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The main pathogenesis of the frozen shoulder is thought to be the inflammation of the intra‐articular synovium and subsequent fibrosis of the shoulder joint capsule. However, the molecular pathogenesis of the frozen shoulder is still unknown. A class of noncoding RNAs, microRNAs contribute to various diseases including musculoskeletal diseases. MicroRNA‐26a (miR‐26a) has been reported to be associated with fibrosis in several organs. This study aims to reveal the role of miR‐26a on fibrosis in the shoulder capsule using a frozen shoulder model in miR‐26a deficient (miR‐26a KO) mice. MiR‐26a KO and wild‐type (WT) mice were investigated using a frozen shoulder model. The range of motion (ROM) of the shoulder, histopathological changes such as synovitis, and fibrosis‐related gene expression in the model mice were evaluated to determine the role of miR‐26a. In WT mice, both inflammatory cell infiltration and thickening of the inferior shoulder joint capsule were observed after 1 week of immobilization, and this thickening further progressed over the subsequent 6 weeks. However, the immobilized shoulder in miR‐26a KO mice consistently exhibited significantly better ROM compared with WT mice at 1 and 6 weeks, and histological changes were significantly less severe. The expression of inflammation‐ and fibrosis‐related genes was decreased in the miR‐26a KO mice compared with WT mice at 1 and 6 weeks. Together, miR‐26a deficiency attenuated the severity of frozen shoulder in the immobilization model mouse. The present study suggests that miR‐26a has the potential to be a target miRNA for therapeutic approach to frozen shoulder. [ABSTRACT FROM AUTHOR]

Given discrepancies identified in current veterinary anatomy textbooks, we aimed to re-examine the anatomic patterns of the extensor tendons of the manus considering their prevalence and measurements. This study was conducted based on the dissection of the right and left distal forelimbs of 22 domestic short-haired cats (12 females and 10 males), fixed in 10% formalin solution. In the most frequent specimens (23 of 44 distal limbs -52.3%-), the m. extensor digitorum lateralis consisted of three bellies which sent three tendons to digits III-V and a tendon branch to digit II, which united with the extensor digiti I et II tendon to that digit, or inserted onto the medial aspect of the metacarpophalangeal joint capsule of digit III in 9.1% of distal limbs. In other cases, the tendon branch to digit II was absent or arose directly from the most medial belly of this muscle in 25% and 13.6% of distal limbs, respectively. The m. extensor digiti I et II was found to have two unequal bellies, leading to two medial and lateral tendons. The tendons exhibited 5 different configurations. In the most common specimens (68.2%), the medial tendon was bifurcated into two branches to digit I and the medial aspect of digit II as well as the lateral tendon ran to the lateral aspect of digit II to join the corresponding tendon of the extensor digitorum communis. According to this study, the current concepts of veterinary anatomical texts about the common pattern of the extensor tendons of the manus of domestic cats need to be revised, which could greatly contribute to the teaching of veterinary anatomy. [ABSTRACT FROM AUTHOR]

Background: Subacromial balloon spacer implantation (SBSI) attempts to decrease glenohumeral joint (GHJ) pain and improve function in patients with an irreparable rotator cuff tear (RCT) and minimal osteoarthritis. Between 12 and 26 weeks post-SBSI, gradual implant resorption may create a "balloon dip" that decreases GHJ function and increases pain. This retrospective cohort study attempted to delineate shoulder function, active mobility, strength, pain, and functional task impairment during the "balloon dip" period. Materials and methods: Sixty-five consecutive patients (55.9 ± 7 years of age, 42 men) with an irreparable RCT treated by the same fellowship-trained shoulder surgeon participated in this study. Outcome measurements pre-SBSI, during Phase I (early pain control ≤ 3 weeks post-SBSI), Phase II (early rehabilitation > 3–11 weeks post-SBSI), Phase III (advanced rehabilitation-early balloon resorption > 11–16 weeks post-SBSI), Phase IV (early strength training > 16–24 weeks post-SBSI), and Phase V (advanced strength training > 24 weeks post-SBSI) included the American Shoulder and Elbow Society (ASES) score for perceived bilateral shoulder function, visual analog scale (VAS) surgical shoulder pain score, active mobility, and shoulder manual muscle strength testing (p ≤ 0.05). Results: The mean final follow-up time was 40 weeks (range = 24.1–89.7 weeks). The surgical shoulder had higher ASES scores at Phase V than pre-SBSI. Surgical shoulder pain was less during Phase V than pre-SBSI. The surgical shoulder had greater flexion during Phase V than at Phase II or pre-SBSI, and greater external rotation (adducted) during Phases V-III than pre-SBSI. Peak shoulder internal rotation to level 12 (thoracic spinous process #10) occurred during Phase V. Peak shoulder flexor, external rotator, and internal rotator strength occurred during Phase V. During Phase I, most subjects were unable to sleep on their surgical shoulder, wash their back/do up their bra, reach a high shelf, or lift 10-lbs overhead. Tasks that were impaired during the "balloon dip" (between Phase III and V) were lifting 10-lbs overhead, reaching a high shelf, and doing normal work. By the end of Phase V, however, most subjects could perform each task with minimal or no difficulty. Conclusion: Surgical shoulder function improved and pain decreased, however, specific perceived functional task impairments remained. During the "balloon dip" phase, the perceived ability to lift 10 lbs above shoulder level, to reach a high shelf, and to do usual work activities were the most impaired tasks. [ABSTRACT FROM AUTHOR]

Background: While the benefits of sonication for improving periprosthetic joint infection (PJI) are well-documented, its potential therapeutic effect against bacterial biofilm remains unstudied. This study aimed to investigate the safety and efficacy of a novel nanoparticle ultrasonication process on methicillin-resistant Staphylococcus aureus (MRSA) bacterial biofilm formation in a PJI rat model. Methods: This novel ultrasonication process was designed to remove attached bacterial biofilm from implant and peri-articular tissues, without damaging native tissues or compromising implant integrity. Twenty-five adult Sprague–Dawley rats underwent a surgical procedure and were colonized with intra-articular MRSA, followed by the insertion of a titanium screw. Three weeks after the index surgery, the animals received a second procedure during which the screws were explanted, and soft tissue was sampled. The intraoperative use of the nanoparticle sonication treatment was employed to assess the device's safety, while ex vivo treatment on the retrieved tissue and implants was used to evaluate its efficacy. Results: Clinical and histological assessments did not indicate any macro- or micro-damage to the host tissue. Sonication of the retrieved tissues demonstrated an average bacterial removal of 2 × 103 CFU/mL and 1 × 104 CFU/gram of tissue. Compared to the standard-of-care group (n = 10), implants treated with sonication (n = 15) had significantly lower remaining bacteria, as indicated by crystal violet absorbance measurements (P = 0.012). Conclusions: This study suggests that nanoparticle sonication technology can successfully remove attached bacterial biofilms from explanted orthopedic hardware and the joint capsule, without negatively affecting native tissue. The study provides initial results supporting the potential of nanoparticle sonication as an adjuvant treatment option during a DAIR (debridement, antibiotics, and implant retention) procedure for PJI, paving the way for future clinical trials. [ABSTRACT FROM AUTHOR]

This study aimed to morphologically and histologically examine whether pig is useful as models for rotator cuff tear (RCT). The morphology of the scapula and humerus bones was evaluated by taking X-ray and three-dimensional computed tomography (3D CT) scans of the right shoulders of five female pigs (age: 4 months). The rotator cuff (RC) footprint at the humeral insertion of these was observed and its shape was measured. Next, they underwent general anesthesia and an acute rotator cuff tear/rotator cuff repair (RCT/RCR) model was created using a deltoid split approach. Four weeks after surgery, the animals were euthanized, the shoulder joints were harvested, and the repaired RC was evaluated by hematoxylin and eosin staining and toluidine blue staining. The scapula of the pig had a vestigial acromion, in contrast to that in humans. The supraspinatus and infraspinatus tendons were connected so as to overlap each other and attached to the postero-superior part of the greater tuberosity. These tendons were located extra-articularly, separate from the joint capsule. The average antero-posterior length of the foot print was 17.4 ± 0.7 mm on the medial margin and 19.1 ± 2.2 mm on the lateral margin. The maximum medial-to-lateral width of it was 5.1 ± 0.5 mm. In all RCT/RCR models at 4 weeks after surgery, the repaired RC compound tendon was visually confirmed to be continuous with the footprint. Histologically, it was confirmed that regeneration of the four-layer structure of the bone-tendon junction had occurred. Porcine supraspinatus and infraspinatus attachment to the greater tuberosity have a structure similar to that of sheep and dogs, which is advantageous for creating the RCT/RCR model. It might be used for future in vivo studies of shoulder joint diseases. Pigs could potentially serve as a viable model for rotator cuff tears. [ABSTRACT FROM AUTHOR]

Osteoarthritis is a common cause of morbidity and mortality in geriatric gazelles. Propionibacterium australiense has been reported as a cause of systemic granulomas in cattle, but there are no descriptions of this bacteria infecting other species nor causing osteoarthritis, to our knowledge. An 8-y-old, castrated male, sand gazelle (Gazella leptoceros leptoceros) was managed for chronic, intermittent, progressive osteoarthritis of the right tarsus. Serial biopsies revealed pyogranulomatous dermatitis with intralesional bacteria. Serial diagnostic imaging identified osseous and soft tissue proliferation with draining tracts. Treatments over 1 y included broad-spectrum antibiotics, anti-inflammatories, joint debridement, and infusion with platelet-rich plasma and stem cells. Despite therapy, lameness persisted, azotemia developed, and subsequently, the animal was euthanized. On postmortem examination, the periarticular tissue of the right tarsus was markedly expanded by pyogranulomas and fibrosis. Histologically, the synovium, joint capsule, and overlying soft tissues were markedly expanded by pyogranulomas and numerous gram-positive and acid-fast–negative filamentous bacteria surrounded by Splendore–Hoeppli material. Within the joint, there was regionally extensive cartilage ulceration, osteonecrosis, osteolysis, and pannus formation. PCR assay of affected formalin-fixed, paraffin-embedded tissue amplified segments of 16S rRNA and β subunit of bacterial RNA polymerase (rpoB) genes with 99.7% and 95.6% identity to P. australiense. This bacterium should be considered a differential for chronic pyogranulomatous osteoarthritis in gazelles. [ABSTRACT FROM AUTHOR]

Synovial myxoma, a rare joint tumor in dogs, has traditionally been considered benign, acknowledging that local invasion into regional tissues including bone may be present. Given the diagnostic challenges in distinguishing synovial myxoma from other joint lesions through clinical features and diagnostic imaging, definitive diagnosis relies on characteristic gross and histologic features. Within the inner surface of the joint capsule, synovial myxomas form nodules of stellate-to-spindle cells within abundant myxomatous matrix. We present here 2 cases of synovial myxoma with metastasis to regional lymph nodes and compare these 2 cases to 3 cases without evidence of lymph node metastasis. Aside from lymphovascular invasion in one case with metastasis, there were no overt histologic features of the primary tumor to suggest aggressive biologic behavior. The finding of lymph node metastasis warrants reconsideration of the term "synovial myxoma" for this neoplasm. We suggest the term "synovial myxosarcoma," considering that histologic features of the primary tumor do not predict biologic behavior. Our case series highlights the importance of lymph node sampling in suspected synovial myxosarcoma cases as well as thorough histologic examination, emphasizing careful evaluation for lymphovascular invasion. [ABSTRACT FROM AUTHOR]

Imaging plays a key role in the diagnosis and management of rheumatic diseases. Although joints and periarticular tissue are commonly involved in rheumatic diseases, entheses further away from joints, such as in the Achilles tendon or plantar fascia insertion onto the calcaneus, as well as skin and subcutaneous tissue, are among other -sometimes overlooked- targets. The link of enthesitis, which describes inflammation at the insertions of ligaments, tendons, or joint capsules, with spondyloarthritis (SpA) was established just before the turn of the century as a characteristic feature based on imaging studies with histopathological correspondence. To highlight the association between enthesitis and synovitis in SpA, the anatomical unit of the "synovioentheseal complex" (SEC) and the concepts of "functional enthesis" and "articular enthesis," apart from the better known "insertional enthesis," were introduced to encompass other inflammatory lesions associated with SpA. Studies from the last two decades revealed the involvement of the SEC in rheumatic and non-rheumatic disorders with different pathogeneses. Although such involvement is sometimes distinctive, it does not necessarily point to a specific diagnosis at other times. Nevertheless, the potential of SEC inflammation in the differentiation of SpA from other forms of arthritis remains important. The purpose of this review was to provide essential information concerning the involvement of the SEC in the diagnosis of rheumatic diseases and arthritis, focusing on imaging characteristics. [ABSTRACT FROM AUTHOR]

Background: Artificial Cervical Disc Replacement (ACDR) is an effective treatment for cervical degenerative disc diseases. However, clinical information regarding the facet joint alterations after ACDR was limited. Facet tropism is common in the sub-axial cervical spine. Our previous research indicated that facet tropism could lead to increased pressure on the cervical facet joints. This study aimed to assess the impact of facet tropism on the facet contact force and facet capsule stress after ACDR. Methods: A C2–T1 cervical finite element model was constructed from computed tomography (CT) scans of a 28-year-old male volunteer. Symmetrical, moderate asymmetrical (7 degrees tropism), and severe asymmetrical (14 degrees tropism) models were created at the C5/C6 level by altering the facet orientation at the C5-C6 level. The C5/C6 ACDR was simulated in the intact, moderate asymmetrical and severe asymmetrical models. A 75-N follower load with 1.0-Nm moments was applied to the top of C2 vertebra in the models to simulate flexion, extension, lateral bending, and axial rotation with the T1 vertebra fixed. The range of motions (ROMs) under all moments, facet contact forces (FCFs) and facet capsule strains were tested. Results: In the asymmetrical model, the right FCFs considerably increased under flexion, extension, right bending, left rotation, especially under right bending the right sided FCF of the severe asymmetrical model was about 5.44 times of the neutral position, and 3.14 times of the symmetrical model. and concentrated on the cephalad part of the facets. The facet capsule stresses on both sides remarkably increased under extension, lateral bending and right rotation. In the moderate and severe asymmetrical models, the capsule strain was greater on both sides of each position than in the symmetric model. Conclusions: The face tropism increased facet contact force and facet capsule strain after ACDR, especially under extension, lateral bending, and rotation, and also could result in abnormal stress distribution on the facet joint surface and facet joint capsule. The results suggest that face tropism might be a risk factor for post-operative facet joint degeneration progression after ACDR. Facet tropism may be noteworthy when ACDR is considered as a surgical option. [ABSTRACT FROM AUTHOR]

OBJECTIVE To determine the accuracy of ultrasound for diagnosing hip luxation in dogs presenting for hind limb lameness. METHODS 24 client-owned dogs presenting with pelvic limb lameness and concern for hip luxation were enrolled in this prospective diagnostic accuracy study from April 1, 2021, to July 1, 2022. An experienced ultrasonographer and a novice ultrasonographer, both masked to the diagnoses, performed hip ultrasonography using a point-of-care ultrasound machine. The experienced evaluator also performed a more comprehensive ultrasonography with a high-end ultrasound machine to characterize concurrent pelvis and hip disease. Pelvic radiographs served as the criterion standard for the diagnosis of hip luxation. RESULTS Ultrasonographic diagnosis of hip luxation demonstrated high accuracy, ranging from 84.2% to 100% for detecting the presence of luxation and 80.6% to 98.1% for diagnosing the direction of luxation for the novice and experienced evaluators, respectively, with substantial interevaluator agreement 0< = 0.722). Compared to radiographs, ultrasound accurately diagnosed the presence of osteoarthrosis with almost perfect agreement (K = 0.913) and the presence of fractures of the femoral head/neck and the nonaxial portions of the pelvis with substantial inter modality agreement (t< = 0.775). In 36% of patients, ultrasound identified injury to soft tissue structures that contribute to hip stability, including the gluteal muscles, gemelli, and joint capsule. CONCLUSIONS Ultrasound can be utilized to accurately diagnose the presence of hip luxation and document concurrent hip and pelvic disease. CLINICAL RELEVANCE Applications include the use of ultrasonography as part of a routine point-of-care protocol to catalogue injuries in patients with acute trauma and in mobile practice or remote settings where radiography is not readily available. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to assess the impact of repairing the hip joint capsule during posterior-lateral approach total hip arthroplasty (THA) on postoperative hip joint function and late dislocation incidence. Methods: A retrospective cohort study included 413 patients, divided into experimental (hip joint capsule repair, n = 204) and control (hip joint capsule excision, n = 209) groups. Patients were followed for five years, evaluating postoperative hip range of motion (ROM), dislocation rate, VAS and HHS scores, inflammatory and coagulation markers, hospitalization, blood loss, and body composition. Statistical analysis included the Student's t-test, Chi-square test, and logistic regression for dislocation risk factors. Results: Joint capsule repair improved postoperative hip flexion and extension within six months and at two years postoperatively, internal and external rotation within three months, and abduction and adduction throughout the entire follow-up period (P < 0.05). Capsular repair also reduced early and late dislocation rates (P < 0.05). Significant differences in HHS and VAS scores, inflammatory and coagulation indicators, hospitalization, blood loss, and body composition were noted (P < 0.05). Multivariate logistic regression indicated hip joint repair, rheumatoid arthritis, epilepsy, and sarcopenia as dislocation risk factors (P < 0.05). Conclusions: Capsular repair during posterior-lateral THA improves postoperative hip function and mobility while reducing dislocation rates, blood loss, pain, inflammation, and economic burden. Patients with rheumatoid arthritis, epilepsy, or sarcopenia require individualized planning and enhanced postoperative care to minimize complications. [ABSTRACT FROM AUTHOR]

Background: Currently, there is no consensus on the adequate management of irreparable rotator cuff tears. Arthroscopic superior capsule reconstruction (SCR) seems to be an alternative treatment option. Purpose/Hypothesis: The purpose of this study was to evaluate patient-reported outcomes up to 2 years after the treatment of irreparable rotator cuff tears with SCR using an acellular porcine dermal xenograft. It was hypothesized that SCR treatment with an acellular porcine dermal xenograft would not result in a significant clinical improvement or pain relief in patients with irreparable rotator cuff tears if the xenograft fails. Study Design: Case series; Level of evidence, 4. Methods: A total of 26 consecutive patients with irreparable rotator cuff tears were enrolled in the study between 2015 and 2019. All patients underwent SCR with acellular porcine dermal xenograft. Patient-reported outcome measures including visual analog scale (VAS) for pain, the American Shoulder and Elbow Surgeons (ASES) score, the Veterans RAND 12- Item Health Survey (VR-12), and the Single Assessment Numeric Evaluation (SANE) were followed up for 2 years. For statistical analysis, the 1-way analysis of variance was used to compare means for VAS, ASES, VR-12, and SANE results between pre- and posttreatment. Magnetic resonance imaging (MRI) records were obtained at 1 year postoperatively to evaluate graft integrity. Results: In total, 22 patients were included in the patient-reported outcomes with 4 being lost at final follow-up. The mean VAS score decreased from 4.2 ± 2.5 to 1.0 ± 1.4 (P <.001) from pretreatment to 2 years postoperatively. The mean ASES – index score improved significantly from 47.7 ± 15.3 to 86.4 ± 12.9 (P <.001) and the SANE score improved from 34.0 ± 20.4 to 77.3 ± 20.2 (P <.001). In addition, a clinically important difference in the patients' quality of life was achieved, as shown by the mean changes in the VR-12 physical (+4.3) and mental scores (+9.3). Based on postoperative MRI, the dermal graft on the humeral side was intact in 15 (68.2%) patients after surgery. Conclusion: Our arthroscopic SCR with an acellular porcine dermal matrix showed significant and continuous improvement in pain and clinical scores up to a 2-year follow-up in patients with irreparable rotator cuff tears, even with structural graft failure. However, further studies and evaluation of larger patient groups are needed to evaluate the long-term effect of this procedure. [ABSTRACT FROM AUTHOR]

We compared the effects of capsule resection versus capsule suturing in patients treated with a dual-mobility trapeziometacarpal joint prosthesis. We included 131 patients with capsular resection and 57 patients with repair. The mean scores for pain and the brief Michigan Hand Outcomes Questionnaire were similar between the groups preoperatively and at 6 weeks and 1 year postoperatively. Mean key pinch strength was also similar in both groups before surgery and at 1 year, but higher in the capsular resection than in the suture group at 6 weeks. The incidence of complications reported throughout the 1-year postoperative period was not significantly different between the groups. One implant in the capsular resection group was revised for reasons most likely unrelated to capsule management. We conclude that the capsule can be safely resected during trapeziometacarpal joint implant arthroplasty. Level of evidence: III [ABSTRACT FROM AUTHOR]

Xiaoxing Tang,1,&ast; Hongjie Yuan,2,&ast; Xuehua Huang,2 Shilin Xiao,2 Yun Ji,2 Yanjing Zhou,1 Hongbo Fu,3 Jingfeng Lu,4 Mingkai Wang,5 Ke Ma2 1Department of Radiology, Nantong Hospital of Traditional Chinese Medicine, Nantong, Jiangsu Province, People’s Republic of China; 2Department of Algology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People’s Republic of China; 3Department of Algology, Nantong Hospital of Traditional Chinese Medicine, Nantong, Jiangsu Province, People’s Republic of China; 4Department of Neurosurgery, Haian People’s Hospital, Nantong, Jiangsu Province, People’s Republic of China; 5Pharmacy Department, Nantong Elderly Rehabilitation Hospital, Nantong, Jiangsu Province, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Ke Ma, Department of Algology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai, 200092, People’s Republic of China, Email marke72@163.comBackground: Dorsal ramus medial branch radiofrequency ablation is reported to be effective for refractory lumbar facet joint syndrome. However, as nerve fibers can regenerate, the therapeutic effect was reported to be short and last only 6 to 12 months. Previously, we reported a novel endoscopic joint capsule and articular process excision procedure. In that case, a satisfying effect was achieved by removing the culprit hyperplastic articular synovial entrapped in the joint space endoscopically. We presume this treatment is an etiologic treatment and can exert longer-term efficacy.Aim: This retrospective clinical trial aimed to elucidate the longer-term efficacy as well as the safety profile of the procedure.Methods: This was a retrospective descriptive study. The participants underwent endoscopic joint capsule and articular process excision procedures. The Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) before the operation, and at 3 months, 6 months, 1 year, and 2 years post-operation were recorded by reviewing medical charts and conducting telephone interviews.Results: A total of 234 participants were evaluated in the trial. After participant screening, 13 participants were included in the final analysis. The VAS score was reduced from (median (P25, P75)) 6 (4.5, 6) at pre-operation to 2 (0, 4) at 1-year post-operation and 0 (0, 1) at 2-year pre-operation. The ODI score was reduced from 37.78 (27.09, 59.95) at pre-operation to 8.89 (2.22, 24.34) at 1-year post-operation and 6 (0.02, 11.11) at 2-year post-operation. The difference was statistically significant. Further subgroup analysis demonstrated that a narrowed intervertebral space was a possible relevant factor for poor outcomes. No procedure-related complications were reported.Conclusion: Endoscopic joint capsule and articular process excision is an effective and safe procedure for refractory lumbar facet joint syndrome. The effectiveness duration can last up to 1 to 2 years.Keywords: endoscopic, lumbar facet joint syndrome, synovial entrapment, joint capsule, radiofrequency, VAS, ODI

Aims: The antidiabetic agent metformin inhibits fibrosis in various organs. This study aims to elucidate the effects of hyperglycaemia and metformin on knee joint capsule fibrosis in mice. Methods: Eight-week-old wild-type (WT) and type 2 diabetic (db/db) mice were divided into four groups without or with metformin treatment (WT met(-/+), Db met(-/+)). Mice received daily intraperitoneal administration of metformin and were killed at 12 and 14 weeks of age. Fibrosis morphology and its related genes and proteins were evaluated. Fibroblasts were extracted from the capsules of 14-week-old mice, and the expression of fibrosis-related genes in response to glucose and metformin was evaluated in vitro. Results: The expression of all fibrosis-related genes was higher in Db met(-) than in WT met(-) and was suppressed by metformin. Increased levels of fibrosis-related genes, posterior capsule thickness, and collagen density were observed in the capsules of db/db mice compared with those in WT mice; these effects were suppressed by metformin. Glucose addition increased fibrosis-related gene expression in both groups of mice in vitro. When glucose was added, metformin inhibited the expression of fibrosis-related genes other than cellular communication network factor 2 (Ccn2) in WT mouse cells. Conclusion: Hyperglycaemia promotes fibrosis in the mouse knee joint capsule, which is inhibited by metformin. These findings can help inform the development of novel strategies for treating knee joint capsule fibrosis. Cite this article: Bone Joint Res 2024;13(7):321–331.

Abstract The meniscal position within the knee is critical to maintain normal knee function. The joint capsule might dynamically coordinate the medial meniscus (MM) by transmitting a semimembranosus action. However, their interrelationships in vivo are unclear. We aimed to determine relationships among the MM, joint capsule, and semimembranosus during passive tibial external-internal and isometric tibial internal rotation at the medial and posteromedial knees of 10 healthy individuals in vivo using ultrasound. We analyzed images of the MM and joint capsule locations at the medial and posteromedial knee and the velocity waveform similarity of each structure during rotational tasks. Both isometric internal rotation with semimembranosus action and passive tibial external rotation displaced the MM inward at the medial knee. The MM and joint capsule during these MM displacements coordinately moved with more than moderate cross-correlation coefficients (passive external and isometric internal rotations, ≥ 0.54 and ≥ 0.90, respectively). The movements of the MM and joint capsule to the semimembranosus during isometric internal rotation also coordinated with moderate cross-correlation coefficients (≥ 0.62). Therefore, the joint capsule might dynamically coordinate the MM by transmitting semimembranosus action. Whether increased tibial internal rotation or semimembranosus shortening causes MM extrusion awaits further investigation.

Purpose: Joint contracture is a common disease in clinical practice, joint bleeding is an important factor affecting the progression of joint contracture. This study aimed to explore the effect of extracorporeal shock wave on alleviating joint capsule fibrosis caused by intra-articular hemorrhage in rats. Methods: Forty two SD rats were randomly divided into seven groups. Perform simple fixation and fixation after blood injection separately. Measure the range of motion of each group's knee joints and calculate the corresponding degree of contraction. Use HE staining and Masson staining to detect the number of anterior joint capsule cells and collagen deposition. Detection of changes in Wnt1, β-catenin protein expression in joint capsule using Western blotting. Results: Compared to group C, the degree of knee joint contracture in M1 and M2 groups of rats increased, and collagen deposition, cell number and Wnt1, β-catenin protein expression also increased accordingly. Compared to M1 and M2 groups, the degree of knee contraction in E1 and E2 groups were reduced, while collagen deposition, cell number and Wnt1, β-catenin protein expression were decreased, and the degree of joint contracture in NR1 and NR2 groups showed no significant improvement. Compared to NR1 and NR2 groups, the degree of knee contraction in E1 and E2 groups were reduced, while collagen deposition, cell number and Wnt1, β-catenin protein expression were decreased. Conclusions: Both rat models of knee joint contracture were successful, and joint bleeding can exacerbate joint contracture. Extracorporeal shock waves alleviate joint capsule fibrosis caused by intra-articular bleeding in rats. [ABSTRACT FROM AUTHOR]

Articular joints facilitate motion and transfer loads to underlying bone through a combination of cartilage tissue and synovial fluid, which together generate a low‐friction contact surface. Traumatic injury delivered to cartilage and the surrounding joint capsule causes secretion of proinflammatory cytokines by chondrocytes and the synovium, triggering cartilage matrix breakdown and impairing the ability of synovial fluid to lubricate the joint. Once these inflammatory processes become chronic, posttraumatic osteoarthritis (PTOA) development begins. However, the exact mechanism by which negative alterations to synovial fluid leads to PTOA pathogenesis is not fully understood. We hypothesize that removing the lubricating macromolecules from synovial fluid alters the relationship between mechanical loads and subsequent chondrocyte behavior in injured cartilage. To test this hypothesis, we utilized an ex vivo model of PTOA that involves subjecting cartilage explants to a single rapid impact followed by continuous articulation within a lubricating bath of either healthy synovial fluid, phosphate‐buffered saline (PBS), synovial fluid treated with hyaluronidase, or synovial fluid treated with trypsin. These treatments degrade the main macromolecules attributed with providing synovial fluid with its lubricating properties; hyaluronic acid and lubricin. Explants were then bisected and fluorescently stained to assess global and depth‐dependent cell death, caspase activity, and mitochondrial depolarization. Explants were tested via confocal elastography to determine the local shear strain profile generated in each lubricant. These results show that degrading hyaluronic acid or lubricin in synovial fluid significantly increases middle zone chondrocyte damage and shear strain loading magnitudes, while also altering chondrocyte sensitivity to loading. [ABSTRACT FROM AUTHOR]

Background: Previous biomechanical studies have identified capsular closure, labral repair or reconstruction, and osteochondroplasty as important surgical interventions to improve hip stability. Purpose: To investigate the outcome metrics used to quantify hip stability and assess and measure the relative contributions of the labrum, capsule, and bone to hip stability through a quantitative analysis. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: PubMed and Embase databases were searched using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies evaluated cadaveric hip biomechanics related to capsular, labral, and bony management during hip arthroscopy. Studies were assessed for distraction force and distance, fluid measures, and contact forces used to quantify the suction seal. Exclusion criteria included open surgery, arthroplasty, reorientation osteotomy, or traumatic dislocation. Results: A total of 33 biomechanical studies comprising 322 hips that evaluated 1 or more of the following were included: distraction force or distance (24 studies), fluid measures (10 studies), and contact forces (6 studies). Compared with a capsulotomy or capsulectomy, capsular repair or reconstruction demonstrated greater resistance to distraction (standardized mean difference [SMD], 1.13; 95% CI, 0.46-1.80; P =.0009). Compared with a labral tear, a labral repair or reconstruction demonstrated less resistance to distraction (SMD, −0.67; 95% CI, −1.25 to −0.09; P =.02). Compared with a labral debridement, repair or reconstruction demonstrated greater resistance to distraction (SMD, 1.74; 95% CI, 1.23 to 2.26; P <.00001). No quantitative analysis was feasible from studies evaluating the effect of osseous resection due to the heterogeneity in methodology and outcome metrics assessed. Conclusion: Most biomechanical evidence supports capsulotomy repair or reconstruction to improve hip distractive stability at the end of hip arthroscopic surgery. While the repair of a torn labrum does not improve distractive resistance, it is superior to labral debridement in most biomechanical studies. [ABSTRACT FROM AUTHOR]

Introduction: Over the last decades, arthroscopic surgery has become increasingly relevant as its minimally invasive approach offers many benefits. To investigate the risks of orthoscopic surgery at the elbow, this study aimed to investigate the development of temperatures in elbow joints while performing radiofrequency ablation in arthroscopic surgery. Materials and methods: We performed standard arthroscopic surgeries with posterolateral, transtricipital and anterolateral approaches on seven cadaveric elbows and performed ablation on predefined locations with or without irrigation. Two temperature probes were positioned into the olecranon fossa and between the ulnar nerve and the medial joint capsule. The temperature data were recorded using a real-time data logger. A bipolar radiofrequency ablation (bRFA) device was used at the medial and lateral recess and in the fossa olecrani over a defined period. Data was then analyzed using Matlab. Results: Using bRFA without irrigation results in rapidly increasing temperature within the joint. A significant temperature increase was found within only 5 s without irrigation (p = 0.0052) in the fossa olecrani. We did not observe critical temperatures above 41 °C close to the ulnar nerve within 30 s under constant irrigation (p = 0.0747). Conclusions: Radiofrequency ablation (RFA) can be safely used in elbow arthroscopy with irrigation. The continuous use without irrigation should be limited to 3 s. Despite the anatomical proximity of the ulnar nerve and capsule, we were able to show that a possible rise in temperature most likely does not affect the ulnar nerve. [ABSTRACT FROM AUTHOR]

Background: Due to a lack of routine, there is often uncertainty regarding diagnostics of tumours around the knee joint. This study aimed to provide knowledge about the frequency, distribution and diagnostic algorithm of different bone and soft tissue tumour entities of the knee at a large referral university hospital in Germany. Methods: Retrospective, longitudinal, single-centre study that reviewed adult patients from 2010 until 2020 with a suspected tumours diagnosis around the knee at a university cancer centre. Inclusion criteria were adults with true bone or soft-tissue tumours in the knee joint and in its adjacent compartments. Suspected diagnosis, histological tumour entity, localization and its surgical treatment by biopsy, resection, osteosynthesis or tumour endoprosthesis were investigated. Results: A total number of 310 adult patients were included with a mean age of 54.2 ± 18.8 years. In total 160 (51.6%) soft-tissue tumours (69/43.1% benign; 74/46.2% malignant; 17/10.6% intermediate), 92 (29.6%) primary bone tumours (46/50% benign; 39/42.3% malignant; 7/7.6% intermediate), 36 (11.6%) metastases and 22 (7.1%) lymphomas were detected. 171 (55.1%) tumours were classified as malignant. Suspected diagnosis was matched with histology in 74.5% (231/310) of all cases. In 6 cases a primarily suspected benign diagnosis turned out to be malignant. The majority of primary bone tumours was cartilage derived (63.1%;58/92) and located in the distal 2/3 of the femur, whereas intracapsular tumours of the knee joint were rare (13.0%). Soft-tissue tumours were located primarily in the middle third of the thigh (36.8%). The MRI was the diagnostic tool of choice in 98.1% of soft tissue tumours and 82.6% bone tumours. Conclusion: Awareness is crucial for detecting rare and malignant tumours around the knee, with adipocytic tumours being the most common soft tissue tumour and chondrogenic tumours as the most prevalent malignant bone tumour. Accurate diagnosis of bone tumours necessitates radiographs and frequently an additional MRI scan, while soft tissue tumours require mandatory MRI scans. Incorrectly diagnosing a tumour can have severe consequences, emphasizing the need for histological confirmation in all cases. Additionally, malignant tumours within joint capsules in adults are infrequent. [ABSTRACT FROM AUTHOR]

Femoroacetabular impingement (FAI), characterized by a pathological contact between the proximal femur and acetabulum, is a common precursor of hip osteoarthritis. Cam morphology is a bony prominence that causes FAI and frequently forms on the anterosuperior femoral head–neck junction. Despite anatomical consensus regarding the femoral head–neck junction as a boundary area covered by the articular cartilage and joint capsule, it remains unclear whether the joint capsule is continuous with the anterosuperior articular cartilage. For the anatomical consideration of cam morphology formation, this study aimed to investigate the histological characteristics of the capsular attachment on the anterosuperior femoral head–neck junction, particularly focusing on the presence or absence of continuity of the joint capsule to the articular cartilage. A total of 21 anterosuperior regions (seven hips each for the 12:00, 1:30, and 3:00 positions) from seven hips (three males and four females; mean age at death, 68.7 years) were histologically analyzed in this study for quantitative evaluation of the capsular thickness using histological sections stained with Masson's trichrome, as well as qualitative evaluation of the capsular attachment. The present study showed that the joint capsule, which folded proximally to the femoral head–neck junction from the recess, exhibited a blend of the fibrous and synovial regions. Notably, it not only continued with the superficial layer of the articular cartilage, but also attached to the articular cartilage via the fibrocartilage. This continuous region was relatively fibrous with dense connective tissue running in the longitudinal direction. The capsular thickness at the recess point (mean, 1.7 ± 0.9 mm) and those at the distal end of the articular cartilage (0.35 ± 0.16 mm) were significantly greater than the control value for the most superficial layer thickness of the articular cartilage (0.019 ± 0.003 mm) (Dunnett's T3, both p‐value <0.001). Based on the fibrous continuity between the joint capsule and articular cartilage and its thickness, this study suggests the anatomical possibility that some mechanical stress can be transmitted from the joint capsule to the articular cartilage at the frequent sites of cam morphology. [ABSTRACT FROM AUTHOR]

Differences between serum C-reactive protein (SCRP) and synovial fluid C-reactive protein (SFCRP) concentrations in healthy animals may be influenced by the sex of the individual and associated with various factors. The objective of this study was to evaluate the disparities in SCRP and SFCRP concentrations between females and males, as well as within each sex. Sixty healthy dogs (N = 60), comprising both sexes, were enrolled in the study. Peripheral blood and knee synovial fluid samples were collected for SCRP and SFCRP analysis, respectively. Serum C-reactive protein (SCRP) and SFCRP concentrations were measured, with mean of 9.61 ± 4.96 mg/L for SCRP and 1.28 ± 3.05 mg/L for SFCRP. Notably, SFCRP concentrations were consistently lower than SCRP concentrations in both sexes. Statistically significant differences were observed between sexes for both SCRP (P = 0.021) and SFCRP (P = 0.007). Further analysis within females revealed statistically significant differences between SCRP and SFCRP concentrations (P = 0.002), whereas in males, such differences were not significant (P = 0.175). Additionally, weak correlations were found between SCRP and SFCRP concentrations for both sexes (females r = 0.07; males r = 0.29). Joint capsule thickness was assessed using ultrasonography, revealing thicker joint capsules in males. A robust positive association was noted between joint capsule thickness and the SFCRP concentration in both sexes. These findings offer valuable insights into the dynamics of CRP in the context of joint health in male and female patients, elucidating the underlying pathological mechanisms of joint disease and inflammation. Overall, this underscores the importance of considering sex-specific factors in the assessment and management of joint health, as well as in the design and interpretation of studies involving SFCRP concentrations. [ABSTRACT FROM AUTHOR]

Background and Objectives: This study aimed to evaluate the relationship between SLAP lesions and the shoulder joint capsule thickness via MR arthrography. Understanding the relationship between SLAP lesions and the joint capsule thickness is important because an increased capsule thickness may indicate chronic inflammation and contribute to persistent pain and dysfunction. These findings have significant clinical implications for the diagnosis, management, and treatment strategies of shoulder joint pathologies. Materials and Methods: We retrospectively analyzed the MR arthrography results of 78 patients who underwent shoulder imaging at Düzce University Medical Faculty between October 2021 and November 2024. The study included patients diagnosed with SLAP lesions and compared them with a control group without such pathology. Data on joint capsule thickness at the level of the axillary recess, SLAP lesion type, cuff pathology, and demographic information were collected and analyzed. Results: The study included 32 patients with SLAP lesions and 46 control subjects. The mean age of the patients was 44.75 ± 14.18 years, whereas the control group had a mean age of 38.76 ± 13 years. The patient group presented a significantly greater mean anterior capsule thickness (3.13 ± 1.28 mm vs. 1.72 ± 0.7 mm, p = 0.0001), posterior capsule thickness (3.35 ± 1.32 mm vs. 1.95 ± 1.06 mm, p = 0.0001), and maximum capsule thickness (3.6 ± 1.32 mm vs. 2.06 ± 1.01 mm, p = 0.0001) in the axillary recess. SLAP type 2 lesions were the most common type (43.76%) in the patient group. Conclusions: This study revealed a significant association between SLAP lesions and an increased shoulder joint capsule thickness. These findings suggest that MR arthrography is an effective tool for assessing the joint capsule changes associated with labral tears, contributing to the better diagnosis and management of shoulder joint pathologies in clinical practice. [ABSTRACT FROM AUTHOR]

The meniscal position within the knee is critical to maintain normal knee function. The joint capsule might dynamically coordinate the medial meniscus (MM) by transmitting a semimembranosus action. However, their interrelationships in vivo are unclear. We aimed to determine relationships among the MM, joint capsule, and semimembranosus during passive tibial external-internal and isometric tibial internal rotation at the medial and posteromedial knees of 10 healthy individuals in vivo using ultrasound. We analyzed images of the MM and joint capsule locations at the medial and posteromedial knee and the velocity waveform similarity of each structure during rotational tasks. Both isometric internal rotation with semimembranosus action and passive tibial external rotation displaced the MM inward at the medial knee. The MM and joint capsule during these MM displacements coordinately moved with more than moderate cross-correlation coefficients (passive external and isometric internal rotations, ≥ 0.54 and ≥ 0.90, respectively). The movements of the MM and joint capsule to the semimembranosus during isometric internal rotation also coordinated with moderate cross-correlation coefficients (≥ 0.62). Therefore, the joint capsule might dynamically coordinate the MM by transmitting semimembranosus action. Whether increased tibial internal rotation or semimembranosus shortening causes MM extrusion awaits further investigation. [ABSTRACT FROM AUTHOR]

Injections are one way of delivering drugs directly to the joint capsule. Employing this possibility, local anesthetic, such as bupivacaine (Bu), in the form of the suspension can be administered. The aim of this work was to propose a methylcellulose-based hydrogel-incorporated bupivacaine for intra-articular injections and to study the release kinetics of the drug from the hydrogel to different acceptor media, reflecting the synovial fluid of a healthy joint and the synovial fluid of an inflamed joint. The drug release studies were performed employing the flow apparatus. The drug was released to four different acceptor fluids: phosphate buffer pH = 7.4 (PBS7.4), phosphate buffer pH = 6.8 (PBS6.8), phosphate buffer pH = 7.4 with the high-molecular-weight sodium hyaluronate (PBS7.4H), and phosphate buffer pH = 6.8 with the low-molecular-weight sodium hyaluronate (PBS6.8L). The investigation was carried out at the temperature of 37 °C. The absorbance of the Bu released was measured at the wavelength of 262 nm every 2 min for 24 h. The release profiles of Bu to the acceptor media PBS7.4, PBS6.8, PBS7.4H, and PBS6.8L were described best by the first-order kinetics and the second-order equation. According to these models, the release rate constants were the highest when Bu was released to the fluid PBS7.4 and were k1 = (7.20 ± 0.01) × 10−5 min−1 and k2 = (3.00 ± 0.04) × 10−6 mg−1 × min−1, respectively. The relative viscosity of the acceptor medium, its pH, and the addition of high-molecular-weight or low-molecular-weight sodium hyaluronate (HAH or HAL) to the acceptor fluid influenced the drug dissolution. The release of Bu into the medium reflecting healthy synovial fluid takes a different pattern from its release into the fluid of an inflamed joint. [ABSTRACT FROM AUTHOR]

The severity of hallux valgus (HV) deformity is associated with recurrence after corrective surgery because of the degenerative change of the medial capsule including the medial collateral ligament (MCL) at the metatarsophalangeal joint. This study aimed to assess the effectiveness of the MCL augmentation using a suture tape anchor of the recurrence of HV and to evaluate the histological changes of the medial joint capsule in HV patients. Thirty-four feet with severe hallux valgus were included and divided into 2 groups. Seventeen feet had the MCL reconstruction using suture tape anchor with a combination of the corrective osteotomy as the suture tape group (mean age, 64.0 years), and other seventeen feet had the corrective osteotomy without MCL reconstruction as the control group (mean age, 62.0 years). HV angle (HVA) and intermetatarsal angle (IMA) on the weight-bearing radiograms and the Japanese Society for Surgery of the Foot (JSSF) score in both groups were compared at the final follow-up. The medial capsule was harvested from other 20 feet with HV and the relationship between the severity of HV and the histological findings was analyzed. HVA, IMA, and JSSF scores in both groups were significantly improved from preoperatively to the final follow-up (P < 0.01). At the final follow-up, HVA in the suture tape group (9.2°) was significantly smaller than that in the control (15.4°) (P < 0.01). There were no significant differences in the IMA and the JSSF score at the final follow-up between both groups. Histological scores in HV with ≥40° HVA was significantly worse than those in <40°. The medial joint capsule in severe HV deformity showed the degenerative change and the MCL reconstruction using suture tape combined with osteotomy provides a strong medial constraint to prevent the recurrence of the deformity in severe hallux valgus. 3 [ABSTRACT FROM AUTHOR]

Background: There is a paucity of literature evaluating long-term outcomes and survivorship of patients undergoing primary hip arthroscopy with capsular repair for femoroacetabular impingement syndrome (FAIS). Purpose: To report 10-year survivorship and patient-reported outcomes (PROs) after primary hip arthroscopy with capsular repair for FAIS and evaluate the effect of capsular repair in patients at the highest risk for conversion to arthroplasty. Study Design: Cohort study; Level of evidence, 3. Methods: Data were prospectively collected and retrospectively reviewed on all patients undergoing primary hip arthroscopy with capsular repair between October 2008 and February 2011. Patients with a minimum 10-year follow-up on the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), and visual analog scale for pain (VAS) scores were selected. The preoperative and minimum 10-year follow-up Hip Outcome Score—Sports Specific Subscale (HOS-SSS) scores were also reported, if available. Patients with ipsilateral hip surgery, worker's compensation, Tönnis osteoarthritis grade >1, and hip dysplasia (lateral center-edge angle <25°) were excluded. Survivorship, PROS, and clinical benefit—minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS)—were reported. An additional propensity-matched subanalysis was performed on patients at the highest risk for conversion to arthroplasty, comparing patients undergoing capsular repair to patients with unrepaired capsules. Results: A total of 145 (n = 130 patients) out of 180 eligible hips (n = 165 patients) had a minimum 10-year follow-up (80.6%). Also, 126 hips (86.9%) belonged to women, and 19 hips (13.1%) belonged to men. The mean patient age was 30.3 ± 12.9 years. The survivorship rate was 91% at the 10-year follow-up. The cohort experienced significant improvements (P <.001) in the mHHS, NAHS, HOS-SSS, and VAS for pain scores. Moreover, the cohort achieved high rates of the PASS for the mHHS (89.8%), high rates of the MCID for the mHHS (82.4%), and high rates of the MCID for VAS for pain (80.6%) scores. In the propensity-matched subanalysis performed on patients with the highest risk for arthroplasty, 29 hips with capsular repair were matched to 81 hips with unrepaired capsules. While both groups experienced significant improvements in all PROs (P <.05), the group without capsule repair trended toward a higher conversion to arthroplasty rate when compared with the repair group. In addition, an odds ratio was calculated for the likelihood of converting to arthroplasty after having an unrepaired capsule compared with capsular repair (2.54 [95% CI, 0.873-7.37]; P =.087). Conclusion: Patients undergoing primary hip arthroscopy with capsular repair experienced a high survivorship rate of 91% at a minimum 10-year follow-up. Patients who did not convert to arthroplasty saw favorable improvements in PROs and achieved high clinical benefit rates. In addition, among those patients at the highest risk for conversion to arthroplasty, a trend toward greater survivorship was observed with capsular repair. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the validity of using tibial capsular reflection and septum in the posterior compartment as landmark during posterior cruciate ligament (PCL) reconstruction (PCLR). Methods: Anatomic measurements were obtained for 12 fresh human cadaveric knee specimens to observe the spatial position of the tibial insertion of the PCL in relation to the posterior septum and the capsular reflection in the posterior compartment. Sixty patients who underwent reconstruction of the PCL between 2020 and 2023 were also retrospectively investigated. The tibial tunnel was replaced in all patients using the same method (with reference to the tibial capsular reflection and the posterior septum). The placement of the tibial tunnel was assessed using X‐ray fluoroscopy intraoperatively and computed tomography and three‐dimensional reconstruction postoperatively. Results: All fibres in the tibial insertion of the PCL in the 12 cadaveric specimens were located in the posteromedial compartment, adjacent to the posterior septum. The inferior border of the PCL insertion is adjacent to the tibial capsular reflection, which is attached at the champagne glass drop‐off of the posterior tibia. In our previous cases, none of the patients experienced postoperative or intraoperative complications such as neurovascular injury, and the angle between the pin and the PCL facet was 93.1 ± 3.9° as measured on intraoperative radiographs. The mean distance from the centre of the tibial tunnel outlet to the inferior border of the PCL insertion was 5.6 ± 1.1 mm, and the distance from the centre of the tibial tunnel outlet to the outer border of the PCL insertion as a percentage of the length of the inferior border of PCL insertion was 42.2 ± 6.3%. Conclusion: The tibial capsular reflection and septum in the posterior compartment are safe and reliable soft‐tissue landmark for tibial tunnel drilling in PCLR. Level of Evidence: Level Ⅳ. [ABSTRACT FROM AUTHOR]

Objective: The goals of this study were (i) to assess the association between hip capsule morphology and pain in patients without any other MRI abnormalities that would correlate with pain and (ii) to investigate whether hip capsule morphology in hip pain patients is different from that of controls. Methods: In this study, 76 adults with hip pain who did not show any structural abnormalities on MRI and 46 asymptomatic volunteers were included. Manual segmentation of the anterior and posterior hip capsules was performed. Total and mean anterior hip capsule area, posterior capsule area, anterior-to-posterior capsule area ratio, and medial-to-lateral area ratio in the anterior capsule were quantified. Differences between the pain and control groups were evaluated using logistic regression models. Results: Patients with hip pain showed a significantly lower anterior-to-posterior area ratio as compared with the control group (p = 0.002). The pain group's posterior hip capsule area was significantly larger than that of controls (p = 0.001). Additionally, the ratio between the medial and lateral sections of the anterior capsule was significantly lower in the pain group (p = 0.004). Conclusions: Patients with hip pain are more likely to have thicker posterior capsules and a lower ratio of the anterior-to-posterior capsule area and thinner medial anterior capsules with a lower ratio of the medial-to-lateral anterior hip capsule compartment, compared with controls. Clinical relevance statement: During MRI evaluations of patients with hip pain, morphology of the hip capsule should be assessed. This study aims to be a foundation for future analyses to identify thresholds distinguishing normal from abnormal hip capsule measurements. Key Points: • Even with modern image modalities such as MRI, one of the biggest challenges in handling hip pain patients is finding a structural link for their pain. • Hip capsule morphologies that correlated with hip pain showed a larger posterior hip capsule area and a lower anterior-to-posterior capsule area ratio, as well as a smaller medial anterior capsule area with a lower medial-to-lateral anterior hip capsule ratio. • The hip capsule morphology is correlated with hip pain in patients who do not show other morphology abnormalities in MRI and should get more attention in clinical practice. [ABSTRACT FROM AUTHOR]

Objectives: In recent investigations, there has been increased focus on hip laxity and hip capsular instability, particularly in the setting of hip arthroscopy. The capsule and its internal negative pressure effects have been shown to be major contributors to hip joint stability, however, the relative contributory role of these elements remains unknown. Intraoperatively, improved understanding of hip capsule biomechanics is imperative for optimization of arthroscopic technique to access the central compartment with minimal soft tissue trauma. In turn, this can help reduce the risk of hip instability and maximize patient outcomes. The purpose of this study was to define the stiffness coefficient of the hip capsule and vacuum phenomenon in response to hip axial traction. Our hypothesis was that the vacuum phenomenon would have a greater relative contribution to axial distraction stiffness at mid-range distraction, and that the hip capsule stiffness coefficient would be greater at terminal distraction. Methods: A review of a prospectively collected database of patients undergoing hip arthroscopy was conducted from 1 July 2021 to 31 June 2022. Patients in this database underwent hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS). Inclusion criteria were 1) completion of the study traction protocol and 2) completion of hip joint venting prior to capsulotomy. Exclusion criteria were 1) previous hip surgery and 2) lack of hip distraction at 50 pounds of axial traction. The study traction protocol involved applying axial traction prior to instrumentation (Native State) of the hip using a post-free distraction system. Hips were then vented using a spinal needle and the traction protocol was repeated (Vented State). Traction intervals were 0, 50, and 100 lbs of force. Fluoroscopic images were taken at each traction interval and standardized to preoperative radiographs, which allowed for a calculation of the lateral joint space width at each interval. Overall distraction distance was calculated as the difference between 0 lbs traction and 50 and 100 lbs traction. The stiffness coefficient was calculated as k = traction force interval/distraction distance in both the Native and Vented States. Comparisons using paired-samples t-tests were conducted between the stiffness coefficients of the Native State and Vented State at 50 lbs and at 100 lbs. A p-value of <0.05 was utilized to indicate statistical significance. Results: Twenty-one patients were identified who met inclusion criteria. Mean age was 34.4 ± 13.4 years with 100% female and a mean BMI of 24.2 ± 4.8 points. Mean stiffness coefficient at 50 lbs in the Native State (10.9 ± 3.3) was significantly higher than the Vented State (4.9 ± 0.7, p < 0.001), with similar findings at 100 lbs in the Native State (10.1 ± 1.7) and Vented State (8.7 ± 1.3, p < 0.001). In the Vented State, the stiffness coefficient was significantly greater at 100 lbs (8.7 ± 1.3) than at 50 lbs (4.9 ± 0.7, p < 0.001). Conclusions: Our results provide an objective characterization of the individual contributions of the hip soft tissue restraints and the vacuum phenomenon to hip resistance to axial traction. At 50 pounds of traction, the vacuum effect contributes to ~55% of the axial distraction stiffness (resistance to axial distraction). At 100 pounds of traction force, the vacuum effect contributes only ~14% of the axial distraction stiffness. The resistance of the hip to axial distraction is of substantial clinical significance as minimization of traction force decreases intraoperative soft tissue trauma. This, however, needs to be balanced with obtaining sufficient working space within the hip joint. There is still substantial controversy regarding the biomechanics of the hip and the optimal methods for minimizing traction force related injury (e.g., post-less traction, minimization of traction time, air arthrogram, and joint venting). These data demonstrate that soft tissues have a proportionally greater effect on restraint of the of the hip at terminal distraction (~1 cm distraction), whereas the vacuum effect has a greater influence on mid-range distraction (~0.5 cm distraction). The proposed model for this phenomenon is that the negative pressure and the soft tissue tension work in parallel to restrain the hip joint. The increased influence of the soft tissue tension at end-range distraction may be due to a check rein effect of the soft tissues; once the iliofemoral ligament has been tensioned to its maximum length its stiffness and capacity for transfer of tensile force increases rapidly. In conclusion, at 50 pounds of traction, the vacuum effect contributes to ~55% of the axial distraction stiffness (resistance to axial distraction). At 100 pounds of traction force, the vacuum effect contributes only ~14% of the axial distraction stiffness. These results demonstrate that the vacuum effect is a significant restraint to axial traction applied across the hip at mid-range distraction. Additionally, the hip capsule has a relatively greater contribution to terminal distraction stiffness. [ABSTRACT FROM AUTHOR]

Purpose: To explore the early diagnostic value of superb microvascular imaging (SMI) features within the rotator cuff gap for frozen shoulder. Patients and Methods: This prospective study enrolled patients with acute early-stage frozen shoulder seeking treatment at Zhabei Central Hospital in Jing'an District, Shanghai, between July 2021 and December 2022 were enrolled in this study. Healthy controls were collected in a 1:1 ratio from the same hospital's physical examination center. All participants underwent SMI and power Doppler ultrasound (PDUS) of the rotator cuff gap. Results: The study included 79 patients with frozen shoulder and 77 healthy controls. Compared with the healthy control group, the patient group had a higher proportion of hypoechoic rotator cuff gap (81.0% vs 48.1%, P< 0.001), a thicker coracohumeral ligament (2.60± 1.01 vs 2.03± 0.97, P< 0.001), a thicker glenohumeral joint capsule (3.10± 0.99 vs 2.46± 1.17, P< 0.001), and elevated blood grading using SMI (P< 0.001) and PDUS (P=0.014). The highest area under the curve (AUC) was observed for SMI blood flow grading (AUC=0.824, 95% CI: 0.755– 0.880, P< 0.001), resulting in 82% sensitivity and 77% specificity when using a cutoff of 1. SMI blood flow grading was associated with external rotation < 30° (P=0.007) and abduction < 30° (P=0.013) but not with internal rotation < 30° (P=0.630) or flexion < 30° (P=0.562). Conclusion: The grading of SMI blood flow may emerge as a valuable predictive indicator for the early stages of frozen shoulder. This simple ultrasound technique holds the potential to enhance the diagnostic process, enabling early initiation of treatment and potentially improving patient outcomes. [ABSTRACT FROM AUTHOR]

Several studies have indicated that Camitz transfer for severe carpal tunnel does not adequately restore thumb opposition. The aim of this study was to determine whether modification of the distal insertion of the transferred palmaris longus tendon could provide more effective opposition. We used 12 fresh-frozen upper extremity specimens. For spatial analysis, we used a three-dimensional motion-tracking device. At 0 N and 5 N of traction force, the pronation angle was significantly larger for the modified procedure than for the conventional procedure. There was no significant difference in the palmar abduction angle between the two groups. The modified palmaris longus tendon insertion on the ulnar side of the thumb metacarpophalangeal joint provides more effective thumb pronation than conventional Camitz opponensplasty in a cadaver model. [ABSTRACT FROM AUTHOR]

The article discusses the use of cutting-edge transcriptomic technologies to study soft tissue joint diseases, emphasizing the need for standardized annotations and cross-species analysis to advance therapeutic targeting. It highlights the challenges in translating large data sets into effective therapies for conditions like arthritis and tendinopathy. The authors propose the formation of a joint soft tissue omics consortium to address these challenges and move towards clinical translation, drawing parallels with successful initiatives in other fields. The ultimate goal is to create a common database for multimodal analysis of joint soft tissues to inform precision therapeutic strategies. [Extracted from the article]

Pyomyositis, accompanied by aseptic arthritis, has been previously documented in several publications. However, none of the authors in the mentioned case reports offered a pathophysiological explanation for this unusual phenomenon or proposed a treatment protocol. We present a case of a healthy, 70‐year‐old male who was presented to the emergency department 4 days after tripping over a pile of wooden planks and getting stabbed by a nail to his thigh. The right thigh was swollen. Unproportional pain was produced by a light touch to the thigh. A laboratory test and a CT scan were obtained. The working diagnosis was pyomyositis of the thigh and septic arthritis of the ipsilateral knee. The patient underwent urgent debridement and irrigation of his right thigh. An arthroscopic knee lavage was performed as well. Intraoperative cultures from the thigh revealed the growth of Streptococcus pyogenes and Staphylococcus aureus. Cultures from synovial fluid were sterile; thus, septic arthritis was very unlikely. The source of the knee effusion might have been an aseptic inflammatory response due to the proximity of the thigh infection. Anatomically, the quadriceps muscle inserts on the patella, and its tendon fuses with the knee capsule, creating a direct fascial track from the thigh to the knee. The inflammatory response surrounding the infection may have followed this track, creating a domino effect, affecting adjacent capillaries within the joint capsule, and causing plasma leakage into the synovial space, leading to joint effusion. Our suggested treatment is addressing the primary infection with antibiotics and considering adding anti‐inflammatory therapy, given our suspicion that this process has an inflammatory component. [ABSTRACT FROM AUTHOR]

Worldwide, osteoarthritis (OA) is the most common cause of joint pain in older people. Many factors contribute to osteoarthritis' development and progression, including secondary osteoarthritis' underlying causes. It is important to note that osteoarthritis affects all four tissues: cartilage, bone, joint capsule, and articular apparatus. An increasingly prominent area of research in osteoarthritis regulation is microRNAs (miRNAs), a small, single-stranded RNA molecule that controls gene expression in eukaryotes. We aimed to assess and summarize current knowledge about the mechanisms of the action of miRNAs and their clinical significance. Osteoarthritis (OA) is affected by the interaction between miRNAs and inflammatory processes, as well as cartilage metabolism. MiRNAs also influence cartilage cell apoptosis, contributing to the degradation of the cartilage in OA. Studies have shown that miRNAs may have both an inhibitory and promoting effect on osteoporosis progression through their influence on molecular mechanisms. By identifying these regulators, targeted treatments for osteoarthritis may be developed. In addition, microRNA may also serve as a biomarker for osteoarthritis. By using these biomarkers, the disease could be detected faster, and early intervention can be instituted to prevent mobility loss and slow deterioration. [ABSTRACT FROM AUTHOR]

Rubber band constriction syndrome has been described in the literature, although there are very few case reports. Non-healing recurrent tenosynovitis and synovitis of the wrist joint demonstrating a circular rubber band on imaging has not been described before. Imaging studies showed retained circular band deep to the extensor tendons, embedded within the joint capsule. Surgical removal of the band by open incision led to a dramatic improvement in the outcome of the patient. Level of evidence V. [ABSTRACT FROM AUTHOR]

The posteromedial corner (PMC) of the knee is an anatomical region formed by ligamentous structures (medial collateral ligament, posterior oblique ligament, oblique popliteal ligament), the semimembranosus tendon and its expansions, the posteromedial joint capsule, and the posterior horn of the medial meniscus. Injuries to the structures of the PMC frequently occur in acute knee trauma in association with other ligamentous or meniscal tears. The correct assessment of PMC injuries is crucial because the deficiency of these supporting structures can lead to anteromedial rotation instability or the failure of cruciate ligaments grafts. This article reviews the anatomy and biomechanics of the PMC to aid radiologists in identifying injuries potentially involving PMC components. [ABSTRACT FROM AUTHOR]

The shoulder joint has a high degree of freedom and an extremely complex and unstable kinematic mechanism. Coordinated contraction of the rotator cuff muscles that stop around the humeral head and the deltoid muscles and the extensibility of soft tissues, such as the joint capsule, labrum, and ligaments, contribute to shoulder-joint stability. Understanding the mechanics of shoulder-joint movement, including soft-tissue characteristics, is important for disease prevention and the development of a device for disease treatment. This study aimed to create a musculoskeletal shoulder model to represent the realistic behavior of joint movement and soft-tissue deformation as a dynamic simulation using a rigid-body model for bones and a soft-body model for soft tissues via a spring–damper–mass system. To reproduce the muscle-contraction properties of organisms, we used a muscle-expansion representation and Hill's mechanical muscle model. Shoulder motion, including the movement of the center of rotation in joints, was reproduced, and the strain in the joint capsule during dynamic shoulder movement was quantified. Furthermore, we investigated narrowing of the acromiohumeral distance in several situations to induce tissue damage due to rotator cuff impingement at the anterior–subacromial border during shoulder abduction. Given that the model can analyze exercises under disease conditions, such as muscle and tendon injuries and impingement syndrome, the proposed model is expected to help elucidate disease mechanisms and develop treatment guidelines. [ABSTRACT FROM AUTHOR]

Osteoartritis (OA) is a debilitating disease affecting both humans and animals. In the early stages, OA is characterized by damage to the extracellular matrix (ECM) and apoptosis and depletion of chondrocytes. OA progression is characterized by hyaline cartilage loss, chondrophyte and osteophyte formation, thickening of the joint capsule and function loss in the later stages. As the regenerative potential of cartilage is very limited and osteoarthritic changes are irreversible, prevention of OA, modulation of existing osteoarthritic joint inflammation, reducing joint pain and supporting joint function are the only options. Progression of OA and pain may necessitate surgical intervention with joint replacement or arthrodesis as end-stage procedures. In human medicine, the role of adipokines in the development and progression of OA has received increasing interest. At present, the known adipokines include leptin, adiponectin, visfatin, resistin, progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin. Adipokines have been demonstrated to play a pivotal role in joint homeostasis by modulating anabolic and catabolic balance, autophagy, apoptosis and inflammatory responses. In small animals, in terms of dogs and cats, naturally occurring OA has been clearly demonstrated as a clinical problem. Similar to humans, the etiology of OA is multifactorial and has not been fully elucidated. Humans, dogs and cats share many joint related degenerative diseases leading to OA. In this review, joint homeostasis, OA, adipokines and the most common joint diseases in small animals leading to naturally occurring OA and their relation with adipokines are discussed. The purpose of this review is highlighting the translational potential of OA and adipokines research in small animal patients. [ABSTRACT FROM AUTHOR]

Background: Many recent studies have shown that patients who undergo capsular repair after hip arthroscopy achieve superior clinical outcomes compared with those who do not. However, patients with dysplasia or generalized ligamentous laxity (GLL) were not excluded from most of these studies, which may have affected the outcomes. Purpose: To determine whether capsular repair influences the outcomes of hip arthroscopy for patients without dysplasia or GLL. Study Design: Systematic review; Level of evidence, 1. Methods: Under the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, randomized controlled trials comparing the outcomes of capsulotomy with versus without repair were included, but studies that included patients with dysplasia or GLL were excluded. The study outcomes were patient-reported outcome measures (PROMs) at 6 months and 2 years postoperatively—including the modified Harris Hip Score (mHHS), Hip Outcome Score–Activities of Daily Living (HOS-ADL), and Hip Outcome Score–Sport-Specific Subscale (HOS-SSS)— and were compared between the repair and no-repair groups. A narrative analysis and meta-analysis were performed to integrate and compare the results of the 2 groups. In the meta-analysis of the outcome measures, studies with significant differences in the preoperative scores between the repair and no-repair groups were excluded because previous studies have shown that these can affect the outcomes. Results: A total of 761 studies were initially identified, of which 3 were included. Of the 322 included patients, 136 underwent capsular repair, and 186 underwent capsulotomy with no repair. The meta-analysis showed that capsular repair was associated with significantly higher postoperative PROMs: the mHHS at 2 years (P =.03), the HOS-ADL at 6 months (P =.02) and 2 years (P <.0001), and the HOS-SSS at 6 months (P =.02) and 2 years (P =.001). Conclusion: Capsular repair after hip arthroscopy was associated with superior clinical outcomes when compared with no capsular repair in patients without dysplasia or GLL. [ABSTRACT FROM AUTHOR]

A 2‐year‐old, female, entire, German shepherd dog presented for investigation of non‐weight‐bearing right hindlimb lameness following a suspected road traffic accident 1 day prior. Orthopaedic examination confirmed right lateral patellar luxation. Stifle radiographs revealed normal patella positioning with stifle joint effusion and periarticular soft tissue swelling. A surgical approach to the stifle was performed via a craniomedial parapatellar incision. A 10 cm proximodistal tear was present in the medial retinacular muscular fascia, vastus medialis, medial parapatellar fibrocartilage and joint capsule. The soft tissues were meticulously reconstructed using absorbable monofilament sutures. Surgical repair of the traumatised medial soft tissues allowed for complete resolution of the traumatic lateral patellar luxation. Moderate right hindlimb lameness persisted immediately postoperatively and improved to only a mild lameness before discharge (4 days postoperatively). The dog returned to normal exercise, with no lameness or postoperative complications reported at short‐ or long‐term follow‐up (42 and 424 days, respectively). [ABSTRACT FROM AUTHOR]

Joint contracture is one of the common diseases clinically, and joint capsule fibrosis is considered to be one of the most important pathological changes of joint contracture. However, the underlying mechanism of joint capsule fibrosis is still controversial. The present study aims to establish an animal model of knee extending joint contracture in rats, and to investigate the role of hypoxia-mediated pyroptosis in the progression of joint contracture using this animal model. 36 male SD rats were selected, 6 of which were not immobilized and were used as control group, while 30 rats were divided into I-1 group (immobilized for 1 week following 7 weeks of free movement), I-2 group (immobilized for 2 weeks following 6 weeks of free movement), I-4 group (immobilized for 4 weeks following 4 weeks of free movement), I-6 group (immobilized for 6 weeks following 2 weeks of free movement) and I-8 group (immobilized for 8 weeks) according to different immobilizing time. The progression of joint contracture was assessed by the measurement of knee joint range of motion, collagen deposition in joint capsule was examined with Masson staining, protein expression levels of HIF-1α, NLRP3, Caspase-1, GSDMD-N, TGF-β1, α-SMA and p-Smad3 in joint capsule were assessed using western blotting, and the morphological changes of fibroblasts were observed by transmission electron microscopy. The degree of total and arthrogenic contracture progressed from the first week and lasted until the first eight weeks after immobilization. The degree of total and arthrogenic contracture progressed rapidly in the first four weeks after immobilization and then progressed slowly. Masson staining indicated that collagen deposition in joint capsule gradually increased in the first 8 weeks following immobilization. Western blotting analysis showed that the protein levels of HIF-1α continued to increase during the first 8 weeks of immobilization, and the protein levels of pyroptosis-related proteins NLRP3, Caspase-1, GSDMD-N continued to increase in the first 4 weeks after immobilization and then decreased. The protein levels of fibrosis-related proteins TGF-β1, p-Smad3 and α-SMA continued to increase in the first 8 weeks after immobilization. Transmission electron microscopy showed that 4 weeks of immobilization induced cell membrane rupture and cell contents overflow, which further indicated the activation of pyroptosis. Knee extending joint contracture animal model can be established by external immobilization orthosis in rats, and the activation of hypoxia-mediated pyroptosis may play a stimulating role in the process of joint capsule fibrosis and joint contracture. [ABSTRACT FROM AUTHOR]

Frozen shoulder (FS) is a common disorder characterized by spontaneous onset of shoulder pain accompanied by progressive loss of range-of-motions. The cause of FS is still unclear, and radical therapy has not been established. With the final aim of preventing or curing FS at an earlier stage, we reviewed the pathological and biological features of this disease. Many studies indicate that the main pathology of FS is inflammation initially and fibrosis later. There are inflammatory cytokines, immune cells, fibrotic growth factors, and type-III collagen in the synovium and the joint capsule. The immune cell landscape switches from the macrophages to T cells. Activated fibroblasts seem to regulate the inflammatory and fibrotic processes. The imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteases might promote fibrosis. Additionally, advanced glycation end-products are noted in the FS synovium. Diabetes mellitus and hypothyroidism are closely related to the development of FS. In terms of nonsurgical treatment, oral or intra-articular glucocorticoids are the only drugs that provide early benefit. Some other anti-inflammatory or antifibrotic drugs may potentially control the FS, but have not been proven effective in the clinical setting. Future studies should be targeted to develop steroid-sparing agents that inhibit biological events in FS. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) tears account for 40% to 50% of all ligamentous knee injuries. Most patients with ACL ruptures undergo surgical treatment. There is currently no objective, well-documented, repeatable, and standardized nonsurgical method for ACL tear treatment. This study aimed to investigate ACL outcomes in patients who underwent a novel nanosurgery and bioengineering treatment (NSBT) for an ACL tear. Methods: This was a double-blind randomized trial including 44 patients with a history of traumatic knee injury and a confirmed ACL tear. The final sample comprised 40 patients who met all the eligibility criteria. The patients were divided into two groups: the treatment group (n = 30) and the control group (n = 10). The treatment group underwent nanosurgery with an ultrasound-guided injection of modified platelet-rich plasma (PRP) using human cell memory (RP-hCM). The control group was treated with an ultrasound-guided PRP injection into the joint capsule. At baseline and post-treatment, all patients underwent both ultrasonography and magnetic resonance imaging (MRI), and the following clinical variables were assessed: the WOMAC score, the Lysholm knee score, the visual analog scale score, and knee instability. In most patients, the clinical outcome was verified using nanoscopy. Results: The median WOMAC, VAS, and LKS scores, as well as knee instability, improved significantly 12 weeks after the procedure in the treatment group (p < 0.001). We found a significantly larger improvement in the assessed parameters in the treatment group compared to the control group (p < 0.001). In the treatment group, all the patients had good and very good clinical outcomes, while 90% of the patients had a normal ACL signal in a follow-up MRI scan. In the control group, a physical examination revealed no changes in knee stability after treatment. Conclusions: This study showed that there is a significant difference in patient experience and the duration of recovery for patients with ACL tears treated with NSBT. The novel nonsurgical method was shown to be repeatable, objective, well documented, standardized, and highly effective. [ABSTRACT FROM AUTHOR]

Background: Hip arthroscopy has proved successful in treating femoroacetabular impingement syndrome (FAIS) in patients with and without borderline hip dysplasia (BHD). Despite a high prevalence of BHD in patients who participate in sports with high flexibility requirements, a paucity of literature evaluates the efficacy of hip arthroscopy in treating FAIS in flexibility sport athletes with BHD. Purpose: To compare minimum 2-year patient-reported outcomes (PROs) and achievement of clinically significant outcomes in flexibility sport athletes with BHD undergoing primary hip arthroscopy for FAIS with capsular plication with results in flexibility sport athletes without dysplasia. Study Design: Cohort study; Level of evidence, 3. Methods: Data were prospectively collected for patients undergoing primary hip arthroscopy for FAIS with BHD, defined as a lateral center-edge angle of 18° to 25°, who reported participation in a sport with a high flexibility requirement, including dance, gymnastics, figure skating, yoga, cheerleading, and martial arts, according to previous literature. These patients were matched 1:2 to flexibility sport athletes without dysplasia, controlling for age, sex, and body mass index. Preoperative and minimum 2-year postoperative PROs were collected and compared between groups. Cohort-specific minimal clinically important difference and patient acceptable symptom state achievement was compared between groups. Results: In total, 52 flexibility sport athletes with BHD were matched to 104 flexibility sport athletes without BHD. Both groups showed similar sport participation (P =.874) and a similar level of competition (P =.877). Preoperative lateral center-edge angle (22.2°± 1.6° vs 31.5°± 3.9°; P <.001) and Tönnis angle (10.9°± 3.7° vs 5.8°± 4.4°; P <.001) differed between groups. Capsular plication was performed in all cases. Both groups achieved significant improvement in all PROs (P <.001) with no differences in postoperative PROs between groups (P ≥.147). High minimal clinically important difference (BHD group: 95.7%; control group: 94.8%) and patient acceptable symptom state (BHD group: 71.7%; control group: 72.2%) achievement for any PRO was observed with no differences between groups (P ≥.835). Conclusion: Flexibility sport athletes with BHD achieved similar outcomes as those of flexibility sport athletes without BHD after hip arthroscopy for FAIS with capsular plication. [ABSTRACT FROM AUTHOR]

Background: Superior capsular reconstruction (SCR) and lower trapezius tendon transfer (LTT) have recently been used to manage irreparable posterosuperior rotator cuff tears (PSRCTs). There has been a paucity of comparative biomechanical considerations between the 2 procedures. Purpose: To compare the glenohumeral stability and biomechanical properties between SCR and LTT in PSRCTs involving the entire infraspinatus tendon region. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders were tested at 0°, 20°, and 40° of shoulder abduction. Maximum internal, external, and total humeral range of motion (ROM), superior translation of the humeral head, and subacromial contact characteristics were compared among 4 conditions: (1) intact rotator cuff, (2) PSRCTs involving the entire infraspinatus tendon region, (3) LTT using Achilles allograft (12 N and 24 N of loading), and (4) SCR using fascia lata allograft. Results: Although a decrease in total ROM was noted in LTT with 12 N compared with the tear condition, LTT with both 12 N and 24 N as well as SCR did not restrict total rotational ROM compared with the intact condition. LTT had decreased total ROM compared with tear condition at 20° of abduction (P =.042), while no significant decrease was confirmed at all abduction angles after SCR. SCR and LTT with 24 N decreased superior translation compared with the PSRCT condition at 0° and 20° of abduction (P <.037) but not significantly at 40° of abduction, whereas LTT with a 24-N load decreased glenohumeral superior translation at all abduction angles (P <.039). Both SCR and LTT decreased subacromial contact pressure compared with the tear condition (P <.014) at all abduction angles. SCR decreased subacromial contact pressure at 0° and 40° of abduction (P =.019 and P =.048, respectively) compared with LTT with 12 N of loading, while there was no difference between SCR and LTT with 24 N of loading in all abduction angles. SCR increased the contact area compared with the PSRCT condition at all abduction angles (P <.023), whereas LTT did not increase the contact area. Conclusion: SCR and LTT decreased glenohumeral superior translation and contact pressure compared with PSRCT conditions. The LTT was superior to SCR in terms of superior translation of the humeral head at a higher shoulder abduction angle, whereas the SCR showed more advantageous subacromial contact characteristics compared with LTT. Clinical Relevance: These biomechanical findings provide insights into these 2 fundamentally different procedures for the treatment of young and active patients with PSRCTs involving the entire infraspinatus tendon region. [ABSTRACT FROM AUTHOR]