Amadio, Peter C.

ABSTRACT Based on anecdotal observation of fatty infiltration (FI) of the opponens pollicis (OPP) muscle in patients with thumb carpometacarpal (CMC) Osteoarthritis (OA), we sought to examine the association of FI with CMC OA. We reviewed 747 consecutive 3 T wrist magnetic resonance imaging (MRI) studies for evidence of FI in the thenar muscles. This population was divided into two cohorts based on radiographic analysis: a cohort without thumb CMC OA ( n = 440) and a second cohort with thumb CMC OA ( n = 307), staged according to the Eaton–Littler classification. Statistical analysis using logistic regression was performed to investigate clinical factors associated with the presence of FI in the thenar muscles. FI was present in 133 patients with CMC OA (43.3%). FI, when present, was located only in the OPP. We found no OPP FI in the cohort without CMC OA (440 patients). Among patients with CMC OA, increasing age, male sex and advanced OA stage were significantly associated with the presence of OPP FI. OPP FI is a frequent finding in CMC OA. This FI could affect the biomechanical function of the OPP. In the future, we plan to analyze clinical outcomes in CMC OA patients with and without FI, and more focused in vivo studies of OPP function. OPP FI could potentially affect the function and the stability of the thumb CMC joint in patients with CMC OA. Orthopaedic Research Society. Journal of Orthopaedic Research® 00:00–00, 2026.

ABSTRACT Tendon adhesion is a major complication following tendon reconstruction surgery in the hand. Previous studies showed that a combination of hyaluronic acid (HA) and gelatin, covalently bound to the tendon surface, can provide a durable gliding surface to reduce adhesions in animal models both in‐vitro and in‐vivo. We have developed a similar product using good manufacturing practice (GMP) standards, in preparation for use in humans. This study aimed to examine the frictional properties and elastic modulus of the Manufactured Tendon Lubricant (MTL) when applied to an extrasynovial canine peroneus longus (PL) tendon in‐vitro. Twenty PL tendons along with the 2nd and 5th digits from adult canine forepaws, were obtained (mean age: 12 months, weight: 35 kg) from animals sacrificed in Institutional Animal Care and Use Committee (IACUC) approved protocols. Tendons were treated either with the MTL or saline solution, as a control. Eight tendons from each group (MTL vs saline‐treated) underwent friction testing, using a previously described protocol, followed by indentation testing to assess tendon elastic modulus (a marker of successful crosslinking). Two tendons from each group were not tested and were sent for scanning electron microscopy (SEM). The MTL group had significantly ( p < 0.001) lower friction and gliding resistance as well as higher elastic modulus of the PL tendons, compared to the saline group. This study demonstrates that MTL provides lubricating effects and fixation to the tendon surface and may be suitable for human testing.

Background: The radiolunate joint is conventionally thought to be spared from radiocarpal osteoarthritis, but proximal lunate degenerative changes have been noted. An investigation of radiolunate arthrokinematics in ostensibly healthy wrists may improve understanding of posttraumatic and postoperative outcomes. We hypothesize that four-dimensional computed tomography (4DCT)-derived radiolunate arthrokinematics during motion will differ between wrists with type 1 and type 2 lunates. The clinical-translational relevance of this analysis is highlighted using a 4DCT case study of scaphoid excision with 4-corner arthrodesis (SEFCA). Methods: Four-dimensional computed tomography data were collected during flexion-extension and radioulnar deviation in 19 healthy wrists (mean [SD] age: 43.6 [11.7] years, 21.1% female) and 1 wrist 3 years after SEFCA (male, 52 years). Carpal osteokinematics and joint arthrokinematics were calculated to derive median radiolunate interosseous proximities at each 4DCT-captured timepoint. Results: Median radiolunate interosseous proximities during motion are well approximated by second-order regressions in uninjured wrists. In the arthrodesed wrist, closest proximities occurred at the extremes of motion except maximum radial deviation. Conclusions: This study quantifies a normative range of median radiolunate interosseous proximities during wrist motion. The normative 4DCT datasets provide a reference range for evaluating postoperative arthrokinematics, suggesting the clinical-translational potential of dynamic imaging. The case study highlights applications for patient-level postoperative evaluation, which can be expanded to other pathologies, surgeries, or conditions in the future.

Knowledge of the adaptation of the soft tissue to mechanical factors and biomolecules would be essential to better understand the mechanism of tendon injury and to improve the outcome of tendon repair. The responses to these factors could be different for the distinct types of cells in the tendon: cells from the tendon sheath, fibroblasts from the epitenon surface, or fibroblasts from the internal endotenon. In this study, we examined the mechanical and histological characteristics of the rate of contraction of the collagen gel seeded with epitenon and endotenon fibroblasts. The rate of contraction and the mechanical property of the contracted construct depend on the gel concentration and also the treatment of TGF-β 1 .

AbstractThis study aimed to compare the clinically established autologous extrasynovial tendon graft to a newly developed tissue‐engineered allograft (Eng‐allograft) in terms of functional outcomes following flexor tendon reconstruction in a canine model. The second and fifth flexor digitorum profundus (FDP) tendons from 16 dogs were transected and repaired in Zone II. After 6 weeks of cage activity, the repaired tendons were intentionally ruptured, creating a clinically relevant model for reconstruction. The re‐ruptured FDP tendons were then reconstructed using either the clinically standard autologous extrasynovial tendon graft or the Eng‐allograft, which had been revitalized with autologous bone marrow‐derived mesenchymal stem cells (BMSCs) and synovialized using carbodiimide derivatized synovial fluid (cd‐SYN). Following 12 weeks of postoperative rehabilitation, the functional outcomes of the surgical digits were evaluated. The Eng‐allograft group exhibited improved digital function, including lower digit work of flexion and reduced adhesion status, while maintaining similar tendon gliding resistance compared to the autograft group. However, the failure load of both the distal and proximal host/graft conjunctions in the Eng‐allograft group was significantly lower than that of the autograft group with higher graft rupture at the host−graft junction. In conclusion, the decellularized allogenic intrasynovial tendon, when revitalized BMSCs and synovialized with cd‐SYN, demonstrates positive effects on digital function improvement and adhesion reduction. However, the healing at both proximal and distal graft/host junctions is far lower than the autograft. Further research is needed to enhance the healing capacity of allograft conjunctions, aiming to achieve a comparable level of healing seen with autografts.

AbstractIntroduction/AimsUltrasound shear wave elastography (SWE) of the thenar muscles has the potential to provide a simple and noninvasive assessment of the severity of carpal tunnel syndrome (CTS), but its reliability is unknown. The purpose of this study was to assess the intra‐ and inter‐rater reliability of SWE measurements of the elastic modulus of individual thenar muscles, to assess their suitability for clinical application.MethodsFourteen healthy volunteers, seven male and seven female, participated in this study. The elastic modulus of the thenar muscles was measured with SWE, with two independent examiners to assess inter‐rater reliability. The first examiner also performed a second measurement after an interval of least 1 day to assess intra‐rater reliability. Reliability was evaluated using an intraclass correlation coefficient (ICC) and 95% confidence interval (CI).ResultsFor the abductor pollicis brevis (APB) and opponens pollicis (OPP), the CI of ICC in intra‐rater reliability was 0.47–0.85 and 0.56–0.88, respectively. The CI of ICC in inter‐rater reliability was 0.27–0.78 for the APB and 0.22–0.76 for the OPP. The ICCs of intra‐ and/or inter‐rater reliability of other thenar muscles were less than 0.5.DiscussionIn this study, SWE evaluations of thenar muscles were quite variable in terms of their reliability. A larger study will be needed to determine the source of this variability, improve reliability, and assess the value of SWE in the evaluation of the severity of CTS.

AbstractSeveral tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: “Why, Who, What, Where, When, and How” (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.

Background: Flexor digitorum profundus (FDP) tendon injury is common in hand trauma, and flexor tendon reconstruction is one of the most challenging procedures in hand surgery because of severe adhesion that exceeds 25% and hinders hand function. The surface properties of a graft from extrasynovial tendons are inferior to those of the native intrasynovial FDP tendons, which has been reported as one of the major causations. Improved surface gliding ability of the extrasynovial graft is needed. Thus, this study used carbodiimide-derivatized synovial fluid and gelatin (cd-SF-gel) to modify the surface of the graft, thus improving functional outcomes using a dog in vivo model. Methods: Forty FDP tendons from the second and fifth digits of 20 adult women underwent reconstruction with a peroneus longus (PL) autograft after creation of a tendon repair failure model for 6 weeks. Graft tendons were either coated with cd-SF-gel (n = 20) or not. Animals were euthanized 24 weeks after reconstruction, and digits were collected after the animals were euthanized for biomechanical and histologic analyses. Results: Adhesion score (cd-SF-gel, 3.15 ± 1.53; control, 5 ± 1.26; P < 0.00017), normalized work of flexion (cd-SF-gel, 0.47 ± 0.28 N-mm/degree; control, 1.4 ± 1.45 N-mm/degree; P < 0.014), and distal interphalangeal joint motion (cd-SF-gel, 17.63 ± 6.77 degrees; control, 7.07 ± 12.99 degrees; P < 0.0015) in treated grafts all showed significant differences compared with nontreated grafts. However, there was no significant difference in repair conjunction strength between the two groups. Conclusion: Autograft tendon surface modification with cd-SF-gel improves tendon gliding ability, reduces adhesion formation, and enhances digit function without interfering with graft-host healing. Clinical Relevance Statement: The authors demonstrate a clinically relevant and translational technology by using the patient’s own synovial fluid to “synovialize” an autologous extrasynovial tendon graft to improve functional outcomes following flexor tendon reconstruction.

Background: Nerve injuries can result in detrimental functional outcomes. Currently, autologous nerve graft offers the best outcome for segmental peripheral nerve injury. Allografts are alternatives, but do not have comparable results. This study evaluated whether plasma-derived exosome can improve nerve regeneration and functional recovery when combined with decellularized nerve allografts. Methods: The effect of exosomes on Schwann cell proliferation and migration were evaluated. A rat model of sciatic nerve repair was used to evaluate the effect on nerve regeneration and functional recovery. A fibrin sealant was used as the scaffold for exosome. Eighty-four Lewis rats were divided into autograft, allograft, and allograft with exosome groups. Gene expression of nerve regeneration factors was analyzed on postoperative day 7. At 12 and 16 weeks, rats were subjected to maximum isometric tetanic force and compound muscle action potential. Nerve specimens were then analyzed by means of histology and immunohistochemistry. Results: Exosomes were readily taken up by Schwann cells that resulted in improved Schwann cell viability and migration. The treated allograft group had functional recovery (compound muscle action potential, isometric tetanic force) comparable to that of the autograft group. Similar results were observed in gene expression analysis of nerve regenerating factors. Histologic analysis showed no statistically significant differences between treated allograft and autograft groups in terms of axonal density, fascicular area, and myelin sheath thickness. Conclusions: Plasma-derived exosome treatment of decellularized nerve allograft may provide comparable clinical outcomes to that of an autograft. This can be a promising strategy in the future as an alternative for segmental peripheral nerve repair. Clinical Relevance Statement: Off-the-shelf exosomes may improve recovery in nerve allografts.