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1
Jiang, Man, and Dan Zhang. "Wave propagation and soliton behavior in biomechanical tissues: A mathematical approach." Molecular & Cellular Biomechanics 21, no. 3 (November 14, 2024): 424. http://dx.doi.org/10.62617/mcb424.
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This study presents a mathematical model for understanding wave propagation and soliton behavior in biomechanical tissues, explicitly focusing on the Achilles tendon. Utilizing the Korteweg-de Vries (KdV) equation, the research incorporates the Achilles tendons’ nonlinear elastic and viscoelastic properties to explore how mechanical waves propagate through this complex tissue. The tendon’s nonlinear elasticity leads to wave steepening, while its viscoelasticity introduces dispersive effects that counteract this steepening, resulting in the formation of solitons—stable, localized waves that maintain their shape as they propagate. Key findings from this study reveal that the formation and propagation of solitons are strongly influenced by the tendon’s mechanical properties. Numerical simulations show that stiffer tendons, characterized by a higher elasticity modulus, support faster soliton propagation, with wave speeds ranging from 18.9 m/s in damaged tendons to 28.6 m/s in stiffened tendons. Additionally, soliton amplitude increases with tissue stiffness, with the highest amplitude observed in stiffened tendons (5.1 mm) and the lowest in damaged tendons (3.2 mm). The study also demonstrates that energy dissipation due to the tendon’s viscoelasticity plays a critical role in soliton behavior. Damaged tendons exhibit the highest energy loss (18.6%), leading to shorter soliton propagation distances, while stiffer tendons retain more energy (96.1%) and allow solitons to travel further distances (up to 180 mm). Moreover, the balance between nonlinearity and dispersion is crucial for maintaining soliton stability. Excessive nonlinearity leads to unstable solitons, while higher levels of dispersion contribute to more stable waveforms.
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Sharafeldin, Tamer A., Qingshan Chen, Sunil K. Mor, Sagar M. Goyal, and Robert E. Porter. "Altered Biomechanical Properties of Gastrocnemius Tendons of Turkeys Infected with Turkey Arthritis Reovirus." Veterinary Medicine International 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/7829138.
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Turkey arthritis reovirus (TARV) causes lameness and tenosynovitis in commercial turkeys and is often associated with gastrocnemius tendon rupture by the marketing age. This study was undertaken to characterize the biomechanical properties of tendons from reovirus-infected turkeys. One-week-old turkey poults were orally inoculated with O’Neil strain of TARV and observed for up to 16 weeks of age. Lameness was first observed at 8 weeks of age, which continued at 12 and 16 weeks. At 4, 8, 12, and 16 weeks of age, samples were collected from legs. Left intertarsal joint with adjacent gastrocnemius tendon was collected and processed for histological examination. The right gastrocnemius tendon’s tensile strength and elasticity modulus were analyzed by stressing each tendon to the point of rupture. At 16 weeks of age, gastrocnemius tendons of TARV-infected turkeys showed significantly reduced (P<0.05) tensile strength and modulus of elasticity as compared to those of noninfected control turkeys. Gastrocnemius tendons revealed lymphocytic tendinitis/tenosynovitis beginning at 4 weeks of age, continuing through 8 and 12 weeks, and progressing to fibrosis from 12 to 16 weeks of age. We propose that tendon fibrosis is one of the key features contributing to reduction in tensile strength and elasticity of gastrocnemius tendons in TARV-infected turkeys.
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Wellings, Elizabeth P., Tony Chieh-Ting Huang, Jialun Li, Timothy E. Peterson, Alexander W. Hooke, Andrew Rosenbaum, Chunfeng D. Zhao, Atta Behfar, Steven L. Moran, and Matthew T. Houdek. "Intrinsic Tendon Regeneration After Application of Purified Exosome Product: An In Vivo Study." Orthopaedic Journal of Sports Medicine 9, no. 12 (December 1, 2021): 232596712110629. http://dx.doi.org/10.1177/23259671211062929.
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Background: Tendons are primarily acellular, limiting their intrinsic regenerative capabilities. This limited regenerative potential contributes to delayed healing, rupture, and adhesion formation after tendon injury. Purpose: To determine if a tendon’s intrinsic regenerative potential could be improved after the application of a purified exosome product (PEP) when loaded onto a collagen scaffold. Study Design: Controlled laboratory study. Methods: An in vivo rabbit Achilles tendon model was used and consisted of 3 groups: (1) Achilles tenotomy with suture repair, (2) Achilles tenotomy with suture repair and collagen scaffold, and (3) Achilles tenotomy with suture repair and collagen scaffold loaded with PEP at 1 × 1012 exosomes/mL. Each group consisted of 15 rabbits for a total of 45 specimens. Mechanical and histologic analyses were performed at both 3 and 6 weeks. Results: The load to failure and ultimate tensile stress were found to be similar across all groups ( P ≥ .15). The tendon cross-sectional area was significantly smaller for tendons treated with PEP compared with the control groups at 6 weeks, which was primarily related to an absence of external adhesions ( P = .04). Histologic analysis confirmed these findings, demonstrating significantly lower adhesion grade both macroscopically ( P = .0006) and microscopically ( P = .0062) when tendons were treated with PEP. Immunohistochemical staining showed a greater intensity for type 1 collagen for PEP-treated tendons compared with collagen-only or control tendons. Conclusion: Mechanical and histologic results suggested that healing in the PEP-treated group favored intrinsic healing (absence of adhesions) while control animals and animals treated with collagen only healed primarily via extrinsic scar formation. Despite a smaller cross-sectional area, treated tendons had the same ultimate tensile stress. This pilot investigation shows promise for PEP as a means of effectively treating tendon injuries and enhancing intrinsic healing. Clinical Relevance: The production of a cell-free, off-the-shelf product that can promote tendon regeneration would provide a viable solution for physicians and patients to enhance tendon healing and decrease adhesions as well as shorten the time required to return to work or sports.
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Mao, W. F., Y. F. Wu, Y. L. Zhou, and J. B. Tang. "A study of the anatomy and repair strengths of porcine flexor and extensor tendons: are they appropriate experimental models?" Journal of Hand Surgery (European Volume) 36, no. 8 (July 18, 2011): 663–69. http://dx.doi.org/10.1177/1753193411414117.
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Although both porcine flexor and extensor tendons have been used in tendon repair research, no studies have specifically studied the anatomical differences and repair strengths in both types of tendons. We used 12 pig trotters to observe the anatomy of these tendons and compared the 2 mm gap and ultimate strengths of flexor and extensor tendons. There were four annular (A1, A2, A3, and A4) pulleys and one oblique pulley, which form a fibro-osseous tunnel for the flexor tendons, but the anatomy of the porcine extensor tendons was markedly different from the human flexor or extensor tendons. The diameter of flexor tendons was significantly greater than that of the extensors. The 2 mm gap and ultimate strengths of the flexor tendon with either two-strand or four-strand repairs were significantly greater than those of the extensor tendon. We conclude that the porcine flexor tendon systems are similar to those in the human, but the extensor tendons are not similar to either the flexor or extensor tendons in humans. Flexor and extensor tendons have different repair strengths which should be taken into account when interpreting findings from investigations using these tendons.
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Ilahi, Omer A., Eugene F. Stautberg, David J. Mansfield, and Ali A. Qadeer. "Relationship of Musculotendinous Junction Location to Harvested Semitendinosus and Gracilis Tendon Length." Orthopaedic Journal of Sports Medicine 5, no. 5 (May 1, 2017): 232596711770463. http://dx.doi.org/10.1177/2325967117704630.
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Background: Harvested hamstring tendon length has received scant attention in published anterior cruciate ligament (ACL) reconstruction literature, yet length can limit the ability to increase graft diameter by folding the tendon over more than once. Indeed, some ultrashort tendons may be too short to yield a clinically useful graft after being folded over just once. Ultimately, the total length of a harvested hamstring tendon may depend on the length of the tendon distal to its musculotendinous (MT) junction. Purpose: To compare the lengths of harvested hamstring tendons to the location of the MT junction to help predict abnormally short tendon harvest. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Eighty-four consecutive patients undergoing primary ACL reconstruction using hamstring tendon autografts underwent intraoperative measurement of the total length of each harvested semitendinosus (ST) and gracilis (G) tendon, as well as the distance from the MT junction to that tendon’s distal end (ie, the “tendon-only” length). Results: The ratio of the tendon-only portion to total harvested tendon length averaged 0.52 (range, 0.39-0.71) for the ST and 0.52 (range, 0.43-0.71) for the G, suggesting a 95% chance of harvesting a tendon <15 cm in length for the tendon-only portion is <6.45 cm for ST or <6.75 cm for G tendons. There was moderate correlation between the lengths of harvested ST and G tendons with patient height as well as with the diameter of the combined, quadruple-stranded graft. Conclusion: The ratio of the tendon-only length to total harvested length for both the ST and G appear to range from approximately 0.4 to 0.7. Patients with abnormally distal MT junctions of either their ST or G are likely to have an abnormally short harvest of that tendon, even in the absence of technical harvesting error.
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Peltz, Tim Sebastian, Stuart William Hoffman, Peter James Scougall, Mark Peter Gianoutsos, Robert Savage, Rema Antoinette Oliver, and William Robert Walsh. "Animal Models for Tendon Repair Experiments: A Comparison of Pig, Sheep and Human Deep Flexor Tendons in Zone II." Journal of Hand Surgery (Asian-Pacific Volume) 22, no. 03 (August 4, 2017): 329–36. http://dx.doi.org/10.1142/s0218810417500381.
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Background: This laboratory study compared pig, sheep and human deep flexor tendons in regards to their biomechanical comparability. Methods: To investigate the relevant biomechanical properties for tendon repair experiments, the tendons resistance to cheese-wiring (suture drag/splitting) was assessed. Cheese-wiring of a suture through a tendon is an essential factor for repair gapping and failure in a tendon repair. Results: Biomechanical testing showed that forces required to pulling a uniform suture loop through sheep or pig tendons in Zone II were higher than in human tendons. At time point zero of testing these differences did not reach statistical significance, but differences became more pronounced when forces were measured beyond initial cheese-wiring (2 mm, 5 mm and 10 mm). The stronger resistance to cheese-wiring was more pronounced in the pig tendons. Also regarding size and histology, sheep tendons were more comparable to human tendons than pig tendons. Conclusions: Differences in tendon bio-properties should be kept in mind when comparing and interpreting the results of laboratory tendon experiments.
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Gaughan, E. M., R. M. DeBowes, J. P. Douglass, R. K. Frank, R. D. Klemm, and L. J. Gift. "The Influence of Intratendinous Sodium Hyaluronate on Tendon Healing in Horses." Veterinary and Comparative Orthopaedics and Traumatology 05, no. 04 (1992): 151–57. http://dx.doi.org/10.1055/s-0038-1633108.
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SummaryAcute tendinitis was created bilaterally in the mid-metacarpal region of the deep digital flexor tendons of six horses with intratendinous collagenase administration. The collagenase-induced lesion in one deep digital flexor tendon of each horse was injected 48 h later with 10.0 mg of sodium hyaluronate (1.0 ml) while employing ultrasound guidance. To serve as a control, the lesion in the contralateral deep digital flexor tendon was injected with 1.0 ml of 0.9% sodium chloride. Sequential ultra-sonographic examinations revealed that the sodium hyaluronate treated deep digital flexor tendons were significantly less enlarged and the collagenase-induced tendon lesions significantly smaller than control tendons and tendon lesions. Difference could not be detected between sodium hyaluronate treated tendons and control tendons using histological and video-interactive planar morphometric evaluation six weeks after treatment.Collagenase-induced tendinitis lesions were treated with intratendinous administration of sodium hyaluronate in six horses. The size of the tendon lesions and the amount of tendon enlargement were significantly less in the sodium hyaluronate treated tendons compared to control tendons. A significant difference in the rate or quality of healing was not detected in the sodium hyaluronate treated tendons.
8
Biju, Urumese Palatty, V. Raveendranath, and KY Manjunath. "Anatomical Study of Extensor Tendons of Medial Four Fingers in Adults and Fetuses-A Cadaveric Study." PJSR 8, no. 1 (June 1, 2015): 1–13. https://doi.org/10.5281/zenodo.8249589.
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Hand is the most frequently used part of our body, rendering it vulnerable to injury. It is mandatory to enhance the existing anatomical knowledge of the extensor tendons of the hand and their common variations whenever reconstructive surgery is planned in this region. That the human extensor muscles of the hand have great variability is now a wellestablished fact. In the present study, data was collected by dissection of fifty hands of formalin fixed adult cadavers and also stillborn full term fetuses. All extensor tendons to the fingers were identified, cleaned and the number and width of the tendon splits and strands were recorded. Single Extensor indicis tendon were found in 39 (78 %), hands while double and triple together were found in nine (18%) hands. Extensor digitorum to the index finger was absent in one (2%) hand, with a single tendon in 45(90%), double and triple together in the remaining four (8%) hands. The Extensor digitorum to middle finger with single tendon were found in 36(72%), double and triple together in 13(26%) and in one case with multiple tendons (2%). The Extensor digitorum to ring finger with single tendon were found in 22(44%), double and triple together in 22(44%) and six (12%) hands had multiple tendons. The Extensor digitorum to ring finger with single tendon were found in 22(44%), double and triple together in 22(44%) and in six (12%) hands with multiple tendons. No tendons of Extensor digitorum to little finger were found in 29(58%) hands ; single tendon was found in 11 (22%) hands and double in 10(20%).Extensor digiti minimi tendons were absent in one (2%) hand, single in nine (18%), and in 35(70%) with double tendons and five (10%) had triple tendons. Abductor pollicis longus with a single tendon were found in 38(76%) hands, absent in one case (2%), double and triple together in 11(22%) hands. The Extensor pollics brevis tendons were single in 47(94%) hands and in the remaining three (6%) hands the tendons were double stranded. Extensor pollicis longus tendons were single in 43(86%); in remaining seven (14%) hands, the tendons were double stranded. Anomalous Abductor pollicis longus, Extensor indicis and an Extensor medii proprius were also observed during the study. Anatomical knowledge of the extensor tendons is important for successful tenosynovectomy in the treatment of De Quervain disease. Knowledge of anomalous extensor tendons may also be helpful in identifying and planning tendon transfer or graft surgeries. Presence of multiple tendons may be beneficial in tendon transfer operations.
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Loiselle, A. E. "AGE-RELATED MECHANISMS OF ALTERED TENDON STRUCTURE AND FUNCTION." Orthopaedic Proceedings 106-B, SUPP_1 (January 2, 2024): 72. http://dx.doi.org/10.1302/1358-992x.2024.1.072.
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During aging, tendons demonstrate substantial disruptions in homeostasis, leading to impairments in structure-function. Impaired tendon function contributes to substantial declines quality of life during aging. Aged tendons are more likely to undergo spontaneous rupture, and the healing response following injury is impaired in aged tendons. Thus, there is a need to develop strategies to maintain tendon homeostasis and healing capacity through the lifespan. Tendon cell density sharply declines by ∼12 months of age in mice, and this low cell density is retained in geriatric tendons. Our data suggests that this decline in cellularity initiates a degenerative cascade due to insufficient production of the extracellular matrix (ECM) components needed to maintain tendon homeostasis. Thus, preventing this decline in tendon cellularity has great potential for maintaining tendon health. Single cell RNA sequencing analysis identifies two changes in the aged tendon cell environment. First, aged tendons primarily lose tenocytes that are associated with ECM biosynthesis functions. Second, the tenocytes that remain in aged tendons have disruptions in proteostasis and an increased pro-inflammatory phenotype, with these changes collectively termed ‘programmatic skewing'. To determine which of these changes drives homeostatic disruption, we developed a model of tenocyte depletion in young animals. This model decreases tendon cellularity to that of an aged tendon, including decreased biosynthetic tenocyte function, while age-related programmatic skewing is absent. Loss of biosynthetic tenocyte function in young tendons was sufficient to induce homeostatic disruption comparable to natural aging, including deficits in ECM organization, composition, and material quality, suggesting loss biosynthetic tenocytes as an initiator of tendon degeneration. In contrast, our data suggest that programmatic skewing underpins impaired healing in aged tendons. Indeed, despite similar declines in the tenocyte environment, middle-aged and young-depleted tendons mount a physiological healing response characterized by robust ECM synthesis and remodeling, while aged tendons heal with insufficient ECM.
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Shama, Kariman A., Zachary Franklin Greenberg, Chadine Tammame, Mei He, and Brittany L. Taylor. "Diseased Tendon Models Demonstrate Influence of Extracellular Matrix Alterations on Extracellular Vesicle Profile." Bioengineering 11, no. 10 (October 12, 2024): 1019. http://dx.doi.org/10.3390/bioengineering11101019.
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Tendons enable movement through their highly aligned extracellular matrix (ECM), predominantly composed of collagen I. Tendinopathies disrupt the structural integrity of tendons by causing fragmentation of collagen fibers, disorganization of fiber bundles, and an increase in glycosaminoglycans and microvasculature, thereby driving the apparent biomechanical and regenerative capacity in patients. Moreover, the complex cellular communication within the tendon microenvironment ultimately dictates the fate between healthy and diseased tendon, wherein extracellular vesicles (EVs) may facilitate the tendon’s fate by transporting biomolecules within the tissue. In this study, we aimed to elucidate how the EV functionality is altered in the context of tendon microenvironments by using polycaprolactone (PCL) electrospun scaffolds mimicking healthy and pathological tendon matrices. Scaffolds were characterized for fiber alignment, mechanical properties, and cellular activity. EVs were isolated and analyzed for concentration, heterogeneity, and protein content. Our results show that our mimicked healthy tendon led to an increase in EV secretion and baseline metabolic activity over the mimicked diseased tendon, where reduced EV secretion and a significant increase in metabolic activity over 5 days were observed. These findings suggest that scaffold mechanics may influence EV functionality, offering insights into tendon homeostasis. Future research should further investigate how EV cargo affects the tendon’s microenvironment.
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DUFFY, F. J., J. G. SEILER, C. A. HERGRUETER, J. KANDEL, and R. H. GELBERMAN. "Intrinsic Mitogenic Potential of Canine Flexor Tendons." Journal of Hand Surgery 17, no. 3 (June 1992): 275–77. http://dx.doi.org/10.1016/0266-7681(92)90114-h.
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Recent studies have demonstrated an intrinsic neovascular response in intrasynovial healing tendons, introducing the possibility of mitogenic and/or angiogenic capability of intrasynovial tendon. To explore this hypothesis, healing canine flexor tendons were treated with early passive mobilization and the repair sites analysed at three, ten and 17 days. Specimens were mechanically digested and subjected to a standard BALB/c 3T3 mitogenic assay, which measures the capacity of tissue extracts to induce DNA synthesis and cell division in fibroblasts. Results revealed that both control and repaired flexor tendons possessed mitogenic activity, with the greatest activity observed in control specimens. Decreasing activity was noted as the time between repair and analysis increased. These data provide increasing evidence for the flexor tendon’s active role in the healing process, and support the concept that mitogenic or growth-promoting factors are associated with flexor tendons and may be released following injury, during the early stages of healing.
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Hashimoto, T., A. R. Thoreson, K. N. An, P. C. Amadio, and C. Zhao. "Comparison of step-cut and Pulvertaft attachment for flexor tendon graft: a biomechanics evaluation in an in vitro canine model." Journal of Hand Surgery (European Volume) 37, no. 9 (April 4, 2012): 848–54. http://dx.doi.org/10.1177/1753193412442460.
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The purpose of this study was to compare two different methods of joining tendons of similar and dissimilar sizes between recipient and donor tendons for flexor tendon grafts. Flexor digitorum profundus (FDP) and peroneus longus (PL) canine tendons were harvested and divided into four groups. The repair technique we compared was a step-cut (SC) suture and a Pulvertaft weave (PW). FDP tendons were significantly larger in diameter than PL tendons ( p < 0.05). The volume of the SC repairs using either FDP or PL tendon as a graft was significantly smaller than PW repairs ( p < 0.05). The ultimate load to failure and repair stiffness in FDP graft tendons significantly increased compared with the PL graft tendons ( p < 0.05). The SC suture can be used as an alternative to the PW, with similar strength and less bulk for repairs using graft tendons of similar diameter. Surgeons should be aware of the effect of graft tendon size and repair method on strength and bulk when performing flexor tendon grafts.
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Ito, Ko, Yasuhiro Go, Shoji Tatsumoto, Chika Usui, Yosuke Mizuno, Eiji Ikami, Yuta Isozaki, et al. "Gene expression profiling of the masticatory muscle tendons and Achilles tendons under tensile strain in the Japanese macaque Macaca fuscata." PLOS ONE 18, no. 1 (January 19, 2023): e0280649. http://dx.doi.org/10.1371/journal.pone.0280649.
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Both Achilles and masticatory muscle tendons are large load-bearing structures, and excessive mechanical loading leads to hypertrophic changes in these tendons. In the maxillofacial region, hyperplasia of the masticatory muscle tendons and aponeurosis affect muscle extensibility resulting in limited mouth opening. Although gene expression profiles of Achilles and patellar tendons under mechanical strain are well investigated in rodents, the gene expression profile of the masticatory muscle tendons remains unexplored. Herein, we examined the gene expression pattern of masticatory muscle tendons and compared it with that of Achilles tendons under tensile strain conditions in the Japanese macaque Macaca fuscata. Primary tenocytes isolated from the masticatory muscle tendons (temporal tendon and masseter aponeurosis) and Achilles tendons were mechanically loaded using the tensile force and gene expression was analyzed using the next-generation sequencing. In tendons exposed to tensile strain, we identified 1076 differentially expressed genes with a false discovery rate (FDR) < 10−10. To identify genes that are differentially expressed in temporal tendon and masseter aponeurosis, an FDR of < 10−10 was used, whereas the FDR for Achilles tendons was set at > 0.05. Results showed that 147 genes are differentially expressed between temporal tendons and masseter aponeurosis, out of which, 125 human orthologs were identified using the Ensemble database. Eight of these orthologs were related to tendons and among them the expression of the glycoprotein nmb and sphingosine kinase 1 was increased in temporal tendons and masseter aponeurosis following exposure to tensile strain. Moreover, the expression of tubulin beta 3 class III, which promotes cell cycle progression, and septin 9, which promotes cytoskeletal rearrangements, were decreased in stretched Achilles tendon cells and their expression was increased in stretched masseter aponeurosis and temporal tendon cells. In conclusion, cyclic strain differentially affects gene expression in Achilles tendons and tendons of the masticatory muscles.
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Ferreira Arquez, Humberto. "Bilateral anatomical variations of the hand extensors." Bangladesh Journal of Medical Science 15, no. 2 (August 10, 2016): 278–82. http://dx.doi.org/10.3329/bjms.v15i2.19481.
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Background: The purpose of this paper is to describe an anatomical variation of the hand extensor on the little finger of the right hand which receives four tendons, condition unknown, as it is the first case reported so far in the literature. The human extensor tendons of hand often display an array of variations. Awareness of the anatomy and variations of the extensor tendons on the dorsum of the hand is necessary not only for the anatomist but also for surgeons when considering tendons for hand surgery, tendon rerouting or transplants. Materials and Methods: Bilateral anatomical variation in the upper limb was found during routine dissection in a 75-year-old male cadaver in the Morphology Laboratory at the University of Pamplona. The variations were recorded and photographed. Result: In the left hand the extensor digitorum there was a single tendon to the index, double tendon to the middle, triple tendon to the ring finger, a single tendon to the little finger or digiti minimi. The extensor digiti minimi has double tendon. In the right hand the extensor digitorum there was a single tendon to the index, triple tendon to the middle finger, triple tendons to the ring finger, a double tendon to the little finger. The extensor digiti minimi has double tendon. The little finger receives four tendons, 2 of extensor digitorum and 2 of extensor digiti minimi. The dorsum of the left hand and right showed juncturae tendinum type 2, between the extensors tendons in the 3rd intermetacarpal space; type 3, between the extensors tendons in the 4th inter metacarpal space. Conclusion: The presence of multiple tendons may alter the kinematics around the site of attachment to the phalanx. Knowledge of anatomical variations and normal anatomy of the extensor tendons, may be helpful while performing graft and tendon transfer operations.Bangladesh Journal of Medical Science Vol.15(2) 2016 p.278-282
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Sakaguchi, Takefumi, Bisei Ohkawara, Yasuzumi Kishimoto, Kentaro Miyamoto, Shinya Ishizuka, Hideki Hiraiwa, Naoki Ishiguro, Shiro Imagama та Kinji Ohno. "Promethazine Downregulates Wnt/β-Catenin Signaling and Increases the Biomechanical Forces of the Injured Achilles Tendon in the Early Stage of Healing". American Journal of Sports Medicine 50, № 5 (2 березня 2022): 1317–27. http://dx.doi.org/10.1177/03635465221077116.
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Background: Wnt/β-catenin signaling suppresses the differentiation of cultured tenocytes, but its roles in tendon repair remain mostly elusive. No chemical compounds are currently available to treat tendon injury. Hypothesis: We hypothesized that the inhibition of Wnt/β-catenin signaling would accelerate tendon healing. Study Design: Controlled laboratory study. Methods: Tendon-derived cells (TDCs) were isolated from rat Achilles tendons. The right Achilles tendon was injured via a dermal punch, while the left tendon was sham operated. A Wnt/β-catenin inhibitor, IWR-1, and an antihistamine agent, promethazine (PH), were locally and intramuscularly injected, respectively, for 2 weeks after surgery. The healing tendons were histologically and biomechanically evaluated. Results: The amount of β-catenin protein was increased in the injured tendons from postoperative weeks 0.5 to 2. Inhibition of Wnt/β-catenin signaling by IWR-1 in healing tendons improved the histological abnormalities and decreased β-catenin, but it compromised the biomechanical properties. As we previously reported that antihistamine agents suppressed Wnt/β-catenin signaling in human chondrosarcoma cells, we examined the effects of antihistamines on TDCs. We found that a first-generation antihistamine agent, PH, increased the expression of the tendon marker genes Mkx and Tnmd in TDCs. Intramuscular injection of PH did not improve histological abnormalities, but it decreased β-catenin in healing tendons and increased the peak force and stiffness of the healing tendons on postoperative week 2. On postoperative week 8, however, the biomechanical properties of vehicle-treated tendons became similar to those of PH-treated tendons. Conclusion: IWR-1 and PH suppressed Wnt/β-catenin signaling and improved the histological abnormalities of healing tendons. IWR-1, however, compromised the biomechanical properties of healing tendons, whereas PH improved them. Clinical Relevance: PH is a candidate repositioned drug that potentially accelerates tendon repair.
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Zhang, Kairui, Michael W. Hast, Soutarou Izumi, Yu Usami, Snehal Shetye, Ngozi Akabudike, Nancy J. Philp, et al. "Modulating Glucose Metabolism and Lactate Synthesis in Injured Mouse Tendons: Treatment With Dichloroacetate, a Lactate Synthesis Inhibitor, Improves Tendon Healing." American Journal of Sports Medicine 46, no. 9 (June 21, 2018): 2222–31. http://dx.doi.org/10.1177/0363546518778789.
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Background: Tendon injuries are common problems among athletes. Complete recovery of the mechanical structure and function of ruptured tendons is challenging. It has been demonstrated that upregulation of glycolysis and lactate production occurs in wounds, inflammation sites, and cancerous tumors, and these metabolic changes also control growth and differentiation of stem and progenitor cells. Similar metabolic changes have been reported in human healing tendons. In addition, lactate production has increased in progenitors isolated from injured tendons after treatment with IL-1β. It is thought that the metabolic changes play a role in tendon healing after injury. Hypothesis: Glucose metabolism is altered during tendon injury and healing, and modulation of this altered metabolism improves tendon repair. Study Design: Controlled laboratory study. Methods: The authors used the tendon injury model involving a complete incision of the Achilles tendon in C57BL/6J female mice and studied alterations of glucose metabolism in injured tendons with [U-13C]glucose and metabolomics analysis 1 and 4 weeks after surgery. They also examined the effects of dichloroacetate (DCA; an indirect lactate synthesis inhibitor) treatment on the recovery of structure and mechanical properties of injured tendons 4 weeks after surgery in the same mouse model. Results: Significant changes in glucose metabolism in tendons after injury surgery were detected. 13C enrichment of metabolites and intermediates, flux through glycolysis, and lactate synthesis, as well as tricarboxylic acid cycle activity, were acutely increased 1 week after injury. Increased glycolysis and lactate generation were also found 4 weeks after injury. DCA-treated injured tendons showed decreased cross-sectional area and higher values of modulus, maximum stress, and maximum force when compared with vehicle-treated injured tendons. Improved alignment of the collagen fibers was also observed in the DCA group. Furthermore, DCA treatment reduced mucoid accumulation and ectopic calcification in injured tendons. Conclusion: The findings indicate that injured tendons acutely increase glycolysis and lactate synthesis after injury and that the inhibition of lactate synthesis by DCA is beneficial for tendon healing. Clinical Relevance: Changing metabolism in injured tendons may be a therapeutic target for tendon repair.
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Pike, A. V., R. F. Ker, and R. M. Alexander. "The development of fatigue quality in high- and low-stressed tendons of sheep (Ovis aries)." Journal of Experimental Biology 203, no. 14 (July 15, 2000): 2187–93. http://dx.doi.org/10.1242/jeb.203.14.2187.
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The time taken to rupture in cyclic fatigue tests, to a stress of 45 MPa, was used to compare the fatigue quality of tendons from sheep of varying ages. Muscle and tendon cross-sectional areas were used to calculate the stress-in-life of each tendon. For any given age, high-stressed plantaris tendons were of a higher fatigue quality than low-stressed extensor tendons. Both fatigue quality and stress-in-life increased with age for each tendon type. High-stressed tendons are subjected to large increases in stress-in-life during growth, and fatigue quality increased significantly with this stress. This relationship was not seen, however, in low-stressed tendons, which are not subjected to a comparable range of stresses over time. It is possible that cells modify tendon fatigue quality in response to tendon loading history. Whilst Young's modulus was seen to increase with age, no difference was detected between high- and low-stressed tendons.
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Thorpe, Chavaunne T., Chineye P. Udeze, Helen L. Birch, Peter D. Clegg, and Hazel R. C. Screen. "Specialization of tendon mechanical properties results from interfascicular differences." Journal of The Royal Society Interface 9, no. 76 (July 4, 2012): 3108–17. http://dx.doi.org/10.1098/rsif.2012.0362.
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Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial digital flexor tendon (SDFT), also store and return energy. For efficient function, energy-storing tendons need to be more extensible than positional tendons such as the common digital extensor tendon (CDET), and when tested in vitro have a lower modulus and failure stress, but a higher failure strain. It is not known how differences in matrix organization contribute to distinct mechanical properties in functionally different tendons. We investigated the properties of whole tendons, tendon fascicles and the fascicular interface in the high-strain energy-storing SDFT and low-strain positional CDET. Fascicles failed at lower stresses and strains than tendons. The SDFT was more extensible than the CDET, but SDFT fascicles failed at lower strains than CDET fascicles, resulting in large differences between tendon and fascicle failure strain in the SDFT. At physiological loads, the stiffness at the fascicular interface was lower in the SDFT samples, enabling a greater fascicle sliding that could account for differences in tendon and fascicle failure strain. Sliding between fascicles prior to fascicle extension in the SDFT may allow the large extensions required in energy-storing tendons while protecting fascicles from damage.
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Bramlage, L. R., M. Bailey, A. L. Bertone, S. E. Weisbrode, and R. W. Henninger. "Effects of Tendon Splitting on Experimentally-Induced Acute Equine Tendinitis." Veterinary and Comparative Orthopaedics and Traumatology 05, no. 01 (1992): 01–09. http://dx.doi.org/10.1055/s-0038-1633122.
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SummaryThe objective of this study was to compare the early phases of healing between surgically split and unsplit (control) tendons in a superficial digital flexor tendinitis model. Tendinitis was induced in both forelimbs of six horses by injection with collagenase. One tendon from each horse was randomly chosen to undergo tendon splitting. In six horses, the tendons were evaluated by ultrasonography before (week 0) and after (week 1) the onset of tendinitis and at weeks two, three, and four following tendon splitting. Three horses were euthanatized at the end of week four. Three horses were maintained for an additional month and evaluated at week eight before euthanasia. Following euthanasia, microangiographic and histologic evaluations were performed. Ultrasonographic evaluation revealed a significant (p <0.05) decrease in mean tendon lesion area in the split tendons when compared to the controls at weeks three, four, and eight. By week eight, all lesions had resolved in the split but not the control tendons. Mean lesion grade was lower in the split tendons at weeks two, three, four, and eight. Tendon area was similar (p >0.05) between groups at all periods after surgery. There was a more mature vascular pattern and greater peritendinous vascular response in the split tendons compared to control tendons. Histological examination under plain and polarized light revealed more normal collagen orientation and wave formation in the repair tissue in the split tendons at weeks four and eight. The fibroblast nuclei density was significantly (p <0.05) lower in the split tendons at week eight. These findings suggest that during the time period of this study, tendon splitting results in a more rapid decrease in lesion size and superior repair tissue organization when compared to controls.In a collagenase-induced tendinitis model, tendon splitting was shown to result in a greater reduction in tendon lesion size and superior repair tissue organization when compared to control tendons.
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Hayashi, M., C. Zhao, K. N. An, and P. C. Amadio. "The effects of growth and differentiation factor 5 on bone marrow stromal cell transplants in an in vitro tendon healing model." Journal of Hand Surgery (European Volume) 36, no. 4 (May 2011): 271–79. http://dx.doi.org/10.1177/1753193410394521.
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The effects of growth differentiation factor-5 (GDF-5) and bone marrow stromal cells (BMSCs) on tendon healing were investigated under in vitro tissue culture conditions. BMSCs and GDF-5 placed in a collagen gel were interpositioned between the cut ends of dog flexor digitorum profundus tendons. The tendons were randomly assigned into four groups: 1) repaired tendon without gel; 2) repaired tendon with BMSC-seeded gel; 3) repaired tendon with GDF-5 gel without cells; and 4) repaired tendon with GDF-5 treated BMSC-seeded gel. At 2 and 4 weeks, the maximal strength of repaired tendons with GDF-5 treated BMSCs-seeded gel was significantly higher than in tendons without gel interposition. However, neither BMSCs nor GDF-5 alone significantly increased the maximal strength of healing tendons at 2 or 4 weeks. These results suggest that the combination of BMSCs and GDF-5 accelerates tendon healing, but either BMSCs or GDF-5 alone are not effective in this model.
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Beger, Orhan, Gamze Tumentemür, Coşar Uzun, Elif Nedret Keskinöz, Özlem Elvan, Deniz Uzmansel, Mert Keskinbora, Nurten Erdal, Bahar Taşdelen, and Zeliha Kurtoğlu. "Biomechanical and Morphometric Properties of the Long Flexor Tendons of the Toes: A Cadaver Study." Journal of the American Podiatric Medical Association 109, no. 4 (July 1, 2019): 282–90. http://dx.doi.org/10.7547/17-063.
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Background: We sought to show the biomechanical and morphometric properties of flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendon grafts harvested by specific surgical approaches and to assess the contribution of FHL slips to the long flexor tendons of the toes. Methods: Thirteen fresh-frozen amputated feet (average age, 79 years) were dissected. The connections between the FHL and FDL tendons and the contribution of FHL slips to the long flexor tendons were classified. The biomechanical properties of the tendons and slips were measured using a tensile device. Results: The connections between the FHL and FDL tendons were reviewed in two groups. Group 1 had FHL slips (11 cases) and group 2 had cross-slips (two cases). The FHL slips joined the second and third toe long flexor tendon structures. Tendon length decreased significantly from the second to the fifth toe (P &lt; .001). Apart from the second toe tendon being thicker than that of the fourth toe (P = .02) and Young's modulus being relatively smaller in the third versus the fourth toe tendon (P = .01), biomechanical and morphometric properties of second to fourth tendons were similar. Mechanical properties of those tendons were significantly different from fifth toe tendons and FHL slips. Morphometric and biomechanical properties of FHL slips were similar to those of the fifth toe tendon. Conclusions: Herein, FHL slips were shown to have biomechanical properties that might contribute to flexor functions of the toes. During the harvesting of tendon grafts from the FHL by minimally invasive incision techniques from the distal plane of the master knot of Henry, cutting slips between FHL and FDL tendons could be considered a cause of postoperative function loss in toes.
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Havulinna, J., O. V. Leppänen, T. L. N. Järvinen, and H. Göransson. "Comparison of modified Kessler tendon suture at different levels in the human flexor digitorum profundus tendon and porcine flexors and porcine extensors: an experimental biomechanical study." Journal of Hand Surgery (European Volume) 36, no. 8 (August 4, 2011): 670–76. http://dx.doi.org/10.1177/1753193411415936.
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This study compared the biomechanical behaviour of repairs in the human flexor digitorum profundus tendon in zones I, II and III with repairs of different segments of the porcine flexor tendon of the second digit and the extensor digiti quarti proprius tendon, in order to assess the validity of porcine tendons as models for human flexor tendon repairs. These porcine tendons were selected after comparing their size with the human flexor digitorum profundus tendon. The tendon repairs were done in three segments of each porcine tendon and repairs in the human tendons were done in zones I,II and III. Ten tendons in each group yielded a total of 90 specimens. A modified Kessler repair was done with 3-0 coated braided polyester suture and subjected to uniaxial tensile testing. In human flexor tendons, the ultimate force was higher in zones I and II than in zone III. The porcine flexor digitorum profundus tendon from the second digit and the proximal segment of the extensor digiti quarti proprius tendon behaved similarly to the human flexor tendon in zone III and can be considered as surrogates for the human flexor tendon.
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Sobel, Mark, Mark J. Geppert, Jo A. Hannafin, Walther H. O. Bohne, and Steven P. Arnoczky. "Microvascular Anatomy of the Peroneal Tendons." Foot & Ankle 13, no. 8 (October 1992): 469–72. http://dx.doi.org/10.1177/107110079201300807.
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The etiology of longitudinal splitting of the peroneus brevis tendon is unclear. It has been hypothesized that compressive load applied to the tendon as it passes through the fibular groove may compromise the vascularity of the tendon with resultant inhibition of the repair response and degeneration of tendon structure. To investigate this possibility, a study of the microvascularity of the peroneal tendons was undertaken. Twelve fresh, frozen cadaveric limbs were injected with India ink. The vascularity of the peroneal tendons was examined in situ and the tendons were harvested and cleared using a modified Spalteholz technique. The vascularity of the cleared tendons was evaluated utilizing a dissecting microscope. The vascular supply of the peroneal tendons arises from two posterolateral vincula, one for the peroneus longus tendon and one for the peroneus brevis tendon. These vincula are supplied by branches of the posterior peroneal artery. A zone of hypovascularity within the peroneus brevis or peroneus longus tendon correlating with the site of peroneus brevis splits was not found. There was no relationship between increasing age of specimens and alteration in vascular supply.
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Aneja, Arun, Spero G. Karas, Paul S. Weinhold, Hessam M. Afshari, and Laurence E. Dahners. "Suture Plication, Thermal Shrinkage, and Sclerosing Agents." American Journal of Sports Medicine 33, no. 11 (November 2005): 1729–34. http://dx.doi.org/10.1177/0363546505275492.
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Background Shortening or tightening of dense, collagenous tissues is often desirable in the treatment of laxity. Purpose To compare the effect of stress-protection suture, radiofrequency thermal shrinkage combined with stress-protection suture, and a 5% sodium morrhuate sclerosing injection on the length and biomechanical strength of the rat patellar tendon. Hypothesis Sclerosing agents will increase tendon mechanical strength. Thermal shrinkage combined with stress-protection suture and stress-protection suture only will cause a short-term decrease in tendon strength. All 3 methods will produce equivalent shortening of the tendon. Study Design Controlled laboratory study. Methods Forty-six female retired breeder rats were split into 4 groups, each receiving 1 of the 3 aforementioned treatments plus a control group that received a saline injection. After 4 weeks’ survival, the length and biomechanical properties of the patellar tendons were measured and compared to the contralateral untreated tendon. Results Rats treated with stress-protection suture had shorter tendons. Radiofrequency thermal shrinkage combined with stress-protection suture yielded tendons that were both shorter and stronger than were the untreated contralateral tendons. The sodium morrhuate-injected tendons were stronger whereas the saline-treated tendons were weaker than were their respective untreated contralateral tendons. Conclusion Surgical stress-protection suture without radiofrequency shrinkage is most effective at shortening the length of the rat patellar tendon, whereas radiofrequency thermal shrinkage combined with stress-protection suture as well as sodium morrhuate are effective at increasing the strength of rat patellar tendons. Clinical Relevance Judicious use of thermal shrinkage in combination with stress protection may improve ligament strength and decrease laxity.
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PRING, D. J., A. A. AMIS, and R. R. H. COOMBS. "The Mechanical Properties of Human Flexor Tendons in Relation to Artificial Tendons." Journal of Hand Surgery 10, no. 3 (October 1985): 331–36. http://dx.doi.org/10.1016/s0266-7681_85_80055-3.
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The continuation of an unacceptable failure rate with tendon repair or grafting procedures, largely due to adhesions, suggested that an artificial flexor tendon could be an attractive alternative. A literature search found no published data of the mechanical properties of fresh human finger flexor tendons, so a study of the strength and extensibility of 153 tendons was carried out. The bone insertion strength of twenty middle finger tendons was also examined. The results showed that an artificial tendon should have a strength of approximately 1500N, and that it should extend 13% at that load, an elongation of 26mm for a tendon 200mm long. The insertion strength was less than a half of the tendon strength. This data will allow an artificial flexor tendon to be designed with sufficient strength and the correct elastic properties to allow its function to integrate reliably with natural tendons in adjacent fingers.
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Kagan, I. I., V. V. Ivlev, and A. M. Gur'yanov. "Differences and regularities of the macro- and microscopic structure of the limb tendons." Journal of Anatomy and Histopathology 11, no. 1 (March 30, 2022): 36–43. http://dx.doi.org/10.18499/2225-7357-2022-11-1-36-43.
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The aim of the study was to present differences and regularities in the macro- and microscopic structure of the muscle tendons of the limbs identified by comparative analysis and generalization of the obtained findings.Material and methods. The study included transverse histotopograms of 519 tendons of 17 different muscles of the upper and lower limbs. Histotopograms were received from 93 human cadavers and amputated limbs of 10 patients. Transverse sections of tendons up to 20 μm thick were stained with picrofuchsin according to Van Gieson, and hematoxylin–eosin. Histotopograms were studied and photographed using a stereoscopic microscope MBS-10.Results. The authors have generalized data on the macro- and microscopic structure of the limb tendons. General regularities of the internal macro- and microscopic structure of the tendons have been specified. It has been demonstrated that these regularities are of applied relevance for improvement of restorative tendon microsurgery. Individual differences and differences between the tendons of different muscles at the structural level were revealed: the number, size, architectonics of the tendon bundles of the 1st order. Tendon bundles of the 1st order are the main structural units of the macro- and microscopic structure of the limb muscle tendons. Depending on the size of the cross-sectional area, they can be divided into small (0.004–0.009 mm2), medium (0.01–0.04 mm2), large (0.05–0.09 mm2) and very large (0.1–0.5 mm2). There were detected differences in the number, ratio and architectonics of the tendon bundles at different levels within one tendon; this allows assuming division and fusion of tendon bundles of the 1st order throughout the tendon.Conclusion. The macro- and microscopic structure of the muscle tendons of the upper and lower limbs demonstrates general regularities and differences in the structure of the various muscle tendons, the fact being of theoretical and applied significance.
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WIIG, M., and S. O. ABRAHAMSSON. "Hyaluronic Acid Modulates Cell Proliferation Unequally in Intrasynovial and Extrasynovial Rabbit Tendons In Vitro." Journal of Hand Surgery 25, no. 2 (April 2000): 183–87. http://dx.doi.org/10.1054/jhsb.1999.0354.
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As tendons differ in biochemical composition and cellular capacities, we have compared dose response effects of hyaluronic acid on cell proliferation and synthesis of matrix components in intermediate and proximal segments of intrasynovial deep flexor tendons and extrasynovial peroneus rabbit tendons in vitro. Compared with matched control tendons, hyaluronic acid inhibited cell proliferation in intermediate and proximal intrasynovial flexor tendon segments at the concentrations of 0.1–2.0 mg/ml and 0.5–2.0 mg/ml respectively, but in extrasynovial tendon segments only at the concentration of 0.5 mg/ml. Hyaluronic acid did not affect synthesis of proteoglycan, collagen and non-collagen protein in either type of tendon. These results show that hyaluronic acid modulates cell proliferation unequally in intra- and extrasynovial tendons without affecting the synthesis of matrix components in the two types of tendons, indicating differential hyaluronic acid sensitivity and a possible mechanism of action.
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Suzuki, Takeshi, and Akiko Okamoto. "Marked Multiple Tendinitis at the Onset of Rheumatoid Arthritis in a Patient with Heterozygous Familial Hypercholesterolemia: Ultrasonographic Observation." Case Reports in Rheumatology 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/486348.
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A 59-year-old woman who had been diagnosed with heterozygous familial hypercholesterolemia developed rheumatoid arthritis (RA). She presented with marked tendinitis of the Achilles tendons, patellar tendons, and finger extensor tendons at the onset of RA. Ultrasonographic examination revealed that tendon lesions were predominantly tendinitis rather than paratenonitis, and that the tendinitis was of the noninsertional variety, rather than the insertional variety. Preexisting tendon xanthomas might have contributed to the unusually dominant noninsertional tendinitis of multiple tendons.
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Forthofer, BS, Michael J., Katherine M. Arnold, MS, Ramona L. Reisdorf, BS, Peter C. Amadio, MD, and Chunfeng Zhao, MD. "The Effect of Gelatin Molecular Weight on Tendon Lubrication Utilizing an Extrasynovialized Turkey Flexor Tendon Model." Military Medicine 186, Supplement_1 (January 1, 2021): 729–36. http://dx.doi.org/10.1093/milmed/usaa265.
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ABSTRACT Introduction Flexor tendon injuries are common hand injuries among the military population often resulting in functional impairment. Flexor tendon gliding friction has been linked to adhesion formation, especially with the use of extrasynovial grafts. Carbodiimide-derivatized hyaluronic acid with gelatin (cd-HA-gelatin) can reduce gliding friction of the tendon graft; however, the effects of gelatin molecular weight (MW) have not been studied. The turkey model has been shown to better match humans, but extrasynovial tendons are unavailable. The purpose of this study was to (1) manually roughen turkey flexor digitorum profundus (FDP) tendons to simulate extrasynovial tendons and (2) investigate the effects of gelatin MW on tendon friction. Materials and Methods The third digit of (n = 48) turkeys were dissected with the proximal pulley, and FDP tendon and the flexor superficialis tendon were preserved. Digits were randomly assigned into four groups: one saline control and three cd-HA-gelatin-treated groups of varying gelatin MW. Flexor digitorum profundus tendon friction was measured at its original condition, serving as a baseline. Tendons were roughened using a custom rig, and tendon friction was measured again. All four groups received treatment and gliding friction was measured every 100 cycles to a total of 1,000 cycles. Results Tendon friction significantly increased (P &lt; 0.05) after roughening. Friction in the saline control group increased steadily over repeated cycles, whereas friction of all gelatin-treated tendons decreased significantly compared with the saline control group (P &lt; 0.05), maintaining low friction to 1,000 cycles representing human tendons. There was no significant difference found between gelatin-treated groups. Conclusions We have developed a method to roughen synovial FDP tendons to create extrasynovial-like tendons for lubrication material evaluations. Cd-HA-gelatin effectively reduces tendon friction in this model. Our data suggest medium or low MW gelatin may provide a better reduction in friction compared with high MW gelatin.
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Biehl, C., M. Rupp, S. Kern, C. Heiss, T. ElKhassawna, and G. Szalay. "Extensor tendon ruptures in rheumatoid wrists." European Journal of Orthopaedic Surgery & Traumatology 30, no. 8 (July 3, 2020): 1499–504. http://dx.doi.org/10.1007/s00590-020-02731-1.
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Abstract Background and aims Rheumatoid arthritis is a chronic inflammatory disease. The associated involvement of hands and tendons is over 90% and impairs overall function. In the course of the disease, the joints are often operated on. During this operation, ruptures of the extensor tendons are found by chance without the patients noticing them. The aim of this retrospective study is the prevalence of extensor tendon rupture. Which tendon is destroyed most frequently? How can the functional outcome be measured after reconstruction? Materials and methods From 1572 operations on rheumatoid wrists, 61 extensor tendon ruptures were identified in 41 patients. The average time between the first rheumatic symptoms of the hand and surgery was 6.4 years. The average duration of RA was 7.8 years. 26 patients with 27 tendon reconstructions were included in the follow-up with an average postoperative duration of 4.6 years (3 to 14.2 years). Results Extensor tendons ruptures typically occurred at mechanically stressed sites. The most frequent rupture was found in the extensor pollicis longus tendon (21 tendons), followed by the small finger extensor tendon (14 tendons). A transfer was performed on 7 tendons. Fifty-five tendon lesions were sutured at other intact tendons. Free grafts were not used. The results in Clayton and QuickDASH scores were significantly different. Functional improvement was consistent with the results of tendon reconstructions in healthy control groups. Conclusion In rheumatoid patients, a rupture of an extensor tendon must be expected at 4%. Patients tolerate and compensate this damage for a long time. The function of the hand including the tendon function is the most important factor in assessing the success of the operation. The subjective patient acceptance depends on the progress of the underlying disease, postoperative care (ergotherapy, physiotherapy, orthosis) and the patients' demands.
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Paul, Shipra, and Srijit Das. "Anomalous extensor tendons of hand: a case report with clinical importance." Colombia Medica 38, no. 2 (June 29, 2007): 140–42. http://dx.doi.org/10.25100/cm.v38i2.497.
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The extensor digitorum muscle of the hand originates from the common extensor origin i.e., from the lateral epicondyle of the humerus and ends in four tendons, one for each digit except for the thumb. This paper reports a case, in which the tendon of the extensor digitorum ended as four tendons to the index, middle, ring and little fingers, but displayed variations in the number of tendons to each finger. Two tendons of extensor digitorum were observed in the ring and the little finger. Such an arrangement of the tendons of the extensor digitorum may have clinical importance. The presence of multiple tendons may also alter the kinematics around the site of attachment to the phalanx. Knowledge of abnormal and normal anatomy of the extensor tendons, may be helpful while performing graft and tendon transfer operations.
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McKay, K. S., and M. A. Erki. "Grouted anchorages for aramid fibre reinforced plastic prestressing tendons." Canadian Journal of Civil Engineering 20, no. 6 (December 1, 1993): 1065–69. http://dx.doi.org/10.1139/l93-137.
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Nonmetallic prestressing tendons, made of fibre-reinforced composite materials, are being proposed as alternatives to steel prestressing tendons for bridges and parking garage structures, where corrosion is the leading cause of structural deterioration. One type of commercially available nonmetallic tendons is made of pultruded aramid fibres. One of the main problems for these tendons, which is common to all nonmetallic tendons, is that the high ratio of the axial to lateral strength of fibre-reinforced materials requires special attention to the type of anchorage used. For the aramid tendon, the simplest grouted anchorage consists of a steel tube filled with nonshrink grout, into which the end of the tendon is embedded. This note presents the test results of a parametric study on grouted anchorages for pultruded aramid tendons. Key words: prestressed concrete, nonmetallic tendons, aramid fibre, grouted anchorage.
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WANG, B., and J. B. TANG. "Increased Suture Embedment in Tendons: An Effective Method to Improve Repair Strength." Journal of Hand Surgery 27, no. 4 (August 2002): 333–36. http://dx.doi.org/10.1054/jhsb.2002.0773.
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We evaluated the effect of length of suture embedment within tendons on the tensile strength of repaired tendons. Thirty fresh pig flexor tendons were divided into three groups and subjected to repairs with the Halsted tendon sutures in which 1/3, 1/2, and 2/3 of the length of the longitudinal sutures was embedded within the tendons. The repaired tendons were pulled to complete failure by an Instron tensile testing machine. The 2 mm gap-formation force, ultimate strength, stiffness, and energy to failure were greatest when 2/3 of the suture length was embedded within the tendon. The results indicate that suture embedment is an important contributor to the tensile properties of the repair, and that increase in length of suture embedment is an effective way to strengthen tendon repairs.
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CAO, Y., R. G. XIE, and J. B. TANG. "Dorsal-Enhanced Sutures Improve Tension Resistance of Tendon Repair." Journal of Hand Surgery 27, no. 2 (April 2002): 161–64. http://dx.doi.org/10.1054/jhsb.2001.0687.
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Thirty-six fresh pig flexor tendons were repaired using either the modified Kessler method or the Tang method. Nine tendons from each group were tested in an Instron tensile testing machine with the tendons passing 90° around a pulley. The other nine tendons from each group were pulled linearly by the testing machine. The 2mm gap formation force of the tendons repaired with the modified Kessler and Tang methods and pulled at 90° were 64%±5% and 79%±9% respectively of those forces recorded during linear testing. The ultimate strengths of tendons repaired by the modified Kessler and Tang methods and pulled at 90° were 76%±6% and 81%±8% respectively of the forces measured during linear testing. The percentage gap formation and ultimate strength of the Tang method was significantly higher than that of the modified Kessler suture when the tendons were pulled around a pulley. This demonstrates that the Tang suture, with its main components in the dorsal part of the repaired tendon, has greater tension resistance capacity than conventional tendon sutures which are placed in the middle of the tendon. This study suggests that dorsally-enhanced multiple tendon sutures are better placed to sustain the tension generated during active finger flexion.
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Lee, G. J., S. Kwak, H. K. Kim, S. H. Ha, H. J. Lee, and G. H. Baek. "Spontaneous Zone III rupture of the flexor tendons of the ulnar three digits in elderly Korean farmers." Journal of Hand Surgery (European Volume) 40, no. 3 (July 8, 2014): 281–86. http://dx.doi.org/10.1177/1753193414541221.
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Spontaneous flexor tendon rupture is a rare condition and the aetiology is not clear. We report 12 elderly Korean farmers with spontaneous flexor tendon ruptures. We found the rupture in the dominant hand in ten patients. A rupture in the little finger was found in all 12 patients (seven with both flexor tendons ruptured and five with only the profundus ruptured), in the ring finger in four patients (the profundus ruptured in all and both flexor tendons in two patients), and in the middle finger a partial rupture of the profundus in one patient. The tendons were ruptured close to the hook of the hamate. Repetitive friction between the flexor tendons and the hamate hook may cause the ruptures. The hamate hook was excised and the ruptured profundus tendons were reconstructed with tendon transfers with quite favourable functional recovery at follow-up of 1 to 2 years. The ruptured superficialis tendons were not reconstructed. Level of Evidence IV
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WADA, A., H. KUBOTA, K. MIYANISHI, H. HATANAKA, H. MIURA, and Y. IWAMOTO. "Comparison of Postoperative Early Active Mobilization and Immobilization in Vivo Utilising a Four-Strand Flexor Tendon Repair." Journal of Hand Surgery 26, no. 4 (August 2001): 301–6. http://dx.doi.org/10.1054/jhsb.2000.0547.
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We evaluated a technique of four-strand double-modified locking Kessler flexor tendon repair in healing tendons. Seventy-two canine flexor digitorum profundus tendons in Zone 2 were repaired and evaluated following either active mobilization or immobilization at 0, 7, 14, 28 and 42 days after surgery. Fifty-six tendons were examined for gap and ultimate strength using a tensile testing machine and 16 were evaluated with standard hematoxylin and eosin, and Masson’s trichrome staining. All tendons healed without rupture or gap formation of more than 1 mm, thus demonstrating that this repair technique has enough tensile strength to withstand early active mobilization. The gap and ultimate strength of actively mobilized tendons did not decrease significantly during the first 7 days, and were significantly greater than those of immobilized tendons throughout the 42-day study period. Actively mobilized tendons healed without the extrinsic adhesions and large tendon calluses that were found in immobilized tendons.
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Müller, Sebastian A., Nicholas P. Quirk, Julia A. Müller-Lebschi, Patricia E. Heisterbach, Lutz Dürselen, Martin Majewski, and Christopher H. Evans. "Response of the Injured Tendon to Growth Factors in the Presence or Absence of the Paratenon." American Journal of Sports Medicine 47, no. 2 (December 14, 2018): 462–67. http://dx.doi.org/10.1177/0363546518814534.
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Background: The paratenon is important for Achilles tendon healing. There is much interest in the use of exogenous growth factors (GFs) as potential agents for accelerating the healing of damaged Achilles tendons. Purpose/Hypothesis: The present study used a rat model to study the responses of the injured Achilles tendon to GFs in the presence or absence of the paratenon. The hypothesis was that responses of the injured tendon to GFs would be lower in the absence of a paratenon. Study Design: Controlled laboratory study. Methods: A 4-mm defect was created in the right Achilles tendon of 60 skeletally mature rats, which were treated with a validated combination of GFs (bFGF, BMP-12, and TGF-β1). Animals were randomly assigned to the intact paratenon (IP) group or resected paratenon (RP) group. Healing was studied anatomically, mechanically, and histologically after 1, 2, and 4 weeks. Results: IP tendons showed improved healing compared with RP tendons. IP tendons were significantly stronger (32.2 N and 48.9 N, respectively) than RP tendons (20.1 N and 31.1 N, respectively) after 1 and 2 weeks. IP tendons did not elongate as much as RP tendons and had greater cross-sectional areas (18.0 mm2, 14.4 mm2, and 16.4 mm2, respectively) after 1, 2, and 4 weeks compared with RP tendons (10.5 mm2, 8.4 mm2, and 11.9 mm2, respectively). On histology, earlier collagen deposition and parallel orientation of fibrils were found for IP tendons. Conclusion: The paratenon is essential for efficient Achilles tendon healing. Healing with GFs in this Achilles tendon defect model was superior in the presence of the paratenon. Clinical Relevance: Biological approaches to tendon engineering using GFs are in vogue and have been shown to improve healing of the rat Achilles tendon, most likely by inducing progenitor cells located within the paratenon. Clinically, resection or incision of the paratenon has been proposed for wound closure. Our data demonstrate the fundamental importance of the paratenon, which therefore should be preserved during Achilles tendon repair, especially if augmented with products such as platelet-rich plasma or autologous conditioned serum that are rich in GFs.
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Li, Jing, Mingxing Wen, Sujuan Zhang, Lingfei Du, Xin Fan, Hao Liang, Hong Wang, et al. "Research Progress on the Preparation and Application of Decellularized Tendons." Current Issues in Molecular Biology 47, no. 4 (April 6, 2025): 251. https://doi.org/10.3390/cimb47040251.
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Tendons connect animal skeletons to skeletal muscles, playing a crucial role in weight-bearing and maintaining motor functions. After decellularization, tendon extracellular matrix (tECM) retains the physicochemical characteristics similar to those of native tendons. This has made tECM a promising biomaterial in the fields of tissue engineering and regenerative medicine in recent years. This paper summarizes the origin, structure, and ECM components of animal tendons, reviews decellularization methods, and discusses recent advancements in the research and applications of decellularized tendons. Furthermore, it explores future development trends of xenogeneic decellularized tendon materials, aiming to provide a reference for fundamental research and the development of biomaterials related to decellularized tendons.
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Forslund, Carina, and Per Aspenberg. "Improved Healing of Transected Rabbit Achilles Tendon after a Single Injection of Cartilage-Derived Morphogenetic Protein-2." American Journal of Sports Medicine 31, no. 4 (July 2003): 555–59. http://dx.doi.org/10.1177/03635465030310041301.
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Background Achilles tendon ruptures in humans might be treated more efficiently with the help of a growth factor. Cartilage-derived morphogenetic protein-2 has been shown to induce formation of tendon-like tissue. Hypothesis Cartilage-derived morphogenetic protein-2 has a positive effect on mechanical parameters for tendon healing in a rabbit model with Achilles tendon transection. Study Design Controlled laboratory study. Methods The right Achilles tendon of 40 rabbits was transected without tendon suture. Cartilage-derived morphogenetic protein-2 (10 μg) or vehicle control (acetate buffer) was injected locally 2 hours postoperatively. All tendons were tested biomechanically at 8 and 14 days, and treated tendons were histologically and radiographically evaluated at 56 days. Results At 14 days, both failure load and stiffness of treated tendons were increased by 35%. The treated tendons had significantly larger callus size at 8 and 14 days. Histologic and radiographic examination showed no signs of ossification in the treated tendons after 56 days. Conclusions A single injection of cartilage-derived morphogenetic protein-2 led to a stronger and stiffer tendon callus than that in the controls without inducing bone formation. Clinical Relevance Similar results from a larger animal model would suggest a possible future use of cartilage-derived morphogenetic protein-2 in the treatment of human Achilles tendon ruptures.
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Janvier, Adam J., Emily G. Pendleton, Luke J. Mortensen, Daniel C. Green, James R. Henstock, and Elizabeth G. Canty-Laird. "Multimodal analysis of the differential effects of cyclic strain on collagen isoform composition, fibril architecture and biomechanics of tissue engineered tendon." Journal of Tissue Engineering 13 (January 2022): 204173142211304. http://dx.doi.org/10.1177/20417314221130486.
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Tendon is predominantly composed of aligned type I collagen, but additional isoforms are known to influence fibril architecture and maturation, which contribute to the tendon’s overall biomechanical performance. The role of the less well-studied collagen isoforms on fibrillogenesis in tissue engineered tendons is currently unknown, and correlating their relative abundance with biomechanical changes in response to cyclic strain is a promising method for characterising optimised bioengineered tendon grafts. In this study, human mesenchymal stem cells (MSCs) were cultured in a fibrin scaffold with 3%, 5% or 10% cyclic strain at 0.5 Hz for 3 weeks, and a comprehensive multimodal analysis comprising qPCR, western blotting, histology, mechanical testing, fluorescent probe CLSM, TEM and label-free second-harmonic imaging was performed. Molecular data indicated complex transcriptional and translational regulation of collagen isoforms I, II, III, V XI, XII and XIV in response to cyclic strain. Isoforms (XII and XIV) associated with embryonic tenogenesis were deposited in the formation of neo-tendons from hMSCs, suggesting that these engineered tendons form through some recapitulation of a developmental pathway. Tendons cultured with 3% strain had the smallest median fibril diameter but highest resistance to stress, whilst at 10% strain tendons had the highest median fibril diameter and the highest rate of stress relaxation. Second harmonic generation exposed distinct structural arrangements of collagen fibres in each strain group. Fluorescent probe images correlated increasing cyclic strain with increased fibril alignment from 40% (static strain) to 61.5% alignment (10% cyclic strain). These results indicate that cyclic strain rates stimulate differential cell responses via complex regulation of collagen isoforms which influence the structural organisation of developing fibril architectures.
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Pathan, Arshad A. "Study and Analysis of Post Tension Flat Slab for Different Tendon Layouts." International Journal for Research in Applied Science and Engineering Technology 9, no. VIII (August 15, 2021): 512–17. http://dx.doi.org/10.22214/ijraset.2021.37428.
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The main purpose of this paper is to study of post tension flat slab and study of their various tendon profiles. In this paper the analysis of various different tendon layouts with different sizes is done. In this paper different sizes of slab is considered and analysis is done with the help of SAFE software. With help of analysis we know the deflection of PT slab for different layouts. In this paper tendon layouts are as banded tendons in main direction, banded tendons in both directions, distributed tendons in both directions, banded and distributed tendons in both directions are considered with different sizes. This paper also includes PT strip stress diagram and layouts.
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Pennisi, E. "Tending Tender Tendons." Science 295, no. 5557 (February 8, 2002): 1011. http://dx.doi.org/10.1126/science.295.5557.1011.
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Hullfish, Todd J., Kenton L. Hagan, Ellen Casey, and Josh R. Baxter. "Achilles tendon structure differs between competitive distance runners and nonrunners despite no clinical signs or symptoms of midsubstance tendinopathy." Journal of Applied Physiology 125, no. 2 (August 1, 2018): 453–58. http://dx.doi.org/10.1152/japplphysiol.00012.2018.
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Achilles tendinopathy affects many running athletes and often leads to chronic pain and functional deficits. Although changes in tendon structure have been linked with tendinopathy, the effects of distance running on tendon structure are not well understood. Therefore, the purpose of this study was to characterize structural differences in the Achilles tendons in healthy young adults and competitive distance runners using quantitative ultrasound analyses. We hypothesized that competitive distance runners with no clinical signs or symptoms of tendinopathy would have quantitative signs of tendon damage, characterized by decreased collagen alignment and echogenicity, in addition to previous reports of thicker tendons. Longitudinal ultrasound images of the right Achilles tendon midsubstance were acquired in competitive distance runners and recreationally active adults. Collagen organization, mean echogenicity, and tendon thickness were quantified using image processing techniques. Clinical assessments confirmed that runners had no signs or symptoms of tendinopathy, and controls were only included if they had no history of Achilles tendon pain or injuries. Runner tendons were 40% less organized, 48% thicker, and 41% less echogenic compared with the control tendons ( P < 0.001). Young adults engaged in competitive distance running have structurally different tendons than recreationally active young adults. NEW & NOTEWORTHY In this study, we quantified the Achilles tendon substructure in distance runners, and a control group of young adults, to determine whether distance running elicits structural adaptations of the tendon. We found that competitive distance runners have structurally compromised Achilles tendons despite not showing any clinical signs or symptoms of tendon injury. These findings suggest that distance running may stimulate structural changes as a protective mechanism against tendon pain and dysfunction.
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Smallcomb, Molly, and Julianna C. Simon. "Histotripsy of healthy and tendinopathic ex vivo bovine tendons." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A316. http://dx.doi.org/10.1121/10.0018982.
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Histotripsy has successfully fractionated most soft tissues; however, highly collagenous tissues like tendon have been resistant to histotripsy fractionation. Previously, we showed that some histotripsy parameters could create mild mechanical microdamage in healthy ex vivo rat tendons. Our objective here is to evaluate whether complete histotripsy fractionation is possible in tendons. Eight bovine tendons were injected with collagenase to induce tendinopathy; an additional four tendons were unaltered. Tendons were exposed to single- or dual-frequency histotripsy at 1.07-, 1.5-, and/or 3.68-MHz with 10-ms pulses delivered at 1 Hz for 60 s. Treatments were monitored with passive cavitation detection (PCD) and samples were evaluated for damage. Results show that exposure of tendinopathic tendons to 1.5- and 3.68-MHz dual-frequency histotripsy produces a distinct, fractionated hole; 1.5- and 3.68-MHz single-frequency histotripsy produces partial fractionation without a distinct hole. No fractionation was observed in healthy tendons, or in tendinopathic tendons exposed to 1.07 MHz single- or dual-frequency histotripsy. Histologically, all tendons showed evidence of thermal necrosis independent of whether a hole was observed. PCD showsincreases in amplitude and sustainment of cavitation in exposures that successfully fractionated tendon. These results suggest histotripsy fractionation is possible in tendinopathic tendons. [Work supported by NIH R21EB027886 and R01EB032860.]
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O'Connor, Kathryn, Elaine Schmidt, Todd J. Hullfish, Michael W. Hast, and Josh R. Baxter. "Ultrasound Stress-Imaging is a Promising Tool to Detect Achilles Tendon Damage." Foot & Ankle Orthopaedics 7, no. 1 (January 2022): 2473011421S0038. http://dx.doi.org/10.1177/2473011421s00380.
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Category: Sports; Basic Sciences/Biologics Introduction/Purpose: Achilles tendon disorders are among the most common conditions observed by sports medicine physicians and among the most difficult to diagnose using current clinical tools. While qualitative imaging is a validated method to grade the severity of tendinopathy, predicting the risk of these patients progressing or suffering tendon ruptures remains a major clinical need. Therefore, the purpose of this study was to determine the efficacy of quantitative ultrasound imaging to explain in vitro fatigue-induced degradation of Achilles tendon mechanical properties. We hypothesized that decreases in mean echogenicity would be linked to in vitro tendon fatigue characterized by decreased mechanical properties. Methods: In this cadaveric tendon study, we cyclically fatigued 10 cadaveric Achilles tendons (7 donors; sex: 4M, 3F; age: 60+-15 years) and acquired b-mode ultrasound images to determine if stress-imaging biomarkers provide new insight into tendon status. We cut dog-bone shapes to concentrate tendon damage at the mid-substance where we acquired ultrasound images. In a custom- built testing bath, we cyclically applied 10-20 MPa of tendon stress at 1 Hz for 150,00 or until the specimen failed. Every 500th cycle, we applied 2 slow (0.25 Hz) tendon stresses of 10-20 MPa while acquiring ultrasound images using an 18MHz transducer. We calculated the change in tendon echogenicity caused by the applied stress to determine if this stress-imaging biomarker was associated with tendon failure. We compared these stress-imaging biomarkers from the tendons that failed (N=6) and the tendons that survived (N=4) cyclic fatigue damage using an unpaired t-test (p < 0.05). Results: Quantitative analysis of the ultrasound images indicated 2 key differences between tendons that failed during the cyclic loading protocol and those that did not (Figure 1 shows representative data of tendons with similar demographics but one tendon exhibited increased change in echogenicity before failing while the other tendon exhibited smaller changes in echogenicity and did not rupture). First, mean echogenicity decreased before failure. Second, the average change in mean echogenicity was significantly greater in tendons that failed (p = 0.031). For most tendons that did fail, mean echogenicity decreased during the third phase of fatigue life. For the tendons that did not fail, mean echogenicity plateaued along with strain during the second phase of fatigue. Conclusion: This study found detectable differences in image echogenicity during a stress test between tendons that fail during cyclic loading and those that do not. While preliminary, our findings indicate that B-mode ultrasound has potential as a clinically viable tool to predict severe tendon injuries. Our future work is focused on developing computer-based predictive tools to assess Achilles tendon fatigue in patients with tendinopathy following prolonged tendon loading to establish quantitative imaging thresholds that can serve as clinical benchmarks.
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Liu, Yibin, Xing Li, Lei Jiang, and Jinjin Ma. "Identification of age-related genes in rotator cuff tendon." Bone & Joint Research 13, no. 9 (September 10, 2024): 474–84. http://dx.doi.org/10.1302/2046-3758.139.bjr-2023-0398.r1.
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AimsRotator cuff tear (RCT) is the leading cause of shoulder pain, primarily associated with age-related tendon degeneration. This study aimed to elucidate the potential differential gene expressions in tendons across different age groups, and to investigate their roles in tendon degeneration.MethodsLinear regression and differential expression (DE) analyses were performed on two transcriptome profiling datasets of torn supraspinatus tendons to identify age-related genes. Subsequent functional analyses were conducted on these candidate genes to explore their potential roles in tendon ageing. Additionally, a secondary DE analysis was performed on candidate genes by comparing their expressions between lesioned and normal tendons to explore their correlations with RCTs.ResultsWe identified 49 genes in torn supraspinatus tendons associated with advancing age. Among them, five age-related genes showed DE in lesioned tendons compared to normal tendons. Functional analyses and previous studies have highlighted their specific enrichments in biological functions, such as muscle development (e.g. myosin heavy chain 3 (MYH3)), transcription regulation (e.g. CCAAT enhancer binding brotein delta (CEBPD)), and metal ion homeostasis (e.g. metallothionein 1X (MT1X)).ConclusionThis study uncovered molecular aspects of tendon ageing and their potential links to RCT development, offering insights for targeted interventions. These findings enhance our understanding of the mechanisms of tendon degeneration, allowing potential strategies to be made for reducing the incidence of RCT.Cite this article: Bone Joint Res 2024;13(9):474–484.
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Qin, Ting Wu, Shujiang Zhang, Zhi Ming Yang, Xiang Tao Mo, and Xiu Qun Li. "Mechanical Properties and Related Histological Alterations of Engineered Tendons In Vivo." Key Engineering Materials 288-289 (June 2005): 11–14. http://dx.doi.org/10.4028/www.scientific.net/kem.288-289.11.
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The purpose of this research is to find out the interaction between histological alterations and mechanical properties of engineered tendon implanted in situ. Defects of 0.5cm-1.0cm were made at deep flexor tendons by surgical procedure. Engineered tendons using degradable scaffolds polyglytic acid (PGA) mesh and tendon cells were implanted to repair the defects. Chickens were killed respectively at 2 weeks, 4 weeks, 6 weeks, and 8 weeks after surgery. The implants were taken out for histological examination, biomechanical test, and collagen synthesis assay. The results showed that after surgery the PGA scaffolds degraded fast and took precedence of collagen synthesis. There were not enough amount and maturation of the collagen fibers of the new tendon at 2-8 weeks after surgery. The biomechanical properties of new tendons were less than those of the normal tendon. Therefore, it is necessary to construct engineered tendons with better degradation rate of scaffolds and suitable biomechanical stimulation so that more collagen synthesis and better biomechanical properties of new tendons can be developed early after implantation.
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Newton, Joseph B., Courtney A. Nuss, Stephanie N. Weiss, Rebecca L. Betts, Chandra M. Sehgal, and Louis J. Soslowsky. "In Vivo Photoacoustic Ultrasound (PAUS) Assay for Monitoring Tendon Collagen Compositional Changes during Injury and Healing." Diagnostics 14, no. 14 (July 12, 2024): 1498. http://dx.doi.org/10.3390/diagnostics14141498.
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Tendon injury and healing involve significant changes to tissue biology and composition. Current techniques often require animal sacrifice or tissue destruction, limiting assessment of dynamic changes in tendons, including treatment response, disease development, rupture risk, and healing progression. Changes in tendon composition, such as altered collagen content, can significantly impact tendon mechanics and function. Analyses of compositional changes typically require ex vivo techniques with animal sacrifice or destruction of the tissue. In vivo evaluation of tendons is critical for longitudinal assessment. We hypothesize that photoacoustic ultrasound detects differences in collagen concentration throughout healing. We utilized photoacoustic ultrasound, a hybrid imaging modality that combines ultrasound and laser-induced photoacoustic signals to create detailed and high-resolution images of tendons, to identify its endogenous collagen composition. We correlated the photoacoustic signal to picrosirius red staining. The results show that the photoacoustic ultrasound-estimated collagen content in tendons correlates well with picrosirius red staining. This study demonstrates that photoacoustic ultrasound can assess injury-induced compositional changes within tendons and is the first study to image these targets in rat Achilles tendon in vivo.
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Suijkerbuijk, Mathijs A. M., Max Reijman, Edwin H. G. Oei, Belle L. van Meer, Ewoud R. A. van Arkel, and Duncan E. Meuffels. "Predictive Factors of Hamstring Tendon Regeneration and Functional Recovery After Harvesting: A Prospective Follow-up Study." American Journal of Sports Medicine 46, no. 5 (February 8, 2018): 1166–74. http://dx.doi.org/10.1177/0363546517751660.
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Background: Semitendinosus and gracilis tendons may regenerate after harvesting for ligament reconstruction procedures. However, predictive factors of tendon regeneration and the extent of functional recovery remain unclear. Purpose: To identify predictive factors for hamstring tendon regeneration and to examine the morbidity of nonregenerated hamstring tendons. Study Design: Cohort study; Level of evidence, 3. Methods: Of the 154 patients who were included in a prospective follow-up study, 79 underwent reconstruction of the anterior cruciate ligament entailing the hamstring tendons and met the following inclusion criteria: (1) anterior cruciate ligament rupture diagnosed by physical examination and magnetic resonance imaging (MRI), (2) MRI within 6 months after trauma, (3) age between 18 and 45 years, and (4) 2-year follow-up MRI data available. Hamstring tendon regeneration was assessed as complete if a tendon-like structure could be visualized at the level of the joint line or more cranially. Patient characteristics—such as age, sex, body mass index, alcohol/nicotine use, activity level (Tegner scores), and functional instability (1-legged hop test)—were evaluated preoperatively and at 2 years to determine predictive factors for tendon regeneration or examine functional recovery of hamstring tendon regeneration. Results: At 2 years’ follow-up, 67.1% of the patients showed regeneration of semitendinosus tendons, 81.0% of gracilis tendons, and 59.5% of both tendons. The likelihood of semitendinosus tendon regeneration significantly decreased with aging (odds ratio [OR], 0.92 change per year of age; 95% CI, 0.84-0.99; P = .03) and smoking (OR, 0.20; 95% CI, 0.05-0.77; P = .02). No predictive factor was found for gracilis tendon regeneration. Regeneration of the semitendinosus and gracilis tendons was negatively related with smoking (OR, 0.22; 95% CI, 0.06-0.79; P = .02). Patients without regeneration showed similar postoperative visual analog scale scores during physical activity, similar Tegner scores, and a significant decrease of the upper leg circumference, as compared with their preoperative results. Regardless of the regeneration status, 1-legged hop test results significantly increased at 2-year follow-up. Conclusion: Hamstring tendon regeneration occurs less frequently in older patients and in smokers. However, absence of regenerated tendons does not seem to cause a loss of function.
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Sakuma, Yu, Kensuke Ochi, Takuji Iwamoto, Asami Saito, Koichiro Yano, Yurino Naito, Shinji Yoshida, Katsunori Ikari, and Shigeki Momohara. "Number of Ruptured Tendons and Surgical Delay as Prognostic Factors for the Surgical Repair of Extensor Tendon Ruptures in the Rheumatoid Wrist." Journal of Rheumatology 41, no. 2 (January 15, 2014): 265–69. http://dx.doi.org/10.3899/jrheum.130861.
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Objective.Extensor tendon ruptures in the rheumatoid wrist are usually restored by extensor tendon reconstruction surgery. However, the factors significantly correlated with the outcomes of extensor tendon reconstruction have not been defined. We examined factors showing a statistically significant correlation with postoperative active motion after tendon reconstruction.Methods.Spontaneous extensor tendon ruptures of 66 wrists in patients (mean age, 52.6 yrs) with rheumatoid arthritis (RA) were evaluated. All patients underwent tendon reconstruction surgery with wrist arthroplasty or arthrodesis. Active ranges of motion of the affected fingers were evaluated at 12 weeks postsurgery. Statistical significance was determined using multiple and single regression analyses.Results.Forty-six (69.6%) wrists had “good” results, while 13 (19.7%) and 7 (10.6%) wrists had “fair” and “poor” results, respectively. In multiple regression analysis, an increased number of ruptured tendons and the age at operation were independent variables significantly correlated with the postoperative active motion of reconstructed tendons (p = 0.009). Single regression analysis also showed a significant association between the number of ruptured tendons and surgical delay (p = 0.02).Conclusion.The number of ruptured extensor tendons was significantly correlated with the results of tendon reconstruction, and the number of ruptured tendons was significantly correlated with preoperative surgical delay. Our results indicate that, in patients presenting with possible finger extensor tendon rupture, rheumatologists should consult with hand surgeons promptly to preserve hand function.