Improvement of Coracoid Process Union Rates: A Comparative Study of Conventional Open and Arthroscopic-assisted Bristow Procedures for Treating Anterior Shoulder Instability in Rugby Players.

BACKGROUND: The Bristow coracoid transfer procedure is a reliable technique for treating anterior shoulder instability in patients with large glenoid bone loss or those involved in collision sports. However, its success is marred by its inferior bone union rate of the coracoid process as compared to the Latarjet procedure. This study aimed to evaluate whether arthroscopic confirmation of the secured coracoid fixation during the Bristow procedure improves the bone union rate and clinical outcomes as compared to the open procedure. METHODS: We retrospectively reviewed 104 rugby players (n = 111 shoulders) who underwent an open (n = 66 shoulders) or arthroscopy-assisted (AS-assisted; n = 45 shoulders) Bristow procedure at our center from 2007 to April 2019. In the AS-assisted group, the screw fixation and coracoid stability and contact were confirmed under arthroscopic visualization. Graft union was evaluated through computed tomography at 3 months, 6 months, and 1 year postoperatively. Patient-reported outcome measures were assessed based on the American Shoulder and Elbow Surgeons (ASES) score, Rowe score, and satisfaction rate. Recurrence, the rate of return to play (RTP), and the frequency of pain after RTP were also assessed. RESULTS: The mean follow-up period was 73.5 (range: 45-160) months for the open group and 32.3 (range: 24-56) months for the AS-assisted group. In the former, the rates of bone union were 50%, 72.7%, and 88.9% at 3 months, 6 months, and 1 year, respectively. In contrast, the AS-assisted group had significantly greater bone union rates-88.9%, 93.3%, and 95.6% at 3 months, 6 months, and 1 year, respectively. Both groups showed significant improvement in the ASES and Rowe scores compared to preoperative values as well as high satisfaction rates (open: 92%; AS-assisted: 95.7%). There were no statistically significant differences in the recurrence and RTP rates as well as the frequency of pain after RTP between the two groups. CONCLUSION: The AS-assisted procedure allows early and high bone healing without compromising the clinical outcomes.

Repair of osteochondral defects: efficacy of a tissue-engineered hybrid implant containing both human MSC and human iPSC-cartilaginous particles.

Both mesenchymal stromal cells (MSC) and induced pluripotent stem cells (iPSC) offer the potential for repair of damaged connective tissues. The use of hybrid implants containing both human MSC and iPSC was investigated to assess their combined potential to yield enhanced repair of osteochondral defects. Human iPSC-CP wrapped with tissue engineered constructs (TEC) containing human MSC attained secure defect filling with good integration to adjacent tissue in a rat osteochondral injury model. The presence of living MSC in the hybrid implants was required for effective biphasic osteochondral repair. Thus, the TEC component of such hybrid implants serves several critical functions including, adhesion to the defect site via the matrix and facilitation of the repair via live MSC, as well as enhanced angiogenesis and neovascularization. Based on these encouraging studies, such hybrid implants may offer an effective future intervention for repair of complex osteochondral defects.

The prevalence of shoulders with a large glenoid defect and small bone fragment increases after several instability events during conservative treatment for traumatic anterior instability.

Background: Unstable shoulders with a large glenoid defect and small bone fragment are at higher risk for postoperative recurrence after arthroscopic Bankart repair. The purpose of the present study was to clarify the changes in the prevalence of such shoulders during conservative treatment for traumatic anterior instability. Methods: We retrospectively investigated 114 shoulders that underwent conservative treatment and computed tomography (CT) examination at least twice after an instability event in the period from July 2004 to December 2021. We investigated the changes in glenoid rim morphology, glenoid defect size, and bone fragment size from the first to the final CT. Results: At first CT, 51 shoulders showed no glenoid bone defect, 12 showed glenoid erosion, and 51 showed a glenoid bone fragment [33 small bone fragment (<7.5%) and 18 large bone fragment (≥7.5%); mean size: 4.9 ± 4.2% (0-17.9%)]. Among patients with glenoid defect (fragment and erosion), the mean glenoid defect was 5.4 ± 6.6% (0-26.6%); 49 were considered a small glenoid defect (<13.5%) and 14 were a large glenoid defect (≥13.5%). While all 14 shoulders with large glenoid defect had a bone fragment, small fragment was solely seen in 4 shoulders. At final CT, 23 of the 51 shoulders persisted without glenoid defect. The number of shoulders presenting glenoid erosion increased from 12 to 24, and the number of shoulders with bone fragment increased from 51 to 67 [36 small bone fragment and 31 large bone fragment; mean size: 5.1 ± 4.9% (0-21.1%)]. The prevalence of shoulders with no or a small bone fragment did not increase from first CT (71.4%) to final CT (65.9%; P = .488), and the bone fragment size did not decrease (P = .753). The number of shoulders with glenoid defect increased from 63 to 91 and the mean glenoid defect significantly increased to 9.9 ± 6.6% (0-28.4%) (P < .001). The number of shoulders with large glenoid defect increased from 14 to 42 (P < .001). Of these 42 shoulders, 19 had no or a small bone fragment. Accordingly, among a total of 114 shoulders, the increase from first to final CT in the prevalence of a large glenoid defect accompanied by no or a small bone fragment was significant [4 shoulders (3.5%) vs. 19 shoulders (16.7%); P = .002]. Conclusions: The prevalence of shoulders with a large glenoid defect and small bone fragment increases significantly after several instability events.

Association Between Preoperative Glenoid Bone Loss and Postoperative Outcomes After Coracoid Transfer Combined With Open Bankart Repair: Comparison of the Bristow and Latarjet Techniques.

Background: Whether the extent of glenoid bone loss (GBL) affects clinical outcome after coracoid process transfer (CPT) is still unclear. Purpose: To evaluate postoperative outcomes after CPT combined with open Bankart repair in young rugby players in terms of the extent of GBL and between the Bristow and Latarjet techniques. Study Design: Cohort study; Level of evidence, 3. Methods: The authors investigated 101 shoulders in 91 competitive rugby players who underwent CPT combined with open Bankart repair by the Bristow (group B; 66 shoulders) or Latarjet (group L; 35 shoulders) procedure between 2007 and 2017. The extent of GBL was calculated from the en face view of the glenoid on preoperative 3-dimensional computed tomography scans and was used to categorize shoulders into 4 grades (grade 0, 0%; grade 1, >0% and ≤10%; grade 2, >10% and ≤20%; grade 3, >20%). At the minimum 2-year follow-up, the authors analyzed the relationship between GBL or GBL grade and postoperative outcome scores (American Shoulder and Elbow Surgeons score, Rowe score, Western Ontario Shoulder Instability Index, and patient satisfaction), return-to-play (RTP) times, graft failure (insufficient union or translocation), and recurrence. Results: The mean GBL in all shoulders was 10.9% ± 9.2% and was not significantly different between the 2 groups. There were no significant correlations between GBL and any outcome measure in either group. The mean RTP time was significantly shorter in group L versus group B (4.8 ± 1.1 vs 5.8 ± 1.8 months, respectively; P = .002), but it was not associated with GBL. In group B, the rate of graft failure was not significantly higher in shoulders with grade 0 or 1 GBL versus grade 2 or 3 GBL (8 [25.0%] vs 4 [11.8%], respectively; P = .21). In group B, graft failure was confirmed in 12 shoulders (18.2%), compared with 1 shoulder (2.9%) in group L. Postoperative recurrence occurred in significantly fewer shoulders in group B than in group L (2 [3.0%] vs 5 [14.3%], respectively; P = .047). Conclusion: The extent of GBL did not affect outcome scores after CPT, regardless of operative procedure.

Small extracellular vesicles derived from human adipose-derived mesenchymal stromal cells cultured in a new chemically-defined contaminate-free media exhibit enhanced biological and therapeutic effects on human chondrocytes in vitro and in a mouse osteoarthritis model.

Human small extracellular vesicles (sEVs) derived from adipose-derived mesenchymal stromal cells (ASC) have been reported to suppress the progression of osteoarthritis (OA) in animal studies and subsequently, translation of this potential to assess their clinical efficacy is anticipated. However, fabrication protocols for sEVs to eliminate potential contamination by culture medium-derived components need to be established prior to their clinical use. The purpose of the present studies was to elucidate the influence of medium-derived contaminants on the biological effects of sEVs, and to establish isolation methods for sEVs using a new clinical grade chemically-defined media (CDM). The quantity and purity of ASC-derived sEVs cultured in four different CDMs (CDM1, 2, 3 and 4) were evaluated. The concentrates of the four media incubated without cells were used as the background (BG) control for each set of sEVs. The biological effect of sEVs fabricated in the four different CDMs on normal human articular chondrocytes (hACs) were evaluated in vitro using a variety of methodological assessments. Finally, the sEVs with the highest purity were tested for their ability to suppress the progression of knee OA mouse model. Analysis of the BG controls revealed that CDM1-3 contained detectable particles, while there was no visible contamination of culture media-derived components detected with CDM4. Accordingly, the sEVs fabricated with CDM4 (CDM4-sEVs) exhibited the highest purity and yield. Notably, the CDM4-sEVs were the most efficient in promoting the cellular proliferation, migration, chondrogenic differentiation, and anti-apoptotic activity of hACs. Furthermore, CDM4-sEVs significantly suppressed the osteochondral degeneration in vivo model. Small EVs derived from ASCs cultured in a CDM without detectable contaminants demonstrated enhanced biological effects on hACs and the progression of OA. Thus, sEVs isolated with CDM4 most optimally meet the requirements of efficacy and safety for assessment in their future clinical applications.

Freeze-dried noncoagulating platelet-derived factor concentrate is a safe and effective treatment for early knee osteoarthritis.

PURPOSE: While a wide variety of platelet-rich plasma (PRP) solutions has been developed, innovation continues. In this case, the freeze-dried platelet factor concentrate (PFC-FD) represents another step in PRP refinement. The preparation of PFC-FD at a central laboratory with freeze drying for shelf stabilization should provide additional quality improvements if clinical effectiveness can be demonstrated. Therefore, this study was undertaken to assess the safety and effectiveness of PFC-FD in a prospective open-label trial of patients suffering from knee osteoarthritis (OA). METHODS: 312 consecutive knee OA patients (67% female, mean age 63 ± 10 years), were prospectively recruited in an outpatient knee clinic in Japan. Of these, 10 (3.2%) were lost to follow-up at < 12 months and 17 (5.5%) sought additional knee therapy during the follow-up period. The primary outcome of interest was achievement of the OMERACT-OARSI responder criteria with secondary outcomes of adverse events and PROMs scores 1, 3, 6, 12 months following a single PFC-FD injection. RESULTS: 285 patients (91%) completed 12 month PROMs. The 17 who sought additional therapy were considered failures leaving an effective sample size of 302 for our primary outcome in which 62% of patients achieved OMERACT-OARSI responder status by 12 months. This varied by OA class with Kellgren-Lawrence grade 4 patients 3.6 times less likely to be responders than grade 1-2 patients. 6% of patients experienced a non-serious adverse event, primarily pain or swelling at the injection site. CONCLUSIONS: PFC-FD provides an observable clinical improvement in 62% of knee OA patients at 12 months post-injection with very little risk of any clinically relevant adverse event. Of course, nearly 40% of patients did not experience an observable clinical improvement, primarily among those with worse KL grades. LEVEL OF EVIDENCE: Therapeutic, Level II.

Anterior glenoid rim erosion in the early stage after arthroscopic Bankart repair affects postoperative recurrence.

Background: Recent studies reported that anterior glenoid rim erosion can occur in the early period after arthroscopic Bankart repair (ABR) for traumatic anterior shoulder instability. However, it is unknown whether such erosion is a risk factor for postoperative recurrence. This study evaluated risk factors for postoperative recurrence after ABR, specifically aiming to elucidate whether reduction of postoperative glenoid width due to anterior glenoid rim erosion is one of such factors. Methods: A total of 220 shoulders that underwent ABR alone between 2013 and 2020 were retrospectively investigated. Patient age at surgery, whether the patient was a collision/contact athlete, anchor placement, preoperative glenoid bone defect (%), localization of the Hill-Sachs lesion, and change of glenoid width (%) in the 6 months after surgery were investigated for their statistical relation to recurrence by univariate and multiple logistic regression analysis. Results: Postoperative recurrence occurred in 32 of 220 shoulders (14.5%). In univariate analysis, being a collision/contact athlete was the only variable with a significant effect on recurrence (odds ratio [OR], 2.555; 95% confidence interval [CI], 1.123-5.814; P = .03). Change of glenoid width reduction was larger in those with recurrence than without recurrence, but the difference was not statistically significant (-7.0 ± 6.6% vs. -5.0 ± 9.3%; P = .14). However, in multivariate logistic analysis, preoperative glenoid bone defect (%) (adjusted unit OR, 1.076; 95% CI, 1.018-1.137; P = .010) and postoperative change of glenoid width (%) (adjusted unit OR, 0.946; 95% CI, 0.900-0.994; P = .028) had a significant influence on postoperative recurrence. Conclusion: Glenoid width reduction due to anterior glenoid rim erosion after ABR is a risk factor for recurrence.

Mechanistic insights into glenohumeral kinematics derived from positional relationship between the contact path and humeral tuberosity.

Although three-dimensional (3D) glenohumeral (GH) motion has generally been expressed only by rotational elements, its mechanistic details, including GH rotations, remain unknown owing to a lack of geometric investigations. This study aims to investigate the positional relationship between the contact path and humeral tuberosities at the GH joint during arm elevation and to consider the mechanism of GH kinematics. Shoulder kinematics were captured using two-dimensional and 3D single-plane image registration techniques in 15 young healthy subjects during flexion, scaption, and abduction. The glenoid movement relative to the humeral head was calculated to describe the contact path on the humeral head. From the start to 45° of flexion, scaption, and abduction, the glenoid center moved from the anteromedial to the anterior, central, and posterior portions of the humeral head, respectively, as the GH joint rotated externally. From 45° to the maximal elevation for all elevation planes, the glenoid center moved upward to the humeral head and came close to the bicipital groove (BG) at maximal elevation, while the glenoid maintained a constant inclination at 20°-40° relative to the humerus. To investigate this mechanism, the position of humeral tuberosities relative to the glenoid was calculated, and the BG was found to face the supraglenoid tubercle, the attachment site of the long head of biceps (LHB). GH external rotation mainly occurred depending on the elevation planes in the early phase of elevation, and it might be kept constant by the LHB and rotator cuff in the mid- to end range of elevation.

Unrecognized glenoid fracture in opposite shoulders with symptomatic anterior instability.

BACKGROUND: The purpose of the present study was to investigate the characteristics of unrecognized glenoid fracture in opposite shoulders with symptomatic anterior instability. METHODS: Participants were 38 patients, who had complaints of instability on only one side (symptomatic shoulder) and had no complaints despite of a glenoid fracture on the other shoulder (asymptomatic shoulder) from 2011 to 2020. Factors that could influence the onset of symptoms including glenoid rim morphology were retrospectively investigated. RESULTS: Among the asymptomatic shoulders, 16 had a single traumatic event and 22 had no history of trauma. The glenoid morphology was normal in 6, erosion in 12 and bony Bankart in 20 on the symptomatic side, whereas the respective shoulders were 0, 16 and 22 on the asymptomatic side. Bone union of bony Bankart was complete in 9, partial in 3 and non-union in 8 on the symptomatic side, whereas the respective shoulders were 18, 3 and 1 on the asymptomatic side. The mean glenoid defect size was 10.4% and 7.8%, and the mean bone fragment size was 5.0% and 4.5%, respectively. The mean medial displacement of bone fragments was 2.6 mm and 1.0 mm, respectively (p < 0.001). A larger glenoid defect (≥10%) was recognized in 19 symptomatic shoulders and 10 asymptomatic shoulders. Among them, erosion was solely recognized in 5 symptomatic shoulders. In shoulders with bony Bankart, all 10 asymptomatic shoulders had a completely or partially united fragment with less than 2 mm displacement. On the other hand, among 14 symptomatic shoulders, united fragment was solely recognized in 8 shoulders, in which medial displacement was less than 2 mm in 3 shoulders. CONCLUSIONS: Even if a glenoid fracture occurred, symptom such as instability or pain was not always recognized by all patients. Regardless of glenoid defect size, shoulders with a completely or partially united bone fragment and with less than 2 mm displacement were found to be asymptomatic.

Clinical Safety and Effectiveness of Adipose-Derived Stromal Cell vs Stromal Vascular Fraction Injection for Treatment of Knee Osteoarthritis: 2-Year Results of Parallel Single-Arm Trials.

BACKGROUND: There are currently no disease-modifying treatments available for knee osteoarthritis (OA), although cultured adipose-derived stromal cells (ASCs) have shown promise in experimental models. However, given the regulatory limits on the use of cultured cells in humans, previous trials have focused primarily on the stromal vascular fraction (SVF) intra-articular injection. Therefore, the therapeutic value of ASCs for knee OA remains unknown. PURPOSE: To study ASC versus SVF intra-articular injection in patients with Kellgren-Lawrence (KL) knee OA grades 2 to 4 in parallel single-arm trials. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 80 patients were enrolled, with 42 (72 knees) receiving ASC intra-articular injection and 38 (69 knees) receiving SVF. Patient-reported outcome measures were assessed at 1, 3, 6, 12, and 24 months using the Knee injury and Osteoarthritis Outcome Score 5 (KOOS5) and pain visual analog scale (VAS). The percentages of patients achieving the minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) were also calculated. Per protocol, a subset of the ASC group received an ASC booster injection after 6 months. A repeated-measures analysis of variance compared results between treatment arms and by KL grade over time. RESULTS: Patient-reported outcome measures improved substantially after both treatments (P < .05 at all time points), with the ASC group more likely to achieve the MCID (50% vs 24%; P = .01) and PASS (45% vs 24%; P = .04) for the pain VAS and the MCID (43% vs 16%; P = .02) for the KOOS5 at 12 months, although not at 24 months. Knees treated with ASC for KL grade 2/3 OA had significantly superior outcomes compared with those with KL grade 4 OA for the KOOS5 (P = .01) and pain VAS (P = .03), but no such difference was observed in knees treated with SVF. Three patients receiving ASCs (7%; all KL grade 3) sought additional nonoperative treatment by 24 months versus 9 patients receiving SVF (24%; all KL grade 3) (P = .06). ASC booster injections conferred no additional benefit. Notably, patients in the ASC cohort reported more injection-site pain and swelling after the booster injection than after the initial injection (P < .01). CONCLUSION: This represents the first head-to-head comparison of ASCs and SVF for the treatment of knee OA in humans. ASC and SVF injections both substantially improved knee pain and function at all follow-up time points, although ASC injections demonstrated significantly better improvements with regard to the MCID and PASS for the pain VAS and the MCID for the KOOS5 at 12 months. There appears to be no benefit to a booster ASC injection after initial treatment. Given less donor-site morbidity and equivalent superior outcomes at 2 years, the use of ASCs over SVF in the treatment of knee OA may be warranted.

Open Bristow Versus Open Latarjet for Anterior Shoulder Instability in Rugby Players: Radiological and Clinical Outcomes.

Background: Coracoid transfer is a reliable method for managing anterior shoulder instability in athletes who play contact sports; however, differences between the Bristow and Latarjet procedures are unclear. Purpose: To compare clinical outcomes and rates of bone union and bone resorption of the coracoid process between the open Bristow and open Latarjet procedures in rugby players. Study Design: Cohort study; Level of evidence, 3. Methods: Rugby players who underwent an open Bristow or an open Latarjet procedure were retrospectively reviewed for anterior shoulder instability, and 66 shoulders in the Bristow group and 35 in the Latarjet group were included. Graft union and resorption were evaluated using computed tomography at 3 months to 1 year postoperatively. Patient-reported outcome measures (American Shoulder and Elbow Surgeons score, Rowe score, and satisfaction rate) were obtained at a mean follow-up of 74 months (range, 45-160 months) for Bristow and 64 months (range, 50-76 months) for Latarjet procedures. Recurrence and the rate of return to play (RTP), frequency of pain after RTP, and retirement rate after RTP were also assessed. Results: In 97.1% of the Latarjet procedure cases, bone union of the coracoid was achieved at 3 months postoperatively; however, bone union was achieved in only 72.7% of the Bristow procedure cases at 6 months postoperatively. Bone resorption of the coracoid process occurred in 6.1% of shoulders after the Bristow procedure, whereas 100% of shoulders showed bone resorption after the Latarjet procedure. No statistical differences were found in outcome scores between the 2 procedures. Subluxation and persistent pain after returning to sports were identified at a significantly higher rate in the Latarjet group (5 shoulders [14%] and 9 shoulders [26%], respectively) than in the Bristow group (2 shoulders [3%] and 2 shoulders [3%]) (P = .0471 and P = .001, respectively). Conclusion: The Latarjet procedure had an advantage in the early and high rate of bone union but was at a disadvantage in bone resorption compared with the Bristow procedure. Subluxation and pain after returning to sports were more frequent in patients who underwent the open Latarjet procedure than in those who underwent the open Bristow procedure.

Accuracy of shoulder joint injections with ultrasound guidance: Confirmed by magnetic resonance arthrography.

BACKGROUND: Intra-articular glenohumeral joint injections are essential procedures for treating various shoulder disorders. Fluoroscopy-guided injections have been extensively used; however, they pose a risk of radiation exposure and are expensive and time-consuming. Recently, it has been suggested that ultrasound-guided injections are accurate and cost effective procedures. AIM: To evaluate the accuracy of ultrasound-guided glenohumeral injections using a posterior approach that is confirmed using magnetic resonance arthrography (MRA). METHODS: The study included 179 shoulders of patients with recurrent anterior instability (150 patients; 103 and 76 right and left shoulders, respectively; 160 males and 19 females; average age = 20.5 years; age range: 14-63 years) who underwent MRA for preoperative diagnosis. They were injected with 12 mL lidocaine (1%) using the ultrasound-guided posterior approach and then underwent magnetic resonance imaging. Two shoulder surgeons, except for the injector, evaluated the transverse relaxation (T2)-weighted images of axial planes and classified the intra-articular condition of injected contrast into three groups based on one of the three following scenarios: no leakage, injection into the glenohumeral joint without leakage; minor leakage, practical intra-articular injection with some leakage outside the posterior rotator cuffs; and major leakage, inaccurate injection with mass leakage without any contrast into the joint. The inter-rater reliability between two assessors was also evaluated by calculating Cohen's kappa coefficient. The learning curve was assessed regarding the inaccurate injection rate by analyzing Spearman's rank correlation coefficient. RESULTS: Of the 179 injections, 163 shoulders (91.0%) had no leakage, 10 shoulders (5.6%) had minor leakage, and six shoulders (3.4%) had major leakage. In total, 173 shoulders (96.6%) were intra-articularly injected; thus, we could detect anterior labrum and capsular pathologies. Regarding the inter-rater reliability, the kappa coefficient was 0.925, indicating consistency in the evaluations by both examiners. Regression analysis of the inaccurate injection rate for assessingtechnical learning showed a logarithmic curve with a downward trend (R2 = 0.887, P < 0.001). Three (50%) of the six inaccurate injections classified into "major leakage" were observed in the first 30 injections, indicating that the accurate injection showed a leaning effect. CONCLUSION: Ultrasound-guided intra-articular glenohumeral injections using a posterior approach had high accuracy; however, injection accuracy depends on clinical experience.

Triple-Row Technique Confers a Lower Retear Rate Than Standard Suture Bridge Technique in Arthroscopic Rotator Cuff Repairs.

PURPOSE: To compare the structural and clinical results between the knotless suture bridge (SB) and triple-row (TR) techniques. METHODS: This study is a retrospective study and included 212 shoulders with repairable rotator cuff tears treated with the SB technique and 206 shoulders treated with the TR technique. In the TR technique, medial and lateral anchors were placed as they would be for the SB technique, with a middle row anchor added on the edge of footprint to reduce the torn tendons. All patients underwent primary arthroscopic rotator cuff repair and had magnetic resonance imaging 6 months postoperatively to evaluate for retear. Sugaya's classification was used to classify the retear pattern. The function of all patients preoperatively and 2 years postoperatively were assessed by the American Shoulder and Elbow Surgeons shoulder index and the University of California at Los Angeles rating scale. RESULTS: According to Sugaya's classification, 24 (11.3%), 6 (2.8%), and 20 (9.4%) in SB-treated shoulders and 16 (7.8%), 12 (5.8%), and 8 (3.9%) in TR-treated shoulders, respectively had types 3, 4, and 5. There was a statistically significant greater type 5 retear in SB-treated shoulders (P = .038) than in TR-treated shoulders. The average clinical outcome scores at the final follow-up improved significantly relative to those before the surgeries in both groups. There were no statistical differences in the clinical outcome scores at the final follow-up between SB and TR groups. CONCLUSIONS: The use of the TR technique in arthroscopic rotator cuff repair resulted in a lower large-size retear rate when compared with the use of the SB technique. No clinical differences were noted in the outcomes between the 2 groups. LEVEL OF EVIDENCE: Level III, therapeutic, retrospective cohort study.

Potential of Soluble Decellularized Extracellular Matrix for Musculoskeletal Tissue Engineering - Comparison of Various Mesenchymal Tissues.

BACKGROUND: It is well studied that preparations of decellularized extracellular matrix (ECM) obtained from mesenchymal tissues can function as biological scaffolds to regenerate injured musculoskeletal tissues. Previously, we reported that soluble decellularized ECMs derived from meniscal tissue demonstrated excellent biocompatibility and produced meniscal regenerate with native meniscal anatomy and biochemical characteristics. We therefore hypothesized that decellularized mesenchymal tissue ECMs from various mesenchymal tissues should exhibit tissue-specific bioactivity. The purpose of this study was to test this hypothesis using porcine tissues, for potential applications in musculoskeletal tissue engineering. METHODS: Nine types of porcine tissue, including cartilage, meniscus, ligament, tendon, muscle, synovium, fat pad, fat, and bone, were decellularized using established methods and solubilized. Although the current trend is to develop tissue specific decellularization protocols, we selected a simple standard protocol across all tissues using Triton X-100 and DNase/RNase after mincing to compare the outcome. The content of sulfated glycosaminoglycan (sGAG) and hydroxyproline were quantified to determine the biochemical composition of each tissue. Along with the concentration of several growth factors, known to be involved in tissue repair and/or maturation, including bFGF, IGF-1, VEGF, and TGF-ß1. The effect of soluble ECMs on cell differentiation was explored by combining them with 3D collagen scaffold culturing human synovium derived mesenchymal stem cells (hSMSCs). RESULTS: The decellularization of each tissue was performed and confirmed both histologically [hematoxylin and eosin (H&E) and 4',6-diamidino-2-phenylindole (DAPI) staining] and on the basis of dsDNA quantification. The content of hydroxyproline of each tissue was relatively unchanged during the decellularization process when comparing the native and decellularized tissue. Cartilage and meniscus exhibited a significant decrease in sGAG content. The content of hydroxyproline in meniscus-derived ECM was the highest when compared with other tissues, while sGAG content in cartilage was the highest. Interestingly, a tissue-specific composition of most of the growth factors was measured in each soluble decellularized ECM and specific differentiation potential was particularly evident in cartilage, ligament and bone derived ECMs. CONCLUSION: In this study, soluble decellularized ECMs exhibited differences based on their tissue of origin and the present results are important going forward in the field of musculoskeletal regeneration therapy.

The Development Process of Bipolar Bone Defects From Primary to Recurrent Instability in Shoulders With Traumatic Anterior Instability.

BACKGROUND: Recurrence of glenohumeral joint instability after primary traumatic anterior instability is not rare, and bipolar bone loss is one of the most critical factors for recurrent instability, but the development process of bipolar bone defects is still unclear. PURPOSE: To investigate the development process of bipolar bone defects from primary to recurrent instability among shoulders with traumatic anterior instability evaluated at least twice by computed tomography (CT). STUDY DESIGN: Case series; Level of evidence, 4. METHODS: There were 44 patients (47 shoulders) with recurrence after primary instability in which bone morphology was evaluated by 3-dimensional reconstructed CT at primary instability (initial CT) and after recurrence. As CT was performed 3 times for 3 shoulders including primary injury and the second episode of instability (first recurrence), there were 50 CT evaluations. Morphological changes between the initial CT evaluation at primary instability and the second CT evaluation at first recurrence were investigated for 25 shoulders, with the mean interval since initial CT being 9.8 months (range, 2-23 months). Changes between initial CT evaluation and final CT evaluation after ≥2 recurrences were also investigated for 25 shoulders, while the mean number of instability episodes including primary instability was 8.0 (range, 3-40) and the mean interval since initial CT was 18.5 months (range, 5-56 months). RESULTS: At primary instability, the prevalence of Hill-Sachs lesions (66.0%) was almost double that of glenoid defects (34.0%), but their prevalence was different between shoulders with primary subluxation (42.3% and 23.8%, respectively) and those with primary dislocation (84.7% and 42.3%, respectively). After recurrence, glenoid defects became significantly more frequent (at first recurrence, 72%; after ≥2 recurrences, 76%), while Hill-Sachs lesions showed a smaller increase (88% and 80%, respectively), so there was no difference between the prevalence of the 2 lesions. The sizes of glenoid defects and Hill-Sachs lesions also enlarged after recurrence, and large bone defects were frequently recognized after recurrence. While bipolar bone loss was not so frequent at primary instability (29.8%), bipolar bone loss increased significantly after recurrence (at first recurrence, 72%; after ≥2 recurrences, 72%). All Hill-Sachs lesions were on track at primary instability, but off-track lesions were recognized in 3 of 47 shoulders (6.4%) after recurrence. CONCLUSION: In most shoulders with recurrent instability, a Hill-Sachs lesion developed first, followed by a glenoid defect, leading to bipolar bone loss. Off-track Hill-Sachs lesions were detected only after recurrence.

Bipolar Bone Loss in Male Athletes With Traumatic Anterior Shoulder Instability: An Evaluation Using a New Scoring System.

BACKGROUND: The combination of a glenoid defect and a Hill-Sachs lesion in a shoulder with anterior instability has recently been termed "bipolar bone loss," but the prevalence and influence of this condition on postoperative recurrence after arthroscopic Bankart repair are still unclear. PURPOSE: To investigate bipolar bone loss in male athletes using a new scoring system and to evaluate its efficacy by comparing it with the glenoid track concept. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: The sizes of both lesions were evaluated retrospectively in 80 male athletes (85 shoulders) using computed tomography. The glenoid defects and the length, width, and depth of the Hill-Sachs lesions were classified into 5 size categories and were allocated scores from "0" for no defect to "4" for the largest defect. Patients were then classified into 5 classes according to the total score for both lesions: class 1, 0-1 point; class 2, 2 points; class 3, 3 points; class 4, 4 points; and class 5, ≥5 points. The prevalence of bipolar bone loss and postoperative recurrence rates for patients with at least 2 years of follow-up were compared among the classes. The recurrence rate for each class was also compared between shoulders with an off-track lesion and shoulders with an on-track lesion as well as among 3 sporting categories: rugby, American football, and other sports. RESULTS: Based on the combination of glenoid defect size and Hill-Sachs lesion length, the postoperative recurrence rate was 0% for shoulders in class 1, 12.5% for class 2, 33.3% for class 3, 28.6% for class 4, and 31.3% for class 5, while the recurrence rates were 0%, 16.7%, 28.6%, 27.3%, and 31.6%, respectively, for the combination of glenoid defect size and Hill-Sachs lesion width and 0%, 8.3%, 26.7%, 28.6%, and 35.3%, respectively, for the combination of glenoid defect size and Hill-Sachs lesion depth. Postoperative recurrence was frequently recognized regardless of the presence of off-track Hill-Sachs lesions. No recurrence was recognized in class 1 shoulders among rugby players, in classes 1 and 2 among American football players, and in classes 1 through 3 among other athletes based on the combination of glenoid defect size and Hill-Sachs lesion size. CONCLUSION: Our scoring system for bipolar bone loss was useful to evaluate the influence on postoperative recurrence in male athletes. The postoperative recurrence rate was influenced by the extent of bipolar bone loss and the sporting category regardless of the presence of off-track lesions.