Journal articles: 'Buttress'

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Memmott, Jane, and Stephen L. Sutton. "Sandfly stratification on tree buttresses in a Costa Rican tropical rainforest." Journal of Tropical Ecology 10, no. 1 (February 1994): 87–101. http://dx.doi.org/10.1017/s0266467400007732.

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ABSTRACTIn humid forests tree buttresses and tree trunks are used as diurnal resting sites by phlebotomine sandflies (Diptera: Psychodidae). When several species are present on the same buttress, the sandfly species are spatially segregated resulting in a pattern of vertical stratification on the buttress within 100 cm of ground level. A change in the distribution of one species induces a change in the distribution of an adjacent species. This is demonstrated under both natural and experimental conditions. Observations of sandflies at dawn and dusk have revealed that the buttress is used as a swarming site; this behaviour provides our favoured explanation for the patterns of vertical stratification on tree buttresses.

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CHAPMAN, COLIN A., LES KAUFMAN, and LAUREN J. CHAPMAN. "Buttress formation and directional stress experienced during critical phases of tree development." Journal of Tropical Ecology 14, no. 3 (May 1998): 341–49. http://dx.doi.org/10.1017/s0266467498000261.

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Patterns of buttress formation in tropical trees vary greatly within and among species. In Kibale National Park, Uganda, some form of a buttres was found on 23% of the 78 species (1785 trees) sampled from a variety of distantly related families. Large differences in buttress formation were documented within a single family and even within the same genus. Previous studies have suggested that buttresses are mechanical adaptations to counter asymmetric loads experienced during brief critical phases in a tree’s development and these persist after the need for a mechanical support has disappeared. As a tree grows from the understorey, up to the canopy, or emerges from the canopy, the potential number of occasions that a tree will experience directional stress increases. Many canopy level trees will probably have been in the vicinity of a treefall gap during their development, while emergent trees may experience gap exposure in addition to wind stresses associated with canopy emergence. Therefore, it is predicted that understorey trees should have fewer and less developed buttresses (after correcting for overall tree size) than canopy trees, which should have fewer and less developed buttresses than emergent trees. Detailed measurements of buttresses from 194 trees of eight species support this prediction. There was no evidence that trees thought to have experienced directional stress associated with selective logging almost 30 y ago had increased the number or size of existing buttresses. The pattern of buttressing in Kibale generally supports the idea that buttresses are mechanical adaptations to counter episodic asymmetric loads, and that buttresses persist after the need for a mechanical support has disappeared.

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WANG, YU-TZU, PO-FANG WANG, CHIEN-TZUNG CHEN, CHIH-HAO CHEN, and CHUN-LI LIN. "BIOMECHANICAL ANALYSIS TO VERIFY THE BUTTRESS THEORY WHEN USING THE ANATOMICAL THIN TITANIUM MESH PLATE FOR ZYGOMATICOMAXILLARY COMPLEX BONE FRACTURE." Journal of Mechanics in Medicine and Biology 19, no. 02 (March 2019): 1940025. http://dx.doi.org/10.1142/s0219519419400256.

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Objective: The aim of this study was to investigate the biomechanics of the facial skeletal for understanding the buttress after fixation with standard and modified anatomical thin titanium mesh (ATTM) plates by finite element (FE) analysis. Methods: Standard ATTM (SATTM) plate designed as the “L”-shape anticipated to be fixed in the ZMC anterior maxilla and lateral buttress to increase the fixation screw anchoring strength and another modified ATTM (MATTM) plate with a protrusion in the medial side and a slot and barb design in the lateral side to enhance the zygomaticomaxillary/nasomaxillary buttresses and provide precise positioning to the ZMC segments were studied by the FE analysis under masticatory forces with 250[Formula: see text]N. Result: The FE simulation results indicated that the total displacement distribution of the maxillary for ZMC fracture fixation with MATTM plate was smaller than that of SATTM plate. Stress concentration was found at the frontal and alveolar processes of the maxillary bone for SATTM plate fixation. Local vector plots of the first principal stress near the frontal process of the maxillary and zygomaticofacial formen of the zygomatic indicated that the stress flow for MATTM plate fixation was relatively close to nasomaxillary buttress, and the zygomaticomaxillary buttress, respectively. Conclusions: This study concluded that “L”-shape ATTM plate designed with a protrusion in the medial side and a slot and barb design in the lateral side can enhance the zygomaticomaxillary/nasomaxillary buttresses under uniform occlusal condition.

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Ukleja, Janusz. "Application of Spatial Supporting Construction as an Effective Method for Stabilising a Landslide." Geosciences 10, no. 11 (November 6, 2020): 440. http://dx.doi.org/10.3390/geosciences10110440.

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Buttresses constitute a spatial supporting construction (SSC) that can convey large loads coming from the pressure of unstable soil on deeper, more stable layers to make it safer with respect to the load-bearing capacity. They make the counteraction against the pressure, which initiates sliding when the forces to move the landslide body, not balanced by the internal frictional forces in the soil. Some specific features of known construction elements were used in the buttress, such as sheet pile walls and drilled piles. Although beneficial in this case, the specific shape of the axis of the wall made from piles and sheets formed a wave created from circle sections (in plan view). Thus, a stable steel buttress was formed. The interaction of the buttress with the soil mass pressure over it, which stabilises the landslide mass, was considered. To further strengthen the buttress, a reinforced concrete slab was added on the upper edge of the thin walls of sheets and piles, thereby integrating and stiffening the whole structure. The application of the concrete slab enabled the use of the stabilisation role of additional forces (become from its weight and above laysoil)to stabilise the buttress. The results of this study achieved a substantial stabilising effect, increasing maximal forces reacting against the pressure of the unstable soil block. Assumptions madeand the applied calculations confirm thestability of the buttress (by increasing the stability of the whole slump block of landslide) are described. Two cases are presented to illustrate the stabilisation and control of movement in which the block body moves along inadvance of the determined slip surface.

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Clancy, Andrew. "The casual buttress." Architectural Research Quarterly 17, no. 1 (March 2013): 92–96. http://dx.doi.org/10.1017/s1359135513000390.

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Jackson, Roger P., and Anne C. McManus. "The Iliac Buttress." Spine 18, no. 10 (August 1993): 1318–28. http://dx.doi.org/10.1097/00007632-199308000-00011.

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Roy, Sanjoy, Yuexi Wang, Rajesh Mallampati, and Stephen Johnston. "Surgical Outcomes, Health Care Utilization, and Costs Associated with Staple Line Buttressing Among Primary Sleeve Gastrectomy Patients." Obesity Surgery 30, no. 12 (September 10, 2020): 4935–44. http://dx.doi.org/10.1007/s11695-020-04917-2.

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Abstract Purpose Staple line buttressing is a method of reinforcing surgical staple lines using buttress materials. This study evaluated surgical outcomes, hospital utilization, and hospital costs associated with staple line buttressing among patients who underwent primary laparoscopic sleeve gastrectomy (PLSG) in the United States. Methods This was a retrospective cohort study using Premier Healthcare Database data from January 1, 2012 to December 31, 2017. Patients aged ≥ 18 years who underwent PLSG were selected and assigned to buttress or non-buttress cohorts based on the use of buttress material during their hospitalization for PLSG (index). Propensity score matching (PSM) was conducted to balance patient demographic and clinical characteristics between the cohorts. Generalized estimating equation models were used to compare the clinical and economic outcomes of the matched buttress and non-buttress users during the index hospitalization. Results A total of 38,231 buttress and 27,349 non-buttress patients were included in the study. After PSM, 24,049 patients were retained in each cohort. Compared with non-buttress cohort, the buttress cohort patients had a similar rate of in-hospital leaks (0.28% vs 0.39%; p = 0.160) and a lower rate of bleeding (1.37% vs 1.80%, p = 0.015), transfusion (0.56% vs 0.77%, p = 0.050), and composite bleeding/transfusion (1.57% vs 2.04%, p = 0.019). Total costs ($12,201 vs $10,986, p < 0.001) and supply costs ($5366 vs $4320, p < 0.001) were higher in the buttress cohort compared with the non-buttress cohort. Conclusions Staple line buttressing was associated with an improvement in complication rates for bleeding and transfusion. Total and supply costs were higher in the buttress cohort, necessitating further research into cost-effective buttressing materials.

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Zhao, Guanglei, Changquan Liu, Kangming Chen, Jinyang Lyu, Jie Chen, Jingsheng Shi, Feiyan Chen, et al. "Nonanatomical Reduction of Femoral Neck Fractures in Young Patients (≤65 Years Old) with Internal Fixation Using Three Parallel Cannulated Screws." BioMed Research International 2021 (January 4, 2021): 1–12. http://dx.doi.org/10.1155/2021/3069129.

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Purpose. The study is aimed at investigating the association between different reduction classifications (anatomic reduction, positive buttress position reduction, and negative buttress position reduction) and two end points (complications and reoperations). Methods. The study retrospectively analyzed 110 patients undergoing internal fixation with three parallel cannulated screws from January 2012 to January 2019 in Huashan Hospital. Based on the principles of the “Gotfried reduction,” all enrolled patients were divided into three groups: anatomic reduction, positive buttress position reduction, and negative buttress position reduction intraoperatively or immediately after surgery. Clinical characteristics including age, sex, side, Garden classification, Pauwels classification, fracture level, reduction classification, Garden alignment index angles, cortical thickness index (CTI), tip-caput distance (TCD), angle of the inferior screw, and the two ending points (complications and reoperations) were included in the statistical analysis. The Mann-Whitney U -test, the chi-square test, Fisher’s exact test, and multiple logistic regression analysis were used in the study. Results. Of the 110 patients included in our study, the mean ± standard deviation SD of age was 51.4 ± 10.4 years; 41 patients showed anatomic reduction, 35 patients showed positive buttress position reduction, and 34 patients showed negative buttress position reduction. For the outcomes, 24 patients (anatomic reduction: 6 [14.6%]; positive buttress position reduction: 5 [14.3%]; negative buttress position reduction: 13 [38.2%]) had complications, while 18 patients (anatomic reduction: 5 [12.2%]; positive buttress position reduction: 3 [8.6%]; negative buttress position reduction: 10 [29.4%]) underwent reoperations after surgery. In the multivariate logistic regression analysis of complications, negative buttress position reduction (negative buttress position reduction vs. anatomic reduction, OR = 4.309 , 95 % CI = 1.137 to 16.322 , and p = 0.032 ) was found to be correlated with higher risk of complications. The same variable (negative buttress position reduction vs. anatomic reduction, OR = 5.744 , 95 % CI = 1.177 to 28.042 , and p = 0.031 ) was also identified as risk factor in the multivariate logistic regression analysis of reoperations. However, no significant difference between positive reduction and anatomical reduction was investigated in the analysis of risk factors for complications, not reoperations. Conclusion. Positive buttress position reduction of femoral neck fractures in young patients showed a similar incidence of complications and reoperations compared with those of anatomic reduction. For irreversible femoral neck fractures, if positive buttress position reduction has been achieved intraoperatively, it is not necessary to pursue anatomical reduction; however, negative reduction needs to be avoided.

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Ferretti, Elena. "Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons." European Journal of Engineering and Formal Sciences 2, no. 3 (December 1, 2018): 6–16. http://dx.doi.org/10.2478/ejef-2018-0012.

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Abstract One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.

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Ferretti, Elena. "Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons." European Journal of Engineering and Formal Sciences 2, no. 3 (December 29, 2018): 7. http://dx.doi.org/10.26417/ejef.v2i3.p7-17.

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One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.

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Stanley, Robert B. "Buttress fixation with plates." Operative Techniques in Otolaryngology-Head and Neck Surgery 6, no. 2 (June 1995): 97–103. http://dx.doi.org/10.1016/s1043-1810(05)80018-1.

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FELIX, EDWARD L., and CONSTANTINE MICHAS. "Double-Buttress Laparoscopic Herniorrhaphy." Journal of Laparoendoscopic Surgery 3, no. 1 (February 1993): 1–8. http://dx.doi.org/10.1089/lps.1993.3.1.

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Alhamdani, Faaiz, Khawla H. Rasheed, and Amjed Mahdi. "Stress Distribution Around Two Dental Implant Materials with New Designs: Comparative Finite Element Analysis Study." Indonesian Journal of Dental Medicine 4, no. 1 (June 30, 2021): 19. http://dx.doi.org/10.20473/ijdm.v4i1.2021.19-25.

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Background: The introduction of modified thread designs is one of the research areas of interest in the dental implantology field. Two suggested Buttress and Reverse Buttress thread designs in TiG5 and TiG4 models are tested against a standard TiG5 Fin Thread design (IBS®). Purpose: The study aims to compare stress distribution around the suggested designs and Fin Thread design. Methods: Three dental implant models: Fin Thread design, and newly suggested Buttress and Reverse Buttress designs of both TiG5 and TiG4 models were tested using FEA for stress distribution using static (70N, 0°) and (400N, 30°) occlusal loads. Results: The main difference between the suggested Buttress design and Fin Thread design lies in the overload (400N, 30°) condition. Maximum Von Mises stress is less in Buttress design than Fin Thread design. On the other hand the level of Von Mises stress over the buccolingual slop of the cancellous bone in Fin Thread design liess within the lowest stress level. The suggested Reverse Buttress design, on the other hand showed almost uniform stress distribution in both TiG4 and TiG4 models with maximum Von Mises stress higher than the elastic modulus of cancellous bone in overload (400N, 30°) condition. Conclusion: The suggested TiG4 Buttress design might have a minor advantage of stress level in cases of stress overload. In contrast, Fin Thread design shows minimal stress over the buccolingual slop of the cancellous bone. The suggested Reverse Buttress design might be more suitable for the D1 bone quality region with the advantage of almost uniform stress distribution

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Xu, Lei. "Shape Optimization Design of Gravity Buttress of Arch Dam Based on Asynchronous Particle Swarm Optimization Method." Applied Mechanics and Materials 662 (October 2014): 160–63. http://dx.doi.org/10.4028/www.scientific.net/amm.662.160.

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The optimization design method was rarely used to design the gravity buttress of arch dam in the past. With this in mind, the parametric description of gravity buttress is given, and the auto-calculation of its exerting loads and the safety coefficient of anti-slide stability are realized subsequently. Then, the optimization design model of gravity buttress and the procedures of optimization design are presented using the asynchronous particle swarm optimization method. Finally, ODGB software, which is short for Optimization Design of Gravity Buttress software, is developed and verified.

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Foo, Gen-Lin, Amit K. Ramruttun, Andre Eujin Cheah, Alphonsus Kin-Sze Chong, and Tun-Lin Foo. "Biomechanics of Internal Fixation Modalities for Middle Phalangeal Base Fracture Dislocation." Journal of Hand Surgery (Asian-Pacific Volume) 22, no. 01 (February 16, 2017): 14–17. http://dx.doi.org/10.1142/s0218810417500022.

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Background: Internal fixation modalities of unstable (>50 percent articular involvement) middle phalangeal volar lip fracture-dislocations include interfragmentary screw and volar buttress plating. This study investigates the mechanical properties (yield strength, ultimate tensile strength, and stiffness) of interfragmentary screw (IS), simple buttress plating (BP) and buttress plating with subchondral screw (BP+S). Methods: Fifteen cadaveric digits (5 index, 5 middle, and 5 ring) were prepared by excising its skin envelope and flexor tendons while preserving the structures around the proximal interphalangeal joint. An oblique osteotomy involving 50 percent of the articular surface was performed, and this was fixed with based on its study group: interfragmentary screw (IS), simple buttress plating (BP) and buttress plating with subchondral screw (BP+S). These specimens were then loaded to failure. Results: Yield strength was as follows: BP+S (33.5±9.76 N), IS (13.6±5.46 N), and BP (8.1±3.84 N). Ultimate tensile strength was as follows: BP+S (49.1±21.4 N), IS (15.6±5.19 N), and BP (8.86±3.99 N). Stiffness was as follows: BP+S (4.77±1.32 N/mm), IS (2.44±0.86 N/mm), and BP (1.84±0.71 N/mm). Conclusions: A buttress plate and screw construct confers significantly more stability than either interfragmentary screw or buttress plate only fixation in an experimental model.

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An, Qing Long, Guo Giang Guo, X. H. Zheng, Ming Chen, Gang Liu, and Yun Shan Zhang. "Experimental Study on Cutting Characteristics for Buttress Thread Turning of 13%Cr Stainless Steel." Key Engineering Materials 443 (June 2010): 262–67. http://dx.doi.org/10.4028/www.scientific.net/kem.443.262.

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13%Cr stainless steel has good comprehensive performance, which makes it suitable to work under the condition of high temperature, high pressure and corrosive environment, such as petroleum industry. It can be used as materials of petroleum pipes with buttress thread. Buttress thread turning is a heavy-load machining, which places high requirement on the cutting tool. Based on the cutting characteristics of buttress thread, the machinability of 13%Cr stainless steel is studied by turning experiments. Two kinds of inserts with different geometries were employed in buttress thread turning experiments. Experimental results show that less cutting force, longer tool life, better chip curling effect and surface quality was acquired for the insert with rake angle of 12° , clearance angle of 3° and chip-curling groove during 13%Cr stainless steel buttress thread turning process.

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Rosenbaugh, Scott K., Jennifer D. Schmidt, and Ronald K. Faller. "Development of a Standardized Buttress for Approach Guardrail Transitions." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 39 (April 19, 2018): 41–51. http://dx.doi.org/10.1177/0361198118758676.

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Approach guardrail transitions (AGTs) incorporate increased post and rail sizes, reduced post spacings, and specialized buttress end geometries to smoothly transition from deformable W-beam guardrail to rigid barriers. This transition in barrier stiffness makes AGTs sensitive systems that require specific combinations of these components to function properly. Changing components, or even the removal of a curb below the rail, can negatively affect the safety performance of an otherwise crashworthy system. However, recent full-scale crash testing has indicated that a properly designed buttress at the downstream end of an AGT may be utilized with multiple AGT systems. Thus, the objective of this project was to develop a standardized buttress to reduce vehicle snag and be compatible with a wide variety of previously developed Thrie beam AGT systems, either with or without a curb. The standardized buttress was designed with a dual taper on its front upstream edge. A longer lower taper was designed to mitigate tire snag below the rail, while a shorter upper taper was designed to prevent vehicle snag and limit the unsupported span length of the rail. This buttress design was evaluated in combination with a critically weak AGT without a curb, which represented the worst-case scenario. The standardized buttress was successfully crash tested to MASH TL-3. Guidance was provided for both the attachment of the buttress to various Thrie beam AGTs as well as how to transition the shape of the buttress to adjacent bridge rails or rigid parapets downstream of the AGT.

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Ngomanda, Alfred, Quentin Moundounga Mavouroulou, Nestor Laurier Engone Obiang, Donald Midoko Iponga, Jacques-François Mavoungou, Nicaise Lépengué, Nicolas Picard, and Bertrand Mbatchi. "Derivation of diameter measurements for buttressed trees, an example from Gabon." Journal of Tropical Ecology 28, no. 3 (April 12, 2012): 299–302. http://dx.doi.org/10.1017/s0266467412000144.

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Many tropical tree species have buttresses at the standard breast height (1.3 m above ground) of diameter measurement, with a presumable role in improving nutrient acquisition or tree anchorage in the ground (Newbery et al. 2009, Richter 1984). Measuring the diameter using standard dendrometrical tools such as callipers or graduated tapes, which require that the cross-section of the trunk has a convex shape, is then impossible (Nogueira et al. 2006). The recommended method in this case is to measure the diameter above the buttress (DAB), thus possibly leading to biased estimates of the basal area (West 2009), of tree above-ground biomass (Dean & Roxburgh 2006, Dean et al. 2003) and of tree growth (Metcalf et al. 2009). As an alternative, one can measure the basal area at breast height of buttressed trees, using a method that can deal with the irregular non-convex shape of the cross-section of the stem such as the Picus calliper, photogrammetry or 3D laser scanning (Badia et al. 2003, Dean 2003, Newbery et al. 2009).

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Niu, Wen Jie. "Discussions on the Principle to Reduce the Sliding Fall Rock Impact Force against Protective Structure." Advanced Materials Research 378-379 (October 2011): 23–26. http://dx.doi.org/10.4028/www.scientific.net/amr.378-379.23.

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Passive ductile protective system is widely used because of its better performance than buttress wall. This paper intends to determine the sliding fall rock impact force against a steel column at first. Then the rigid protective structure and ductile protective structure were compared. At last the hidden principle that passive ductile protective system can reduce the impact force was revealed. Results indicate that rings for energy dissipation in passive ductile protective system can significantly decrease the bending stiffness EI and decrease the impact force. Buttress wall encounters a lot more impact force than passive ductile protective system because of its bulkiness. Thus to ensure the buttress wall non-destructive, the thickness of buttress wall increases and it is not economic.

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Malaviya, Pallavi, and Sandeep Choudhary. "Zygomaticomaxillary buttress and its dilemma." Journal of the Korean Association of Oral and Maxillofacial Surgeons 44, no. 4 (2018): 151. http://dx.doi.org/10.5125/jkaoms.2018.44.4.151.

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Trost, Olivier, and Jean-Marc Peron. "Regarding unilateral nasomaxillary buttress fractures." Journal of Plastic, Reconstructive & Aesthetic Surgery 67, no. 11 (November 2014): e278-e279. http://dx.doi.org/10.1016/j.bjps.2014.07.012.

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Rimell, Frank, and Lawrence J. Marentette. "Injuries of the Hard Palate and the Horizontal Buttress of the Midface." Otolaryngology–Head and Neck Surgery 109, no. 3 (September 1993): 499–505. http://dx.doi.org/10.1177/019459989310900319.

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Traumatic injuries to the hard palate occurred In 20% of all Le Fort midfacial fractures. The side of a palatal split was directly related to the side that received the highest Le Fort injury. In a symmetric midfacial injury, the palate had a true midline split. Repair of palatal injuries from blunt trauma involved either wire and splinting (eight patients) or miniplate fixation without a splint (11 patients). There were fewer complications in those treated by the miniplate fixation technique (two of 11), as compared to those treated with wire and splinting (four of eight). In miniplate fixation of midfacial fractures, attention is focused on the reconstruction of the supporting buttresses of the midface, both vertical and horizontal. In regard to the palate, this requires union of the inferior horizontal buttress. Gunshot wounds accounted for 21% of the patients and resulted in large bony disruption of the palate, which required free soft tissue and bone grafts for repair of the inferior horizontal buttress. (OTOLARYNGOL HEAD NECK SURG 1993;109:499-505.)

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Feng, Xiaoreng, Weichen Qi, Christian X. Fang, William W. Lu, Frankie K. L. Leung, and Bin Chen. "Can barb thread design improve the pullout strength of bone screws?" Bone & Joint Research 10, no. 2 (February 1, 2021): 105–12. http://dx.doi.org/10.1302/2046-3758.102.bjr-2020-0072.r2.

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Aims To draw a comparison of the pullout strengths of buttress thread, barb thread, and reverse buttress thread bone screws. Methods Buttress thread, barb thread, and reverse buttress thread bone screws were inserted into synthetic cancellous bone blocks. Five screw-block constructs per group were tested to failure in an axial pullout test. The pullout strengths were calculated and compared. A finite element analysis (FEA) was performed to explore the underlying failure mechanisms. FEA models of the three different screw-bone constructs were developed. A pullout force of 250 N was applied to the screw head with a fixed bone model. The compressive and tensile strain contours of the midsagittal plane of the three bone models were plotted and compared. Results The barb thread demonstrated the lowest pullout strength (mean 176.16 N (SD 3.10)) among the three thread types. It formed a considerably larger region with high tensile strains and a slightly smaller region with high compressive strains within the surrounding bone structure. The reverse buttress thread demonstrated the highest pullout strength (mean 254.69 N (SD 4.15)) among the three types of thread. It formed a considerably larger region with high compressive strains and a slightly smaller region with high tensile strains within the surrounding bone structure. Conclusion Bone screws with a reverse buttress thread design will significantly increase the pullout strength. Cite this article: Bone Joint Res 2021;10(2):105–112.

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Gross, Allan E., and Michael Solomon. "The flying buttress acetabular bone-graft." Journal of Arthroplasty 12, no. 6 (September 1997): 706–8. http://dx.doi.org/10.1016/s0883-5403(97)90146-7.

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Holmes, S. B., P. S. G. Hardee, and R. R. Mani. "Percutaneous osteosynthesis of the zygomatic buttress." British Journal of Oral and Maxillofacial Surgery 39, no. 4 (August 2001): 286–88. http://dx.doi.org/10.1054/bjom.2000.0566.

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Nolan, Jessica M. "Environmental Policies Can Buttress Conservation Norms." Society & Natural Resources 30, no. 2 (August 5, 2016): 228–44. http://dx.doi.org/10.1080/08941920.2016.1209266.

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Bluebond-Langner, Rachel, and Eduardo D. Rodriguez. "Application of Skeletal Buttress Analogy in Composite Facial Reconstruction." Craniomaxillofacial Trauma & Reconstruction 2, no. 1 (March 2009): 19–25. http://dx.doi.org/10.1055/s-0028-1098966.

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Reconstructive algorithms for composite craniofacial defects have focused on soft tissue flaps with or without bone grafts. However, volumetric loss over time limits long-term preservation of facial contour. Application of craniofacial skeletal buttress principles to high-energy trauma or oncologic defects with composite vascularized bone flaps restores the soft tissue as well as the buttresses and ultimately preserves facial contour. We conducted a retrospective review of 34 patients with craniofacial defects treated by a single surgeon with composite bone flaps at R Adams Cowley Shock Trauma Center and Johns Hopkins Hospital from 2001 to 2007. Data collected included age, sex, mechanism of injury, type of defect, type of reconstructive procedures, and outcome. Thirty-four patients with composite tissue loss, primarily males ( n = 24) with an average age of 37.4 years, underwent reconstruction with vascularized bone flaps (28 fibula flaps and 6 iliac crest flaps). There were 4 cranial defects, 8 periorbital defects, 18 maxillary defects, and 4 maxillary and periorbital defects. Flap survival rate was 94.1% with an average follow-up time of 20.5 months. Restoration of facial height, width, and projection is achieved through replacement of skeletal buttresses and is essential for facial harmony. Since 2001, our unit has undergone a paradigm shift with regard to treatment of composite oncologic and traumatic defects, advocating vascularized bone flaps to achieve predictable long-term outcomes.

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Metcalf, C. Jessica E., James S. Clark, and Deborah A. Clark. "Tree growth inference and prediction when the point of measurement changes: modelling around buttresses in tropical forests." Journal of Tropical Ecology 25, no. 1 (January 2009): 1–12. http://dx.doi.org/10.1017/s0266467408005646.

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Abstract:Estimation of tree growth is generally based on repeated diameter measurements. A buttress at the height of measurement will lead to overestimates of tree diameter. Because buttresses grow up the trunk through time, it has become common practice to increase the height of measurement, to ensure that measurements remain above the buttress. However, tapering of the trunk means that increasing measurement height will bias estimates of diameter downward by up to 10% per m of height. This bias could affect inference concerning species differences and climate effects on tree demography and on biomass accumulation. Here we introduce a hierarchical state space method that allows formal integration of data on diameter taken at different heights and can include individual variation, temporal effects or other covariates. We illustrate our approach using species from Barro Colorado Island, Panama, and La Selva, Costa Rica. Results include trends that are consistent with some of those previously reported for climate responses and changes over time, but differ in relative magnitude. By including the full data-set and accounting for bias and variation among individuals and over time, our approach allows for quantification of climate responses and the uncertainty associated with measurements and the underlying growth process.

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Li, Zhong, Lai Bin Zhang, Fan Luo, Bai Ling Zhang, and Shu Ying Tan. "Mechanical Property Analysis of Materials and Application of Buttress Thread Buckle Marine Conductor." Advanced Materials Research 233-235 (May 2011): 2043–46. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.2043.

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At present, offshore drilling operations often use buttress thread casing as surface casing. The design conception of buttress thread casing comes from the offshore drilling’s demands and this kind of casing is mainly used as surface casing. This paper has taken material mechanical experiment, numerical simulation analysis and field test, the research results show that the various parameters of buttress thread casing fully complies with the drilling design requirements and the offshore oilfield production demands. This product can reduce drilling cost effectively, improve working efficiency and safety, and realize manufacture domestically. Meanwhile, the development of this project will fill the blank of the ERW (Electrical Resistance Weld) casing in CNOOC (China National Offshore Oil Corporation), and have a broad prospect of application.

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Pease, F., AJ Ward, AJ Stevenson, JL Cunningham, O. Sabri, M. Acharya, and TJS Chesser. "Posterior wall acetabular fracture fixation: A mechanical analysis of fixation methods." Journal of Orthopaedic Surgery 27, no. 3 (July 16, 2019): 230949901985983. http://dx.doi.org/10.1177/2309499019859838.

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Stable, anatomical fixation of acetabular fractures gives the best chance of successful outcome, while penetration of the acetabular articular surface with screws is associated with poor outcomes. Spring plates are an alternative to interfragmentary lag screws when penetration is a concern. A mechanical study comparing fracture stability and construct stiffness of three fixation methods for posterior wall acetabular fractures with transverse comminutions was performed. The three fixation methods tested were a posterior wall rim plate, a posterior wall buttress plate with separate lag screws and a posterior wall plate with two spring plates. Nine samples were tested, three for each fixation method. Two-dimensional motion analysis was used to measure fracture fragment displacement and construct stiffness. After two 6000 cycle-loading protocols, to a maximum 1.5 kN, the mean fracture displacement was 0.154 mm for the rim plate model, 0.326 mm for the buttress plate and 0.254 mm for the spring plate model. Mean maximum displacement was significantly less for the rim plate fixation than the buttress plate ( p = 0.015) and spring plate fixation ( p = 0.02). The rim plate was the stiffest construct 10,962 N/mm, followed by the spring plate model 5637 N/mm and the buttress plate model 4882 N/mm. Based on data obtained in this study, where possible a rim plate with interfragmentary lag screws should be used for isolated posterior wall fractures as this is the stiffest and most stable construct. When this method is not possible, spring plate fixation is a safe and a superior alternative to a posterior buttress plate method.

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Yoo, Jae Chul, Yong Seuk Lee, Suk Kee Tae, Jung Ho Park, Jong Woong Park, and Hae Chan Ha. "Magnetic Resonance Imaging Appearance of a Repaired Capsulolabral Complex after Arthroscopic Bankart Repair." American Journal of Sports Medicine 36, no. 12 (September 5, 2008): 2310–16. http://dx.doi.org/10.1177/0363546508322477.

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Background Revision Bankart operations frequently show capsulolabral buttress loss and recurrent soft tissue Bankart lesion. Capsulolabral augmentation is designed to increase glenohumeral stability by 2 separate mechanisms: deepening the glenoid concavity and reducing capsular laxity. This is accomplished by shifting the capsule to buttress the glenoid labrum. Hypothesis A retained capsulolabral buttress may show loss of height and slope at a certain period after surgery, regardless of stability. Thus, the authors wanted to confirm the importance of an intraoperative establishment of capsulolabral buttress in terms of stability. Study Design Case-control study; Level of evidence, 3. Methods Arthroscopically repaired Bankart lesions in 21 consecutive shoulders that showed no frank dislocation were evaluated using axial and oblique coronal T2-weighted magnetic resonance imaging at 3 timepoints (preoperative period, average postoperative week 6 and a nearly full range of motion recovery, and postoperative month 6 with a return to daily activity). The authors measured 2 parameters (height and slope) on axial (mainly capsulolabral containment) and oblique coronal images (mainly inferior glenohumeral ligament) at the anteroinferior portion of the glenoid (5 mm above the most inferior anchor). In addition, they compared the above-mentioned parameters at postoperative month 6 by magnetic resonance imaging in 21 controls and in 21 patients whose instability recurred after surgery (not included in the prospective study). Results There was a significant increase between the preoperative period and postoperative week 6 in all 4 parameters ( P < .0001). There was also a significant increase between the preoperative period and postoperative month 6 in all 4 parameters ( P < .0001). However, no statistically significant difference was observed between postoperative week 6 and postoperative month 6 in all 4 parameters ( P > .1). Furthermore, significant differences were observed between normal controls and patients with recurrent instability ( P < .001) and between the authors’ cases and patients with recurrent instability not in the study (P < .001). However, no difference was observed between their cases and normal shoulders ( P > .1). Conclusion After suture anchor Bankart repair, initial capsulolabral buttress property was maintained at 6 months postoperatively. Furthermore, the buttress was more prominent in stable and normal shoulders than in recurrent instability shoulders. Therefore, the authors believe that the establishment of a capsulolabral buttress is meaningful during Bankart repair.

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PALUMBO, P., and L. PIRODDI. "SEISMIC BEHAVIOUR OF BUTTRESS DAMS: NON-LINEAR MODELLING OF A DAMAGED BUTTRESS BASED ON ARX/NARX MODELS." Journal of Sound and Vibration 239, no. 3 (January 2001): 405–22. http://dx.doi.org/10.1006/jsvi.2000.3171.

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Barlow, Jos, Bernard O. Lagan, and Carlos A. Peres. "Morphological correlates of fire-induced tree mortality in a central Amazonian forest." Journal of Tropical Ecology 19, no. 3 (April 28, 2003): 291–99. http://dx.doi.org/10.1017/s0266467403003328.

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Tree characteristics were recorded from 2829 standing trees in 24 0.25-ha terra firme forest plots in central Amazonia, 3 y after a surface fire had swept through the study area. Sixteen of the plots were within forest that burnt for the first time at the end of the 1997-98 El Niño (ENSO) event, and the remaining eight plots were within unburnt primary forest. In order to investigate the morphological correlates of tree mortality, we measured tree diameter at breast height (dbh) and bark thickness, and recorded burn height, bark roughness and the presence of latex, resin and buttress roots. Leaf litter depth was also recorded at the base of all trees in the unburnt forest. Using logistic regression models, tree mortality was best explained by the burn height, although dbh and the presence of buttresses were also important. Buttressed trees were associated with deeper leaf litter accumulation at their bases and higher char heights than trees without buttresses. Moreover, trees surviving the fire had significantly thicker bark than living trees in unburnt forest plots, indicating that thin-barked trees are more prone to selective mortality induced by heat stress. Latex did not appear to have had any significant effects on mortality, though resins were less abundant amongst the live trees in the burnt forest than in the unburnt controls. Levels of fire-mediated tree mortality in this study are compared with those in other Amazonian forest regions in light of historical factors affecting tree resistance to fires.

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Lee, Il Hwan, Do Hyun Kim, Jae-Sung Park, Sin-Soo Jeun, Yong-Kil Hong, and Sung Won Kim. "Cerebrospinal fluid leakage repair of various grades developing during endoscopic transnasal transsphenoidal surgery." PLOS ONE 16, no. 3 (March 26, 2021): e0248229. http://dx.doi.org/10.1371/journal.pone.0248229.

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Objectives We describe the strategy used to repair intraoperative leaks of various grades and define factors for preventing postoperative cerebrospinal fluid leakage (CSF) after surgery via the endoscopic endonasal transsphenoidal approach (EETA). Study design Retrospective chart review at a tertiary referral center. Methods Patients who underwent surgery via EETA from January 2009 to May 2020 were retrospectively reviewed. Intraoperative CSF leakage was graded 0–3 in terms of the dural defect size; various repairs were used depending on the grade. Results A total of 777 patients underwent 869 operations via EETA; 609 (70.1%) experienced no intraoperative CSF leakage (grade 0) but 260 (29.9%) did. Leakage was of grade 1 in 135 cases (15.5%), grade 2 in 83 (9.6%), and grade 3 in 42 (4.8%). In 260 patients with intraoperative CSF leakage, a buttress was wedged into the sellar defect site in 178 cases (68.5%) and a pedicled flap was placed in 105 cases (40.4%). Autologous fat (108 cases, 41.5%) and a synthetic dural substitute (91 cases, 35%) were used to fill the dead space of the sellar resection cavity. Postoperative CSF leakage developed in 21 patients: 6 of grade 1, 7 of grade 2, and 8 of grade 3. Buttress placement significantly decreased postoperative leakage in grade 1 patients (p = 0.041). In patients of perioperative leakage grades 2 and 3, postoperative CSF leakage was significantly reduced only when both fat and a buttress were applied (p = 0.042 and p = 0.043, respectively). Conclusion A buttress prevented postoperative CSF leakage in grade 1 patients; both fat and buttress were required by patients with intraoperative leakage of grades 2 and 3.

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Гайворонский, Иван Васильевич, А. А. Родионов, Геннадий Иванович Ничипорук, Инга Александровна Горячева, and Мария Георгиевна Гайворонская. "HUMAN PELVIS BUTTRESS SYSTEM AND THE ROLE OF SKELETAL MUSCLES IN ITS FORMATION (REVIEW ARTICLE)." Морфология, no. 4-5 (September 30, 2020): 93–100. http://dx.doi.org/10.34922/ae.2020.158.4.014.

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В связи с вертикальным положением тела на таз человека действуют такие механические силы, как масса тела, внутренностей, внутрибрюшное давление, тяга мышц, связочного аппарата. Под воздействием этих сил происходит моделирование костных структур - внутренних пластинок губчатого вещества и замыкательных пластинок компактного вещества, наибольшая концентрация которых происходит в местах воздействия сил сжатия и растяжении. Указанные места повышенной плотности костной ткани в составе костного таза являются его контрфорсами. Связующим фундаментом контрфорсной системы таза является крестец, воспринимающий воздействия механических сил и передающих их на тазовые кости. Авторами выделены следующие костные контрфорсы: 1 - пояснично-крестцово-подвздошно-бедренный; 2 - пояснично-крестцово-подвздошно-седалищный; 3 - крестцово-седалищный; 4 - крестцово-бедренный; 5 - крестцово-подвздошнолобковый. Рассматривать контрфорсы таза необходимо с позиций арочных конструкций с обязательным взаимодействием контралатеральных сторон. Арочные конструкции, образованные пояснично-крестцово-подвздошно-бедренным, крестцовобедренным и крестцово-подвздошно-лобковыми контрфорсами, функционируют при вертикальном положении тела, а пояснично-крестцово-подвздошно-седалищные и крестцово-седалищные контрфорсы - при сидячем положении тела. Важнейшую роль в формировании и поддержании костных контрфорсов также играют скелетные мышцы, прикрепляющиеся к костям таза. Они не только изменяют его костную структуру, но и передают напряжение при своем сокращении на другие кости, формируя мышечные контрфорсные системы. В работе доказано наличие следующих костно-мышечных контрфорсов: 1 - наружного и внутреннего подвздошно-бедренного; 2 - наружного и внутреннего запирательнобедренного; 3 - лобково-седалищно-бедренно-большеберцового; 4 - седалищно-большеберцово-малоберцового контрфорсов. Показано, что таз является важнейшей частью опорно-двигательного аппарата человека и стабилизационным кольцом для свободной нижней конечности. In connection with the vertical position of the body, such mechanical forces as body weight, viscera, intra-abdominal pressure, traction of muscles, tendons and ligament apparatus act on the human pelvis. The bone structures - the internal plates of the spongy substance and the end plates of the compact substance, the highest concentration of which occurs at the sites of compression and tension - are modeled under the influence of these forces. The aforementioned places of increased bone density in the composition of the bone pelvis are its buttresses. The connecting foundation of the buttress system of the pelvis is the sacrum, perceiving the effects of mechanical forces and transmitting them to the pelvic bones. The authors distinguished the following bone buttresses: 1 - lumbo-sacral-iliac-femoral; 2 - lumbo-sacral-iliac-sciatic; 3 - sacro-sciatic; 4 - sacro-femoral; 5 - sacro-iliac-pubical. It is necessary to consider buttresses of the pelvis from the position of arched structures, with the obligatory interaction of the contralateral sides. Arched structures formed by the lumbo-sacral-iliac-femoral, sacro-femoral and sacro-iliac-pubic buttresses function when the body is in vertical position, and the lumbo-sacral-iliac-sciatic and sacroiliac buttresses when the body is in seated position. Skeletal muscles attached to the bones of the pelvis also play an important role in the formation and maintenance of bone buttresses. They not only change its bone structure, but during their contraction also transmit tension to other bones, forming muscle buttress systems. In the work, the presence of the following musculoskeletal buttresses is proved: 1 - the external and internal ileo-femoral; 2 - external and internal obturator-femoral; 3 - pubic-sciaticfemoral-tibial; 4 - sciatic-tibial-fibular buttresses. It is shown that the pelvis is the most important part of the human musculoskeletal system and the stabilization ring for the free lower limb.

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WEISS, R. E., and E. COHEN. "Erosion of Buttress Following Bladder Neck Suspension." British Journal of Urology 69, no. 6 (June 1992): 656–57. http://dx.doi.org/10.1111/j.1464-410x.1992.tb15642.x.

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Suemitsu, Ryuichi, Takaaki Tokito, Masao Ichiki, Sadanori Takeo, Seiya Momosaki, and Kiyomi Furuya. "Complication of bovine pericardial buttress: pulmonary pseudotumor." Asian Cardiovascular and Thoracic Annals 19, no. 1 (February 2011): 64–65. http://dx.doi.org/10.1177/0218492310390053.

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McClelland, Damian, and Simon N. Bell. "Free Coracoid Buttress Graft for Anterior Instability." Techniques in Shoulder and Elbow Surgery 6, no. 4 (December 2005): 214–17. http://dx.doi.org/10.1097/01.bte.0000181151.01061.0b.

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SHIOHATA, Hidetoshi, Tomoyoshi UYAMA, Kenya TAKAHASHI, Takeshi NISHIHATA, Toru YAMASHITA, Toshiyasu MIYOSHI, Norio HAYASHI, and Yasuhiro OKUBO. "DEVELOPMENT OF WAVE ABSORBING BREAKWATER USING BUTTRESS." Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) 74, no. 2 (2018): I_49—I_54. http://dx.doi.org/10.2208/jscejoe.74.i_49.

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Ji, Dong Yu. "Three-Dimensional Finite Element Analysis of Henggangling Buttress Type Inverted Siphon." Advanced Materials Research 804 (September 2013): 343–46. http://dx.doi.org/10.4028/www.scientific.net/amr.804.343.

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nverted siphon structure is a common water conveyance buildings, this paper adopts finite element method to carry out three-dimensional finite element simulation analysis for Henggangling buttress type inverted siphon structure. Deducing variation law of the inverted siphons stress and displacement in construction process and operational process. Analysis results further verified that design scheme is reasonable and safe, it has certain reference value. Henggangling buttress type inverted siphon structure is safety, it meets the requirements for engineering.

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Conger, Andrew, Fan Zhao, Xiaowen Wang, Amalia Eisenberg, Chester Griffiths, Felice Esposito, Ricardo L. Carrau, Garni Barkhoudarian, and Daniel F. Kelly. "Evolution of the graded repair of CSF leaks and skull base defects in endonasal endoscopic tumor surgery: trends in repair failure and meningitis rates in 509 patients." Journal of Neurosurgery 130, no. 3 (March 2019): 861–75. http://dx.doi.org/10.3171/2017.11.jns172141.

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OBJECTIVEThe authors previously described a graded approach to skull base repair following endonasal microscopic or endoscope-assisted tumor surgery. In this paper they review their experience with skull base reconstruction in the endoscopic era.METHODSA retrospective review of a single-institution endonasal endoscopic patient database (April 2010–April 2017) was undertaken. Intraoperative CSF leaks were graded based on size (grade 0 [no leak], 1, 2, or 3), and repair technique was documented across grades. The series was divided into 2 epochs based on implementation of a strict perioperative antibiotic protocol and more liberal use of permanent and/or temporary buttresses; repair failure rates and postoperative meningitis rates were assessed for the 2 epochs and compared.RESULTSIn total, 551 operations were performed in 509 patients for parasellar pathology, including pituitary adenoma (66%), Rathke’s cleft cyst (7%), meningioma (6%), craniopharyngioma (4%), and other (17%). Extended approaches were used in 41% of cases. There were 9 postoperative CSF leaks (1.6%) and 6 cases of meningitis (1.1%). Postoperative leak rates for all 551 operations by grade 0, 1, 2, and 3 were 0%, 1.9%, 3.1%, and 4.8%, respectively. Fat grafts were used in 33%, 84%, 97%, and 100% of grade 0, 1, 2, and 3 leaks, respectively. Pedicled mucosal flaps (78 total) were used in 2.6% of grade 0–2 leaks (combined) and 79.5% of grade 3 leaks (60 nasoseptal and 6 middle turbinate flaps). Nasoseptal flap usage was highest for craniopharyngioma operations (80%) and lowest for pituitary adenoma operations (2%). Two (3%) nasoseptal flaps failed. Contributing factors for the 9 repair failures were BMI ≥ 30 (7/9), lack of buttress (4/9), grade 3 leak (4/9), and postoperative vomiting (4/9). Comparison of the epochs showed that grade 1–3 repair failures decreased from 6/143 (4.1%) to 3/141 (2.1%) and grade 1–3 meningitis rates decreased from 5 (3.5%) to 1 (0.7%) (p = 0.08). Prophylactic lumbar CSF drainage was used in only 4 cases (< 1%), was associated with a higher meningitis rate in grades 1–3 (25% vs 2%), and was discontinued in 2012. Comparison of the 2 epochs showed increase buttress use in the second, with use of a permanent buttress in grade 1 and 3 leaks increasing from 13% to 55% and 32% to 76%, respectively (p < 0.001), and use of autologous septal/keel bone as a permanent buttress in grade 1, 2, and 3 leaks increasing from 15% to 51% (p < 0.001).CONCLUSIONSA graded approach to skull base repair after endonasal surgery remains valid in the endoscopic era. However, the technique has evolved significantly, with further reduction of postoperative CSF leak rates. These data suggest that buttresses are beneficial for repair of most grade 1 and 2 leaks and all grade 3 leaks. Similarly, pedicled flaps appear advantageous for grade 3 leaks, while CSF diversion may be unnecessary and a risk factor for meningitis. High BMI should prompt an aggressive multilayered repair strategy. Achieving repair failure and meningitis rates lower than 1% is a reasonable goal in endoscopic skull base tumor surgery.

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Szőke, Balázs. "A székesfehérvári Szűz Mária prépostság egykori boltozatai." Kaposvári Rippl-Rónai Múzeum Közleményei, no. 2 (2013): 103–14. http://dx.doi.org/10.26080/krrmkozl.2013.2.103.

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The Provostry and Church of the Virgin Mary (Szűz Mária) at Székesfehérvár went through several reconstructions in the Middle ages. The last significant expansion was initiated by Matthias Corvinus. The late Gothic elements of the Provostry’s vault was found by Imre Henszlmann in the territory of the ruined monument in the 1860’s. The rib vault dating back to the period of Matthias Corvinus was annexed to the buttress built in the angevin era. The construction with internal buttresses could come into existence as a consequence of this fixity in the building technique. examples for this can be found in the Franciscan Church in Szeged-alsóváros, and in several churches in Transylvania.

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Dragoni, E. "Effect of Thread Shape on Screw Stress Concentration by Photoelastic Measurements." Journal of Offshore Mechanics and Arctic Engineering 116, no. 4 (November 1, 1994): 228–32. http://dx.doi.org/10.1115/1.2920156.

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The screw stress concentration for six nut-bolt connections embodying three different thread profiles and two nut shapes is measured photoelastically. Buttress (nearly zero flank angle), trapezoidal (15-deg flank angle), and triangular (30-deg flank angle) thread forms are examined in combination with standard and lip-type nuts. The effect of the thread profile on the screw stress concentration appears to be dependent upon the kind of nut considered. If the fastening incorporates a standard nut, the buttress thread is stronger than the triangular one, which, in turn, behaves better than the trapezoidal contour. The improvement is roughly a 20-percent reduction in the stress concentration factor from the trapezoidal to the buttress thread. In the case of lip nut, conversely, this tendency is somewhat reversed, with the trapezoidal thread performing slightly (but not decidedly) better than the other two shapes. Finally, averaged over all three thread forms, the lip nut exhibits a stress concentration factor which is about 50 percent lower than that of the standard nut.

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Zhang, Ming-Zhu, and Guang-rong Yu. "Treatment outcomes of buttress plating for posterior pilon fractures." Foot & Ankle Orthopaedics 3, no. 3 (July 1, 2018): 2473011418S0053. http://dx.doi.org/10.1177/2473011418s00538.

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Category: Ankle Introduction/Purpose: The purpose of current study was to retrospectively analyze the clinical outcomes of buttress plate treatment of posterior pilon fractures. Methods: Between January 2005 and December 2016, 58 patients with posterior pilon fractures underwent buttress plate fixation. There were 32 males and 26 females and the mean age was 40.2years (range, 23 to 73 years). Preoperative radiographs, CT scans and three dimensional reconstructions were used to evaluate the fracture patterns. On the basis of the extension of the fracture lines presented on the CT scans, a posterolateral approach or a combination of both posterolateral and posteromedial approaches were used to reduce and fixate the posterior malleolar fragments. Clinical and radiographic examinations were used for postoperative follow-up. The American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and the Visual Analogue Scale (VAS) were used to evaluate the functional outcomes. Results: According to the CT scan images, the posterior pilon fractures were classified into 3 types. 51 patients were available for follow-up. The mean time of follow-up was 44.8 months. The mean AOFAS score was 84.3 points, and the mean VAS score was 1.6 points. One patient was found with ankle joint swelling and long term walking discomfort at 2-year follow-up. Other patients received favorable functional outcomes. No hardware failure occurred. Conclusion: The clinical outcomes of buttress plate treatment of posterior pilon fractures were satisfactory. Buttress plating availed the patients to return to earlier weight-bearing and functional exercises.

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Bassil, Joseph, Alain Abi Sleiman, Stephanie Mrad, and Ziad Noujeim. "The Zygomatic Buttress as an Efficient Intraoral Donor Site for Limited Maxillary Reconstructions: A Case Series and Brief Literature Review." Case Reports in Dentistry 2021 (May 3, 2021): 1–6. http://dx.doi.org/10.1155/2021/5539185.

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Limited maxillary defects are commonly grafted with bone blocks harvested from the symphysis or the ramus; harvesting a second surgical site in the mandible increases both operative time and patient’s postoperative morbidity. To overcome these disadvantages, the zygomatic buttress (ZB) was suggested as an alternative maxillary source of autogenous bone. This intraoral donor site has a natural convex shape and can be accessed along with the recipient site through the same flap design. We report a case series describing this uncommon technique of bone harvesting from the zygomatic buttress to reconstruct limited alveolar defects in the maxilla.

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Kim, Sungtae, Jungjoo Kim, Taesu Kyeon, and Hankyu Yoo. "Study on Optimum Screen Spacing of Buttress Dam." Journal of the Korean Society of Hazard Mitigation 18, no. 4 (June 30, 2018): 165–73. http://dx.doi.org/10.9798/kosham.2018.18.4.165.

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Mikhailov, Valentin. "Book Publishing: A Buttress of Stalinism in Russia?" Russian Politics 5, no. 1 (April 2, 2020): 1–28. http://dx.doi.org/10.30965/24518921-00501001.

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Abstract In today’s Russia, there is a constant clash of opinions when it comes to perceptions of the past, and to what can be learned from Russia’s Soviet experience in general and Stalinist repression in particular. A consensus which seemed just over the horizon between 1998 and 1991 now grows ever more distant. Nearly half of those surveyed in 2017 say that Stalin should not be seen as a state criminal; that the repressions are best discussed less rather than more, and that there is nothing to be gained by dredging up the past. The only way for Russia to pursue a future of democracy and respect for human rights is to leave all of that baggage behind. How has this come to be? What are the roots of these myths of a great and just Stalin that now emerge 65 years after his death? A series of scholars posit that the key lies in Russian society itself, with its tendency towards being ruled with a firm hand and a state that merely takes a neutral position between the liberals and the Stalinists. Others assert that these are successful constructs of the Kremlin, which seeks to inculcate domestic support for authoritarian rule. In order to resolve this disagreement, we studied the book market for Stalin-related literature published within the last twenty years. The study indicates that the market comprises two mostly separate areas: books by Stalin apologists on the one hand, and books by professional historians and recollections by victims of repressions on the other. Quantitative analysis shows that the former receive markedly greater support, which reflects the state’s role over the past fifteen years in forming a positive image of Stalin.

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BENOIST, L. A., and A. E. FREELAND. "Buttress Pinning in the Unstable Distal Radial Fracture." Journal of Hand Surgery 20, no. 1 (February 1995): 82–96. http://dx.doi.org/10.1016/s0266-7681(05)80024-5.

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Between 1989 and 1993, 20 patients with distal radial fractures were treated with a buttressing technique felt to be safe, effective and simple. Out of the initial 20 patients, 16 have been followed-up and are reported. The technique uses an intramedullary styloid pin and a combined extramedullary–intramedullary dorsal buttress pin. The insertion technique and the use of a medial corner pin are illustrated. Results are evaluated from both final X-ray appearance as well as return of function using the five X-ray parameters of Abbasazadegan et al (1989) and the Mayo modification of the Green and O’Brien wrist score (Cooney et al, 1987). The average score on return of function was 78 (two excellent, eight good, six fair). Final axial shortening averaged –1.4mm (+5 mm– –4 mm), radial displacement averaged 0.68 mm (0 mm–5 mm), radial angle averaged 24.75° (18°–34°), dorsal angle averaged +8.25° (–5°–25°) and dorsal displacement averaged +1.31 (0 mm–+12 mm). From this study we recognize the need for a posterior medial pin, and that routine stress views after pinning can yield information concerning carpal instability, palmar instability and the need for bone grafting.

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Richardson, W. "Teflon buttress inhibits recanalization of uncut stapled bowel,." Journal of Gastrointestinal Surgery 4, no. 4 (August 2000): 424–29. http://dx.doi.org/10.1016/s1091-255x(00)80023-2.

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Ou, C. Y., F. C. Teng, R. B. Seed, and I. W. Wang. "Using buttress walls to reduce excavation-induced movements." Proceedings of the Institution of Civil Engineers - Geotechnical Engineering 161, no. 4 (August 2008): 209–22. http://dx.doi.org/10.1680/geng.2008.161.4.209.

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Journal articles on the topic 'Buttress'

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