Pectoralis muscle injuries in Major and Minor League Baseball.

BACKGROUND AND HYPOTHESIS: Although shoulder and elbow injuries in professional baseball players have been thoroughly studied, little is known about the frequency and impact of pectoralis muscle injuries in this population. The purpose of this study was to use the official league injury surveillance system to describe pectoralis muscle injuries in professional baseball players in Major League Baseball (MLB) and Minor League Baseball (MiLB). Specifically, (1) player demographic characteristics, (2) return to play (RTP), (3) injury mechanism, (4) throwing- and batting-side dominance, and (5) injury rate per athlete exposure (AE) were characterized to guide future injury prevention strategies. METHODS: The MLB Health and Injury Tracking System database was used to compile all pectoralis muscle injuries in MLB and MiLB athletes in the 2011-2017 seasons. Injury-related data including diagnosis (tear or rupture vs. strain), player demographic characteristics, injury timing, need for surgical intervention, RTP, and mechanism of injury were recorded. Subanalyses of throwing- and batting-side dominance, as well as MLB vs. MiLB injury frequency, were performed. RESULTS: A total of 138 pectoralis muscle injuries (32 MLB and 106 MiLB injuries) were reported in the study period (5 tears or ruptures and 133 strains), with 5 of these being recurrent injuries. Operative intervention was performed in 4 athletes (2.9%). Of the 138 injuries, 116 (84.1%) resulted in missed days of play, with a mean time to RTP of 19.5 days. Starting pitchers sustained the greatest proportion of pectoralis injuries (48.1%), with pitching being the most common activity at the time of injury (45.9%). A majority of injuries (86.5%) were sustained during non-contact play. Overall, 87.5% of injuries occurred on the player's dominant throwing side and 81.3% occurred on the player's dominant batting side. There was no significant difference in the rate of pectoralis injuries in the MLB regular season (0.584 per 10,000 AEs) vs. the MiLB regular season (0.425 per 10,000 AEs) (P = .1018). CONCLUSION: Pectoralis muscle injuries are most frequently non-contact injuries, most commonly sustained by pitchers. An understanding of these injuries can guide athletic trainers and management in expectation management and decision making, in addition to directing future efforts at injury prevention.

Prognostic utility of an magnetic resonance imaging-based classification for operative versus nonoperative management of ulnar collateral ligament tears: one-year follow-up.

BACKGROUND: A recently introduced classification of medial ulnar collateral ligament (UCL) tears has demonstrated high interobserver and intraobserver reliability, but little is known about its prognostic utility. The purpose of this study was to assess the relationship of the magnetic resonance imaging (MRI)-based classification system and nonoperative vs. operative management. Secondary objectives included subanalysis of baseball players. METHODS: Eighty-five consecutive patients with UCL tears after a standardized treatment paradigm were categorized as operative vs. nonoperative. UCL tears of patients with a minimum of 1-year follow-up were retrospectively classified using the MRI-based classification system. Subanalyses for baseball players included return-to-play and return-to-prior performance. RESULTS: A total of 80 patients (62 baseball players, 54 pitchers) met inclusion criteria. A total of 51 patients underwent surgery, and 29 patients completed nonoperative management. In baseball players, 59% of the proximal tears were treated nonoperatively and 97% of the distal tears were treated operatively; 100% of the proximal partial-thickness tears and 100% of the distal complete tears were treated nonoperatively and operatively, respectively. Patients with distal (odds ratio: 48.4, P < .0001) and complete (odds ratio: 5.0, P = .004) tears were more likely to undergo surgery. Baseball players, regardless of position, were determinants of operative management, and there was no difference in return-to-play clearance and return-to-prior performance between the operative and nonoperative groups. CONCLUSION: A reliable 6-stage MRI-based classification addressing UCL tear grade and location may confer decision making between operative and nonoperative management. Complete and distal tears carry a markedly increased risk of failing nonoperative care compared with proximal, partial tears.

Biomechanical analysis of elbow medial ulnar collateral ligament tear location and its effect on rotational stability.

BACKGROUND: Recent anatomic and clinical studies have shown that the location of the injury to the elbow ulnar collateral ligament (UCL) is an important variable in deciding on surgical intervention; however, no studies have evaluated these findings biomechanically. METHODS: This study tested 16 intact elbow specimens. Valgus torques of 2.5 and 5 Nm were applied to the elbow at various flexion angles, and the resulting valgus angles were measured. The valgus angles were applied to the elbows in their intact states and again after partial and complete cuts were made on the proximal and distal insertions of the UCL. Resulting valgus torques were measured, and stiffness was calculated for each elbow flexion angle. Unpaired t tests were used to evaluate the effects of cut location and flexion angle on joint rotational stability and stiffness. RESULTS: The posterior-distal insertion contributed the most to stability. At valgus angles generated from 2.5 Nm intact torques, the posterior-distal insertions contributed to 51% ± 26% (P < .03) intact rotational stability, and at valgus angles generated from 5 Nm intact torques, the posterior-distal insertions contributed to 41% ± 17% (P < .02) intact rotational stability. For overall stiffness, the posterior-distal insertions contributed to 31% ± 12% (P < .045) intact stiffness. CONCLUSION: Overall, the posterior distal insertion of the UCL contributed most to rotational stability and stiffness of the medial elbow when subjected to valgus stress at 90° and 120° of elbow flexion. At higher elbow flexion angles, the posterior insertions contributed more to stability, whereas the anterior insertions had a greater effect at lower flexion angles.

Performance of implant sonication culture for the diagnosis of periprosthetic shoulder infection.

BACKGROUND: Diagnosing infection after shoulder arthroplasty can be a challenge because of the high prevalence of low-virulence organisms, such as Propionibacterium acnes. The purpose of this study was to evaluate the utility of implant sonication fluid cultures in the diagnosis of periprosthetic joint infection compared with standard culture techniques in patients undergoing revision shoulder arthroplasty. METHODS: Routine perioperative testing was performed in 53 patients who underwent revision shoulder arthroplasty. In addition to routine tissue and fluid culture, the retrieved shoulder implants underwent sonication with culture of the sonicate fluid. Diagnostic performance of implant sonication culture was determined on the basis of previously defined infection criteria and compared with standard intraoperative cultures. RESULTS: Of the 53 revision cases that underwent implant sonication fluid culture, 25 (47%) were classified as infected. Intraoperative culture (tissue and fluid) sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 96%, 75%, 77%, 95%, and 85%, respectively. Using a cutoff of >20 colony-forming units per milliliter to exclude contaminants, the sensitivity, specificity, PPV, NPV, and accuracy of implant sonicate culture were 56% (P < .001, compared with standard intraoperative cultures), 93% (P = .07), 88% (P = .4), 70% (P = .02), and 75% (P = .22), respectively. Without use of a sonication fluid culture cutoff value, the sensitivity, specificity, PPV, NPV, and accuracy of implant sonicate culture were 96% (P = 1.0, compared with standard intraoperative cultures), 64% (P = .38), 71% (P = .53), 95% (P = .9), and 79% (P = .45). CONCLUSIONS: Implant sonication fluid culture in revision shoulder arthroplasty showed no significant benefits over standard intraoperative cultures in diagnostic utility for periprosthetic joint infection.

Neer Award 2015: Analysis of cytokine profiles in the diagnosis of periprosthetic joint infections of the shoulder.

BACKGROUND: Periprosthetic joint infection (PJI) after shoulder arthroplasty can present a diagnostic and therapeutic challenge. This study evaluated the diagnostic utility of broader synovial fluid cytokine analysis for identifying PJI in patients undergoing revision shoulder arthroplasty. METHODS: Synovial fluid levels of 9 cytokines (interleukin [IL] 6, granulocyte-macrophage colony-stimulating factor, IL-1ß, IL-12, IL-2, IL-8, interferon-γ, IL-10, and tumor necrosis factor-α) were measured in 75 cases of revision shoulder arthroplasty with a multiplex immunoassay. Cases were classified into infection categories and groups based on objective perioperative findings. Differences in cytokine levels among infection groups were evaluated. Receiver operating characteristic curves were used to assess the diagnostic utility of the individual synovial fluid cytokines and combinations of cytokines in determining infection status. RESULTS: Synovial IL-6, granulocyte-macrophage colony-stimulating factor, interferon-γ, IL-1ß, IL-2, IL-8, and IL-10 were significantly elevated in cases of revision shoulder arthroplasty classified as infected. Individually, IL-6, IL-1ß, IL-8, and IL-10 showed the best combination of sensitivity and specificity for predicting infection, and a combined cytokine model consisting of IL-6, tumor necrosis factor-α, and IL-2 showed better diagnostic test characteristics than any cytokine alone, with sensitivity of 0.80, specificity of 0.93,, positive and negative predictive values of 0.87 and 0.89, and positive and negative likelihood ratios of 12.0 and 0.21. CONCLUSIONS: Individual and combined synovial fluid cytokine analysis were both more effective than routine perioperative testing, such as serum erythrocyte sedimentation rate and C-reactive protein, in the diagnosis of PJI of the shoulder. Once validated, combined synovial fluid cytokine analysis could be used as a predictive tool to determine the probability of PJI in patients undergoing revision shoulder arthroplasty and better guide treatment.

Synovial Cytokines and the MSIS Criteria Are Not Useful for Determining Infection Resolution After Periprosthetic Joint Infection Explantation.

BACKGROUND: Diagnosing periprosthetic joint infection (PJI) requires a combination of clinical and laboratory parameters, which may be expensive and difficult to interpret. Synovial fluid cytokines have been shown to accurately differentiate septic from aseptic failed total knee (TKA) and hip (THA) arthroplasties. However, after first-stage explantation, there is still no reliable test to rule out PJI before a second-stage reimplantation procedure. QUESTIONS/PURPOSES: (1) Which synovial fluid cytokines have the highest diagnostic accuracy for PJI? (2) Which cytokine shows the greatest decrease associated with the resolution of infection in the same patient between explantation and subsequent reimplantation of an infected arthroplasty? (3) What is the accuracy of synovial fluid cytokines and the Musculoskeletal Infection Society (MSIS) criteria to rule out PJI after first-stage explantation? (4) What are the most studied synovial fluid cytokines for diagnosing PJI as reported in the literature and what are their cumulative diagnostic accuracy? METHODS: Between May 2013 and March 2014, 104 patients with painful THA and TKA evaluated for possible PJI were included in our study. Of these, 90 (87%) had cytokine levels measured from synovial fluid samples collected as part of this prospective study (n = 33 hips, n = 57 knees). A second group of 35 patients (n = 36 samples) who presented during the same time period with an antibiotic spacer also had synovial cytokines measured before second-stage reimplantation. For the first group of 90 patients, the MSIS definition classified each joint at the time of surgery as infected (n = 31) or not infected (n = 59) and was used as the standard to test the accuracy in diagnosing PJI. Of the 35 patients with synovial marker data before second-stage surgery, 15 patients had cytokine measurements both at explantation and reimplantation and were used to quantify the change between stages. The reimplantation group had a minimum 1-year followup (with four [11%] patients lost to followup) and was classified into successful or failed treatment based on Delphi-based consensus data and was used to test the accuracy in detecting infection resolution at reimplantation. RESULTS: Interleukin (IL)-1ß and interferon-γ demonstrated the highest diagnostic utility (area under the curve 0.92, 0.91, respectively); IL-1ß and IL-6 had the highest sensitivities (0.90 [95% confidence interval {CI}, 0.74-0.98] and 0.81 [0.63-0.93]). As a measure of infection resolution, IL-1ß had the greatest decrease (12.4-fold; level at explantation: 232.4 [range, 23.1-1545.7]; level at reimplantation: 18.8 (range 1.2-298.9); mean difference: 325.5 [95% CI, 65.0-596.0]; p = 0.0001), and IL-6 had a nearly similar decrease (11.2-fold; level at explantation: 228.1 [range, 10,158.4-182,725.0]; level at reimplantation: 2518.2 [range, 10.4-41,319.3]; mean difference: 33,176.0 [95% CI, 7543.6-58,808.3]; p < 0.0001). Cytokines and MSIS criteria had low sensitivity to rule out infection in a joint treated for PJI. CONCLUSIONS: IL-6 and IL-1ß demonstrated high sensitivities to diagnose PJI and showed the greatest decrease between first and second stages, which may potentially be used to monitor treatment response to PJI. However, cytokines and MSIS criteria had low sensitivity to rule out infection before reimplantation. LEVEL OF EVIDENCE: Level III, diagnostic study.

α-Defensin Accuracy to Diagnose Periprosthetic Joint Infection-Best Available Test?

BACKGROUND: The purpose of this study was to test the accuracy of a single synovial fluid biomarker, α-defensin, in diagnosing periprosthetic joint infection in revision total hip and revision total knee arthroplasty. METHODS: A total of 102 patients comprising 116 revision total hip arthroplasty and revision total knee arthroplasty procedures performed between May 2013 and March 2014 were prospectively evaluated. Cases were categorized as infected or notinfected using Musculoskeletal Infection Society criteria. Synovial fluid was obtained and tested for α-defensin using a commercially available kit (Synovasure [CD Diagnostics, Baltimore, Maryland]). RESULTS: For first-stage and single-stage revisions, the α-defensin test had a sensitivity of 100% (95% confidence interval [CI], 86%-100%) and a specificity of 98% (95% CI, 90%-100%) with a positive predictive value of 96% (95% CI, 80%-99%) and negative predictive value of 100% (95% CI, 93%-100%). CONCLUSION: A positive α-defensin test result was significantly more sensitive and specific for predicting infection than current diagnostic testing and should be considered when managing periprosthetic joint infection. LEVEL OF EVIDENCE: Level III, Study of Diagnostic Test.

α-Defensin as a predictor of periprosthetic shoulder infection.

BACKGROUND: Diagnosis of periprosthetic joint infection (PJI) in revision shoulder arthroplasty can be challenging because of the indolent nature of the common offending organisms. The purpose of this study was to evaluate the diagnostic utility of synovial fluid α-defensin levels in identifying PJI of the shoulder. METHODS: Thirty patients evaluated for painful shoulder arthroplasty were prospectively enrolled and underwent revision surgery (n = 33 cases). Cases were categorized into infection (n = 11) and no-infection (n = 22) groups on the basis of preoperative and intraoperative findings. Synovial fluid was obtained from preoperative aspirations or intraoperative aspiration before arthrotomy. α-Defensin was tested by the Synovasure (CD Diagnostics, Wynnewood, PA, USA) test for joint infection. Synovial fluid was also obtained intraoperatively from a control group undergoing arthroscopic rotator cuff repair (n = 16) for baseline data on normal α-defensin levels in the shoulder. A receiver operating characteristic curve was used to determine the diagnostic utility of synovial fluid α-defensin. RESULTS: Synovial α-defensin had an area under the curve, sensitivity, specificity, and positive and negative likelihood ratios of 0.78, 63%, 95%, 12.1, and 0.38, respectively. There was a significant difference in α-defensin levels between the infection (median, 3.2 S/CO [signal to cutoff ratio]) and no-infection groups (median, 0.21 S/CO; P = .006). Synovial α-defensin was elevated in the presence of a culture positive for Propionibacterium acnes (median, 1.33 S/CO; P = .03) and showed moderate correlation with the number of positive cultures. CONCLUSION: Synovial fluid α-defensin was more effective than current diagnostic testing in predicting positive cultures and may be an effective adjunct in the workup of shoulder PJI.

Poor utility of serum interleukin-6 levels to predict indolent periprosthetic shoulder infections.

BACKGROUND: Infection after shoulder arthroplasty can present a diagnostic challenge. The purpose of this study was to evaluate the utility of serum interleukin-6 (IL-6) levels in diagnosis of periprosthetic infection in patients undergoing revision shoulder arthroplasty. METHODS: We prospectively enrolled 69 patients who underwent revision shoulder arthroplasty at one institution. All patients underwent a standard preoperative and intraoperative workup for infection, which included shoulder aspirate culture, erythrocyte sedimentation rate, C-reactive protein level, tissue culture, and frozen section analysis. In addition, serum levels of IL-6 were measured preoperatively in all patients. Infection classification was divided into 4 groups, (1) definite, (2) probable, (3) possible, and (4) no infection, on the basis of previously reported criteria using intraoperative cultures and preoperative and intraoperative findings of infections. RESULTS: Of the 69 patients, 24 were classified as having a definite or probable infection. Propionibacterium acnes was the offending organism for the majority of these cases (20 of 24, 83%). IL-6 was not a sensitive marker of infection for these patients (sensitivity: 3 of 24, 12%; specificity: 3 of 45, 93%). The sensitivity of serum IL-6 was lower compared with erythrocyte sedimentation rate (sensitivity: 10 of 24, 42%; specificity: 37 of 45, 82%) and C-reactive protein level (sensitivity: 11 of 24, 46%; specificity: 42 of 45, 93%). For the non-P. acnes cases (1 Staphylococcus aureus, 1 Enterobacter cloacae, 2 coagulase-negative Staphylococcus species), the sensitivity of IL-6 was 25% (1 of 4). CONCLUSION: Serum IL-6 is not an effective marker for diagnosis of infection in shoulder arthroplasty. On the basis of this large prospective study, we do not recommend its use as a preoperative diagnostic test in patients undergoing revision shoulder arthroplasty.

Patient Resilience Does Not Conclusively Affect Clinical Outcomes Associated With Arthroscopic Surgery but Substantial Limitations of the Literature Exist.

Purpose: To determine whether low resilience is predictive of worse patient-reported outcomes (PROs) or diminished improvements in clinical outcomes after joint preserving and arthroscopic surgery. Methods: A comprehensive search of PubMed, Medline, Embase, and Science Direct was performed on September 28, 2022, for studies investigating the relationship between resilience and PROs after arthroscopic surgery in accordance with the Preferred Reported Items for Systematic Reviews and Meta-analyses guidelines. Results: Nine articles (level II-IV studies) were included in the final analysis. A total of 887 patients (54% male, average age 45 years) underwent arthroscopic surgery, including general knee (n = 3 studies), ACLR-only knee (n = 1 study), rotator cuff repair (n = 4 studies), and hip (n = 1 study). The Brief Resilience Scale was the most common instrument measuring resilience in 7 of 9 studies (78%). Five of 9 studies (56%) stratified patients based on high, normal, or low resilience cohorts, and these stratification threshold values differed between studies. Only 4 of 9 studies (44%) measured PROs both before and after surgery. Three of 9 studies (33%) reported rates of return to activity, with 2 studies (22%) noting high resilience to be associated with a higher likelihood of return to sport/duty, specifically after knee arthroscopy. However, significant associations between resilience and functional outcomes were not consistently observed, nor was resilience consistently observed to be predictive of subjects' capacity to return to a preinjury level of function. Conclusions: Patient resilience is inconsistently demonstrated to affect clinical outcomes associated with joint preserving and arthroscopic surgery. However, substantial limitations in the existing literature including underpowered sample sizes, lack of standardization in stratifying patients based on pretreatment resilience, and inconsistent collection of PROs throughout the continuum of care, diminish the strength of most conclusions that have been drawn. Level of Evidence: Level IV, systematic review of level II-IV studies.

The Psychology of ACL Injury, Treatment, and Recovery: Current Concepts and Future Directions.

CONTEXT: Interest in the relationship between psychology and the outcomes of anterior cruciate ligament (ACL) reconstruction (ACLR) continues to grow as variable rates of return to preinjury level of activity continue to be observed. EVIDENCE ACQUISITION: Articles were collected from peer-reviewed sources available on PubMed using a combination of search terms, including psychology, resilience, mental health, recovery, and anterior cruciate ligament reconstruction. Further evaluation of the included bibliographies were used to expand the evidence. STUDY DESIGN: Clinical review. LEVEL OF EVIDENCE: Level 4. RESULTS: General mental health and wellbeing, in addition to a host of unique psychological traits (self-efficacy, resilience, psychological readiness and distress, pain catastrophizing, locus of control, and kinesiophobia) have been demonstrated convincingly to affect treatment outcomes. Moreover, compelling evidence suggests that a number of these traits may be modifiable. Although the effect of resilience on outcomes of orthopaedic surgical procedures has been studied extensively, there is very limited information linking this unique psychological trait to the outcomes of ACLR. Similarly, the available information related to other parameters, such as pain catastrophizing, is limited with respect to the existence of adequately sized cohorts capable of accommodating more rigorous and compelling analyses. A better understanding of the specific mechanisms through which psychological traits influence outcomes can inform future interventions intended to improve rates of return to preinjury level of activity after ACLR. CONCLUSION: The impact of psychology on patients' responses to ACL injury and treatment represents a promising avenue for improving low rates of return to preinjury activity levels among certain cohorts. Future research into these areas should focus on specific effects of targeted interventions on known, modifiable risk factors that commonly contribute to suboptimal clinical outcomes. STRENGTH-OF-RECOMMENDATION TAXONOMY (SORT): B.

Surgeon Performance as a Predictor for Patient-Reported Outcomes After Arthroscopic Partial Meniscectomy.

Background: Surgeon performance has been investigated as a factor affecting patient outcomes after orthopaedic procedures to improve transparency between patients and providers. Purpose/Hypothesis: The purpose of this study was to identify whether surgeon performance influenced patient-reported outcomes (PROMs) 1 year after arthroscopic partial meniscectomy (APM). It was hypothesized that there would be no significant difference in PROMs between patients who underwent APM from various surgeons. Study Design: Case-control study; Level of evidence, 3. Methods: A prospective cohort of 794 patients who underwent APM between 2018 and 2019 were included in the analysis. A total of 34 surgeons from a large multicenter health care center were included. Three multivariable models were built to determine whether the surgeon-among demographic and meniscal pathology factors-was a significant variable for predicting the Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain subscale, the Patient Acceptable Symptom State (PASS), and a 10-point improvement in the KOOS-Pain at 1 year after APM. Likelihood ratio (LR) tests were used to determine the significance of the surgeon variable in the models. Results: The 794 patients were identified from the multicenter hospital system. The baseline KOOS-Pain score was a significant predictor of outcome in the 1-year KOOS-Pain model (odds ratio [OR], 2.1 [95% CI, 1.77-2.48]; P < .001), the KOOS-Pain 10-point improvement model (OR, 0.57 [95% CI, 0.44-0.73), and the 1-year PASS model (OR, 1.42 [95% CI, 1.15-1.76]; P = .002) among articular cartilage pathology (bipolar medial cartilage) and patient-factor variables, including body mass index, Veterans RAND 12-Item Health Survey-Mental Component Score, and Area Deprivation Index. The individual surgeon significantly impacted outcomes in the 1-year KOOS-Pain mixed model in the LR test (P = .004). Conclusion: Patient factors and characteristics are better predictors for patient outcomes 1 year after APM than surgeon characteristics, specifically baseline KOOS-Pain, although an individual surgeon influenced the 1-Year KOOS-Pain mixed model in the LR test. This finding has key clinical implications; surgeons who wish to improve patient outcomes after APM should focus on improving patient selection rather than improving the surgical technique. Future research is needed to determine whether surgeon variability has an impact on longer-term patient outcomes.

Fate of large structural allograft for treatment of severe uncontained glenoid bone deficiency.

BACKGROUND: Structural allografts have been used for management of large defects of the glenoid. We describe a surgical technique for graft preparation and the radiographic and clinical results of a series of patients using this technique. MATERIALS AND METHODS: In 19 consecutive patients, a polymethyl methacrylate mold was used to shape a single graft from a fresh-frozen femoral head to press fit within the glenoid defect. We evaluated the clinical and radiographic results with a minimum 2-year follow-up or until revision to another total shoulder replacement. RESULTS: Six patients showed more than 50% resorption of the graft. Four of these six patients also had less than 50% graft incorporation, and these findings were associated with a less favorable clinical outcome. In 3 of 6 cases in which poly-L-lactic acid bioresorbable screws were used, a significant giant cell reaction was noted at the time of revision surgery. Seven of nine patients with metal screw fixation had bent, broken, or worn screws because of graft collapse and contact with the prosthetic humeral head. Four of the five revision cases that were converted to a reverse total shoulder replacement had sufficient bone incorporation and volume of bone to allow for secure glenoid and screw fixation. CONCLUSION: The surgical technique described is useful in creation of a well-fitting graft. The amount of bone resorption and bone incorporation and clinical outcome have wide variability. In those cases where revision was performed with another total shoulder replacement, there was sufficient bone incorporation and sufficient bone mass to allow component fixation.

Differences in Glenohumeral Range of Motion and Humeral Torsion Between Right-Handed and Left-Handed Professional Baseball Pitchers.

BACKGROUND: Elite pitchers have demonstrated significant differences in glenohumeral range of motion and humeral torsion compared with the nonthrowing population. Furthermore, abnormal shoulder range of motion measurements have been associated with different injury risks and challenges in assessing rehabilitation progress. Variations in range of motion and torsion due to handedness in the asymptomatic professional population have yet to be investigated in the literature. HYPOTHESIS: No significant differences in glenohumeral range of motion and humeral torsion would exist between asymptomatic right- and left-handed professional pitchers. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: 217 Major League Baseball pitchers from a single organization were evaluated over a 7-year period between 2013 and 2020. Range of motion was measured with a standard goniometer. Ultrasound scanning was used to determine neutral position of the shoulder, and the degree of humeral torsion was measured with a goniometer. RESULTS: Right-handed pitchers demonstrated significantly greater values of glenohumeral external rotation (118.5° vs 112.7°; P < .001) in their throwing arms compared with their left-handed counterparts. Right-handed pitchers also showed greater values of glenohumeral internal rotation deficit (13.9° vs 4.8°; P < .001) and side-to-side differences in humeral retrotorsion (-23.1° vs -2.2°; P < .001). Left-handed pitchers demonstrated significantly greater flexion deficits in the throwing arm compared with their right-handed counterparts (7.5° vs 0.0°; P < .001). CONCLUSION: In the throwing arm, right-handed pitchers demonstrated significantly greater measures of external rotation, glenohumeral internal rotation deficit, and humeral retrotorsion compared with left-handed counterparts. Furthermore, right-handed pitchers demonstrated a significant side-to-side difference in retrotorsion, whereas left-handed pitchers did not. However, left-handed pitchers demonstrated a side-to-side shoulder flexion deficit that was not present in the cohort of right-handed pitchers. The correlation between humeral retrotorsion and increased external rotation indicates that osseous adaptations may play a role in range of motion differences associated with handedness. Additionally, these findings may explain observed differences in several throwing metrics between right- and left-handed pitchers. Knowledge of these differences can inform rehabilitation programs and shoulder maintenance regimens.

Diagnosis and Management of Subcoracoid Impingement.

Impingement of the subcoracoid space is a poorly understood pathologic cause of anterior shoulder pain. Because of its relative rarity in isolation and nonspecific presentation, diagnosis and management are often challenging for orthopaedic surgeons and their patients. Stenosis of the subcoracoid space between the lesser tuberosity and the coracoid process <6 mm can lead to anterior shoulder pain and associated rotator cuff and biceps pathology. Multiple imaging modalities are available to assess narrowing of the coracohumeral interval, each with its strengths and limitations. If the patient can be accurately diagnosed with subcoracoid impingement, both conservative and surgical management options are available. Despite earlier case series demonstrating promising results with arthroscopic treatment, comparative studies have yet to support these initial claims.

Machine Learning Outperforms Regression Analysis to Predict Next-Season Major League Baseball Player Injuries: Epidemiology and Validation of 13,982 Player-Years From Performance and Injury Profile Trends, 2000-2017.

BACKGROUND: Machine learning (ML) allows for the development of a predictive algorithm capable of imbibing historical data on a Major League Baseball (MLB) player to accurately project the player's future availability. PURPOSE: To determine the validity of an ML model in predicting the next-season injury risk and anatomic injury location for both position players and pitchers in the MLB. STUDY DESIGN: Descriptive epidemiology study. METHODS: Using 4 online baseball databases, we compiled MLB player data, including age, performance metrics, and injury history. A total of 84 ML algorithms were developed. The output of each algorithm reported whether the player would sustain an injury the following season as well as the injury's anatomic site. The area under the receiver operating characteristic curve (AUC) primarily determined validation. RESULTS: Player data were generated from 1931 position players and 1245 pitchers, with a mean follow-up of 4.40 years (13,982 player-years) between the years of 2000 and 2017. Injured players spent a total of 108,656 days on the disabled list, with a mean of 34.21 total days per player. The mean AUC for predicting next-season injuries was 0.76 among position players and 0.65 among pitchers using the top 3 ensemble classification. Back injuries had the highest AUC among both position players and pitchers, at 0.73. Advanced ML models outperformed logistic regression in 13 of 14 cases. CONCLUSION: Advanced ML models generally outperformed logistic regression and demonstrated fair capability in predicting publicly reportable next-season injuries, including the anatomic region for position players, although not for pitchers.

Clinical Utility of an MRI-Based Classification System for Operative Versus Nonoperative Management of Ulnar Collateral Ligament Tears: A 2-Year Follow-up Study.

BACKGROUND: A recently introduced classification system of medial ulnar collateral ligament (UCL) tears accounting for location and severity has demonstrated high interobserver and intraobserver reliability, but little is known about its clinical utility. PURPOSE: The primary purpose of this study was to assess the relationship of the magnetic resonance imaging (MRI)-based classification system in predicting which athletes had success with nonoperative versus operative treatment after completing a standardized rehabilitation program. A secondary objective included return to play (RTP) and return to prior performance (RPP) analyses of baseball players. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: After an a priori power analysis, 58 consecutive patients with UCL tears and a minimum of 2-year follow-up were retrospectively divided into 2 groups: those who successfully completed operative treatment and those who completed nonoperative treatment. The MRI-based classification stages accounting for UCL tear location and severity were compared between the nonoperative and operative groups. A subanalysis for baseball players, including RTP and RPP, was performed. RESULTS: A total of 58 patients (40 baseball players [34 pitchers]) met inclusion criteria. Of these patients 35 (32 baseball players [27 pitchers]) underwent surgery, and 23 (8 baseball players [7 pitchers]) underwent nonoperative management. No patients in the nonoperative arm crossed over to surgery after completing the rehabilitation program. Patients with distal tears (odds ratio, 48.0; P = .0004) and complete tears (odds ratio, 5.4; P = .004) were more likely to undergo surgery. Baseball players, regardless of position, were confounding determinants of operative management, although there was no difference in RTP and RPP between treatment arms. CONCLUSION: A 6-stage MRI-based classification system addressing UCL tear location and severity may help early decision making, as patients likely to fail nonoperative treatment have complete, distal tears, whereas those with proximal, partial tears may be more amenable to nonoperative management.

Establishing Safe Extra-articular Parameters for Cortical Button Distal Fixation During Ulnar Collateral Ligament Reconstruction.

BACKGROUND: A variety of methods exist for fixation during ulnar collateral ligament (UCL) reconstruction on the ulna for the overhead throwing athlete. Current biomechanical evidence suggests that cortical button fixation may fail at a higher load and under more cycles than interference screw fixation alone, while also minimizing the risk of fracture. A safe angle for placement of this cortical button has not yet been determined. PURPOSE: To define a safe angle for cortical button deployment during UCL reconstruction to avoid violation of the proximal radioulnar joint (PRUJ). STUDY DESIGN: Descriptive laboratory study. METHODS: Measurements on 100 cadaveric ulna bones, 50 women and 50 men, were obtained referencing the entry point for ulnar fixation, which is 1 cm distal to the ulnar humeral joint line along the medial UCL ridge. Ulnar width at the entry point and distance to the PRUJ were obtained to calculate safe distal angulation, while distance from the entry point to the posterior ulnar crest ulnarly and distance from the PRUJ to the posterior ulnar crest radially were obtained to calculate safe posterior angulation. Ten bony measurements on the same group of specimens were performed by 3 authors to establish an interobserver reliability. Means, quartiles, and outliers were obtained for the calculated angles. Finally, recommended angles of entry were determined to be approximately 1 interquartile range above the upper limit. RESULTS: The mean distal angle of entry that was obtained was 11.32° (SD, ±4.80°; 95% CI, 10.37°-12.27°; P < .001). Three upper limit outliers were discovered: 24.20°, 23.4°, and 21.1°. The mean posterior angle of entry was 40.44° (SD, ±6.18°; 95% CI, 39.22°-41.67°; P < .001). There were no outliers for the posterior angle of entry. Interobserver reliabilities were strong for the 4 measurements. CONCLUSION: To be safely outside of the PRUJ utilizing a cortical button construct, we recommend 30° distal angulation and 60° posterior angulation for ulnar fixation during UCL reconstruction. Both parameters are 1 quartile above the highest calculated angle of entry. CLINICAL RELEVANCE: These data define safe parameters for distal fixation during UCL reconstruction and highlight a clear entry point for reference.

Variations in Blood Supply From Proximal to Distal in the Ulnar Collateral Ligament of the Elbow: A Qualitative Descriptive Cadaveric Study.

BACKGROUND: The vascular supply of the ulnar collateral ligament (UCL) is unknown. Previous studies reported varying success in return-to-play rates after nonoperative management of partial UCL tears and suggested a varying healing capacity as possibly related to the location of the UCL injury. PURPOSE: To analyze the macroscopic vascular anatomy of the UCL of the elbow. STUDY DESIGN: Descriptive laboratory study. METHODS: Eighteen fresh-frozen male cadaveric elbows from 9 donors were sharply dissected 15 cm proximal to the medial epicondyle. Sixty milliliters of India ink was injected through the brachial artery of each elbow. Arms were then frozen at -10°C, radial side down, in 15° to 20° of elbow flexion. A band saw was used to section the frozen elbows into 5-mm coronal or sagittal sections. Sections were cleared for visualization with the modified Spalteholz technique. Images of the specimens were taken, and qualitative description of UCL vascularity was undertaken. RESULTS: The authors consistently found a dense blood supply to the proximal UCL, while the distal UCL was hypovascular. They also observed a possible osseous contribution to the proximal UCL from the medial epicondyle in addition to an artery from the flexor/pronator musculature that consistently appeared to provide vascularity to the proximal UCL. The degree of vascular penetration from proximal to distal in the UCL ranged from 39% to 68% of the overall UCL length, with a 49% mean length of vascular penetration of the UCL. CONCLUSION: This study found a difference in the vascular supply of the UCL. The proximal UCL was well vascularized, while the distal UCL was hypovascular. This difference in vascular supply may be a factor in the differential healing capacities of the UCL based on the location of injury. CLINICAL RELEVANCE: An improved understanding of the macroscopic vascular supply of the UCL may aid in the clinical management of partial UCL tears and suggests an indication for these treatments with respect to location of UCL injuries.