Effect of Posterior Tibial Slope on Outcomes After Posterior Cruciate Ligament Reconstruction.

Background: Increased posterior tibial slope (PTS) leads to a relative anterior translation of the tibia on the femur. This is thought to decrease the stress on posterior cruciate ligament (PCL) reconstruction (PCLR) grafts. Purpose/Hypothesis: The purpose of this study was to analyze the effect of PTS on knee laxity, graft failure, and patient-reported outcome (PRO) scores after PCLR without concomitant anterior cruciate ligament reconstruction (ACLR). It was hypothesized that patients with higher PTS would have less knee laxity, fewer graft failures, and better PROs compared with patients with lower PTS. Study Design: Case-control study; Level of evidence, 3. Methods: All patients who underwent PCLR between 2001 and 2020 at a single institution were identified. Patients were excluded if they underwent concomitant or prior ACLR or proximal tibial osteotomy, were younger than 18 years, had <2 years of in-person clinical follow-up, and did not have documented PRO scores (Lysholm score and International Knee Documentation Committee [IKDC] score). Data were collected retrospectively from a prospectively gathered database. PTS measurements were recorded from perioperative lateral knee radiographs. A linear regression model was created to analyze PTS in relation to PRO scores. Patients with a grade 1 (1-5 mm) or higher posterior drawer were compared with those who had a negative posterior drawer. Results: A total of 37 knees met inclusion criterion; the mean age was 30.7 years at the time of surgery. The mean clinical follow-up was 5.8 years. No significant correlation was found between either the Lysholm score or the IKDC score and the PTS. Twelve knees (32.4%) had a positive posterior drawer at final follow-up. The mean PTS in knees with a positive posterior drawer was 6.2°, whereas that for knees with a negative posterior drawer was 8.3° (P = .08). No significant differences in PRO scores were identified for knees with versus knees without a positive posterior drawer. No documented graft failures or revisions were found. Conclusion: No significant differences were found in PROs or graft failure rates based on PTS at a mean of 5.8 years after PCLR. Increased tibial slope trended toward being protective against a positive posterior drawer, although this did not reach statistical significance.

Root Repair Has Superior Radiological and Clinical Outcomes Than Partial Meniscectomy and Nonoperative Treatment in the Management of Meniscus Root Tears: A Systematic Review.

PURPOSE: To compile and analyze structural and clinical outcomes after meniscus root tear treatment as currently described in the literature. METHODS: A review was conducted to identify studies published since 2011 on efficacy of repair, meniscectomy, and nonoperative management in the treatment of meniscus root tears. Patient cohorts were grouped into treatment categories, with medial and lateral root tears analyzed separately; data were collected on patient demographics, structural outcomes including joint space width, degree of medial meniscal extrusion, progression to total knee arthroplasty, and patient-reported outcome measures. Risk of bias was assessed using the MINORS (methodological index for non-randomized studies) criteria. Heterogeneity was measured using the I-statistic, and outcomes were summarized using forest plots without pooled means. RESULTS: The 56 included studies comprised a total of 3,191 patients. Mean age among the included studies ranged from 24.6 to 65.6 years, whereas mean follow-up ranged from 12 to 125.9 months. Heterogeneity analysis identified significant differences between studies. Change in joint space width ranged from -2.4 to -0.6 mm (i.e., decreased space) after meniscectomy (n = 186) and -0.9 to -0.1 mm after root repair (n = 209); change in medial meniscal extrusion ranged from -0.6 to 6.5 mm after root repair (n = 521) and 0.2 to 4.2 mm after meniscectomy (n = 66); and event rate for total knee arthroplasty ranged from 0.00 to 0.22 after root repair (n = 205), 0.35 to 0.60 after meniscectomy (n = 53), and 0.27 to 0.35 after nonoperative treatment (n = 93). Root repair produced the greatest numerical increase in International Knee Documentation Committee and Lysholm scores of the 3 treatment arms. In addition, root repair improvements in Knee Injury and Osteoarthritis Outcome Score Pain (range: 22-32), Sports and Recreational Activities (range: 23-36), Quality of Life (range: 22-42), and Symptoms subscales (range: 10-19), in studies with low risk of bias. CONCLUSIONS: The literature reporting on the treatment of meniscus root tears is heterogenous and largely limited to Level III and IV studies. Current evidence suggests root repair may be the most effective treatment strategy in lessening joint space narrowing of the knee and producing improvements in patient-reported outcomes. LEVEL OF EVIDENCE: Level IV, systematic review of Level II-IV studies.

Arthroscopic Lysis of Adhesions for Arthrofibrosis After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Arthrofibrosis (AF) after anterior cruciate ligament reconstruction (ACLR) remains a challenge. There is a paucity of data on arthroscopic interventions for AF after ACLR. PURPOSE: To (1) describe the patient, injury, and surgical characteristics and patient-reported outcomes (PROs) of those requiring an arthroscopic intervention for loss of motion after ACLR and (2) compare outcomes between patients undergoing an early intervention (within 3 months) versus those undergoing a late intervention (after 3 months). STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients with a history of ACLR and a subsequent operative procedure for postoperative AF at a single institution between 2000 and 2018 were retrospectively identified. Arthroscopic interventions included lysis of adhesions, capsular release with or without manipulation under anesthesia, and excision of cyclops lesions. Patients were excluded if they had a knee dislocation or multiple-ligament injury, a periarticular fracture, or less than 2-year follow-up from the arthroscopic intervention. PROs including the Tegner activity score, visual analog scale pain score, and International Knee Documentation Committee score as well as knee range of motion (ROM) were recorded. RESULTS: A total of 40 patients were included with a mean age of 27.2 years (range, 11.0-63.8 years) at surgery and a mean follow-up of 10.0 years (range, 2.9-20.7 years). The mean preoperative flexion and extension were 102° (range, 40°-150°) and 8° (range, 0°-25°), respectively. The mean postoperative flexion and extension were 131° (range, 110° to 150°) and 0° (range, -10° to 5°), respectively. After the arthroscopic intervention, the mean ROM improved from 94° (range, 40°-140°) preoperatively to 131° (range, 107°-152°) at final follow-up (P < .001), and the visual analog scale pain score improved from 3.0 preoperatively to 1.2 postoperatively (P = .001). Overall, 13 patients (32.5%) underwent an intervention within 3 months and 27 (67.5%) after 3 months. The early intervention group had a higher postoperative International Knee Documentation Committee score compared with the late intervention group (86.8 vs 71.7, respectively; P = .035). CONCLUSION: An arthroscopic intervention for AF after ACLR successfully improved knee ROM and pain. Patients who underwent either early or late surgery obtained satisfactory motion and function, although improved PROs were observed when the intervention occurred within 3 months of the primary procedure.

Artificial Intelligence Can Define and Predict the "Optimal Observed Outcome" After Anterior Shoulder Instability Surgery: An Analysis of 200 Patients With 11-Year Mean Follow-Up.

Purpose: The purpose of this study was to use unsupervised machine learning clustering to define the "optimal observed outcome" after surgery for anterior shoulder instability (ASI) and to identify predictors for achieving it. Methods: Medical records, images, and operative reports were reviewed for patients <40 years old undergoing surgery for ASI. Four unsupervised machine learning clustering algorithms partitioned subjects into "optimal observed outcome" or "suboptimal outcome" based on combinations of actually observed outcomes. Demographic, clinical, and treatment variables were compared between groups using descriptive statistics and Kaplan-Meier survival curves. Variables were assessed for prognostic value through multivariate stepwise logistic regression. Results: Two hundred patients with a mean follow-up of 11 years were included. Of these, 146 (64%) obtained the "optimal observed outcome," characterized by decreased: postoperative pain (23% vs 52%; P < 0.001), recurrent instability (12% vs 41%; P < 0.001), revision surgery (10% vs 24%; P = 0.015), osteoarthritis (OA) (5% vs 19%; P = 0.005), and restricted motion (161° vs 168°; P = 0.001). Forty-one percent of patients had a "perfect outcome," defined as ideal performance across all outcomes. Time from initial instability to presentation (odds ratio [OR] = 0.96; 95% confidence interval [CI], 0.92-0.98; P = 0.006) and habitual/voluntary instability (OR = 0.17; 95% CI, 0.04-0.77; P = 0.020) were negative predictors of achieving the "optimal observed outcome." A predilection toward subluxations rather than dislocations before surgery (OR = 1.30; 95% CI, 1.02-1.65; P = 0.030) was a positive predictor. Type of surgery performed was not a significant predictor. Conclusion: After surgery for ASI, 64% of patients achieved the "optimal observed outcome" defined as minimal postoperative pain, no recurrent instability or OA, low revision surgery rates, and increased range of motion, of whom only 41% achieved a "perfect outcome." Positive predictors were shorter time to presentation and predilection toward preoperative subluxations over dislocations. Level of Evidence: Retrospective cohort, level IV.

Management of Partial-Thickness Tears of the Distal Bicep Tendon: Evaluation of 111 Patients With 10-Year Follow-up.

Background: There is a paucity of research on the management of partial-thickness tears of the distal bicep tendon, and even less is known about the long-term outcomes of this condition. Purpose: To identify patients with partial-thickness distal bicep tendon tears and determine (1) patient characteristics and treatment strategies, (2) long-term outcomes, and (3) any identifiable risk factors for progression to surgery or complete tear. Study Design: Case-control study; Level of evidence, 3. Methods: A fellowship-trained musculoskeletal radiologist identified patients diagnosed with a partial-thickness distal bicep tendon tear on magnetic resonance imaging between 1996 and 2016. Medical records were reviewed to confirm the diagnosis and record study details. Multivariate logistic regression models were created using baseline characteristics, injury details, and physical examination findings to predict operative intervention. Results: In total, 111 patients met inclusion criteria (54 treated operatively, 57 treated nonoperatively), with 53% of tears in the nondominant arm and a mean follow-up time after surgery of 9.7 ± 6.5 years. Only 5% of patients progressed to full-thickness tears during the study period, at a mean of 35 months after the initial diagnosis. Patients who were nonoperatively treated were less likely to miss time from work (12% vs 61%; P < .001) and missed fewer days (30 vs 97 days; P < .016) than those treated surgically. Multivariate regression analyses demonstrated increased risk of progression to surgery with older age at initial consult (unit odds ratio [OR], 1.1), tenderness to palpation (OR, 7.5), and supination weakness (OR, 24.8). Supination weakness at initial consult was a statistically significant predictor for surgical intervention (OR, 24.8; P = .001). Conclusion: Clinical outcomes were favorable for patients regardless of treatment strategy. Approximately 50% of patients were treated surgically; patients with supination weakness were 24 times more likely to undergo surgery than those without. Progression to full-thickness tear was a relatively uncommon reason for surgical intervention, with only 5% of patients progressing to full-thickness tears during the study period and the majority occurring within 3 months of initial diagnosis.

Predicting the Risk of Posttraumatic Osteoarthritis After Primary Anterior Cruciate Ligament Reconstruction: A Machine Learning Time-to-Event Analysis.

BACKGROUND: There is a significant long-term risk of posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR). Elucidating the risk factors and successfully identifying at-risk patients is challenging. PURPOSE/HYPOTHESIS: The purpose of this study was to produce machine learning survival models that can identify (1) patients at risk of symptomatic PTOA and (2) patients who are at risk of undergoing total knee arthroplasty (TKA) after ACLR. It was hypothesized that these models would outperform traditional Kaplan-Meier estimators. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A geographic database was used to identify patients undergoing ACLR between 1990 and 2016 with a minimum 7.5-year follow-up. Models were used to analyze various factors to predict the rate and time to (1) symptomatic osteoarthritis and (2) TKA using random survival forest (RSF) algorithms. Performance was measured using out-of-bag (OOB) c-statistic, calibration, and Brier score. The predictive performances of the RSF models were compared with Kaplan-Meier estimators. Model interpretability was enhanced utilizing global variable importance and partial dependence curves. RESULTS: A total of 974 patients with ACLR and a minimum follow-up of 7.5 years were included; among these, 215 (22.1%) developed symptomatic osteoarthritis, and 25 (2.6%) progressed to TKA. The RSF algorithms achieved acceptable good to excellent predictive performance for symptomatic arthritis (OOB c-statistic, 0.75; Brier score, 0.128) and progression to TKA (OOB c-statistic, 0.89; Brier score, 0.026), respectively. Significant predictors of symptomatic PTOA included increased pain scores, older age, increased body mass index, increased time to ACLR, total number of arthroscopic surgeries before the diagnosis of arthritis, positive pivot-shift test after reconstruction, concomitant chondral injury, secondary meniscal tear, early (<250 days) or delayed (>500 days) return to sports or activity, and use of allograft. Significant predictors for TKA included older age, increased pain scores, total number of arthroscopic surgeries, high-demand activity/occupation, hypermobility, higher body mass index, systemic inflammatory disease, increased time to surgery, early (<250 days) or delayed (>500 days) return to sports or activity, and midsubstance tears. The Brier score over time revealed that RSF models outperformed traditional Kaplan-Meier estimators. CONCLUSION: Machine learning survival models were used to reliably identify patients at risk of developing symptomatic PTOA, and these models consistently outperformed traditional Kaplan-Meier estimators. Strong predictors for the development of PTOA after ACLR included increased pain scores at injury and postoperative visit, older age at injury, total number of arthroscopic procedures, positive postoperative pivot-shift test, and secondary meniscal tear.

Osteochondritis Dissecans of the Capitellum of the Elbow: Improved Outcomes in Surgically Treated Versus Nonoperatively Treated Patients at Long-Term Follow-up.

Purpose: To (1) report the long-term outcomes associated with both operative and nonoperative management of capitellar osteochondritis dissecans (OCD), (2) identify factors associated with failure of nonoperative management, and (3) determine whether delay in surgery affects final outcomes. Methods: All patients who received a diagnosis of capitellar OCD from 1995-2020 within a geographic cohort were included. Medical records, imaging studies, and operative reports were manually reviewed to record demographic data, treatment strategies, and outcomes. The cohort was divided into 3 groups: (1) nonoperative management, (2) early surgery, and (3) delayed surgery. Delayed surgery (surgery ≥6 months after symptom onset) was considered failure of nonoperative management. Results: Fifty elbows with a mean follow-up period of 10.5 years (median, 10.3 years; range, 1-25 years) were studied. Of these, 7 (14%) were definitively treated nonoperatively, 16 (32%) underwent delayed surgery after at least 6 months of failed nonoperative treatment, and 27 (54%) underwent early surgical intervention. When compared with nonoperative management, surgical management resulted in superior Mayo Elbow Performance Index pain scores (40.1 vs 33, P = .04), fewer mechanical symptoms (9% vs 50%, P < .01), and better elbow flexion (141° vs 131°, P = .01) at long-term follow-up. Older patients trended toward increased failure of nonoperative management (P = .06). The presence of an intra-articular loose body predicted failure of nonoperative management (P = .01; odds ratio, 13). Plain radiography and magnetic resonance imaging had poor sensitivities for identifying loose bodies (27% and 40%, respectively). Differences in outcomes after early versus delayed surgical management were not observed. Conclusions: Nonoperative management of capitellar OCD failed 70% of the time. Elbows that did not undergo surgery had slightly more symptoms and decreased functional outcomes compared with those treated surgically. The greatest predictors of failure of nonoperative treatment were older age and presence of a loose body; however, an initial trial of nonoperative treatment did not adversely impact the success of future surgery. Level of Evidence: Level III, retrospective cohort study.

Grooveplasty Compared With Trochleoplasty for the Treatment of Trochlear Dysplasia in the Setting of Patellar Instability.

Purpose: To compare the clinical efficacy in the resolution of patellar instability, patient-reported outcomes (PROs), and complication and reoperation rates between patients who underwent grooveplasty (proximal trochleoplasty) and patients who underwent trochleoplasty as part of a combined patellofemoral stabilization procedure. Methods: A retrospective chart review was performed to identify a cohort of patients who underwent grooveplasty and a cohort who underwent trochleoplasty at the time of patellar stabilization. Complications, reoperations, and PRO scores (Tegner, Kujala, and International Knee Documentation Committee scores) were collected at final follow-up. The Kruskal-Wallis test and Fisher exact test were performed when appropriate, and P < .05 was considered significant. Results: Overall, 17 grooveplasty patients (18 knees) and 15 trochleoplasty patients (15 knees) were included. Seventy-nine percent of patients were female, and the average follow-up period was 3.9 years. The mean age at first dislocation was 11.8 years overall; most patients (65%) had more than 10 lifetime instability events and 76% of patients underwent prior knee-stabilizing procedures. Trochlear dysplasia (Dejour classification) was similar between cohorts. Patients who underwent grooveplasty had a higher activity level (P = .007) and a higher degree of patellar facet chondromalacia (P = .008) at baseline. At final follow-up, no patients had recurrent symptomatic instability after grooveplasty compared with 5 patients in the trochleoplasty cohort (P = .013). There were no differences in postoperative International Knee Documentation Committee scores (P = .870), Kujala scores (P = .059), or Tegner scores (P = .052). Additionally, there were no differences in complication rates (17% in grooveplasty cohort vs 13% in trochleoplasty cohort, P > .999) or reoperation rates (22% vs 13%, P = .665). Conclusions: Proximal trochlear reshaping and removal of the supratrochlear spur (grooveplasty) in patients with severe trochlear dysplasia may offer an alternative strategy to complete trochleoplasty for the treatment of trochlear dysplasia in complex cases of patellofemoral instability. Grooveplasty patients showed less recurrent instability and similar PROs and reoperation rates compared with trochleoplasty patients. Level of Evidence: Level III, retrospective comparative study.

Advances in the Treatment of Rotator Cuff Tears: Management of Rotator Cuff Tears in the Athlete.

Unique biomechanical factors in the overhead and throwing athlete lead to a spectrum of rotator cuff pathology, usually with progressive lateralization of the supraspinatus footprint. Initial comprehensive nonoperative management is indicated for all athletes. Progression to arthroscopic debridement, repair of concomitant injuries, and possible rotator cuff repair with a transosseous equivalent technique are the current management strategies for athletes when nonoperative management fails.

Incidence and Epidemiology of Symptomatic Capitellar Osteochondritis Dissecans of the Elbow: A United States Population-Based Study Over a 25-Year Period.

Background: There are limited data on the incidence of capitellar osteochondritis dissecans (OCD) in the United States (US) population. Purpose: To determine the incidence of symptomatic capitellar OCD in a representative US subpopulation and identify changes in its incidence over time and to investigate the relationship between the incidence of capitellar OCD and patient sex and age. Study Design: Descriptive epidemiology study. Methods: A retrospective review was performed of patients aged ≤24 years from Olmsted County, Minnesota, with symptomatic capitellar OCD over a 25-year period (1995-2019). Patients with acute osteochondral injuries, Panner disease, and hereditary arthropathy were excluded. Poisson regression was utilized to identify the predictors of a capitellar OCD diagnosis. Incidence rates (per 100,000) were assessed for changes over time. Age groups of younger (10-15 years) versus older (16-24 years) patients were compared. Results: A total of 45 patients (78% male) were identified. The mean age was 14.5 years (range, 10-24 years); 31 patients were in the younger group, and 14 patients were in the older group. Sport participation was seen in 89%of patients; 90% were overhead athletes, and 58% were throwing athletes. The incidence of capitellar OCD was 6.0 per 100,000 overall, 9.5 per 100,000 for male patients, and 2.6 per 100,000 for female patients. The incidence was highest for male patients in the younger group (15.3/100,000) and lowest for female patients in the older group (0.8/100,000). The estimated incidence rate ratio for younger versus older patients was 3.3 (P < .001), and the incidence rate ratio for male versus female patients was 3.5 (P < .001). There were no changes in the incidence of capitellar OCD over time as a continuous or 5-year categorical variable (P = .290 and P = .460, respectively). Overall, 82% of patients were treated surgically. There were no significant changes in surgical rates over time. Conclusion: In this US subpopulation, the overall incidence of symptomatic capitellar OCD between the ages of 10 and 24 years was 6.0 per 100,000 over the 25-year period studied, which is higher than previously reported US estimates. Incidence rates and treatment strategies did not change significantly over time.

Managing Shoulder Instability in the Overhead Athlete.

PURPOSE OF REVIEW: Shoulder instability in the overhead athlete is a difficult problem because of the balance between necessary laxity for athletic movements and stability of the joint. The purpose of this review is to provide an overview of the clinical evaluation of shoulder instability in the overhead athlete and present evidence-based management strategies for each subtype of shoulder instability, including novel techniques and outcomes. RECENT FINDINGS: Recent investigation has shown that throwers and other overhead athletes are more likely to present with subtle subluxation events rather than discrete dislocations as their primary symptom. While overhead athletes with discrete anterior dislocation events are likely to begin with non-operative management, many progress on to surgical intervention. Surgical management of glenohumeral joint instability continues to pose challenges due to the potential for over-tensioning for the sake of stability at the expense of the adaptive laxity that often confers performance benefits in the overhead athlete. Novel, individualized, and sport/position specific approaches are needed to address this complex issue. The optimal management of shoulder instability in the overhead athlete continues to be a controversial topic due to the complex work-up, an increasing number of surgical options with varying indications, and low volume of high-quality studies comparing any of the treatment options. The Anterior Shoulder Instability International Consensus Group guidelines from February 2022 offer the most updated guidelines on work-up and management. Overall, high-quality randomized controlled trials are required to determine the optimal treatment for specific pathologies and aid in creating patient-centered management plans.

Benefits of Meniscal Repair in Selected Patients Aged 60 Years and Older.

Background: Little is known about the benefits and outcomes of meniscal repair in patients older than 60 years. Purpose: To (1) report the clinical and radiographic outcomes of meniscal repair in patients aged ≥60 years and compare them with matched patients who underwent meniscectomy and (2) identify procedural failures. Study Design: Cohort study; Level of evidence, 2. Methods: We included 32 knees in 32 patients aged ≥60 years (20 female, 12 male; mean age, 64.5 ± 4.6 years) who underwent meniscal repair surgery at a single medical institution between 2010 and 2020. Patients were matched according to age, sex, body mass index, and meniscal tear type with a comparison cohort who underwent meniscectomy (n = 49 patients [49 knees]; 32 female, 17 male). For all patients, demographic information, clinical history, physical examination findings, treatment details, and radiographic images were reviewed and analyzed. At final follow-up (mean, 42.2 months; range, 13-128 months), patients completed the 2000 International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Knee injury and Osteoarthritis Outcome Score (KOOS), and Lysholm score. Clinical failure was defined as revision surgery and/or progression to total knee arthroplasty (TKA). A matched-pairs t test was used to analyze differences between the 2 treatment groups, and Kaplan-Meier analysis was used to determine the rates of knee osteoarthritis and progression to TKA. Results: The majority of patients had a medial meniscal tear (72.8%), whereas the lateral meniscus was torn in 27.2% of cases. Most tears were located in the meniscal root (56.8%), followed by the posterior horn (34.6%) and midbody (8.6%). At final follow-up, all outcome scores were higher in the repair group compared with the meniscectomy group (IKDC, 78.9 ± 13.4 vs 56.0 ± 15.4; KOOS, 86.6 ± 11.9 vs 61.7 ± 16.2; Lysholm, 88.3 ± 13.3 vs 68.7 ± 15.2, respectively; P < .001 for all). Clinical failure was observed in 22% of patients in the repair group. Conclusion: All clinical outcome scores were higher in the meniscal repair group compared with the matched meniscectomy group at final follow-up. The clinical failure rate of the repair group was 22%. These findings support meniscal repair in selected patients aged ≥60 years.

Early ACLR and Risk and Timing of Secondary Meniscal Injury Compared With Delayed ACLR or Nonoperative Treatment: A Time-to-Event Analysis Using Machine Learning.

BACKGROUND: Surgical and nonoperative management of anterior cruciate ligament (ACL) injuries seek to mitigate the risk of knee instability and secondary meniscal injury. However, the associated risk and timing of secondary meniscal tears have not been completely elucidated. PURPOSE: To compare risk and timing of secondary meniscal injury between patients receiving nonoperative management, delayed ACL reconstruction (ACLR), and early ACLR using a machine learning survival analysis. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A geographic database was used to identify and review records of patients with a diagnosis of ACL rupture between 1990 and 2016 with minimum 2-year follow-up. Patients undergoing ACLR were matched 1:1 with nonoperatively treated controls. Rate and time to secondary meniscal tear were compared using random survival forest algorithms; independent models were developed and internally validated for predicting injury-free duration in both cohorts. Performance was measured using out-of-bag c-statistic, calibration, and Brier score. Model interpretability was enhanced using global variable importance and partial dependence curves. RESULTS: The study included 1369 patients who underwent ACLR and 294 patients who had nonoperative treatment. After matching, no significant differences in rates of secondary meniscal tear were found (P = .09); subgroup analysis revealed the shortest periods of meniscal survival in patients undergoing delayed ACLR. The random survival forest algorithm achieved excellent predictive performance for the ACLR cohort, with an out-of-bag c-statistic of 0.80 and a Brier score of 0.11. Significant variables for risk of meniscal tear for the ACLR cohort included time to return to sports or activity ≤350 days, time to surgery ≥50 days, age at injury ≤40 years, and high-impact or rotational landing sports, whereas those in the nonoperative cohort model included time to RTS ≤200 days, visual analog scale pain score >3 at consultation, hypermobility, and noncontact sports. CONCLUSION: Delayed ACLR demonstrated the greatest long-term risk of meniscal injury compared with nonoperative treatment or early ACLR. Risk factors for decreased meniscal survival after ACLR included increased time to surgery, shorter time to return to sports or activity, older age at injury, and involvement in high-impact or rotational landing sports. Pending careful external validation, these models may be deployed in the clinical space to provide real-time insights and enhance decision making.

Machine Learning for Predicting Lower Extremity Muscle Strain in National Basketball Association Athletes.

Background: In professional sports, injuries resulting in loss of playing time have serious implications for both the athlete and the organization. Efforts to quantify injury probability utilizing machine learning have been met with renewed interest, and the development of effective models has the potential to supplement the decision-making process of team physicians. Purpose/Hypothesis: The purpose of this study was to (1) characterize the epidemiology of time-loss lower extremity muscle strains (LEMSs) in the National Basketball Association (NBA) from 1999 to 2019 and (2) determine the validity of a machine-learning model in predicting injury risk. It was hypothesized that time-loss LEMSs would be infrequent in this cohort and that a machine-learning model would outperform conventional methods in the prediction of injury risk. Study Design: Case-control study; Level of evidence, 3. Methods: Performance data and rates of the 4 major muscle strain injury types (hamstring, quadriceps, calf, and groin) were compiled from the 1999 to 2019 NBA seasons. Injuries included all publicly reported injuries that resulted in lost playing time. Models to predict the occurrence of a LEMS were generated using random forest, extreme gradient boosting (XGBoost), neural network, support vector machines, elastic net penalized logistic regression, and generalized logistic regression. Performance was compared utilizing discrimination, calibration, decision curve analysis, and the Brier score. Results: A total of 736 LEMSs resulting in lost playing time occurred among 2103 athletes. Important variables for predicting LEMS included previous number of lower extremity injuries; age; recent history of injuries to the ankle, hamstring, or groin; and recent history of concussion as well as 3-point attempt rate and free throw attempt rate. The XGBoost machine achieved the best performance based on discrimination assessed via internal validation (area under the receiver operating characteristic curve, 0.840), calibration, and decision curve analysis. Conclusion: Machine learning algorithms such as XGBoost outperformed logistic regression in the prediction of a LEMS that will result in lost time. Several variables increased the risk of LEMS, including a history of various lower extremity injuries, recent concussion, and total number of previous injuries.

Patient Age and Surgical Intervention as Risk Factors for the Development of Osteoarthritis After Posterior Shoulder Instability: A Population-Based Study.

Background: Diagnosis and treatment of posterior shoulder instability (PSI) has improved with advances in imaging and surgical technique. However, the relationship between PSI and osteoarthritis (OA) remains unclear. Purpose: To evaluate a population-based cohort to (1) determine the rate of symptomatic OA, (2) identify patient characteristic risk factors for OA, and (3) evaluate the effect of posterior capsulolabral repair on OA progression. Study Design: Case-control study; Level of evidence, 3. Methods: After review of 324 patient records, we included 115 patients (14 female, 101 male) diagnosed with PSI between January 1994 and July 2012 with an average follow-up of 12.5 years (range, 5-23 years). Medical records were reviewed for patient characteristics, injury characteristics, surgical details (if any), and radiographic progression of OA. Kaplan-Meier survival was used to estimate survival free of OA; characteristics associated with OA progression were determined via univariate Cox regression models, and associated 95% CIs and hazard ratios (HRs) are presented. Results: Overall, 14% (16/115) of patients had radiographic progression of symptomatic glenohumeral arthritis, with 5-year survival of 88.3% (95% CI, 79.7%-97.3%). Older age at the time of instability diagnosis was associated with arthritis progression (10-year unit HR, 1.95; 95% CI, 1.26-3.03). Patients who underwent surgery demonstrated increased radiographic progression of OA (HR, 4.03; 95% CI, 1.23-13.23). There was a trend of increased OA in patients treated with labral debridement compared with repair despite lower baseline levels of OA; however, this difference was not statistically significant (P = .09). Conclusion: Symptomatic glenohumeral arthritis is not seen routinely in patients with PSI. Although uncommon, an age of at least 30 years at the time of diagnosis and surgical intervention were identified as risk factors for developing symptomatic arthritis at long-term follow-up.

Arthroscopic Posterior Capsular Release Effectively Reduces Pain and Restores Terminal Knee Extension in Cases of Recalcitrant Flexion Contracture.

Purpose: To 1) evaluate the clinical efficacy of arthroscopic posterior capsular release for improving range of motion (ROM) in cases of recalcitrant flexion contracture and 2) determine patient-reported outcomes (PROs) postoperatively. Methods: Retrospective chart review was performed to identify patients who underwent arthroscopic posterior capsular release due to persistent extension deficit of the knee despite comprehensive nonoperative physical therapy between 2008 and 2021. Knee ROM and PROs (International Knee Documentation Committee [IKDC], Tegner, and visual analog scale [VAS]) were collected at final follow-up. Results: Overall, 22 patients were included with a median age of 37 years (interquartile range [IQR]: 20.5-44.3). Of these, 8 (36%) were male and 14 (64%) were female, and average follow-up was 3.7 ± 3.3 years. The most common etiology was knee flexion contracture after anterior cruciate ligament (ACL) reconstruction (59%). All patients failed a minimum of 3 months of nonoperative management. Prior to operative intervention, 100% of patients received physical therapy, 64% received extension knee bracing or casting, and 36% received corticosteroid injection. Median preoperative extension was 15° (IQR: 10-25) compared to 2° (IQR: 0-5) postoperatively (P < .001). At final follow-up, median extension was 0° (IQR: 0-3.5). Postoperative VAS pain scores at rest (2 vs 0; P = .001) and with use (5 vs 1.8; P = .017) improved at final contact, and most (94%) patients reported maintaining their extension ROM. Patients with ACL-related extension deficit reported better IKDC (81 vs 51.3; P = .008), Tegner (5.8 vs 3.6; P = .007), and VAS pain scores (rest: 0.2 vs 1.8; P = .008; use: 1.3 vs 5; P = .004) compared to other etiologies. Conclusion: Arthroscopic posterior capsular release for recalcitrant flexion contracture provides an effective means for reducing pain and restoring terminal extension. The improvement in extension postoperatively was maintained for most (94%) patients at final follow-up with a 14% reoperation rate.

Shoulder Injuries in Professional Baseball Batters: Analysis of 3,414 Injuries Over an 8-Year Period.

Purpose: To characterize the shoulder injuries experienced by baseball batters and position players (nonpitchers); to quantify the outcomes of these injuries with respect to time out of play, recurrence, and surgery rates; and to identify any injury patterns that are associated with worse outcomes. Methods: Between 2011 and 2017, all Major League Baseball (MLB) and Minor League Baseball (MiLB) players who sustained shoulder injuries were identified using the MLB Health and Injury Tracking System (HITS). Injuries were included if they were sustained during baseball activity, resulted in at least 1 day missed (DM), and occurred in position players (nonpitchers). Results: Over the study period, a total of 3,414 shoulder injuries occurred in batters, resulting in a sum of 68,808 DM and a mean of 22 DM per injury. Most injuries were a result of acute trauma (n = 2125; 62.2%) with throwing as the predominant activity (n = 1292; 38%). Rotator cuff strain/tears was the most common diagnosis (n = 790; 23.1%), and SLAP tears had the highest season-ending rate (35.3%) and need for surgery (45.1%). There was a lower frequency of surgery (6.2% vs 9.2%; P = .002) and reinjury (2.03% vs 3.62%; P = .007) in the throwing shoulder vs the nonthrowing shoulder. There was an increased frequency of surgery for the front versus the back batting shoulder (8.2% vs 6.2%; P = .031) with similar DM (20.7 vs 22.2; P = .333) and return to play rates (94.0% vs 92.2%; P = .135). Conclusions: During the 7-season study period, there were a total of 3,414 shoulder injuries that resulted in nearly 70,000 days of out of play in professional baseball position players/batters (nonpitchers). Although pitchers were intentionally excluded from the analysis, throwing was still the most common mechanism of injury, and rotator cuff injuries were the most common injury. Labral tears were the most likely injury to be season ending and require surgery. Clinical Relevance: This study is meant to help determine characteristics of shoulder injuries that occur in non-pitchers by focusing on professional baseball batters and position players. This information could be helpful to sports medicine practitioners and shoulder specialists to better prognosticate injury recovery.

Current Reviews in Musculoskeletal Medicine: Current Controversies for Treatment of Meniscus Root Tears.

PURPOSE OF REVIEW: The role of the meniscus in preserving the biomechanical function of the knee joint has been clearly defined. The hypothesis that meniscus root integrity is a prerequisite for meniscus function is supported by the development of progressive knee osteoarthritis (OA) following meniscus root tears (MRTs) treated either non-operatively or with meniscectomy. Consequently, there has been a resurgence of interest in the diagnosis and treatment of MRTs. This review examines the contemporary literature surrounding the natural history, clinical presentation, evaluation, preferred surgical repair technique and outcomes. RECENT FINDINGS: Surgeons must have a high index of suspicion in order to diagnose a MRT because of the nonspecific clinical presentation and difficult visualization on imaging. Compared with medial MRTs that commonly occur in middle age/older patients, lateral meniscus root injuries tend to occur in younger males with lower BMIs, less cartilage degeneration, and with concomitant ligament injury. Subchondral insufficiency fractures of the knee have been found to be associated with both MRTs and following arthroscopic procedures. Meniscus root repair has demonstrated good outcomes, and acute injuries with intact cartilage should be repaired. Cartilage degeneration, BMI, and malalignment are important considerations when choosing surgical candidates. Meniscus centralization has emerged as a viable adjunct strategy aimed at correcting meniscus extrusion. Meniscus root repair results in a decreased rate of OA and arthroplasty and is economically advantageous when compared with nonoperative treatment and partial meniscectomy. The transtibial pull-through technique with the addition of centralization for the medial meniscus is associated with encouraging early results.

Inside-Out Approach to Meniscus Repair: Still the Gold Standard?

PURPOSE OF REVIEW: The purpose of this review is to provide an up-to-date summary on the current literature and trends regarding use of the inside-out approach to meniscus repair. Additionally, the paper describes the authors preferred techniques for inside-out meniscus repair utilizing posteromedial and posterolateral exposures. RECENT FINDINGS: There has been a substantial increase in recent publications regarding meniscus repair. However, comparisons regarding the optimal repair technique have not been conclusive. Despite the recent increase in use of all-inside devices, multiple investigations with short-to-mid-term follow-up have demonstrated similar rates of meniscus healing between inside-out and all-inside repair techniques. Similarly, current literature describes comparable failure rates of around 20%. There are variations in the profile of complications, with all-inside devices having more implant-related complications and inside-out techniques with higher neurovascular injuries. Inside-out meniscus repair is a versatile, cost-effective technique that remains the gold standard for management of most meniscus tear patterns. Through a thoughtful approach, efficient suture retrieval and repair can be performed while protecting critical neurovascular structures. All-inside meniscus repair devices have increased in popularity and surgeon access, but this technique is not without limitations and comparisons to inside-out meniscus repair demonstrates equivocal outcomes.

The effect of delay and social distance in the dictator and ultimatum games.

The previous research shows that delaying a reward in the dictator game contributes to less generous offers. If the reason for such results is temporal discounting, it can be expected that the effect of delay would be stronger for persons with a higher discounting rate, as well as the analogous pattern should occur in the ultimatum game. The participants of our study took decisions in the dictator and ultimatum game as proposers and responders. We manipulated delay of a reward (from immediate to in 5 years) and social distance (from the closest person to known only by sight). We observed the expected but weak interaction effect between delay and temporal discounting. However, the correlational analyses did not confirm the significant relationship between temporal discounting and decisions taken in dictator and ultimatum games. Moreover, the offers decline with the social distance, both in the dictator and ultimatum game. However, the social distance does not affect the value of the accepted offer in the ultimatum game. Such a discrepancy between donors' behaviour and beneficiaries' expectations may form a subtle but significant failure of the real-world donation markets.