Development and internal validation of a humeral torsion prediction model in professional baseball pitchers.

BACKGROUND: Humeral torsion (HT) has been linked to pitching arm injury risk after controlling for shoulder range of motion. Currently measuring HT uses expensive equipment, which inhibits clinical assessment. Developing an HT predictive model can aid clinical baseball arm injury risk examination. Therefore, the purpose of this study was to develop and internally validate an HT prediction model using standard clinical tests and measures in professional baseball pitchers. METHODS: An 11-year (2009-2019) prospective professional baseball cohort was used for this study. Participants were included if they were able to participate in all practices and competitions and were under a Minor League Baseball contract. Preseason shoulder range of motion (external rotation [ER], internal rotation [IR], horizontal adduction [HA]) and HT were collected each season. Player age, arm dominance, arm injury history, and continent of origin were also collected. Examiners were blinded to arm dominance. An a priori power analysis determined that 244 players were needed for accurate prediction models. Missing data was low (<3%); thus, a complete case analysis was performed. Model development followed the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) recommendations. Regression models with restricted cubic splines were performed. Following primary model development, bootstrapping with 2000 iterations were performed to reduce overfitting and assess optimism shrinkage. Prediction model performance was assessed through root mean square error (RMSE), R2, and calibration slope with 95% confidence intervals (CIs). Sensitivity analyses included dominant and nondominant HT. RESULTS: A total of 407 professional pitchers (age: 23.2 [standard deviation 2.4] years, left-handed: 17%; arm history prevalence: 21%) participated. Predictors with the highest influence within the model include IR (0.4, 95% CI 0.3, 0.5; P < .001), ER (-0.3, 95% CI -0.4, -0.2; P < .001), HA (0.3, 95% CI 0.2, 0.4; P < .001), and arm dominance (right-handed: -1.9, 95% CI -3.6, -0.1; P = .034). Final model RMSE was 12, R2 was 0.41, and calibration was 1.00 (95% CI 0.94, 1.06). Sensitivity analyses demonstrated similar model performance. CONCLUSIONS: Every 3° of IR explained 1° of HT. Every 3° of ER explained 1° less of HT, and every 7° of HA explained 1° of HT. Right-handers had 2° less HT. Models demonstrated good predictive performance. This predictive model can be used by clinicians to infer HT using standard clinical test and measures. These data can be used to enhance professional baseball arm injury examination.

Preseason shoulder range of motion screening as a predictor of injury among youth and adolescent baseball pitchers.

BACKGROUND: Approximately 6 million youngsters play organized baseball yearly, and injuries are common. Defining of risk factors for injuries in the throwing shoulder has largely been confined to the professional thrower. Unfortunately, these risk factors apply to only 1% of pitchers at risk for injury. Risk factors for injury in youth pitchers have received far less attention than those in more mature professional pitchers. Development of such an understanding would help clarify injury prevention efforts for the other 99% of pitchers actively participating in competitive baseball. This study intended to determine the ability of range of motion (ROM) measures to predict arm injuries in baseball pitchers aged 8 to 18 years. METHODS: Supine passive shoulder ROM was assessed in 115 pitchers with a digital inclinometer. Two trials of ROM were measured before the season. Arm injuries were prospectively tracked. Receiver operating characteristic curves were used to identify athletes who were at high risk for injury. Statistical significance was set a priori (α = .05). RESULTS: There were 33 injured and 82 uninjured pitchers. Side-to-side differences of horizontal adduction >15° and internal rotation >13° may discriminate between those adolescent pitchers at 4 and 6 times greater risk of injury, respectively. CONCLUSION: Preseason ROM differences were able to identify those adolescents at high risk for injury during the season. It appears that the risk profile for adolescent pitchers includes horizontal adduction differences that differ from the established prospective profile in adult pitchers.

A narrative review of little league shoulder: proximal humeral physis widening is only one piece of the puzzle, it is time to consider posterior glenoid dysplasia.

Baseball athletes across all levels of play are at an increased risk for upper extremity injury due to the supraphysiologic demands on the shoulder and elbow during overhead throwing. Little league baseball players present with a unique subset of injuries that can affect the growth plate, commonly at the shoulder or the elbow. Ascertaining a diagnosis and plan of care for little league shoulder (LLS) historically focuses on the proximal humeral physis in skeletally immature throwing athletes presenting with shoulder pain. However, while not a current standard of care, posterior glenoid dysplasia is often present in youth baseball athletes presenting with LLS, warranting a shift in the way clinicians evaluate for and treat the youth baseball athlete's pathologic shoulder. Therefore, purpose of this narrative review is 2-fold: first, to describe the current standard of care as it relates to a diagnosis of LLS, and second, to critically describe a comprehensive evaluation process for youth throwing athletes with shoulder pain that includes screening for evidence of posterior glenoid dysplasia. This paper summarizes the current state of the available evidence for anatomic considerations of LLS in the baseball athletes throwing shoulder. Additionally, we provide a framework for clinical evaluation using a multidisciplinary approach to evaluate the entire kinetic chain of the youth baseball athlete presenting with LLS and posterior glenoid dysplasia. A case study is presented to describe common presentations, clinical and objective examinations, and a plan of care from time of evaluation to return to throwing.

Effectiveness of Manual Therapy and Stretching for Baseball Players With Shoulder Range of Motion Deficits.

BACKGROUND: Baseball players displaying deficits in shoulder range of motion (ROM) are at increased risk of arm injury. Currently, there is a lack of consensus regarding the best available treatment options to restore shoulder ROM. HYPOTHESIS: Instrumented manual therapy with self-stretching will result in clinically significant deficit reductions when compared with self-stretching alone. STUDY DESIGN: Controlled laboratory study. METHODS: Shoulder ROM and humeral torsion were assessed in 60 active baseball players (mean age, 19 ± 2 years) with ROM deficits (nondominant - dominant, ≥15°). Athletes were randomly assigned to receive a single treatment of instrumented manual therapy plus self-stretching (n = 30) or self-stretching only (n = 30). Deficits in internal rotation, horizontal adduction, and total arc of motion were compared between groups immediately before and after a single treatment session. Treatment effectiveness was determined by mean comparison data, and a number-needed-to-treat (NNT) analysis was used for assessing the presence of ROM risk factors. RESULTS: Prior to intervention, players displayed significant ( P < 0.001) dominant-sided deficits in internal rotation (-26°), total arc of motion (-18°), and horizontal adduction (-17°). After the intervention, both groups displayed significant improvements in ROM, with the instrumented manual therapy plus self-stretching group displaying greater increases in internal rotation (+5°, P = 0.010), total arc of motion (+6°, P = 0.010), and horizontal adduction (+7°, P = 0.004) compared with self-stretching alone. For horizontal adduction deficits, the added use of instrumented manual therapy with self-stretching decreased the NNT to 2.2 (95% CI, 2.1-2.4; P = 0.010). CONCLUSION: Instrumented manual therapy with self-stretching significantly reduces ROM risk factors in baseball players with motion deficits when compared with stretching alone. CLINICAL RELEVANCE: The added benefits of manual therapy may help to reduce ROM deficits in clinical scenarios where stretching alone is ineffective.

Humeral Torsion as a Risk Factor for Shoulder and Elbow Injury in Professional Baseball Pitchers.

BACKGROUND: Numerous studies have demonstrated that humeral retrotorsion is increased in the dominant arms of throwing athletes. No study has clearly defined the relationship between humeral retrotorsion and shoulder and elbow injury. HYPOTHESIS: Uninjured professional pitchers will display more dominant humeral torsion (HT) than professional pitchers who sustain shoulder injuries but less than pitchers who sustain elbow injuries. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Pitchers from the Colorado Rockies professional baseball organization were recruited for participation for this prospective injury study from 2009 to 2013. HT was assessed using indirect ultrasonographic techniques and was measured prospectively in 255 pitchers before each spring training (average of 2 trials). From the beginning of the preseason to the end of the postseason, overuse upper extremity injuries (shoulder or elbow) were tracked for each participating athlete. All athletes who reported pain or injury to their coach were referred to the organization's athletic trainer for evaluation and classification of each injury. The difference in HT was calculated by subtracting measurement of the dominant arm from the nondominant arm, and 3 separate mixed-model analyses of variance (side × injury group) were used to compare the dominant and nondominant HT between all pitchers who developed an arm injury (shoulder and elbow combined), as well as comparing pitchers who developed a shoulder or elbow injury to those who did not miss games due to shoulder or elbow injury (α = .05). RESULTS: During the course of the study, 60 arm (30 shoulder; 30 elbow) injuries were observed; 195 pitchers did not suffer an injury. There were no differences when HT was compared between all injured (shoulder and elbow injuries combined) and uninjured pitchers (P = .13; effect size 0.14). There was a significant interaction effect showing that pitchers who suffered a shoulder injury displayed 4° less dominant humeral retrotorsion compared with pitchers without injury (P = .04) and that pitchers with elbow injury displayed 5° greater humeral retrotorsion (P = .04). In addition, those who suffered an ulnar collateral ligament injury requiring reconstruction (n = 17) also displayed 4(o) greater dominant retrotorsion and 5° less nondominant humeral retrotorsion compared with pitchers who did not suffer an injury (n = 195; P = .05). There was not a significant difference between nondominant HT among pitchers who sustained shoulder and elbow injuries and pitchers without injury. CONCLUSION: The results of this study show a contrast in dominant humeral retrotorsion between pitchers who suffered shoulder and elbow injuries compared with those without an injury. Pitchers who sustained shoulder injuries had less dominant humeral retrotorsion compared with noninjured pitchers. In contrast, pitchers who sustained time-loss elbow injuries displayed increased humeral retrotorsion compared with noninjured pitchers. Together, these results suggest that increased adaptive humeral retrotorsion is protective against shoulder injuries but a harmful contributor for elbow injuries in professional pitchers. This is the first study to show differing injury risk profiles for shoulder and elbow injury.

Current rehabilitation applications for shoulder ultrasound imaging.

SYNOPSIS: The available body of knowledge on shoulder ultrasound imaging has grown considerably within the past decade, and physical therapists are among the many health care professions currently exploring the potential clinical integration of this imaging technology and the knowledge derived from it. Therefore, the primary purpose of this commentary was to review the recent evidence and emerging uses of ultrasound imaging for the clinical evaluation of shoulder disorders. This includes a detailed description of common measurement techniques along with their known clinimetric properties. Specifically provided are critical appraisals of the existing measures used to estimate soft tissue and bony morphometry, muscle contractile states, and lean muscle density. These appraisals are intended to help clinicians clarify the scope of physical therapy practice for which these measurement techniques are effectively utilized and to highlight areas in need of further development.

Professional Pitchers With Glenohumeral Internal Rotation Deficit (GIRD) Display Greater Humeral Retrotorsion Than Pitchers Without GIRD.

BACKGROUND: Dominant shoulder glenohumeral internal rotation deficit (GIRD) has been associated with pitching arm injuries. The relationship of humeral torsion on development of GIRD is not clear. HYPOTHESIS: Pitchers displaying GIRD will display greater humeral retrotorsion when compared with those without GIRD. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Humeral torsion and shoulder range of motion (ROM) were measured in 222 professional pitchers before spring training from 2009 to 2012. Shoulder external rotation (ER) and internal rotation (IR) ROM were assessed in 90° of abduction with the scapula stabilized. Humeral torsion was measured via ultrasound using previously described and validated methods. Side-to-side differences in total arc of motion (ER + IR), ER, and IR ROM and humeral torsion were calculated as nondominant minus dominant arm measures for analysis. Pitchers were classified as having GIRD if their dominant arm displayed an IR deficit ≥15° concomitant with a total arc of motion deficit ≥10° compared with their nondominant arm. A mixed-model analysis of variance (side × GIRD) was used to compare dominant and nondominant humeral torsion between pitchers with GIRD (n = 60) and those without GIRD (n = 162). Independent t tests were used to compare the side-to-side difference in humeral torsion between pitchers with GIRD and those without GIRD (α = 0.05). RESULTS: Pitchers with GIRD displayed significantly less humeral torsion (ie, greater retrotorsion) in their dominant arm as compared with those without GIRD (GIRD = 4.5° ± 11.8°, no GIRD = 10.4° ± 11.7°; P = .002). Pitchers with GIRD also displayed a greater side-to-side difference in humeral torsion (GIRD = 19.5° ± 11.9°, no GIRD = 12.3° ± 12.4°; P = .001). However, pitchers with GIRD did not display an increase in dominant ER ROM (dominant ER = 131.8° ± 14.3°, nondominant ER 126.6° ± 13.1°) when compared with those without GIRD (dominant ER = 132.0° ± 14.2°, nondominant ER 122.6° ± 13.1°; P = .03). Pitchers with GIRD displayed expected alterations in ROM (IR = 28.8° ± 9.6°, total arc = 160.6° ± 15.4°; P < .01 for both) when compared with those without GIRD (IR = 39.9° ± 9.9°, total arc = 171.2° ± 15.5°). CONCLUSION: Pitchers with GIRD displayed greater side-to-side differences and dominant humeral retrotorsion as compared with those without GIRD. The greater humeral retrotorsion may place greater stress on the posterior shoulder resulting in ROM deficits. Pitchers with greater humeral retrotorsion appear to be more susceptible to developing ROM deficits associated with injury and may need increased monitoring and customized treatment programs to mitigate their increased injury risk.

Mechanisms of Shoulder Range of Motion Deficits in Asymptomatic Baseball Players.

BACKGROUND: Shoulder range of motion (ROM) deficits have been identified as injury risk factors among baseball athletes. Despite the knowledge surrounding these risk factors, there is a lack of consensus regarding the specific tissues responsible for these deficits in ROM. PURPOSE/HYPOTHESIS: The purpose of this study was to elucidate the primary mechanisms of posterior shoulder tightness (capsular, musculotendinous, bony) by examining the tissue responses that occur with the application of an acute intervention in baseball players with ROM deficits. The hypothesis was that posterior rotator cuff stiffness, not glenohumeral joint mobility, would be primarily responsible for ROM gains observed within an acute treatment setting. STUDY DESIGN: Controlled laboratory study. METHODS: Through use of ultrasound elastography, electromagnetic motion analysis, and ultrasound imaging, posterior rotator cuff stiffness, glenohumeral joint translation, and humeral torsion were examined in 60 asymptomatic baseball players (age, mean ± SD, 19 ± 2 years) with shoulder ROM deficits. Tissue mechanisms were examined concurrently, with the ROM gains elicited by an acute application of instrument-assisted soft tissue mobilization plus self-stretching (n = 30) versus self-stretching only (n = 30). Separate 3-way analyses of variance (group × arm × time) and linear regression analyses were used to determine the treatment effects and relationships between tissue mechanisms and ROM gains. RESULTS: ROM gains were associated with decreases in rotator cuff stiffness (internal rotation: r = 0.35, P = .034; horizontal adduction: r = 0.44, P = .008) and increased humeral retrotorsion (internal rotation: r = -0.35, P = .034), not joint translation (P > .05). Players receiving instrument-assisted soft tissue mobilization plus stretching displayed greater shoulder ROM gains (internal rotation, +5° ± 2° [P = .010]; total arc of motion, +8° ± 6° [P = .010]; horizontal adduction, +7° ± 2° [P = .004]; and decreased posterior rotator cuff stiffness, -0.2 ± 0.3 kPa [P = .050]) compared with players receiving self-stretching alone. CONCLUSION: Decreases in rotator cuff stiffness were associated with acute ROM gains in baseball players. The study results show that changes in rotator cuff stiffness, not glenohumeral joint mobility or humeral torsion, are most likely associated with the ROM deficits observed in adolescent baseball players. CLINICAL RELEVANCE: Reducing rotator cuff stiffness may be beneficial in improving the ROM deficits associated with injury risk in overhead athletes.