 2D video-based measurements of an athlete's full body kinematics during unplanned sidestepping provide a reliable, specific, sensitive and cost-effective means for screening female team sport athletes.

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Hoy, M. G., R. F. Zernicke e J. L. Smith. "Contrasting roles of inertial and muscle moments at knee and ankle during paw-shake response". Journal of Neurophysiology 54, n. 5 (1 novembre 1985): 1282–94. http://dx.doi.org/10.1152/jn.1985.54.5.1282.

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Intralimb kinetics of the paw-shake response (PSR) were studied in four spinal, adult cats. Using rigid body equations of motion to determine the dynamic interactions between limb segments, knee and ankle joint kinetics were calculated for the steady-state cycles as defined in the preceding paper. Hindlimb motion was filmed (200 frames/s) to obtain knee and ankle kinematics. Responses of flexors and extensors at both joints were recorded synchronously with cinefilm. Ankle and knee joint kinematics were determined from 51 steady-state cycles of 16 PSRs. Average maximum displacements, velocities, and accelerations were substantially greater for the ankle than for the knee joint. Knee and ankle motions were out of phase in the first part of the cycle; knee extension occurred simultaneously with ankle flexion. In the second part of the cycle, motions at the two joints were sequential; rapid knee flexion, accompanied by negligible ankle displacement, preceded rapid ankle extension with minimal knee displacement. At the ankle joint, peak net moments tending to cause flexion and extension were similar in magnitude and determined primarily by muscle moments. Moments due to leg angular acceleration contributed significantly to an extensor peak in the net moment near the end of the cycle. Other inertial and gravitational moments were small. At the knee joint, net moments tending to cause flexion and extension were also similar, but smaller than those at the ankle. The knee muscle moments, however, were large and counteracted large inertial moments due to paw angular acceleration. Also, moments due to leg angular acceleration and knee linear acceleration were substantial and opposite in effect. Other inertial and the gravitational moments were negligible. Muscle moments slowed and reversed joint motions, and active muscle force components of muscle moments were derived from lengthening of active musculotendinous units. Segmental interactions, in which proximal segment motion augmented distal segment velocity, increased the effectiveness of PSR steady-state cycles by facilitating the generation of extremely large paw linear accelerations. Limb oscillations during PSR steady-state result from interactions between muscle synergies and motion-dependent limb dynamics. At the ankle, muscle activity functioned to control paw acceleration, whereas at the knee, muscle activity functioned to control leg and paw inertial interactions.(ABSTRACT TRUNCATED AT 400 WORDS)

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Sørensen, Henrik, Dennis B. Nielsen, Julie S. Jacobsen, Kjeld Søballe e Inger Mechlenburg. "Isokinetic dynamometry and gait analysis reveal different hip joint status in patients with hip dysplasia". HIP International 29, n. 2 (9 maggio 2018): 215–21. http://dx.doi.org/10.1177/1120700018773401.

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Background: Objective assessment of hip dysplasia patients’ functional hip joint status routinely involves gait analysis or isokinetic dynamometry. However, these methods have shown equivocal results and have not been employed in the same groups of patients and controls. Purpose: To assess hip flexor and abductor moments by isokinetic dynamometry in the dysplasia patient and controls, for which we previously reported smaller flexor and slightly larger abductor moments during gait in patients compared to controls. Methods: The study was designed as a prospective cohort study (Level of Evidence II) and conducted in a biomechanics laboratory at Aarhus University, Denmark, during 2011. Participants comprised 32 dysplasia patients and 32 age and gender matched controls. Outcome measures were static peak hip flexion moment at 15, 45 and 75° hip flexion; dynamic eccentric and concentric peak hip flexion moment at 60° and 120°/second; dynamic eccentric and concentric hip abductor moment at 30° and 60°/second. Results: Hip dysplasia patients had smaller eccentric peak flexion moments and smaller eccentric and concentric peak abduction moments at all tested velocities. Conclusion: Although dysplasia patients have weaker hip flexion and abductor muscles than controls, their abductor muscles are sufficiently strong to ensure normal function during gait. Hence, gait analysis alone might not reveal the true, subnormal hip joint status in dysplasia patients. We suggest that comprehensive assessment of hip joint function in dysplasia patients should include more strenuous activities than gait, particularly in young(er) patients who are likely to prefer a more active lifestyle.

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Lyle, Mark A., Jake C. Jensen, Jennifer L. Hunnicutt, Jonathan J. Brown, Cynthia P. Chambliss, Michael A. Newsome, John W. Xerogeanes e Liang-Ching Tsai. "Identification of strength and spatiotemporal gait parameters associated with knee loading during gait in persons after anterior cruciate ligament reconstruction". Journal of Athletic Training 2021, preprint (30 luglio 2021): 0000. http://dx.doi.org/10.4085/1062-6050-0186.21.

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ABSTRACT Context: Altered knee moments are common during gait in patients following anterior cruciate ligament reconstruction (ACLR). Modifiable factors that influence knee moments and are feasible to record in clinical settings such as strength and spatiotemporal parameters (e.g. step length, step width) have not been identified in persons after ACLR. Objective: The objective was to identify strength and spatiotemporal gait parameters that can predict knee moments in persons after ACLR. Design: Cross-Sectional Study Setting: Laboratory Patients: Twenty-three participants with ACLR (14.4 ± 17.2 months post-ACLR) participated. Main Outcome Measures: Peak knee flexion and adduction moments were measured while walking at self-selected speeds. Spatiotemporal gait parameters were recorded with a pressure walkway, and peak isokinetic knee extensor strength (60°/s) was recorded on a dynamometer. Pearson coefficients were used to examine the association of peak knee moments with strength and gait parameters. Variables correlated with peak knee flexion and adduction moments were entered into a stepwise regression model. Results: Step width and knee extensor strength were the strongest predictors of knee flexion moment accounting for 44% of data variance, whereas stance phase time and step width were the strongest predictors of knee adduction moment explaining 62% of data variance. Conclusions: The spatiotemporal variables that were identified could be clinically feasible targets for biofeedback to improve gait after ACLR.

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Lambach, Rebecca L., Jay W. Young, David C. Flanigan, Robert A. Siston e Ajit M. W. Chaudhari. "Knee Joint Loading During Lineman-Specific Movements in American Football Players". Journal of Applied Biomechanics 31, n. 3 (giugno 2015): 142–48. http://dx.doi.org/10.1123/jab.2014-0123.

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Linemen are at high risk for knee cartilage injuries and osteoarthritis. High-intensity movements from squatting positions (eg, 3-point stance) may produce high joint loads, increasing the risk for cartilage damage. We hypothesized that knee moments and joint reaction forces during lineman-specific activities would be greater than during walking or jogging. Data were collected using standard motion analysis techniques. Fifteen NCAA linemen (mean ± SD: height = 1.86 ± 0.07 m, mass = 121.45 ± 12.78 kg) walked, jogged, and performed 3 unloaded lineman-specific blocking movements from a 3-point stance. External 3-dimensional knee moments and joint reaction forces were calculated using inverse dynamics equations. MANOVA with subsequent univariate ANOVA and post hoc Tukey comparisons were used to determine differences in peak kinetic variables and the flexion angles at which they occurred. All peak moments and joint reaction forces were significantly higher during jogging than during all blocking drills (all P < .001). Peak moments occurred at average knee flexion angles > 70° during blocking versus < 44° in walking or jogging. The magnitude of moments and joint reaction forces when initiating movement from a 3-point stance do not appear to increase risk for cartilage damage, but the high flexion angles at which they occur may increase risk on the posterior femoral condyles.

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Qiu, Tian-Xia, Ee-Chon Teo e Qing-Hang Zhang. "VALIDATION OF FINITE ELEMENT MODELS OF THORACOLUMBAR T11-T12 AND T12-L1 AND COMPARISON OF THEIR BIOMECHANICAL RESPONSES". Journal of Musculoskeletal Research 09, n. 03 (settembre 2005): 133–43. http://dx.doi.org/10.1142/s0218957705001576.

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The objective of this study was to build and validate the FE models of thoracolumbar junctional T11-T12 and T12-L1 functional spinal units (FSUs) and compare the biomechanical responses of the two FSUs under physiological loading modes: flexion, extension, lateral bending and axial rotation. Anatomically accurate FE models of thoracolumbar T11-T12 and T12-L1 FSUs were developed and validated against published experimental results in terms of load displacement responses and range of motion (ROM) under flexion and extension pure moments of 7.5 Nm, left and right lateral bending pure moments of 7.5 Nm and left and right axial torque of 7.5 Nm. The overall responses predicted by the T11-T12 and T12-L1 FE models showed differences in stiffness under different load configurations. Amongst all loading configurations, the motions at T11-T12 and T12-L1 were the stiffest under axial torque. The lateral bending motions of T11-T12 and T12-L1 were relatively flexible. Under sagittal moments, the motion in extension was greater than in flexion at level T11-T12, while the rotation in flexion was greater than in extension at level T12-L1.

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Herbort, Mirco, Philipp Michel, Michael J. Raschke, Nils Vogel, Martin Schulze, Alexander Zoll, Christian Fink, Wolf Petersen e Christoph Domnick. "Should the Ipsilateral Hamstrings Be Used for Anterior Cruciate Ligament Reconstruction in the Case of Medial Collateral Ligament Insufficiency? Biomechanical Investigation Regarding Dynamic Stabilization of the Medial Compartment by the Hamstring Muscles". American Journal of Sports Medicine 45, n. 4 (28 dicembre 2016): 819–25. http://dx.doi.org/10.1177/0363546516677728.

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Background: Semitendinosus and gracilis muscles are frequently harvested for autologous tendon grafts for cruciate ligament reconstruction. This study investigated the joint-stabilizing effects of these hamstring muscles in cases of insufficiency of the medial collateral ligament (MCL). Hypotheses: First, both the semitendinosus and gracilis muscles can actively stabilize the joint against valgus moments in the MCL-deficient knee. Second, the stabilizing influence of these muscles decreases with an increasing knee flexion angle. Study Design: Controlled laboratory study. Methods: The kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force moment sensor system and an optical tracking system. The knee kinematics under 5- and 10-N·m valgus moments were determined in the different flexion angles of the (1) MCL-intact and (2) MCL-deficient knee using the following simulated muscle loads: (1) 0-N (idle) load, (2) 200-N semitendinosus (ST) load, and (3) 280-N (200/80-N) combined semitendinosus/gracilis (STGT) load. Results: Cutting the MCL increased the valgus angle under all tested conditions and angles compared with the MCL-intact knee by 4.3° to 8.1° for the 5-N·m valgus moment and 6.5° to 11.9° for the 10-N·m valgus moment ( P < .01). The applied 200-N simulated ST load reduced the valgus angle significantly at 0°, 10°, 20°, and 30° of flexion under 5- and 10-N·m valgus moments ( P < .05). At 0°, 10°, and 20° of flexion, these values were close to those for the MCL-intact joint under the respective moments (both P > .05). The combined 280-N simulated STGT load significantly reduced the valgus angle in 0°, 10°, and 20° of flexion under 5- and 10-N·m valgus moments ( P < .05) to values near those for the intact joint (5 N·m: 0°, 10°; 10 N·m: 0°, 10°, 20°; P > .05). In 60° and 90° of flexion, ST and STGT loads did not decrease the resulting valgus angle of the MCL-deficient knee without hamstring loads ( P > .05 vs deficient; P = .0001 vs intact). Conclusion: In this human cadaveric study, semitendinosus and gracilis muscles successfully stabilize valgus moments applied to the MCL-insufficient knee when the knee is near extension. Clinical Relevance: In the valgus-unstable knee, these data suggest that the hamstring muscles should be preserved in (multi-) ligament surgery when possible.

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Andrysek, Jan, Susan Klejman e John Kooy. "Forces and moments in knee–ankle–foot orthoses while walking on irregular surfaces: A case series study". Prosthetics and Orthotics International 38, n. 2 (30 maggio 2013): 104–13. http://dx.doi.org/10.1177/0309364613489145.

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Background: Kinetic data provide important information about the mobility performance of individuals with lower limb impairments and their assistive devices; however, there is limited understanding of this in real-life environments. Objective: To evaluate the effect of real-life irregular surfaces on forces and moments in knee–ankle–foot orthoses. Methods: In this case series study, a load cell was used to measure the forces and moments at the knee joint of knee–ankle–foot orthoses of individuals with unilateral muscle weakness as a result of poliomyelitis while walking on different ground surfaces and at different speeds. Results: Significantly higher shear forces and external peak knee flexion moments were found when walking on irregular surfaces. In individual cases, certain irregular ground conditions elicited large increases in peak flexion moments (>50%) when compared to walking on smooth level ground. Forces and moments were significantly higher at faster walking speeds. Conclusions: Higher external peak knee flexion moments during the stance phase suggest that greater demands for support and stability are placed on individuals and their assistive devices when negotiating real-life ground surfaces. Clinical relevance This study demonstrates that walking on irregular surfaces alters the loads placed on knee–ankle–foot orthoses and that the requirements for knee stabilization increase. This has important clinical implications on the design, prescription, and use of such devices given the structural and functional demands placed on them.

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Mueske, Nicole, Daniel T. Feifer, Curtis VandenBerg, J. Lee Pace, Mia J. Katzel, Tracy Zaslow, Bianca Edison e Tishya Wren. "EFFECT OF STATIC ANATOMIC ALIGNMENT ON DYNAMIC LIMB VALGUS DURING SIDE-STEP CUTTING IN UNINJURED ADOLESCENT ATHLETES". Orthopaedic Journal of Sports Medicine 7, n. 3_suppl (1 marzo 2019): 2325967119S0002. http://dx.doi.org/10.1177/2325967119s00028.

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BACKGROUND Dynamic limb valgus, combining hip adduction and internal rotation with knee abduction posture and moments, has been implicated in ACL injury. However, the contribution of static lower extremity alignment to dynamic limb valgus is unknown. This study assessed the relationships among lower extremity static alignment and dynamic kinematics and kinetics during side-step cutting in uninjured adolescent athletes. METHODS This prospective study included 88 limbs from 44 uninjured athletes aged 8-15 years (mean 12.3, SD 2.3; 19 (44%) female) who were evaluated during an anticipated 45° side-step cut. 3D lower extremity kinematics and kinetics from a custom 6 degree of freedom model were assessed while standing and during the loading phase of the cut from initial contact to peak knee flexion; 2-3 trials per limb were averaged for analysis. Femoral anteversion was measured for each limb with the participant lying prone. Relationships among static and dynamic measures were investigated using correlation and multiple linear regression. RESULTS In terms of static alignment, more static hip internal rotation and more static knee external rotation (tibia external relative to femur) were associated with more internal hip rotation and external knee rotation dynamically during cutting (r=0.34, p=0.001) (Table 1). Static hip adduction was also related to more external hip rotation and less hip flexion dynamically (p=0.24, p=0.02). More static knee abduction, external hip rotation and hip adduction were associated with higher average knee abduction angles during cutting (r=0.25, p=0.02). However, only static external knee rotation was associated with higher dynamic knee abduction moments (r=0.48, p<0.0001) (Figure 1). During cutting, positive associations were observed between hip flexion, knee flexion, and hip internal rotation (r=0.24, p=0.03). Knee adduction angles were related to more hip flexion, internal hip rotation, and knee external rotation (r=0.25, p=0.02). Additionally, lower peak knee flexion was associated with higher peak ground reaction force and more external knee rotation (r=0.24, p=0.02). Both simple correlation and multiple regression analysis indicated that higher knee abduction moments were related dynamically to higher knee abduction angles, greater knee external rotation, higher hip abduction angles, and greater hip internal rotation (R2=0.72, p<0.001). After considering dynamic metrics, no static measure remained significantly related to knee abduction moments. CONCLUSION/SIGNIFICANCE Static knee rotation was the only anatomic alignment measure associated with knee abduction moments during side-step cutting in uninjured adolescent athletes. Knee abduction moments were influenced more by dynamic posture than static alignment. As knee abduction moments have been implicated in ACL injury, this study supports the notion of dynamic limb valgus, specifically increased knee abduction and hip internal rotation, relating to ACL injury. Motion analysis can be used to identify these risky biomechanical patterns, and neuromuscular training can be used to correct them. Since knee abduction moments are primarily determined by dynamic posture, neuromuscular training can be used to reduce these moments and ACL injury risk. [Figure: see text][Table: see text]

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Zhang, L., J. Butler, T. Nishida, G. Nuber, H. Huang e W. Z. Rymer. "In Vivo Determination of the Direction of Rotation and Moment-Angle Relationship of Individual Elbow Muscles". Journal of Biomechanical Engineering 120, n. 5 (1 ottobre 1998): 625–33. http://dx.doi.org/10.1115/1.2834754.

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The direction of rotation (DOR) of individual elbow muscles, defined as the direction in which a muscle rotates the forearm relative to the upper arm in three-dimensional space, was studied in vivo as a function of elbow flexion and forearm rotation. Electrical stimulation was used to activate an individual muscle selectively, and the resultant flexion-extension, supination-pronation, and varus-valgus moments were used to determine the DOR. Furthermore, multi-axis moment-angle relationships of individual muscles were determined by stimulating the muscle at a constant submaximal level across different joint positions, which was assumed to result in a constant level of muscle activation. The muscles generate significant moments about axes other than flexion-extension, which is potentially important for actively controlling joint movement and maintaining stability about all axes. Both the muscle DOR and the multi axis moments vary with the joint position systematically. Variations of the DOR and moment-angle relationship across muscle twitches of different amplitudes in a subject were small, while there were considerable variations between subjects.

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Buchanan, T. S., S. L. Delp e J. A. Solbeck. "Muscular Resistance to Varus and Valgus Loads at the Elbow". Journal of Biomechanical Engineering 120, n. 5 (1 ottobre 1998): 634–39. http://dx.doi.org/10.1115/1.2834755.

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Abstract (sommario):

Although the contributions of passive structures to stability of the elbow have been well documented, the role of active muscular resistance of varus and valgus loads at the elbow remains unclear. We hypothesized that muscles: (1) can produce substantial varus and valgus moments about the elbow, and (2) are activated in response to sustained varus and valgus loading of the elbow. To test the first hypothesis, we developed a detailed musculoskeletal model to estimate the varus and valgus moment-generating capacity of the muscles about the elbow. To test the second hypothesis, we measured EMGs from 11 muscles in four subjects during a series of isometric tasks that included flexion, extension, varus, and valgus moments about the elbow. The EMG recordings were used as inputs to the elbow model to estimate the contributions of individual muscles to flexion-extension and varus-valgus moments. Analysis of the model revealed that nearly all of the muscles that cross the elbow are capable of producing varus or valgus moments; the capacity of the muscles to produce varus moment (34 Nm) and valgus moment (35 Nm) is roughly half of the maximum flexion moment (70 Nm). Analysis of the measured EMGs showed that the anconeus was the most significant contributor to valgus moments and the pronator teres was the largest contributor to varus moments. Although our results show that muscles were activated in response to static varus and valgus loads, their activations were modest and were not sufficient to balance the applied load.

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Hsieh, Y. F., e L. F. Draganich. "Increasing Quadriceps Loads Affect the Lengths of the Ligaments and the Kinematics of the Knee". Journal of Biomechanical Engineering 120, n. 6 (1 dicembre 1998): 750–56. http://dx.doi.org/10.1115/1.2834889.

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The relationships between the lengths of the ligaments and kinematics of the knee and quadriceps load, for low to physiologic levels of quadriceps loads, have not previously been studied. We investigated the effects of increasing levels of quadriceps force, necessary to balance increasing levels of externally applied flexion moments, on the kinematics of the tibiofemoral joint and on the separation distances between insertions of selected fibers of the major ligaments of the knee in twelve cadavera. Static measurements were made using a six-degree-of-freedom digitizer for flexion angles ranging from 0 to 120 deg in 15 deg increments. Quadriceps generated extension of the knee was performed by applying loads to the quadriceps tendon to equilibrate each of four magnitudes of external flexion moments equivalent to 8.33, 16.67, 25.00, and 33.33 percent of values previously reported for maximum isometric extension moments. The magnitude of quadriceps force increased linearly (p < 0.0001) as external flexion moment increased throughout the entire range of flexion. Anterior translation, internal rotation, and abduction of the tibia increased linearly (p < 0.0001, p < 0.001, p < 0.001) as external flexion moment and, hence, quadriceps load increased. For the fibers studied, the anterior cruciate ligament (p < 0.0076), posterior cruciate ligament (p < 0.0001), and medial collateral ligament (p < 0.0383) lengthened linearly while the lateral collateral ligament (p < 0.0124) shortened linearly as quadriceps load increased. Based on these results for low to physiologic levels of quadriceps loads, it is reasonable to assume that the ligament lengths or knee kinematics expected with higher quadriceps loads can be extrapolated.

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19

Tang, Hui, Jiahao Pan, Barry Munkasy, Kim Duffy e Li Li. "Comparison of Lower Extremity Joint Moment and Power Estimated by Markerless and Marker-Based Systems during Treadmill Running". Bioengineering 9, n. 10 (19 ottobre 2022): 574. http://dx.doi.org/10.3390/bioengineering9100574.

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Abstract (sommario):

Background: Markerless (ML) motion capture systems have recently become available for biomechanics applications. Evidence has indicated the potential feasibility of using an ML system to analyze lower extremity kinematics. However, no research has examined ML systems’ estimation of the lower extremity joint moments and powers. This study aimed to compare lower extremity joint moments and powers estimated by marker-based (MB) and ML motion capture systems. Methods: Sixteen volunteers ran on a treadmill for 120 s at 3.58 m/s. The kinematic data were simultaneously recorded by 8 infrared cameras and 8 high-resolution video cameras. The force data were recorded via an instrumented treadmill. Results: Greater peak magnitudes for hip extension and flexion moments, knee flexion moment, and ankle plantarflexion moment, along with their joint powers, were observed in the ML system compared to an MB system (p < 0.0001). For example, greater hip extension (MB: 1.42 ± 0.29 vs. ML: 2.27 ± 0.45) and knee flexion (MB: −0.74 vs. ML: −1.17 nm/kg) moments were observed in the late swing phase. Additionally, the ML system’s estimations resulted in significantly smaller peak magnitudes for knee extension moment, along with the knee production power (p < 0.0001). Conclusions: These observations indicate that inconsistent estimates of joint center position and segment center of mass between the two systems may cause differences in the lower extremity joint moments and powers. However, with the progression of pose estimation in the markerless system, future applications can be promising.

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20

Aagaard, Per, Erik B. Simonsen, S. Peter Magnusson, Benny Larsson e Poul Dyhre-Poulsen. "A New Concept For Isokinetic Hamstring: Quadriceps Muscle Strength Ratio". American Journal of Sports Medicine 26, n. 2 (marzo 1998): 231–37. http://dx.doi.org/10.1177/03635465980260021201.

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Abstract (sommario):

Conventionally, the hamstring:quadriceps strength ratio is calculated by dividing the maximal knee flexor (hamstring) moment by the maximal knee extensor (quadriceps) moment measured at identical angular velocity and contraction mode. The agonist-antagonist strength relationship for knee extension and flexion may, however, be better described by the more functional ratios of eccentric hamstring to concentric quadriceps moments (extension), and concentric hamstring to eccentric quadriceps moments (flexion). We compared functional and conventional isokinetic hamstring: quadriceps strength ratios and examined their relation to knee joint angle and joint angular velocity. Peak and angle-specific (50°, 40°, and 30° of knee flexion) moments were determined during maximal concentric and eccentric muscle contractions (10° to 90° of motion; 30 and 240 deg/sec). Across movement speeds and contraction modes the functional ratios for different moments varied between 0.3 and 1.0 (peak and 50°), 0.4 and 1.1 (40°), and 0.4 and 1.4 (30°). In contrast, conventional hamstring:quadriceps ratios were 0.5 to 0.6 based on peak and 50° moments, 0.6 to 0.7 based on 40° moment, and 0.6 to 0.8 based on 30° moment. The functional hamstring:quadriceps ratio for fast knee extension yielded a 1:1 relationship, which increased with extended knee joint position, indicating a significant capacity of the hamstring muscles to provide dynamic knee joint stability in these conditions. The evaluation of knee joint function by use of isokinetic dynamometry should comprise data on functional and conventional hamstring:quadriceps ratios as well as data on absolute muscle strength.

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21

Jabeen, Saher, Patricia M. Baines, Jaap Harlaar, Heike Vallery e Andrew Berry. "Reaction moments matter when designing lower-extremity robots for tripping recovery". PLOS ONE 18, n. 2 (21 febbraio 2023): e0280158. http://dx.doi.org/10.1371/journal.pone.0280158.

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Abstract (sommario):

Balance recovery after tripping often requires an active adaptation of foot placement. Thus far, few attempts have been made to actively assist forward foot placement for balance recovery employing wearable devices. This study aims to explore the possibilities of active forward foot placement through two paradigms of actuation: assistive moments exerted with the reaction moments either internal or external to the human body, namely ‘joint’ moments and ‘free’ moments, respectively. Both paradigms can be applied to manipulate the motion of segments of the body (e.g., the shank or thigh), but joint actuators also exert opposing reaction moments on neighbouring body segments, altering posture and potentially inhibiting tripping recovery. We therefore hypothesised that a free moment paradigm is more effective in assisting balance recovery following tripping. The simulation software SCONE was used to simulate gait and tripping over various ground-fixed obstacles during the early swing phase. To aid forward foot placement, joint moments and free moments were applied either on the thigh to augment hip flexion or on the shank to augment knee extension. Two realizations of joint moments on the hip were simulated, with the reaction moment applied to either the pelvis or the contralateral thigh. The simulation results show that assisting hip flexion with either actuation paradigm on the thigh can result in full recovery of gait with a margin of stability and leg kinematics closely matching the unperturbed case. However, when assisting knee extension with moments on the shank, free moment effectively assist balance but joint moments with the reaction moment on the thigh do not. For joint moments assisting hip flexion, placement of the reaction moment on the contralateral thigh was more effective in achieving the desired limb dynamics than placing the reaction on the pelvis. Poor choice of placement of reaction moments may therefore have detrimental consequences for balance recovery, and removing them entirely (i.e., free moment) could be a more effective and reliable alternative. These results challenge conventional assumptions and may inform the design and development of a new generation of minimalistic wearable devices to promote balance during gait.

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Maas, Huub, e Peter A. Huijing. "Mechanical effect of rat flexor carpi ulnaris muscle after tendon transfer: does it generate a wrist extension moment?" Journal of Applied Physiology 112, n. 4 (15 febbraio 2012): 607–14. http://dx.doi.org/10.1152/japplphysiol.01275.2011.

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Abstract (sommario):

The mechanical effect of a muscle following agonist-to-antagonist tendon transfers does not always meet the surgeon's expectations. We tested the hypothesis that after flexor carpi ulnaris (FCU) to extensor carpi radialis (ECR) tendon transfer in the rat, the direction (flexion or extension) of the muscle's joint moment is dependent on joint angle. Five weeks after recovery from surgery (tendon transfer group) and in a control group, wrist angle-moment characteristics of selectively activated FCU muscle were assessed for progressive stages of dissection: 1) with minimally disrupted connective tissues, 2) after distal tenotomy, and 3) after maximal tendon and muscle belly dissection, but leaving blood supply and innervations intact. In addition, force transmission from active FCU onto the distal tendon of passive palmaris longus (PL) muscle (a wrist flexor) was assessed. Excitation of control FCU yielded flexion moments at all wrist angles tested. Tenotomy decreased peak FCU moment substantially (by 93%) but not fully. Only after maximal dissection, FCU wrist moment became negligible. The mechanical effect of transferred FCU was bidirectional: extension moments in flexed wrist positions and flexion moments in extended wrist positions. Tenotomy decreased peak extension moment (by 33%) and increased peak flexion moment of transferred FCU (by 41%). Following subsequent maximal FCU dissection, FCU moments decreased to near zero at all wrist angles tested. We confirmed that, after transfer of FCU towards a wrist extensor insertion, force can be transmitted from active FCU to the distal tendon of passive PL. We conclude that mechanical effects of a muscle after tendon transfer to an antagonistic site can be quite different from those predicted based solely on the sign of the new moment arm at the joint.

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23

Dempsey, Alasdair R., Bruce C. Elliott, Bridget J. Munro, Julie R. Steele e David G. Lloyd. "Can Technique Modification Training Reduce Knee Moments in a Landing Task?" Journal of Applied Biomechanics 30, n. 2 (aprile 2014): 231–36. http://dx.doi.org/10.1123/jab.2013-0021.

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Abstract (sommario):

Anterior cruciate ligament (ACL) injuries are costly. Sidestep technique training reduces knee moments that load the ACL. This study examined whether landing technique training alters knee moments. Nineteen team sport athletes completed the study. Motion analysis and ground reaction forces were recorded before and after 6 weeks of technique modification. An inverse dynamic model was used to calculate three-dimensional knee loading. Pre- and postintervention scores were compared using pairedttests. Maximal knee flexion angle during landing was increased following training. There was no change in valgus or flexion moments, but an increase in peak internal rotation moment. This increase in internal rotation moment may increase the risk of ACL injury. However, the increased angle at which the peak internal rotation moment occurred at follow up may mitigate any increase in injury risk by reducing load transmission.

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24

KWON, YURI, JAE-HOON HEO, HYEONG-MIN JEON, SE DONG MIN, JAE-HOON JUN, GYE-RAE TACK, BYUNG KYU PARK, JI-WON KIM e GWANG-MOON EOM. "AGE–GENDER DIFFERENCE IN THE BIOMECHANICAL FEATURES OF SIT-TO-STAND MOVEMENT". Journal of Mechanics in Medicine and Biology 16, n. 08 (25 novembre 2016): 1640027. http://dx.doi.org/10.1142/s0219519416400273.

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Abstract (sommario):

The purpose of this study was to investigate the effects of age and gender on the biomechanical features of sit-to-stand (STS) movement. Twenty young subjects and 20 elderly subjects participated in this study. Nine events during STS movement were defined where joint angles and joint moments were extracted for further analyses. Two-way repeated measures ANOVA was performed for joint angles and joint moments with age and gender as independent factors. Major gender differences were shown in joint angles. Women used a sliding forward strategy more than men (more flexion of ankle and knee joint) during mid-phases of STS movement ([Formula: see text]) and men used an exaggerated trunk flexion strategy more than women (more hip flexion) in later phases of STS movement ([Formula: see text]). Age differences were shown in joint moments. Elderly subjects showed smaller knee extension moment (normalized by body weight) but greater ankle plantar flexion moment than young subjects in mid-to-late phases of STS movement ([Formula: see text]). More anterior positioning of center of mass (COM) in the elderly might be the reason for the strategy difference. That is, the shorter distance of COM from the knee joint would require less knee extension moment, and likewise, the more forward displacement of COM with respect to the ankle joint would need more plantar flexion moment. More anterior positioning of COM in the elderly, compared to the young was reflected on center of pressure (COP), and the forward displacement of COP was correlated well with the higher body mass index (BMI) and shorter thigh length ([Formula: see text]).

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25

Bumbard, Katy Baker, Harold Herrington, Chung-Hyun Goh e Alwathiqbellah Ibrahim. "Incorporation of Torsion Springs in a Knee Exoskeleton for Stance Phase Correction of Crouch Gait". Applied Sciences 12, n. 14 (12 luglio 2022): 7034. http://dx.doi.org/10.3390/app12147034.

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Abstract (sommario):

Crouch gait is a motor complication that is commonly associated with cerebral palsy, spastic diplegia, stroke, and motor-neurological pathologies, broadly defined as knee flexion in excess of 20° in the gait cycle. Uncorrected crouch gait results in fatigue, joint degradation, and loss of ambulation. Torsion springs have been used in cycling to store energy in the knee flexion to reduce fatigue in the quadriceps during knee extension. SolidWorks was used to design a passive exoskeleton for the knee, incorporating torsion springs of stiffnesses 20,000 N/mm and 30,000 N/mm at the knee joint, to correct four different crouch gaits. OpenSim was used to gather data from the moments produced, and knee angles from each crouch gait and the normal gait. Motion analysis of the exoskeleton was simulated using knee angles for each crouch gait and compared with the moments produced with the normal gait moments in the stance phase of the gait cycle. All crouch gait moments were significantly reduced, and the correction of peak crouch moments was achieved, corresponding to the normal gait cycle during the stance phase. These results offer significant potential for nonsurgical and less invasive options for wearable exoskeletons in crouch gait correction.

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26

Gagnon, Dany, Annie-Claude Babineau, Audrey Champagne, Guillaume Desroches e Rachid Aissaoui. "Trunk and Shoulder Kinematic and Kinetic and Electromyographic Adaptations to Slope Increase during Motorized Treadmill Propulsion among Manual Wheelchair Users with a Spinal Cord Injury". BioMed Research International 2015 (2015): 1–15. http://dx.doi.org/10.1155/2015/636319.

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Abstract (sommario):

The main objective was to quantify the effects of five different slopes on trunk and shoulder kinematics as well as shoulder kinetic and muscular demands during manual wheelchair (MWC) propulsion on a motorized treadmill. Eighteen participants with spinal cord injury propelled their MWC at a self-selected constant speed on a motorized treadmill set at different slopes (0°, 2.7°, 3.6°, 4.8°, and 7.1°). Trunk and upper limb movements were recorded with a motion analysis system. Net shoulder joint moments were computed with the forces applied to the handrims measured with an instrumented wheel. To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions. Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper. The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

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27

Yu, Yuanyuan, Hongshi Huang, Shuang Ren, Huijuan Shi, Si Zhang, Zixuan Liang e Yingfang Ao. "Lower Limb Biomechanics During Level Walking After an Isolated Posterior Cruciate Ligament Rupture". Orthopaedic Journal of Sports Medicine 7, n. 12 (1 dicembre 2019): 232596711989116. http://dx.doi.org/10.1177/2325967119891164.

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Abstract (sommario):

Background: The posterior cruciate ligament (PCL) is an important structure in knee stabilization. Knee cartilage degeneration after a PCL injury has been reported in several studies. Understanding the changes in movement patterns of patients with PCL ruptures could help clinicians make specific treatment protocols to restore patients’ sporting ability and prevent joint degeneration. However, the kinematics and kinetics of the lower limb in patients with PCL injuries are still not clear. Purpose: To investigate the biomechanical characteristics during level walking in patients with isolated PCL deficiency. Study Design: Controlled laboratory study. Methods: Three-dimensional videographic and force plate data were collected for 27 healthy male participants (control group) and 25 male patients with isolated PCL-deficiency (PCL-d group) walking at a constant self-selected speed. Paired and independent t tests were performed to determine the differences between the involved and uninvolved legs in the PCL-d group and between the PCL-d and control groups, respectively. Results: Compared with the control leg, both legs in the PCL-d group had smaller knee moments of flexion and internal rotation; greater hip angles of flexion and adduction; greater hip moments of internal rotation; greater ankle angles of extension and adduction; and smaller ankle moments of flexion, adduction, and internal rotation. Moreover, compared with the uninvolved leg in the PCL-d group, the involved leg in the PCL-d group had significantly smaller knee extension angles and moments during the terminal stance phase, greater hip external rotation angles and extension moments, and smaller ankle adduction angles and flexion moments. Conclusion: PCL ruptures altered walking patterns in both the involved and uninvolved legs, which could affect alignment of the lower limb and loading on the knee, hip, and ankle joints. Patients with PCL injuries adapted their hip and ankle to maintain knee stability. Clinical Relevance: The kinematic and kinetic adaptations in the knee, hip, and ankle after a PCL rupture during level walking are likely to be a compensatory strategy for knee instability. The results of this study suggest that these adaptations should be considered in the treatment of patients with PCL ruptures.

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28

Mizutori, Hisashi, Yu Kashiwagi, Noriko Hakamada, Yasunori Tachibana e Kazuo Funato. "Kinematics and joints moments profile during straight arm press to handstand in male gymnasts". PLOS ONE 16, n. 7 (14 luglio 2021): e0253951. http://dx.doi.org/10.1371/journal.pone.0253951.

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Abstract (sommario):

Biomechanical features of the handstand, one of the most fundamental skills required for artistic gymnastics events, have not been well documented. The purpose of this study was to clarify the kinematics and joint moment profiles during straight arm press to handstand in different highly skilled male gymnasts. Fifty-nine male gymnasts performed a straight arm press to handstand on a force platform and were judged on their performance by experienced certified judges. Subjects were divided into two groups (highly-skilled and less-skilled). Kinematic data were obtained using a video camera synchronized with force platform. Joint moments (wrist, shoulder, hip) during each straight arm press to handstand were calculated using the inverse dynamics solution. Larger shoulder flexion moments were observed in less-skilled compared with highly- skilled performers (at 3–59%, p < 0.001) while larger hip flexion moments were observed in highly- skilled performers at 52% (p = 0.045) and 56% (p = 0.048) and normalized time of straight arm press to handstand. Major differences between highly-skilled and less-skilled performers were observed in hip joint moment production as it shifted from extension to flexion from the leg horizontal position to the handstand position in highly-skilled gymnasts. Successful straight arm press to handstand techniques observed in highly-skilled performers were characterized as a more acute pike position at toe-off as well as hip flexor moments at latter phase of the straight arm press to handstand.

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Crewe, Helen, Amity Campbell, Bruce Elliott e Jacqueline Alderson. "Kinetic Sensitivity of a New Lumbo-Pelvic Model to Variation in Segment Parameter Input". Journal of Applied Biomechanics 29, n. 3 (giugno 2013): 354–59. http://dx.doi.org/10.1123/jab.29.3.354.

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Abstract (sommario):

This study aimed to assess variability in lumbo-pelvic forces and moments during a dynamic high-impact activity (cricket fast bowling) when calculated using different body segment parameters (BSPs). The first three BSPs were estimated using methods where the trunk was divided into segments according to nonspinal anatomical landmarks. The final approach defined segment boundaries according to vertebral level. Three-dimensional motion analysis data from nine male cricketers’ bowling trials were processed using the four BSPs. A repeated-measures analysis of variance revealed no significant effect on peak lumbo-pelvic forces. However, the segmentation approach based on vertebral level resulted in significantly larger peak flexion and lateral flexion moments than the other BSP data sets. This has implications for comparisons between studies using different BSPs. Further, given that a method defined with reference to vertebral level more closely corresponds with relevant anatomical structures, this approach may more accurately reflect lumbar moments.

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Yee, Albert G., e C. Daniel Mote. "Forces and Moments at the Knee and Boot Top: Models for an Alpine Skiing Population". Journal of Applied Biomechanics 13, n. 3 (agosto 1997): 373–84. http://dx.doi.org/10.1123/jab.13.3.373.

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Abstract (sommario):

The purpose of this study was to identify regression models to predict moments at the boot top and knee from the force components at the bindings for a sample of skiers. Six subjects skied a slalom course, first with their boots set to the least stiff setting and then with their boots set to the most stiff setting. Six load component dynamometers measured force and moment components at the toe and heel bindings. An electrogoniometer measured ankle flexion. Regression models were developed for the subject sample that predicted quasi-static moment components at the boot top and knee from measurements of ankle flexion and the quasi-static force components at the bindings. Large anterior bending moment was not necessarily accompanied by large ankle flexion, which emphasized that binding designs and standards for injury prevention must account for forces and moments at the sites of potential injury, rather than limiting consideration to boot stiffness or forces at the bindings.

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Sauer, Adrian, Allan Maas, Svenja Ottawa, Alexander Giurea e Thomas M. Grupp. "Towards a New, Pre-Clinical, Subject-Independent Test Model for Kinematic Analysis after Total Knee Arthroplasty—Influence of the Proximo-Distal Patella Position and Patellar Tendon Stiffness". Applied Sciences 11, n. 21 (3 novembre 2021): 10322. http://dx.doi.org/10.3390/app112110322.

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Abstract (sommario):

Although simulation models are heavily used in biomechanical research and testing of TKA implants, pre-clinical tools for a holistic estimation of implant performance under dynamic loading conditions are rare. The objective of this study was the development of an efficient pre-clinical test method for analyzing knee contact mechanics and kinematics based on a dynamic FE model and to evaluate the effects of the proximo-distal patella position and the patellar tendon stiffness on the patellar kinematics. A finite element-based workflow for knee prostheses designs was developed based on standardized in vivo load data, which included the tibial forces and moments. In a new research approach, the tibial forces are used as input for the model, whereas the tibial moments were used to validate the results. For the standardized sit down, stand up, and knee bend load cycles, the calculated tibial moments show only small deviations from the reference values—especially for high flexion angles. For the knee bend cycle, the maximum absolute value of patellar flexion decreases for higher patellar tendon stiffness and more distally placed patellar components. Therefore, patella-related clinical problems caused by patella baja may also arise if the patellar tendon is too weak for high tibiofemoral flexion angles.

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Willwacher, Steffen, Wolfgang Potthast, Markus Konrad e Gert-Peter Brüggemann. "Effect of Heel Construction on Muscular Control Potential of the Ankle Joint in Running". Journal of Applied Biomechanics 29, n. 6 (dicembre 2013): 740–48. http://dx.doi.org/10.1123/jab.29.6.740.

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Abstract (sommario):

The purpose of this study was to investigate the effect of heel construction on ankle joint mechanics during the early stance phase of running. Kinematic and kinetic parameters (ankle joint angles, angular velocities and joint moments, lever arms of ground reaction force, triceps surae muscle tendon unit lengths, and rates of muscle tendon unit length change) were calculated from 19 male subjects running at 3.3 m/s in shoes with different heel constructions. Increasing heel height and posterior wedging amplified initial plantar flexion velocity and range. The potential for a muscle to control the movement of a joint depends upon its ability to produce joint moments. Runners in this study showed decreased external eversion moments and an increase in eversion range. Maximum eversion angles were not significantly affected by shoe conditions. Without considerable tendon prestretch, joint moment generation potentials of triceps surae and deep plantar flexors might be inhibited due to rapid plantar flexion based on the force–velocity relationship. It could be speculated that increasing ankle inversion at heel strike could be a strategy to keep maximum eversion angles inside an adequate range, if joint moment generation potentials of deep plantar flexors are inhibited due to rapid plantar flexion.

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BISI, MARIA CRISTINA, RITA STAGNI, GIANNI GNUDI e ANGELO CAPPELLO. "NON-CIRCULAR CHAIN RING ALLOWS A REDUCTION OF JOINT LOADING IN CYCLING". Journal of Mechanics in Medicine and Biology 10, n. 01 (marzo 2010): 113–22. http://dx.doi.org/10.1142/s0219519410003228.

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Abstract (sommario):

Non-circular (NC) chain rings were primarily designed to improve the mechanical effectiveness of cycling. Their use can be investigated for application in rehabilitation: they could provide a solution to design an effective exercise reducing joint loading. The aim of this study was to analyze the differences in kinematics, energy consumption, and joint moments between circular and NC chain rings, then to identify a profile that can reduce joint loads, maintaining equal mechanical and metabolic works. Five young participants performed two tests on a cycloergometer; one with a circular chain ring and the other with an NC one. The test consisted in 15 min of cycling; during which they were asked to cycle at three different speeds and at two different powers. Stereophotogrammetric and metabolic data were acquired. Statistical analysis was applied on metabolic data. Joint angular velocities were obtained from kinematic data. A two-dimensional (2D) model of cycling was designed to estimate joint moments with both chain rings. A different ring profile was suggested to further reduce joint flexion peak moment. NC chain ring allows a reduction of flexion joint moments with respect to the circular one without significant difference in metabolic and kinematic data. The new profile proposed further decreases maximum knee flexion moment maintaining equal mechanical work.

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Tsitlakidis, Stefanos, Nicholas A. Beckmann, Sebastian I. Wolf, Sébastien Hagmann, Tobias Renkawitz e Marco Götze. "GMFCS Level-Specific Differences in Kinematics and Joint Moments of the Involved Side in Unilateral Cerebral Palsy". Journal of Clinical Medicine 11, n. 9 (2 maggio 2022): 2556. http://dx.doi.org/10.3390/jcm11092556.

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Abstract (sommario):

A variety of gait pathologies is seen in cerebral palsy. Movement patterns between different levels of functional impairment may differ. The objective of this work was the evaluation of Gross Motor Function Classification System (GMFCS) level-specific movement disorders. A total of 89 individuals with unilateral cerebral palsy and no history of prior treatment were included and classified according to their functional impairment. GMFCS level-specific differences, kinematics and joint moments, exclusively of the involved side, were analyzed for all planes for all lower limb joints, including pelvic and trunk movements. GMFCS level I and level II individuals most relevantly showed equinus/reduced dorsiflexion moments, knee flexion/reduced knee extension moments, reduced hip extension moments with pronounced flexion, internal hip rotation and reduced hip abduction. Anterior pelvic tilt, obliquity and retraction were found. Individuals with GMFCS level II were characterized by an additional pronounced reduction in all extensor moments, pronounced rotational malalignment and reduced hip abduction. The most striking characteristics of GMFCS level II were excessive anterior pelvic/trunk tilt and excessive trunk obliquity. Pronounced reduction in extensor moments and excessive trunk lean are distinguishing features of GMFCS level II. These patients would benefit particularly from surgical treatment restoring pelvic symmetry and improving hip abductor leverage. Future studies exploring GMFCS level-specific compensation of the sound limb and GMFCS level-specific malalignment are of interest.

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Fiedler, Goeran, Brooke Slavens, Roger O. Smith, Douglas Briggs e Brian J. Hafner. "Criterion and Construct Validity of Prosthesis-Integrated Measurement of Joint Moment Data in Persons With Transtibial Amputation". Journal of Applied Biomechanics 30, n. 3 (giugno 2014): 431–38. http://dx.doi.org/10.1123/jab.2013-0309.

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Abstract (sommario):

Prosthesis-integrated sensors are appealing for use in clinical settings where gait analysis equipment is unavailable, but accurate knowledge of patients’ performance is desired. Data obtained from load cells (inferring joint moments) may aid clinicians in the prescription, alignment, and gait rehabilitation of persons with limb loss. The purpose of this study was to assess the accuracy of prosthesis-integrated load cells for routine use in clinical practice. Level ground walking of persons with transtibial amputation was concurrently measured with a commercially available prosthesis-integrated load cell, a 10-camera motion analysis system, and piezoelectric force plates. Ankle and knee flexion/extension moments were derived and measurement methods were compared via correlation analysis. Pearson correlation coefficients ranged from 0.661 for ankle pronation/supination moments to 0.915 for ankle flexion/extension moments (P < .001). Root mean squared errors between measurement methods were in the magnitude of 10% of the measured range and were explainable. Differences in results depicted differences between systems in definition and computation of measurement variables. They may not limit clinical use of the load cell, but should be considered when data are compared directly to conventional gait analysis data. Construct validity of the load cell (ie, ability to measure joint moments in-situ) is supported by the study results.

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Richards, Jim, Dominic Thewlis, James Selfe, Andrew Cunningham e Colin Hayes. "A Biomechanical Investigation of A Single-Limb Squat: Implications for Lower Extremity Rehabilitation Exercise". Journal of Athletic Training 43, n. 5 (1 settembre 2008): 477–82. http://dx.doi.org/10.4085/1062-6050-43.5.477.

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Abstract (sommario):

Abstract Context: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. Objective: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Design: Participants acted as their own controls in a repeated-measures design. Patients or Other Participants: We recruited 10 participants who had no pain, injury, or neurologic disorder. Intervention(s): Participants performed single-limb squats at different decline angles. Main Outcome Measure(s): Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. Results: An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P = .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P = .018). Conclusions: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee.

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Saltzman, Charles L., Rhonda L. Aper e Thomas D. Brown. "Anatomic Determinants of First Metatarsophalangeal Flexion Moments in Hallux Valgus". Clinical Orthopaedics and Related Research 339 (giugno 1997): 261–69. http://dx.doi.org/10.1097/00003086-199706000-00035.

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38

Hullfish, Todd J., e Josh R. Baxter. "A simple instrumented insole algorithm to estimate plantar flexion moments". Gait & Posture 79 (giugno 2020): 92–95. http://dx.doi.org/10.1016/j.gaitpost.2020.04.016.

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Chalmers, Brian P., Shady S. Elmasry, Cynthia A. Kahlenberg, David J. Mayman, Timothy M. Wright, Geoffrey H. Westrich, Carl W. Imhauser, Peter K. Sculco e Michael B. Cross. "Additional distal femoral resection increases mid-flexion coronal laxity in posterior-stabilized total knee arthroplasty with flexion contracture". Bone & Joint Journal 103-B, n. 6 Supple A (1 giugno 2021): 87–93. http://dx.doi.org/10.1302/0301-620x.103b6.bjj-2020-2444.r1.

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Aims Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture, which leads to femoral joint line elevation. There is a paucity of data describing the effect of joint line elevation on mid-flexion stability and knee kinematics. Thus, the goal of this study was to quantify the effect of joint line elevation on mid-flexion laxity. Methods Six computational knee models with cadaver-specific capsular and collateral ligament properties were implanted with a posterior-stabilized (PS) TKA. A 10° flexion contracture was created in each model to simulate a capsular contracture. Distal femoral resections of + 2 mm and + 4 mm were then simulated for each knee. The knee models were then extended under a standard moment. Subsequently, varus and valgus moments of 10 Nm were applied as the knee was flexed from 0° to 90° at baseline and repeated after each of the two distal resections. Coronal laxity (the sum of varus and valgus angulation with respective maximum moments) was measured throughout flexion. Results With + 2 mm resection at 30° and 45° of flexion, mean coronal laxity increased by a mean of 3.1° (SD 0.18°) (p < 0.001) and 2.7° (SD 0.30°) (p < 0.001), respectively. With + 4 mm resection at 30° and 45° of flexion, mean coronal laxity increased by 6.5° (SD 0.56°) (p < 0.001) and 5.5° (SD 0.72°) (p < 0.001), respectively. Maximum increased coronal laxity for a + 4 mm resection occurred at a mean 15.7° (11° to 33°) of flexion with a mean increase of 7.8° (SD 0.2°) from baseline. Conclusion With joint line elevation in primary PS TKA, coronal laxity peaks early (about 16°) with a maximum laxity of 8°. Surgeons should restore the joint line if possible; however, if joint line elevation is necessary, we recommend assessment of coronal laxity at 15° to 30° of knee flexion to assess for mid-flexion instability. Further in vivo studies are warranted to understand if this mid-flexion coronal laxity has negative clinical implications. Cite this article: Bone Joint J 2021;103-B(6 Supple A):87–93.

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Gholami, Milad, Alireza Choobineh, Mohammad Abdoli-Eramaki, Azizallah Dehghan e Mohammad Taghi Karimi. "Investigating the Effect of Keyboard Distance on the Posture and 3D Moments of Wrist and Elbow Joints among Males Using OpenSim". Applied Bionics and Biomechanics 2022 (5 maggio 2022): 1–10. http://dx.doi.org/10.1155/2022/5751488.

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Musculoskeletal disorders (MSDs) of the upper extremities and computer use are common in modern societies, and both show a growing trend. This study was conducted to determine the posture and 3D moments of wrist and elbow joints at different keyboard distances on a desk. Twelve healthy right-handed male volunteers attended the motion analysis laboratory. A keyboard was placed at three different distances from the participants’ bodies while performing a standard computer task. The workstation was adjusted according to ANSI/HFES-100-2007 standard for each participant to maintain a comfortable ergonomic posture for controlling confounding variables. Qualisys motion capture system, OpenSim (Ver. 4.1), and visual analog scale were used to collect and analyze the data. The highest levels of wrist flexion and radial deviation as well as elbow flexion and pronation were observed when the keyboard was at the edge of the desk. When the keyboard was 8 cm away from the edge of the desk, the right wrist flexion and radial deviation decreased 83% and 89%, respectively. In the left wrist, flexion and radial deviation decreased 94%. With increasing the distance of the keyboard from the edge of the desk, the right elbow flexion, pronation, and left elbow flexion decreased, 95%, 76%, and 85%, respectively. No significant difference was found for the left elbow pronation, wrist, and elbow joint moments, in the studied keyboard distances. However, a cut-off point has to be specified because large keyboard distances cause high extension and flexion of the limbs. The keyboard position relative to the body is an important parameter in computer work and has a significant impact on the posture of the upper extremities. A keyboard should be located at a distance that allows the upper extremities to remain in a neutral position so that the risk of MSDs is reduced.

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Muller, Antoine, Hakim Mecheri, Philippe Corbeil, André Plamondon e Xavier Robert-Lachaine. "Inertial Motion Capture-Based Estimation of L5/S1 Moments during Manual Materials Handling". Sensors 22, n. 17 (26 agosto 2022): 6454. http://dx.doi.org/10.3390/s22176454.

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Inertial motion capture (IMC) has gained popularity in conducting ergonomic studies in the workplace. Because of the need to measure contact forces, most of these in situ studies are limited to a kinematic analysis, such as posture or working technique analysis. This paper aims to develop and evaluate an IMC-based approach to estimate back loading during manual material handling (MMH) tasks. During various representative workplace MMH tasks performed by nine participants, this approach was evaluated by comparing the results with the ones computed from optical motion capture and a large force platform. Root mean square errors of 21 Nm and 15 Nm were obtained for flexion and asymmetric L5/S1 moments, respectively. Excellent correlations were found between both computations on indicators based on L5/S1 peak and cumulative flexion moments, while lower correlations were found on indicators based on asymmetric moments. Since no force measurement or load kinematics measurement is needed, this study shows the potential of using only the handler’s kinematics measured by IMC to estimate kinetics variables. The assessment of workplace physical exposure, including L5/S1 moments, will allow more complete ergonomics evaluation and will improve the ecological validity compared to laboratory studies, where the situations are often simplified and standardized.

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Xu, Dali, John W. Chow e Y. Tai Wang. "Effects of Turn Angle and Pivot Foot on Lower Extremity Kinetics during Walk and Turn Actions". Journal of Applied Biomechanics 22, n. 1 (febbraio 2006): 74–79. http://dx.doi.org/10.1123/jab.22.1.74.

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This study examined lower extremity joint moments during walk and turn with different turn angles and pivot feet. Seven young adults (age 21 ± 1.3 yrs) were asked to walk at a self-selected speed (1.35 ± 0.15 m/s) and to turn to the right using right (spin turn) and left (step turn) pivot feet at turn angles of 0° (walking straight), 45°, and 90°. Video and forceplate systems were employed for kinematic and kinetic data collection. Inverse dynamics approach was used to compute joint moments using segmental kinematics, ground reaction forces, and moments. The participants decreased their forward speed by increasing the ankle plantar flexion moment as the turn angle increased. The peak ankle plantar flexion moment during the braking phase increased with increasing turn angle for both spin and step turns. Ankle invertor moments were observed only in spin turns, suggesting that more ankle muscles are involved in spin turns than in step turns. The turn angle had a significant effect on the transverse plane moment profiles at the different lower extremity joints. The results suggest that the loading patterns of different anatomical structures in the lower extremity are affected by both turn angle and pivot foot during walk and turn actions.

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Golden, Grace M., Michael J. Pavol e Mark A. Hoffman. "Knee Joint Kinematics and Kinetics During a Lateral False-Step Maneuver". Journal of Athletic Training 44, n. 5 (1 settembre 2009): 503–10. http://dx.doi.org/10.4085/1062-6050-44.5.503.

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Abstract Context: Cutting maneuvers have been implicated as a mechanism of noncontact anterior cruciate ligament (ACL) injuries in collegiate female basketball players. Objective: To investigate knee kinematics and kinetics during running when the width of a single step, relative to the path of travel, was manipulated, a lateral false-step maneuver. Design: Crossover design. Setting: University biomechanics laboratory. Patients or Other Participants: Thirteen female collegiate basketball athletes (age = 19.7 ± 1.1 years, height = 172.3 ± 8.3 cm, mass = 71.8 ± 8.7 kg). Intervention(s): Three conditions: normal straight-ahead running, lateral false step of width 20% of body height, and lateral false step of width 35% of body height. Main Outcome Measure(s): Peak angles and internal moments for knee flexion, extension, abduction, adduction, internal rotation, and external rotation. Results: Differences were noted among conditions in peak knee angles (flexion [P < .01], extension [P = .02], abduction [P < .01], and internal rotation [P < .01]) and peak internal knee moments (abduction [P < .01], adduction [P < .01], and internal rotation [P = .03]). The lateral false step of width 35% of body height was associated with larger peak flexion, abduction, and internal rotation angles and larger peak abduction, adduction, and internal rotation moments than normal running. Peak flexion and internal rotation angles were also larger for the lateral false step of width 20% of body height than for normal running, whereas peak extension angle was smaller. Peak internal rotation angle increased progressively with increasing step width. Conclusions: Performing a lateral false-step maneuver resulted in changes in knee kinematics and kinetics compared with normal running. The differences observed for lateral false steps were consistent with proposed mechanisms of ACL loading, suggesting that lateral false steps represent a hitherto neglected mechanism of noncontact ACL injury.

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Liu, Zhiyong, Chen Yang, Jiabin Yu, Xiaoguang Zhao, Jinan Wu, Yu Zhang, Jianshe Li e Yaodong Gu. "The Effect of Muscles Fatigue on the Knee’s Kinetics and Kinematics Characteristics". Sustainability 15, n. 4 (7 febbraio 2023): 3029. http://dx.doi.org/10.3390/su15043029.

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Badminton is very popular on college campuses. In badminton, the anterior cruciate ligament of the players has a higher risk of injury. There are many studies investigating the impact of fatigue on the injury of professional athletes, but few studies focused on college students. We hypothesized that the knee joint would experience greater ground reaction forces, valgus moments, and flexion moments of lunge contact in amateur after fatigue than those indicators before fatigue. Ten male badminton amateurs were enrolled in this study. They performed a lunge to hit the shuttlecock at the designated position and then quickly returned to the starting position before and after fatigue. Fatigue was induced by repeated isokinetic flexion/extension of the knee. Lower body kinematics and ground reaction force (GRF) were collected and further used to calculate the lower body joint moments from initial contact to maximum knee flexion. Compared to the pre-fatigue condition, the peak flexion moment (p = 0.012) and peak abduction moment of knee joint (p = 0.01), and maximum horizontal ground reaction force (p = 0.027) increased significantly at the initial contact (p=0.01). After muscle fatigue, the knee buckling moment and valgus moment increased significantly at initial contact, and the horizontal backward maximum GRF also increased significantly. These changes might increase the injury risk of anterior cruciate ligament (ACL). The fatigue of the muscles around the knee joint did not change the maximum GRF in the vertical direction at the moment of contact. Combined with the results of our study, badminton coaches and teachers should increase the training of lower extremity muscle strength and endurance in our daily class and training, and also should pay special attention to the coordinated development of muscles.

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Al-Eisawi, Khaled W., Carter J. Kerk e Jerome J. Congleton. "Limitations of Wrist Strength to Manual Exertion Capability in 2D Biomechanical Modeling". Proceedings of the Human Factors and Ergonomics Society Annual Meeting 38, n. 10 (ottobre 1994): 559–63. http://dx.doi.org/10.1177/154193129403801004.

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The objective of this study is to evaluate the assumption in biomechanical models that wrist strength does not limit manual exertion capability. An experiment was designed and run on right-handed males to test isometric elbow flexion strength at two included elbow angles: 90° and 135° and in two forearm positions: supinated and mid between supination and pronation. Isometric wrist flexion strength was also measured at the same elbow angles and at two wrist positions in the flexion/extension plane: neutral and 45° extended. Isometric wrist radial deviation strength was measured at the same two elbow angles and at two wrist positions in the radial/ulnar deviation plane: neutral and 30° ulnarly deviated. An equation was developed to calculate the theoretical minimum wrist strength limits for which wrist strength does not limit maximal moments about the elbow. These calculated limits were compared to the corresponding measured wrist strength moments. In general, wrist strength was found to be non-limiting, but in some specific circumstances, it can be limiting. Among the posture/exertion combinations tested, only wrist flexion strength in the extended wrist posture was found to be limiting. There was some evidence that strong-wrist people show less wrist strength limitations than weak-wrist people in some postures. It was also found that the neutral wrist posture is not associated with the highest wrist strength.

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Wyszomierski, Sarah A., April J. Chambers e Rakié Cham. "Knee Strength Capabilities and Slip Severity". Journal of Applied Biomechanics 25, n. 2 (maggio 2009): 140–48. http://dx.doi.org/10.1123/jab.25.2.140.

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Slips and falls are a serious public health concern in older populations. Reduced muscle strength is associated with increased age and fall incidence. Understanding the relationships between specific joint muscle strength characteristics and propensity to slip is important to identify biomechanical factors responsible for slip-initiated falls and to improve slip/fall prevention programs. Knee corrective moments generated during slipping assist in balance recovery. Therefore, the study goal was to investigate the relationship between knee flexion/extension strength and slip severity. Isometric knee flexion/extension peak torque and rate of torque development (RTD) of the slipping leg were measured in 29 young and 28 older healthy subjects. Motion data were collected for an unexpected slip during self-paced walking. Peak slip velocity (PSV) of the slipping heel served as a slip severity measure. Within-sex and age group regressions relating gait speed-controlled PSV to strength of the slipping leg revealed significant inverse PSV-knee extension peak torque and PSV-knee flexion/extension RTD relationships in young males only. Differences in PSV-strength relationships between sex and age groups may be caused by greater ranges of strength capabilities in young males. In conclusion, the ability to generate higher, more rapid knee flexion/extension muscle moments (greater peak torque/RTD) may assist in recovery from severe slips.

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Miller, S., A. Agarwal, WB Haddon, L. Johnston, G. Arnold, W. Wang e RJ Abboud. "Comparison of gait kinetics in total and unicondylar knee replacement surgery". Annals of The Royal College of Surgeons of England 100, n. 4 (aprile 2018): 267–74. http://dx.doi.org/10.1308/rcsann.2017.0226.

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Introduction The aim of this study was to compare kinetical data from gait analysis of patients who have undergone total and uni-condylar knee replacement. Materials and methods Thirteen patients with unilateral total knee arthroplasty (TKA) and 13 unicondylar knee arthroplasty (UKA), were included, all performed by the same surgeon more than one year prior. The Vicon gait analysis system was used. Statistical power was calculated using SPSS. Results No significant difference was found in the spatiotemporal parameters of gait and survival years of the knee prosthesis between the two groups. The UKA group was found to have significantly larger moments than the TKA group in knee adduction on the operated side and knee flexion moment on the unoperated side during the loading phase. The maximum and minimum sagittal plane moments of the operated sides in the TKA group were significantly lower than the unoperated side. The difference was most significant at pre-swing. The maximum and minimum moments on the operated sides in the UKA group were significantly lower for the knee flexion and adduction moments when compared with the unoperated side and were most prevalent during the loading phase. Conclusions These results are relevant in terms of prosthesis wear. The TKA knees had smaller magnitude moments than the UKA knees in the sagittal and coronal planes. This could explain the higher revision rates for UKA. In both groups, the non-operated knees had significantly larger moments than the operated knees, which implies that after unilateral knee replacement of either type, the non-operated knee is being put under greater stress.

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Mohammadi, Vahid, Amir Letafatkar e Amir Ali Jafarnezhadgero. "Effects of Core Stability Training on Kinematic and Kinetic Variables in Patients With Chronic Low Back Pain". Physical Treatments - Specific Physical Therapy Journal 13, n. 1 (1 gennaio 2023): 55–66. http://dx.doi.org/10.32598/ptj.13.1.551.1.

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Purpose: This study aims to assess the effects of an 8-week core stability training on the kinematics and kinetics of trunk flexion and extension motions in patients with chronic non-specific low back pain (CNSLBP). Methods: A total of 30 CNSLBP patients with the age range of 25 to 45 years were randomly divided into 2 equally sized groups. The subjects were identified through clinical examination. Before and after the training, tests were applied to assess peak 3-dimensional hip joint moments, peak negative and positive hip joint powers, and lumbopelvic coupling angles during trunk flexion and extension motions. The first group underwent an 8-week core stability training program, including the specific exercise of the deep muscles of abdominal along with the lumbar multifidus co-activation. After the 8-week program, the post-test stage was performed similarly to the pre-test. Results: The main effects of “time” (P=0.029, f=0.84) and “time-by-group” interactions (P=0.03, f=0.16) for hip abductor moments and internal rotator moment (P=0.03, f=0.87) were significant. A trend toward the statistically significant main effect of “time” was found for the coupling angle during the flexion phase (P<0.05, f=1.88), extension phase (P=0.02, f=0.93), and “time×group” interaction during the flexion (P<0.05, f=1.96), extension (P=0.01, f=0.96) phases. Conclusion: Core stability training has the potential to improve kinematics and kinetics during trunk flexion and extension motions in patients with CNSLBP.

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Tsitlakidis, Stefanos, Sarah Campos, Paul Mick, Julian Doll, Sébastien Hagmann, Tobias Renkawitz, Marco Götze e Pit Hetto. "Gait Deviations of the Uninvolved Limb and Their Significance in Unilateral Cerebral Palsy". Symmetry 15, n. 10 (16 ottobre 2023): 1922. http://dx.doi.org/10.3390/sym15101922.

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Little is known about the impact of the impaired limb on the uninvolved side, which might influence the overall functional outcome in individuals with unilateral cerebral palsy (CP). The objective of this work was to perform an assessment considering the kinematics/joint moments and ground reaction forces (GRFs). Eighty-nine individuals with unilateral CP were included and classified according to their functional impairment. Level-specific differences according to the Gross Motor Function Classification System (GMFCS), including pelvic and trunk movements, were analyzed using instrumented 3D gait analysis (IGA). Anterior trunk and pelvic tilt, trunk lean/pelvic obliquity, pelvic internal rotation, hip adduction, and external hip rotation, as well as pronounced flexion (ankle dorsiflexion), at all joint levels were significant kinematic alterations. Concerning joint moments, the most remarkable alterations were hip and ankle flexion, hip abduction, knee varus/valgus, and transversal joint moments at all levels (external rotation moments in particular). The most remarkable differences between GMFCS levels were at proximal segments. The kinematics and joint moments of the sound limb in patients with unilateral CP differ significantly from those of healthy individuals—partially concomitant to those of the involved side or as motor strategies to compensate for transversal malalignment and leg-length discrepancies (LLDs). GRF showed almost identical patterns between GMFCS levels I and II, indicating an unloading of the involved limb. Compensatory motor strategies of the sound limb do not influence functional outcomes.

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LIN, HSIU-CHEN, TUNG-WU LU e HORNG-CHAUNG HSU. "THREE-DIMENSIONAL ANALYSIS OF KINEMATIC AND KINETIC COORDINATION OF THE LOWER LIMB JOINTS DURING STAIR ASCENT AND DESCENT". Biomedical Engineering: Applications, Basis and Communications 16, n. 02 (25 aprile 2004): 101–8. http://dx.doi.org/10.4015/s1016237204000153.

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Being a common daily activity, stair locomotion places much higher loads on the lower limb than level walking does so a better understanding of the biomechanics of this activity is important for evaluation and treatment for patients with lower limb problems. The purpose of the present study was to investigate the three-dimensional dynamics and coordination of the joints of the lower limb during the stance phase of stair ascent and descent. Ten normal young adult subjects were recruited to ascend and descend stairs in a gait laboratory where the three-dimensional kinematic and kinetic data as well as muscle electromyography (EMG) were collected. The sagittal ranges of motion during stance phase of stair ascent were from 1.85° extension to 53.5° flexion for the hip, 13.1° to 60.1° flexion for the knee and 13.8° dorsiflexion to 14.0° plantarflexion for the ankle. Corresponding data for stair descent were 4.78( to 13.16( flexion for the hip, 8.3° to 77.6° flexion for the knee and 18.3° dorsiflexion to 27.4° plantarflexion for the ankle. Maximum extensor moments of 8.5% and 15.6% (Nm/BW/LL) were required at the hip and knee respectively during loading response while 19.4% (Nm/BW/LL) at the ankle shortly before toe-off. During stair descent, maximum extensor moments of about 4.4% were required at the hip during loading response and before toe-off while 13.3% and 15.2% (Nm/BW/LL) at the knee and ankle respectively before toe-off The joint angles, moments, and powers in the frontal and transverse planes were relatively small, except for hip abduction. The hip abductor moments and powers were significantly bigger than those of the knee and ankle in both stair activities. Joint powers and the corresponding muscle activation patterns in stair ascent were significantly different from those in descent, with concentric powers generated mostly during stair ascent and with eccentric powers stair descent. The differences of the movements of the lower limb during stair ascent and descent were due to different safety requirements and kinematic and kinetic constraints from the stairs. The complete description of the biomechanics of the lower extremity while performing stair locomotion will be helpful for the planning and evaluation of treatment programs for patients with lower limb problems.

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