Prognostic factors for clinical outcomes after arthroscopic treatment of traumatic central tears of the triangular fibrocartilage complex.

Aims: The study aimed to assess the clinical outcomes of arthroscopic debridement and partial excision in patients with traumatic central tears of the triangular fibrocartilage complex (TFCC), and to identify prognostic factors associated with unfavourable clinical outcomes. Methods: A retrospective analysis was conducted on patients arthroscopically diagnosed with Palmer 1 A lesions who underwent arthroscopic debridement and partial excision from March 2009 to February 2021, with a minimum follow-up of 24 months. Patients were assessed using the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, Mayo Wrist Score (MWS), and visual analogue scale (VAS) for pain. The poor outcome group was defined as patients whose preoperative and last follow-up clinical score difference was less than the minimal clinically important difference of the DASH score (10.83). Baseline characteristics, arthroscopic findings, and radiological factors (ulnar variance, MRI, or arthrography) were evaluated to predict poor clinical outcomes. Results: A total of 114 patients were enrolled in this study, with a mean follow-up period of 29.8 months (SD 14.4). The mean DASH score improved from 36.5 (SD 21.5) to 16.7 (SD 14.3), the mean MWS from 59.7 (SD 17.9) to 79.3 (SD 14.3), and the mean VAS pain score improved from 5.9 (SD 1.8) to 2.2 (SD 2.0) at the last follow-up (all p < 0.001). Among the 114 patients, 16 (14%) experienced poor clinical outcomes and ten (8.8%) required secondary ulnar shortening osteotomy. Positive ulnar variance was the only factor significantly associated with poor clinical outcomes (p < 0.001). Positive ulnar variance was present in 38 patients (33%); among them, eight patients (21%) required additional operations. Conclusion: Arthroscopic debridement alone appears to be an effective and safe initial treatment for patients with traumatic central TFCC tears. The presence of positive ulnar variance was associated with poor clinical outcomes, but close observation after arthroscopic debridement is more likely to be recommended than ulnar shortening osteotomy as a primary treatment.

Comparing the Biomechanical Stability of Cerclage Cable with Plate Insert Versus Locking Screw in Periprosthetic Humeral Fracture.

BACKGROUND: In the setting of periprosthetic humeral fractures, the humeral stem of the implant represents a substantial challenge to the optimal method of proximal fixation. This study aimed to compare the initial biomechanical stability provided by cerclage cables with a locking plate insert versus bicortical locking screws (i.e., the gold standard for fixation) in fresh cadaveric humeri. METHODS: After calculating the sample size, we utilized 10 sets of cadaveric specimens and created a 5-mm osteotomy gap 120 mm distal to the tip of the greater tuberosity, simulating a Wright and Cofield type-B periprosthetic humeral fracture on each specimen. Using 3 locking screws for distal fragment fixation, identical in all specimens, the specimens were assigned to Group A (3 cerclage cables with a plate insert) or Group B (3 locking bicortical screws) for proximal fragment fixation. Biomechanical tests included stiffness in varus and valgus bending, torsion, and axial compression, and a single load to failure. RESULTS: No significant differences were observed in the biomechanical metrics between the 2 groups. CONCLUSIONS: Our study revealed that fixation with use of cerclage cables with a plate insert demonstrated biomechanical stability comparable with that of bicortical locking screw fixation when addressing the proximal fragment in Wright and Cofield type-B periprosthetic humeral fractures. CLINICAL RELEVANCE: For proximal fragment fixation of periprosthetic humeral fractures, cerclage cables with a plate insert can be utilized as an effective fixation method that offers initial fixation strength that is comparable to the use of 3 locking bicortical screws.

Anatomical considerations for nerve transfer in axillary nerve injury.

This study investigated the anatomical details of the axillary and radial nerves in 50 upper limbs from 29 adult formalin-embalmed cadavers, and ten fresh upper limbs. The focus was on understanding the course, division, and ramifications of these nerves to improve treatment of shoulder dysfunction caused by axillary nerve damage. The axillary nerve divided anteriorly and posteriorly before passing the quadrangular space in all specimens, with specific distances to the first ramifications. It was found that the deltoid muscle's clavicular and acromial parts were always innervated by the anterior division of the axillary nerve, whereas the spinous part was variably innervated. The longest and thickest branches of the radial nerve to the triceps muscles were identified, with no statistically significant differences in fiber numbers among triceps branches. The study concludes that nerve transfer to the anterior division of the axillary nerve can restore the deltoid muscle in about 86% of shoulders, and the teres minor muscle can be restored by nerve transfer to the posterior division. The medial head branch and long head branch of radial nerve were identified as the best donor options.

Reaching New Heights: A Comprehensive Study of Hand Transplantations in Korea after Institutionalization of Hand Transplantation Law.

PURPOSE: With the revision of the Organ and Transplantation Act in 2018, the hand has become legal as an area of transplantable organs in Korea. In January 2021, the first hand allotransplantation since legalization was successfully performed, and we have performed a total of three successful hand transplantation since then. By comparing and incorporating our experiences, this study aimed to provide a comprehensive reconstructive solution for hand amputation in Korea. MATERIALS AND METHODS: Recipients were selected through a structured preoperative evaluation, and hand transplantations were performed at the distal forearm level. Postoperatively, patients were treated with three-drug immunosuppressive regimen, and functional outcomes were monitored. RESULTS: The hand transplantations were performed without intraoperative complications. All patients had partial skin necrosis and underwent additional surgical procedures in 2 months after transplantation. After additional operations, no further severe complications were observed. Also, patients developed acute rejection within 3 months of surgery, but all resolved within 2 weeks after steroid pulse therapy. Motor and sensory function improved dramatically, and patients were very satisfied with the appearance and function of their transplanted hands. CONCLUSION: Hand transplantation is a viable reconstructive option, and patients have shown positive functional and psychological outcomes. Although this study has limitations, such as the small number of patients and short follow-up period, we should focus on continued recovery of hand function, and be careful not to develop side effects from immunosuppressive drugs. Through the present study, we will continue to strive for a bright future regarding hand transplantation in Korea.

Prediction of an intracompartmental septum and its effect on outcomes of endoscopic release for de Quervain's syndrome.

LEVEL OF EVIDENCE: IV.

One Year Experience of the Hand Allotransplantation First Performed after Korea Organ Transplantation Act (KOTA) Amendment.

The revision of the Korea Organ Transplantation Act (KOTA) in 2018 included hand/arm among the organs that can be transplanted. The first hand transplantation since the revision of KOTA took place in January 2021. A 62-year-old male patient experienced hand amputation on July 13, 2018, by a catapult injury. The patient first visited our institute 3 months after the injury. After serial interviews and an overall evaluation, the patient was registered on the hand transplantation waiting list in January 2020. On January 9, 2021, the patient underwent hand transplantation at the right distal forearm level. The total operation time was 17 hours 15 minutes, and the cold ischemic time was 4 hours 9 minutes. Postoperative immunosuppression was administered based on the protocol used for kidney transplantation. Two acute rejection episodes occurred, on postoperative days 33 and 41. Both rejection episodes were reversible with rescue therapy of a higher tacrolimus trough level, steroid pulse therapy, and topical immunosuppressants. Controlled passive range of motion exercise was started on postoperative day 10. Dynamic splint was applied on postoperative day 18. At 1 year, graft maintenance and functional improvement were satisfactory, and the patient showed a Disabilities of Arm, Shoulder and Hand score of 25.8. We successfully performed the first hand transplantation surgery under the KOTA amendment. It came from the organic and effective cooperation of plastic, orthopaedic, and transplantation departments and we believe it will guarantee the future ongoing success.

Robot-Assisted Retroauricular Anterior Scalenectomy for Neurogenic Thoracic Outlet Syndrome.

Background: This study described the surgical technique of a robot-assisted retroauricular anterior scalenectomy and assessed clinical outcomes and complications for patients with neurogenic thoracic outlet syndrome (nTOS). Methods: Between February 2014 and August 2016, 5 patients underwent robot-assisted retroauricular anterior scalenectomy using the da Vinci Xi system for nTOS. For clinical assessment, visual analog scale (VAS) symptom score, pinch and grip strength, and disabilities of arm, shoulder and hand (DASH) score were assessed to compare preoperative and postoperative outcomes. Postoperative complications were also reviewed. Results: The VAS symptom, pinch and grip strength, and DASH scores improved 1 year after the operation. All patients were satisfied with the surgical scars. Temporary postoperative complications, which spontaneously resolved within 3 months, were noticed in 2 patients: one with vocal cord palsy and the other with upper brachial plexus palsy. Conclusions: The robot-assisted retroauricular anterior scalenectomy for patients with nTOS seems feasible and safe, providing satisfactory cosmetic results.

Comparison of the Goutallier Classification of Fatty Infiltration for the Subscapularis With a Novel Modified Classification.

Background: Fatty infiltration in the subscapularis muscle extends to the upper portion of the muscle first and then to the lower portion only after some degree of fatty change has taken place in the upper region. Although the Goutallier classification is the most widely used method to categorize fatty infiltration, how to accurately and reliably determine the extent of infiltration is controversial. Purpose: To examine a modified classification that is more reliable in (1) assessing fatty infiltration of the subscapularis muscle and (2) predicting the structural integrity of the repaired tendon by identifying cutoff points for retear. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: This study retrospectively examined the records of 545 patients who underwent arthroscopic repair for a subscapularis tear. Two shoulder surgeons reviewed the preoperative magnetic resonance imaging scans of all enrolled patients and evaluated the fatty infiltration of the subscapularis muscle based on the original Goutallier classification, as well as a novel modified Goutallier classification designed to measure the proportion of fat and muscle in the upper and lower portions of the muscle separately. Intra- and interobserver agreement of the reviewers was calculated using κ statistics. Using receiver operating characteristic curve analysis, we determined the cutoff point for the particular fatty infiltration grade related to the occurrence of retear for each classification scheme. Results: The κ values for interobserver reliability were 0.743 and 0.856 for the original and modified Goutallier classifications, respectively, with the modified classification having significantly higher reliability (Z = 4.064; P < .001). Cutoff points for the fatty infiltration grade associated with retear were 2.5 for the original Goutallier classification (sensitivity, 65.3%; specificity, 95.6%; accuracy, 87.8%) and 3.5 for the modified classification (sensitivity, 52.5%; specificity, 97.8%; accuracy, 89.7%). Conclusion: In assessing fatty infiltration of the subscapularis muscle, the modified Goutallier classification showed higher reliability than the original Goutallier classification. The cutoff point for potential retear (grade 3.5) was at a point where the fatty infiltration extended to the lower portion of the subscapularis muscle.

Radial versus dorsal plating for trapeziometacarpal arthrodesis: a comparative biomechanical study.

Trapeziometacarpal arthrodesis is used for the treatment of advanced arthritis. Insufficient stabilization of the joint may lead to nonunion or hardware problems after arthrodesis. The purpose of this study was to compare the biomechanical properties of dorsal versus radial plate fixation of the trapeziometacarpal joint in ten pairs of fresh-frozen cadaveric hands. The biomechanical performance of each group was measured for stiffness in extension and flexion and load to failure using cantilever bending tests. The stiffness in extension was lower in the dorsally positioned group than in the radially positioned group (12.1 versus 15.2 N/mm, respectively). Load to failure was comparable between both groups (53.9 versus 50.9 N, respectively). A radially positioned locking plate for trapeziometacarpal arthrodesis may be biomechanically advantageous.

Outcomes of Arthroscopic Scaphoid Excision and Lunocapitate Fusion for Advanced Traumatic Arthritis of the Wrist.

Background: Arthroscopic lunocapitate (LC) fusion can be an alternative surgical treatment for scapholunate advanced collapse (SLAC) or scaphoid nonunion advanced collapse (SNAC) of the wrist. We retrospectively reviewed patients who had arthroscopic LC fusion to estimate clinical and radiological outcomes. Methods: From January 2013 to February 2017, all patients with SLAC (stage II or III) or SNAC (stage II or III) wrists, who underwent arthroscopic LC fusion with scaphoidectomy and were followed up for a minimum of 2 years, were enrolled in this retrospective study. Clinical outcomes included visual analog scale (VAS) pain, grip strength, active range of wrist motion, Mayo wrist score (MWS), and the Disabilities of Arm, Shoulder and Hand (DASH) score. Radiologic outcomes included bony union, carpal height ratio, joint space height ratio, and loosening of screws. We also performed group analysis between patients with 1 and 2 headless compression screws to fix the LC interval. Results: Eleven patients were assessed for 32.6 ± 8.0 months. Union was achieved in 10 patients (union rate, 90.9%). There was improvmenet in mean VAS pain score (from 7.9 ± 1.0 to 1.6 ± 0.7, p = 0.003) and grip strength (from 67.5% ± 11.4% to 81.8% ± 8.0%, p = 0.003) postoperatively. The mean MWS and DASH score were 40.9 ± 13.8 and 38.3 ± 8.2, respectively, preoperatively and improved to 75.5 ± 8.2 and 11.3 ± 4.1, respectively, postoperatively (p < 0.001 for all). Radiolucent screw loosening occurred in 3 patients (27.3%), including 1 nonunion patient and 1 patient who underwent screw removal due to the screw migration encroaching the lunate fossa of radius. In group analysis, only the frequency of radiolucent loosening was higher in 1 screw (3 of 4) than 2 screw fixation (0 of 7) (p = 0.024). Conclusions: Arthroscopic scaphoid excision and LC fusion for patients with advanced SLAC or SNAC of the wrist was effective and safe only in cases fixed with 2 headless compression screws. We recommend arthroscopic LC fusion using 2 screws rather than 1 to decrease radiolucent loosening, which might affect complications such as nonunion, delayed union, or screw migration.

Age, Tear Size, Extent of Retraction, and Fatty Infiltration Associated With a High Chance of a Similar Rotator Cuff Tear in the Contralateral Shoulder Regardless of Symptoms in Patients Undergoing Cuff Repair in the Index Shoulder.

PURPOSE: To investigate the prevalence of a contralateral rotator cuff tear (RCT) in patients with a symptomatic RCT requiring repair and to determine whether findings from magnetic resonance imaging (MRI) of the affected shoulder can predict the presence of a contralateral tear. METHODS: Patients with atraumatic RCTs who had undergone arthroscopic repair between March 2019 and February 2021 were reviewed in this study. MRI of both shoulder joints was performed to evaluate the bilaterality of RCT. Demographic factors and MRI findings of index shoulders were assessed using logistic regression analysis to reveal any correlations with the presence of RCT in the contralateral shoulder. RESULTS: A total of 428 patients were enrolled in this study. When the affected shoulders had a posterosuperior rotator cuff (PSRC) or subscapularis tear including either an isolated or combined tear, 63.6% and 67.8% had the same tears on the contralateral side, respectively. A contralateral-side tear was found in 74.6% (185/248) of symptomatic cases and 44.8% (65/145) of asymptomatic cases, which represents a significant difference (P < .001). Logistic regression analysis revealed that age ≥67.5 years, tear size ≥17 mm, Goutallier grade ≥1.5, and Patte grade ≥1.5 were found to be indicative of potential contralateral PSRC tears. By contrast, the presence of a subscapularis tear in the affected shoulder was the only significant risk factor in predicting a potential subscapularis tear in the contralateral shoulder. CONCLUSIONS: Among patients with a symptomatic RCT requiring arthroscopic repair, 63.6% with a PSRC tear and 67.8% with a subscapularis tear in the affected shoulder were found to have a similar tear in the contralateral shoulder regardless of symptoms. Age, tear size, extent of retraction, fatty infiltration of PSRC tears, and the presence of subscapularis tears were identified as factors predictive of tears on the contralateral side. LEVEL OF EVIDENCE: Level IV, case series.

Relation between diameter of a lateral screw and pull-out strength in distal clavicle fracture in plates with different geometry: A cadaveric biomechanical study.

Plate fixation has recently gained popularity among the various surgical methods used to treat Neer type II distal clavicle fractures. The use of a low-profile distal clavicle locking plate is logically considered a better option when there is no significant difference in the fixation strength between insertions of 3.5- and 2.7-mm diameter screws. Therefore, the purpose of this biomechanical study was to investigate any differences in fixation strength among varying sizes of screws that are used to treat distal clavicle fractures. The study was performed with 20 paired shoulder girdles from 10 fresh frozen cadavers. To create a type IIA fracture of Neer classification, osteotomy was performed perpendicularly to the longitudinal axis of the clavicle at the medial end point of the conoid ligament. Two custom-made fixtures designed to be attached to both upper and lower sides of the Instron were fabricated for the evaluation. The mean maximum pull-out strength for fixation using 3.5-mm diameter screws was 241.9 ± 67.8 N, whereas the mean pull-out strength in fixation with 2.7-mm diameter screws was 228.1 ± 63.0 N. There was no statistically significant difference between the two groups. Distal fragment fixation with distal clavicle locking plates using two 2.7-mm diameter screws showed comparable biomechanical pull-out strength at the time-zero setting to fixations with a hook plate using two 3.5-mm diameter screws. Therefore, the fixation of the distal fragment with a low-profile plate and 2.7-mm screws may be preferred as an alternative option if the distal fragment of the fractured clavicle is not extremely small.

Clinical Effects of Korean Red Ginseng in Postmenopausal Women With Hand Osteoarthritis: A Double-Blind, Randomized Controlled Trial.

Background: Although many menopausal Asian women use herbal remedies for joint pain, there are no studies evaluating the efficacy of Korean red ginseng on osteoarthritis symptoms in postmenopausal women. The purpose of this study is to analyze antioxidant enzyme activity, oxidative stress markers, and pain scores before and after red ginseng consumption, to assess its effect in postmenopausal women. METHODS: This prospective, double-blind, randomized controlled trial enrolled 52 postmenopausal women who presented with hand edema and/or pain and were diagnosed as degenerative arthritis of the hand. Patients were randomly assigned to the red ginseng (RG) group (supplemented with 3 g/d of RG for 12 weeks) or the placebo group. Changes in pain and Disability of the Arm, Shoulder, and Hand (DASH) scores, antioxidant enzyme, oxidative stress markers, serum estradiol levels, and endometrial thickness were analyzed. RESULTS: The pain score and DASH score were significantly improved in the RG group (both p < 0.05). The improvement of pain score at rest, during work or sport, and DASH score was significant compared to that of the placebo group. The superoxide dismutase level increased (p < 0.05) and the malondialdehyde level decreased (p < 0.05) significantly in the RG group, while none of the antioxidative factors showed a significant change in the placebo group. Serum estradiol levels and endometrial thickness were not affected by RG supplementation. CONCLUSION: RG may be an effective dietary supplement for postmenopausal women with degenerative osteoarthritis of the hand. It may relieve pain and improve antioxidative activity without the risk of endometrial thickening.

Arthroscopic Revision Rotator Cuff Repair: The Role of Previously Neglected Subscapularis Tears.

BACKGROUND: Concomitant full-thickness tear of the subscapularis tendon is often neglected during primary posterosuperior rotator cuff repair, and its significance has not been investigated by any previous clinical study. PURPOSE: To investigate (1) the clinical and radiological outcomes of revision arthroscopic rotator cuff repair and (2) the number of neglected concomitant subscapularis full-thickness tears in the revision of posterosuperior rotator cuff retears and their structural integrity after repair. STUDY DESIGN: Case series, Level of evidence, 4. METHODS: This study retrospectively examined 58 patients who underwent arthroscopic rotator cuff revision for a retear of a previously repaired posterosuperior rotator cuff. Preoperative and postoperative functional scores and active range of motion (ROM) were assessed. The initial and most recent follow-up magnetic resonance imaging scans before revision and arthroscopic findings at the time of primary repair were reviewed to determine whether the concomitant subscapularis tear was newly developed or preexisting. Final confirmation of the tendon's full-thickness tear was made during the revision procedure. RESULTS: At final follow-up, mean functional shoulder scores and ROM improved significantly compared with the preoperative values (P < .001). Among the 58 revision cases, 25 (43.1%) had a neglected full-thickness tear of the subscapularis tendon. The fatty infiltration grade of the neglected subscapularis tear progressed from a mean of 1.1 before primary repair to a mean of 1.6 before revision, and the change indicated statistically significant deterioration (P < .001). Despite clinical improvement after revision surgery, the retear rate was considerable in the re-repaired cuff tendons (37.9%) as well as for the repaired concomitant subscapularis tears (24%). CONCLUSION: Among revision rotator cuff repairs, 43.1% had neglected subscapularis tears, and fatty infiltration of these initially neglected subscapularis tendons showed further progression at the time of revision. The retear rate after the repair of neglected subscapularis tears was higher than expected. Thus, detecting and treating subscapularis tear via meticulous preoperative evaluation and thorough inspection during primary arthroscopy are essential.

A genome-engineered bioartificial implant for autoregulated anticytokine drug delivery.

Biologic drug therapies are increasingly used for inflammatory diseases such as rheumatoid arthritis but may cause significant adverse effects when delivered continuously at high doses. We used CRISPR-Cas9 genome editing of iPSCs to create a synthetic gene circuit that senses changing levels of endogenous inflammatory cytokines to trigger a proportional therapeutic response. Cells were engineered into cartilaginous constructs that showed rapid activation and recovery in response to inflammation in vitro or in vivo. In the murine K/BxN model of inflammatory arthritis, bioengineered implants significantly mitigated disease severity as measured by joint pain, structural damage, and systemic and local inflammation. Therapeutic implants completely prevented increased pain sensitivity and bone erosions, a feat not achievable by current clinically available disease-modifying drugs. Combination tissue engineering and synthetic biology promises a range of potential applications for treating chronic diseases via custom-designed cells that express therapeutic transgenes in response to dynamically changing biological signals.

Incomplete footprint coverage under tension in repair of isolated supraspinatus full-thickness tear.

Although it is well known that repairing large or massive tears under tension may have an adverse effect on healing of the repaired tendons, only few studies have addressed this issue in medium-sized isolated supraspinatus full-thickness tear. The purpose of this study was to compare the clinical outcomes and structural integrity of arthroscopic rotator cuff repair with tension versus without it. This study retrospectively investigated 90 patients who underwent arthroscopic repair in a single-row for medium-sized isolated supraspinatus full-thickness tear. The patients were assigned to either repaired under tension (Group A, n = 38) or repaired without tension (Group B, n = 52) groups. Functional outcomes were assessed using the patient reported subjective values and the active range of motion (ROM). Postoperative radiographic evaluation was performed 6 months after the surgery to assess the structural integrity of the repaired tendons. Changes in the subjective shoulder scores from initial to 2 years after surgery showed no statistical significance between the two groups. The ROMs measured at initial and 2 years after surgery also showed no statistical difference between the two groups. Postoperative radiological evaluations found a significantly higher re-tear rate in Group A (28.9%, 11/38) than in Group B (9.6%, 5/52). The torn cuff tendons that were repaired under tension as retraction with limited mobility had significantly higher re-tear rate despite having immobilized for 6 weeks after surgery, but their clinical outcomes showed no significant difference from the outcomes of repaired tendons without tension.

Clinical Outcomes for Isolated Subscapularis Tears With Advanced Fatty Infiltration: Nonoperative Treatment Versus Arthroscopic Single-Row Repair.

BACKGROUND: No study has investigated the treatment outcomes of isolated subscapularis tears with advanced fatty infiltration and tear progression to the supraspinatus tendon. PURPOSE: To assess the natural progression of isolated subscapularis tears with advanced fatty infiltration and compare clinical outcomes between nonoperative and operative treatment. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This study included 52 patients who received either operative (group A) or nonoperative (group B) treatment at our institution for isolated subscapularis full-thickness tears with grade 3 or 4 advanced fatty infiltration. All study patients had a minimum 2-year follow-up. The following 4 functional measures were used: visual analog scale for pain, Subjective Shoulder Value, American Shoulder and Elbow Surgeons score, and University of California Los Angeles score. The modified belly-press test was used to assess subscapularis muscle strength. In group A, structural integrity was evaluated using magnetic resonance imaging at 6 months after surgery. In addition, ultrasonographic evaluation was performed on both groups during the follow-up period to assess tear progression into the supraspinatus tendon. RESULTS: At initial presentation, all functional assessment scores were significantly worse in group A versus group B (P ≤ .05 for all 4 scores). When we compared the mean change in scores before treatment versus after treatment, the group A patients were found to have significantly greater improvement than group B patients (P < .001 for all 4 scores); however, no significant difference was seen in final outcome scores between the groups. Although a high retear rate of 78.6% (22/28) was identified in group A, both groups showed no further tear progression to the supraspinatus tendon at the final ultrasonographic evaluation. CONCLUSION: For isolated subscapularis tears with advanced fatty infiltration, clinical improvement was seen with both nonoperative and operative treatment. Although the operatively treated group started with lower baseline scores, there were no significant differences in outcomes at final follow-up. Considering the high retear rate even after repair, surgical treatment of these lesions may not be warranted. Early detection and prompt repair of subscapularis tears, before the lesion becomes advanced with grade 3 or 4 fatty infiltration, are important for better outcomes.

Adipose tissue is a critical regulator of osteoarthritis.

Osteoarthritis (OA), the leading cause of pain and disability worldwide, disproportionally affects individuals with obesity. The mechanisms by which obesity leads to the onset and progression of OA are unclear due to the complex interactions among the metabolic, biomechanical, and inflammatory factors that accompany increased adiposity. We used a murine preclinical model of lipodystrophy (LD) to examine the direct contribution of adipose tissue to OA. Knee joints of LD mice were protected from spontaneous or posttraumatic OA, on either a chow or high-fat diet, despite similar body weight and the presence of systemic inflammation. These findings indicate that adipose tissue itself plays a critical role in the pathophysiology of OA. Susceptibility to posttraumatic OA was reintroduced into LD mice using implantation of a small adipose tissue depot derived from wild-type animals or mouse embryonic fibroblasts that undergo spontaneous adipogenesis, implicating paracrine signaling from fat, rather than body weight, as a mediator of joint degeneration.

Single cell transcriptomic analysis of human pluripotent stem cell chondrogenesis.

The therapeutic application of human induced pluripotent stem cells (hiPSCs) for cartilage regeneration is largely hindered by the low yield of chondrocytes accompanied by unpredictable and heterogeneous off-target differentiation of cells during chondrogenesis. Here, we combine bulk RNA sequencing, single cell RNA sequencing, and bioinformatic analyses, including weighted gene co-expression analysis (WGCNA), to investigate the gene regulatory networks regulating hiPSC differentiation under chondrogenic conditions. We identify specific WNTs and MITF as hub genes governing the generation of off-target differentiation into neural cells and melanocytes during hiPSC chondrogenesis. With heterocellular signaling models, we further show that WNT signaling produced by off-target cells is responsible for inducing chondrocyte hypertrophy. By targeting WNTs and MITF, we eliminate these cell lineages, significantly enhancing the yield and homogeneity of hiPSC-derived chondrocytes. Collectively, our findings identify the trajectories and molecular mechanisms governing cell fate decision in hiPSC chondrogenesis, as well as dynamic transcriptome profiles orchestrating chondrocyte proliferation and differentiation.

Anterior rotator cable disruption does not affect outcomes in rotator cuff tear with subscapularis involvement.

PURPOSE: The purpose of this study was to compare clinical and radiological outcomes after arthroscopic repair of two different rotator cuff tear configurations: anterosuperior rotator cuff tear and rotator cuff tears with subscapularis involvement. It was hypothesized that, although both tear configurations would show significant improvement in clinical outcomes after arthroscopic repair, the rotator cuff tears with subscapularis involvement where the anterior rotator cable maintains its integrity would have better clinical outcomes and structural integrity. METHODS: This study included 226 patients who underwent arthroscopic repair of anterosuperior rotator cuff tears (n = 107, group A) and rotator cuff tears with subscapularis involvement (n = 119, group B). The visual analog scale (VAS) pain score, subjective shoulder value (SSV), American Shoulder and Elbow Surgeons (ASES) score, University of California at Los Angeles (UCLA) shoulder score, and active range of motion (ROM) were assessed. Modified belly press test was performed to assess the strength of the subscapularis muscle. Cuff integrity was evaluated using magnetic resonance arthrography or computed tomographic arthrography at 6 months after operation. RESULTS: At 3-year follow-up, the VAS score, SSVs, ASES scores, UCLA shoulder scores, active ROM, and modified belly press test showed significant improvement in both groups (p < 0.001). However, these improvements showed no statistical significance between the two groups. On follow-up radiologic evaluations, no significant difference in re-tear rates between group A (25 of 107, 23.4%) and group B (23 of 119, 19.3%) was observed. CONCLUSIONS: The presence of anterior cable involvement of the anterosuperior rotator cuff tear did not affect postoperative clinical outcomes and re-tear rate compared to rotator cuff tears with subscapularis involvement where the anterior cable integrity was maintained, although the anterosuperior rotator cuff tear was associated with more significant preoperative supraspinatus fatty infiltration. Therefore, the present study determined that it would not be necessary to differentiate treatment protocols between these patterns. LEVEL OF EVIDENCE: Level III.