Background:
Allograft tendons are frequently used for ligament reconstruction about the knee, but they entail availability and cost challenges. The identification of other tissues that demonstrate ...equivalent performance to preferred tendons would improve limitations.
Hypothesis/Purpose:
We compared the biomechanical properties of 4 soft tissue allograft tendons: tibialis anterior (TA), tibialis posterior (TP), peroneus longus (PL), and semitendinosus (ST). We hypothesized that allograft properties would be similar when standardized by the looped diameter.
Study Design:
Controlled laboratory study.
Methods:
This study consisted of 2 arms evaluating large and small looped-diameter grafts: experiment A consisted of TA, TP, and PL tendons (n = 47 each) with larger looped diameters of 9.0 to 9.5 mm, and experiment B consisted of TA, TP, PL, and ST tendons (n = 53 each) with smaller looped diameters of 7.0 to 7.5 mm. Each specimen underwent mechanical testing to measure the modulus of elasticity (E), ultimate tensile force (UTF), maximal elongation at failure, ultimate tensile stress (UTS), and ultimate tensile strain (UTε).
Results:
Experiment A: No significant differences were noted among tendons for UTF, maximal elongation at failure, and UTϵ. UTS was significantly higher for the PL (54 MPa) compared with the TA (44 MPa) and TP (43 MPa) tendons. E was significantly higher for the PL (501 MPa) compared with the TP (416 MPa) tendons. Equivalence testing showed that the TP and PL tendon properties were equivalent or superior to those of the TA tendons for all outcomes. Experiment B: All groups exhibited a similar E. UTF was again highest in the PL tendons (2294 N) but was significantly different from only the ST tendons (1915 N). UTϵ was significantly higher for the ST (0.22) compared with the TA (0.19) and TP (0.19) tendons. Equivalence testing showed that the TA, TP, and PL tendon properties were equivalent or superior to those of the ST tendons.
Conclusion:
Compared with TA tendons, TP and PL tendons of a given looped diameter exhibited noninferior initial biomechanical strength and stiffness characteristics. ST tendons were mostly similar to TA tendons but exhibited a significantly higher elongation/UTϵ and smaller cross-sectional area. For smaller looped-diameter grafts, all tissues were noninferior to ST tendons. In contrast to previous findings, PL tendons proved to be equally strong.
Clinical Relevance:
The results of this study should encourage surgeons to use these soft tissue allografts interchangeably, which is important as the number of ligament reconstructions performed with allografts continues to rise.
Purpose
To evaluate the utility of semitendinosus tendon (ST) and gracilis tendon (GT) cross‐sectional area (CSA) on magnetic resonance imaging (MRI) and anthropometric characteristics in ...preoperative estimation of graft diameter in patients undergoing anterior cruciate ligament reconstruction (ACLR) with four‐strand hamstring autografts.
Methods
Three databases were searched on 29 August 2023. The authors adhered to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) and R‐AMSTAR (Revised Assessment of Multiple Systematic Review) guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. Data on demographics, anthropometric characteristics, imaging techniques, tendon CSA, correlation coefficients, sensitivities, specificities, regression models and cutoffs for predicting intraoperative graft diameters above 8 mm were recorded.
Results
Forty‐six studies comprising 4140 patients were included. Twelve of 19 (63.2%) studies reporting on ST + GT CSA found a moderate to very high correlation with intraoperative graft diameter. Five of 10 (50%) and one of seven (14.3%) studies reporting on ST CSA and GT CSA, respectively, found a moderate to high correlation with intraoperative graft diameter. Cutoffs of ST + GT CSA for predicting graft diameters above 8 mm ranged from 15.8 to 31.2 mm2. Nine of 35 (25.7%) studies that reported on height found a moderate to very high correlation with graft diameter. Seven of 33 (21.2%) studies reporting on weight found a moderate correlation with graft diameter.
Conclusion
Of the MRI parameters assessed, ST + GT CSA was the most reliable predictor of graft diameter. However, cutoffs, sensitivities, and specificities for predicting diameters above 8 mm were highly variable. Anthropometric characteristics in general were less predictive of graft diameter than MRI parameters. This information can be used by clinicians to predict patients at risk for ACLR failure due to insufficient graft size.
Level of Evidence
Level IV.
The purpose of this study was to investigate Achilles tendon (AT) length changes during a series of tasks that involved combinations of higher/lower force, and larger/smaller length changes of the ...medial gastrocnemius muscle-tendon unit (MTU). We sought to determine if common ultrasound-based estimates of AT length change were consistent with expectations for a passive elastic tendon acting in series with a muscle. We tested 8 healthy individuals during restricted joint calf contractions (high force, low displacement), ankle dorsi-/plantar-flexion (DF/PF) with the foot in the air (low force, high displacement), and heel raises (high force, high displacement). We experimentally estimated AT length change using two ultrasound methods, one based on muscle-tendon junction (MTJ) tracking and one based on muscle fascicle (MF) tracking. Estimates of AT length change were consistent with model expectations during restricted calf contractions, when the MTU underwent minimal length change. However, estimates of AT length changes were inconsistent with model expectations during the ankle DF/PF and heel raise tasks. Specifically, the AT was estimated to shorten substantially, often 10–20 mm, when the ankle plantarflexed beyond neutral position, despite loading conditions in which a passive, stiff spring would be expected to either lengthen (under increasing force) or maintain its length (under low force). These unexpected findings suggest the need for improvements in how we conceptually model and/or experimentally estimate MTU dynamics in vivo during motion analysis studies, particularly when the ankle plantarflexes beyond neutral.
Although glycosaminoglycans constitute a minor portion of native tissues, they play a crucial role in various physiological processes, while their abnormal expression is associated with numerous ...pathophysiologies. Glycosaminoglycans have become increasingly prevalent in biomaterial design for tendon repair, given their low immunogenicity and their inherent capacity to stimulate the regenerative processes, while maintaining resident cell phenotype and function. Further, their incorporation into three-dimensional scaffold conformations significantly improves their mechanical properties, while reducing the formation of peritendinous adhesions. Herein, we discuss the role of glycosaminoglycans in tendon physiology and pathophysiology and the advancements achieved to date using glycosaminoglycan-functionalized scaffolds for tendon repair and regeneration. It is evidenced that glycosaminoglycan functionalization has led to many improvements in tendon tissue engineering and it is anticipated to play a pivotal role in future reparative therapies.
Introduction
Porcine flexor tendons, bovine extensor tendons, and human (semitendinosus) tendons are frequently used as substitutes for human ACL grafts in biomechanical in vitro studies. This study ...compares the biomechanical properties and structural differences of these tendons.
Materials and methods
In this biomechanical study, fresh-frozen porcine flexor tendons, bovine extensor tendons, and human semitendinosus tendons were used (
n
= 36). The tendons were mounted in a uniaxial testing machine (Zwick/Roell) with cryo-clamps, leaving a 60 mm tendon part free between the two clamps. Specimens have been loaded to failure to evaluate the biomechanical parameters stiffness, yield load, and maximum load. A Total Collagen Assay Kit was used to detect differences in the total collagen type I concentration (
n
= 30). A one-way ANOVA was performed to detect differences in the means. The significance level was set at
p
< 0.05.
Results
There were no significant differences in the stiffness between the groups (bovine 194 ± 43 N/mm, porcine 211 ± 63 N/mm, and human cadaveric 208 ± 58 N/mm). The yield and maximum loads were high (>1000 N) in all groups, but they were significantly increased in both animal specimens (means of 1681–1795 N) compared with human cadaveric specimen (means of 1289–1406 N;
p
< 0.01). No difference in the collagen type I concentration was detected (N.S.).
Conclusion
Porcine flexor and bovine extensor tendons are eligible substitutes with similar stiffness and high failure loads compared with human cadaveric semitendinosus tendons in in vitro studies.
The forearm/wrist squeeze/compression test has been used to examine digital flexor tendon injuries with varied names. Furthermore, the test has not been minutely described and its mechanism remains ...unclear. We renamed the test the "distal forearm squeeze test". The purpose of this study was to elaborate on the test and elucidate the mechanism.
Two patients with digital flexor tendons ruptured in zone 3 and zone 1 respectively and 50 outpatients with intact digital tendons underwent the test. Then the test was performed on 3 chickens under 4 conditions. First, when the digital flexor and extensor tendons were all intact. Second, after the flexor tendons of the third toe were transected. Third, after the flexor tendons of all toes of the foot were transected. Finally, after the flexor and extensor tendons of all toes of the foot were transected.
In the patient with digital flexor tendons ruptured in zone 3, the test showed that the injured digit was flexed slightly while the uninjured digits were flexed obviously. In the patient with digital flexor tendon ruptured in zone 1, after separate stabilization of the proximal interphalangeal (PIP) joints of the injured and uninjured fingers in extension, the test showed that the distal interphalangeal joint of the patient's injured finger had no response, while those of the uninjured fingers were flexed. All 50 subjects showed clenched or half-clenched hands in response to the test. The test showed that all toes were flexed when the digital tendons of the chicken were intact. All toes were flexed except the third toe after the flexor tendons of the third toe were transected. All toes were extended after all the digital flexor tendons were transected. All toes had no response after all the digital flexor and extensor tendons were transected.
The distal forearm squeeze test is valuable in examining digital flexor tendon injuries. If only the flexor digitorum profundus tendon is examined, the PIP joint of the finger should be stabilized in extension during the test.
The complex structure of the bone-tendon and muscle-tendon junctions makes their reproduction for tissue engineering applications very difficult. Relatively few studies have investigated the ...characteristics of these regions from a tissue engineering view point.
PubMed, Thomson Reuters, Scopus and Google Scholar databases were searched using various combinations of the keywords 'Tendon', 'Myotendinous junction', 'Osteotendinous junction', 'Tissue engineering' and 'Scaffold'.
The available studies can be divided according to whether the objective is to build an entire composite tissue unit or to assist the recreation of interfaces, such as improving integration of autografts with the surrounding bone or with the muscle. The most used techniques are based on the electrospinning and the self-reorganized constructs process, which were applied to both bone-to-tendon junction (BTJ) and muscle-to-tendon junction (MTJ) regeneration. The use of nanofibers that mimic the hierarchical structure of the extracellular matrix (ECM), eventually functionalized by encapsulation of bioactive components, allowed cell attachment and differentiation.
There have been no translational investigations.
There is a need to devise suitable techniques that allow suitable tissue engineering of BTJ and MTJ.
Appropriately planned studies are needed to translate tissue engineering from a scientific challenge to a clinically applicable technique.
Objectively
Tendinopathy is a common problem in sports medicine which can lead to severe morbidity. Aspirin, as the classical representative of non‐steroidal anti‐inflammatory drugs (NSAIDs) for its ...anti‐inflammatory and analgesic actions, has been commonly used in treating tendinopathy. While its treatment effects on injury tendon healing are lacking, illuminating the underlying mechanism may provide scientific basis for clinical treatment.
Materials and methods
Firstly, we used immunohistochemistry and qRT‐PCR to detect changes in CD14, CD206, iNOS, IL‐6, IL‐10, MMP‐3, TIMP‐3, Col‐1a1, biglycan, Comp, Fibronectin, TGF‐β1，ACAN，EGR‐1 and FMOD. Next, Western blot was used to measure the protein levels (IL‐6, IL‐10, TGF‐β1, COMP, TIMP‐3, STAT‐3/P‐STAT‐3 and JNK/P‐JNK) in TSCs. Then, migration and proliferation of TSCs were measured through wound healing test and BrdU staining. Finally, the mechanical properties of injury tendon were detected.
Results
After aspirin treatment, the inflammation and scar formation in injury tendon were significantly inhibited by aspirin. Still, tendon's ECM was positively balanced. Increasing migration and proliferation ability of TSCs induced by IL‐1β were significantly reversed. JNK/STAT‐3 signalling pathway participated in the process above. In addition, biomechanical properties of injury tendon were significantly improved.
Conclusions
Taken together, the findings suggested that aspirin inhibited inflammation and scar formation via regulation of JNK/STAT‐3 signalling and decreased rerupture risk of injury tendon. Aspirin could be an ideal therapeutic strategy in tendon injury healing.
Effect of aging and exercise on the tendon Svensson, Rene B; Heinemeier, Katja Maria; Couppé, Christian ...
Journal of applied physiology (1985),
2016-Dec-01, Letnik:
121, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Here, we review the literature on how tendons respond and adapt to ageing and exercise. With respect to aging, there are considerable changes early in life, but this seems to be maturation rather ...than aging per se. In vitro data indicate that aging is associated with a decreased potential for cell proliferation and a reduction in the number of stem/progenitor-like cells. Further, there is persuasive evidence that turnover in the core of the tendon after maturity is very slow or absent. Tendon fibril diameter, collagen content, and whole tendon size appear to be largely unchanged with aging, while glycation-derived cross-links increase substantially. Mechanically, aging appears to be associated with a reduction in modulus and strength. With respect to exercise, tendon cells respond by producing growth factors, and there is some support for a loading-induced increase in tendon collagen synthesis in humans, which likely reflects synthesis at the very periphery of the tendon rather than the core. Average collagen fibril diameter is largely unaffected by exercise, while there can be some hypertrophy of the whole tendon. In addition, it seems that resistance training can yield increased stiffness and modulus of the tendon and may reduce the amount of glycation. Exercise thereby tends to counteract the effects of aging.
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