Humeral head retroversion in competitive baseball players and its relationship to glenohumeral rotation range of motion

Humeral retroversion, shoulder range of motion, and functional mobility in striking martial arts athletes

The aim of the study was to evaluate humeral retroversion, shoulder range of motion, and functional mobility in karatekas, boxers, kickboxers, and mixed martial arts fighters. This study investigated adaptive alterations in striking martial arts. Forty young healthy participants took part in the study. 20 people who professionally trained in boxing, kickboxing, karate, and Mixed Martial Arts (MMA) fighters (age: 23.5 ± 7.1, age of participation 11.8 ± 3.65, sports experience 9.55 ± 5.13, body weight 79.2 ± 13 kg, BMI 24.4 ± 3.3) were qualified for the group of athletes. 20 people (age: 27 ± 5.5, body weight 79.4 ± 7.4, BMI 24.5 ± 1.2) were included in the control group, who had no previous experience with striking combat sports. An ultrasound device and a digital inclinometer were used for the examination of the humeral retroversion angle. The mobility of the shoulder was also tested using the Functional Movement Screen (FMS). There was a significant (p < 0.001, r = 0.92) asymmetry between the dominant and non-dominant limb in the humeral retroversion angle in the athlete group. A statistically significant moderate correlation (p < 0.05) was found between the value of the retroversion angle and the range of motion of passive and active internal rotation, and external rotation, and the shoulder mobility in the FMS test. However, there were no statistically significant differences (p > 0.05) in the humeral retroversion angles between groups. The striking martial arts athletes do not exhibit significant differences in humeral retroversion compared to non-athletes, however they display notable asymmetry between limbs, with higher values in the non-dominant arm. Additionally, the observed correlation between humeral retroversion and shoulder rotation range of motion highlights the potential impact of humeral retroversion on upper limb performance and injury risk.

Establishing a Reference Database for Select Clinical Measures in National Basketball Association Players

BACKGROUND

Musculoskeletal injuries are prevalent in the NBA and are associated with a significant number of games missed. There is a lack of reference data for clinical measures in NBA players, making it difficult for sports medicine professionals to set goals and develop programs.

HYPOTHESIS

Values for clinical measures in NBA players will differ from those of the general population but will not differ between dominant (D) and nondominant (ND) limbs.

STUDY DESIGN

Descriptive laboratory study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Clinical measures were taken on 325 players invited to NBA training camp (2008-2022). Measures included range of motion for great toe extension, hip rotation, weightbearing ankle dorsiflexion, flexibility, arch height (AH) indices, and tibial varum.

RESULTS

Clinical values for NBA players differ from reference norms of the general population. Results for NBA players include great toe extension (D, 40.4°; ND, 39.3°), 90/90 hamstring (D, 41.5°; ND, 40.9°), hip internal rotation (D, 29.0°; ND, 28.8°), hip external rotation (D, 29.7°; ND, 30.9°), total hip rotation (D, 60.2°; ND, 60.4°), Ely (D, 109.9°; ND, 108.8°), AH difference (D, 0.5 mm; ND, 0.5 mm), AH index (D, 0.310; ND, 0.307), arch stiffness (D, 0.024; ND, 0.024), arch rigidity (D, 0.924; ND, 0.925), tibial varum (D, 4.6°; ND, 4.5°), and weightbearing ankle dorsiflexion (D, 35.4°; ND, 35.6°). Descriptive statistics are presented; 2-tailed paired t tests show that, whereas most measures demonstrated differences between sides, the results were not statistically significant.

CONCLUSION

Clinical measures of NBA players differ from those reported for the general population and athletes of other sports although there were no statistically significant differences between D and ND limbs.

CLINICAL RELEVANCE

Establishing a reference database may help clinicians develop more sensitive and more effective preseason and return-to-play screening processes, aiding the management of player orthopaedic care and reducing injury risk.

Chronic Adaptation of the Coracohumeral Space and Subscapularis Tendon in Professional Baseball Pitchers

BACKGROUND

Pitchers frequently experience anterior shoulder pain, possibly associated with coracohumeral impingement; however, whether the coracohumeral distance (CHD) and/or subscapularis tendon adapt chronically (bilateral difference) due to pitching, and whether clinical measures are associated with CHD and subscapularis tendon organization have not been evaluated in professional pitchers.

HYPOTHESIS

The authors hypothesized that dominant arm CHD would be smaller than the nondominant arm, dominant subscapularis tendon would have increased spatial frequency (ie, be more disorganized), and humeral retroversion (HR) would predict CHD and subscapularis tendon organization.

LEVEL OF EVIDENCE

Level 4.

METHODS

Healthy professional baseball pitchers were recruited during their preseason physical examination. Bilateral diagnostic ultrasound measured CHD, HR, and posterior capsule thickness (PCT), and quantified subscapularis tendon organization. External rotation, neutral, and crossbody CHD was measured.

RESULTS

Overall, 52 healthy professional baseball pitchers participated. The dominant arm of pitchers demonstrated a significantly narrower CHD in all 3 positions (P < 0.01), increased scapular protraction (163 vs 156 mm; P < 0.01), and increased spatial frequency of the subscapularis tendon (1.8 vs 1.6 peaks/mm; P < 0.01). HR was associated with CHD in 30° of external rotation (R2 = 0.12; P < 0.01), neutral rotation (R2 = 0.11; P < 0.01), and the crossbody position (R2 = 0.28; P < 0.01). PCT was associated with CHD in 30° of external rotation (R2 = 0.16; P = 0.05). HR and CHD in 30° of external rotation was associated most strongly with subscapularis tendon organization (R2 = 0.11; P = 0.03).

CONCLUSION

The dominant shoulder of professional pitchers presents with a smaller CHD, more scapular protraction, and more subscapularis tendon disorganization than the nondominant shoulder.

CLINICAL RELEVANCE

Professional pitchers demonstrate chronic CHD and subscapularis tendon adaptations, which may increase their risk for anterior shoulder pain and subscapularis tendon injury.

Humeral Torsion in Relation to Shoulder Range of Motion in Elite Field Hockey Players

CONTEXT

Sport-specific adaptations in shoulder rotation range of motion (ROM) and the relationship with humeral torsion have been described in overhead-throwing sports. However, information is lacking for other shoulder-loading sports such as field hockey. Therefore, this study's purpose was to evaluate humeral torsion in elite, male field hockey players and explore its association with shoulder ROM.

DESIGN

Cross-sectional study.

METHODS

Twenty-five male, elite field hockey players were included. Humeral torsion and shoulder external and internal rotation ROM were evaluated bilaterally by ultrasound and an inclinometer smartphone application, respectively.

RESULTS

Field hockey players showed a significantly increased humeral retroversion on the dominant compared with the nondominant side (P < .001; Cohen d = 1.75), along with a significantly increased external (P = .004; Cohen d = -0.64) and decreased internal rotation ROM (P = .003; Cohen d = 0.65). This finding illustrates a shift in total shoulder rotational ROM arc. Correlation analysis showed a significant moderate association between the increased humeral retroversion and decreased internal rotation ROM on the dominant side (r = .523).

CONCLUSIONS

Elite male field hockey athletes show sport-specific adaptations regarding humeral torsion and shoulder rotation ROM, similar to throwing athletes. These findings increase our insight into the field hockey athlete's shoulder, which is essential to optimize performance and assist in correctly interpreting shoulder rotational ROM measurements.

Risk Factors for Shoulder Injuries in Female Athletes Playing Overhead Sports: A Systematic Review

CONTEXT

Sports involving overhead motions put substantial biomechanical demands on the shoulder and may result in injuries.

OBJECTIVE

To determine risk factors (RFs) for shoulder injuries in female athletes who play overhead sports and evaluate strategies to reduce shoulder injuries in these athletes.

DATA SOURCES

A systematic electronic search was performed according to Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Databases included were PubMed, Tulane Matas Library Search Engine, and Google Scholar, with search terms: "Overhead injuries/Shoulder AND female athletes AND Risk Factors."

STUDY SELECTION

Of the initial 1574 studies identified, 314 were evaluated for eligibility by full-text review and 291 studies were excluded. Overall, 23 studies were included in this study. Studies were published from 2000 to 2021, subject age range was 15 to 35 years, with documented prevalence of shoulder injuries in female athletes playing overhead sports.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 2.

DATA EXTRACTION

Two independent researchers completed abstract and full-text review. Data extraction used the Covidence and Cochrane Consumer guide template.

RESULTS

Volleyball was the most common sport with shoulder injuries (6/23; 26%) followed by softball 5/23 (22%), swimming 5/23 (22%), gymnastics 4/23 (17%), tennis 3/23 (13%), water polo 2/23 (8%), and basketball 1/23 (4%). Six RFs (dominant shoulder, volume/overuse, time in sport, older age at time of injury, past injury, and multidirectional instability) were described. Of the 23 studies, 9 (39%) identified the dominant shoulder as a RF for sustaining injury (mean risk ratio [RR], 2.04), while 6 (26%) cited volume of repetition and overuse as a prominent RF (RR, 1.45).

CONCLUSION

This systematic review demonstrates important RFs for shoulder injuries in female athletes associated with playing overhead sports. Multiple prevention strategies are described. Prevention programs are helpful in reducing the risk of reinjury.

Relationship between shoulder and elbow range of motion and ultrasonographic structural abnormalities in the elbow of Taiwanese high school baseball players

BACKGROUND

Ultrasonographic structural abnormalities are regarded as one of the risk factors of elbow injuries. Elbow injuries are commonly associated with decreased shoulder/elbow range of motion (ROM). The purpose of this study is to determine the relationship between shoulder/elbow ROM and elbow ultrasonographic structural abnormalities in Taiwan high school baseball players.

METHODS

A total of 533 Taiwan high school baseball players were enrolled. Physical examinations including measurements on shoulder/elbow ROM and elbow sonographic examinations were performed and recorded by professional physicians. The analyses were conducted in three subgroups according to their defensive position because the training programs were different. All players pooled, pitchers-only, and fielders-only, due to several demographic differences among these subgroups. In all the subgroups, univariate analyses were conducted separately for participants with and those without elbow ultrasonographic structural abnormalities, and then multivariate analyses were conducted to identify factors significantly related. The odds ratios (ORs) were used to estimate the risk of elbow ultrasonographic structural abnormalities.

RESULTS

Demographic data showed that pitchers had taller body height (P < 0.001) and greater elbow flexion/extension ROM (P < 0.001). When all players were pooled, significant risk factors included started playing baseball at an younger age (OR = 1.202; 95% CI = 1.064-1.357; P = 0.003), longer experience of official baseball (OR = 1.154; 95% CI = 1.038-1.283; P = 0.008), lower total shoulder rotation angle (OR = 1.007; 95% CI = 1.000-1.014; P = 0.050), and less total elbow arm angle (OR = 1.052; 95% CI = 1.017-1.088; P = 0.003) For pitchers, significant risk factors included longer experience of official baseball (OR = 1.342; 95% CI = 1.098-1.640; P = 0.004), lower total shoulder rotation angle (OR = 1.016; 95% CI = 1.004-1.027; P = 0.006), and lower total elbow arm angle (OR = 1.075; 95% CI = 1.024-1.129; P = 0.004) (Table 5). There were no significant risk factors for elbow structural abnormalities in fielders.

CONCLUSION

For Taiwan high school pitchers, longer official baseball experience, decreased shoulder total rotational angle, and decreased elbow total flexion/extension angle, were related to ultrasonographic structural abnormalities in elbows.

Adaptive pathology: new insights into the physical examination and imaging of the thrower's shoulder and elbow

Throwing with high velocity requires extremes of glenohumeral external rotation of the abducted arm where particularly high forces in the shoulder and elbow are endured. Repeated throwing leads to dominant-arm bony remodeling of the humerus, glenoid, and elbow, and multiple soft tissue changes that would be considered abnormal. Many of these features are thought to be adaptive and protective. The purpose of this work is to (1) define the concept of adaptive pathology; (2) review the mechanics of the throwing motion; (3) review pertinent physical examination and imaging findings seen in asymptomatic throwers' shoulders and elbows and describe how these changes develop and may be adaptive-allowing the thrower to perform at high levels; and then (4) review the principles of surgical treatment in the throwing athletes, which should focus on reducing symptoms, but not necessarily restoring the thrower's anatomy to normal.

Prevalence, diagnosis and management of musculoskeletal disorders in elite athletes: A mini-review

Musculoskeletal injuries in elite sports are ones of the most impact issue because their remarkable impact on performance caused by drastic absence of training and competition and a progressive deterioration in physical health, emotional and social athletes' dimensions. Also, the prevalence of epidemiologic research found an incidence of musculoskeletal disorders vary within sports and in elite athletes which is even higher as a consequence of higher demand physical performance. This way, the loss of physical performance due to an sport injury impacts not only the individual economic sphere of the professional but also that ofsports entities, reaching, according to some studies, a loss estimated in the range of 74.7 million pounds. Thus, the purpose of this article is to review and to provide an overview of the most common musculoskeletal injuries in elite sports precipitating factors, clinical presentation, evidence-based diagnostic evaluation, and treatment recommendations with a view to preventing medical conditions or musculoskeletal injuries that may alter performance and general health in the elite athletes.

Glenohumeral Instability and Arm Pain in Overhead Throwing Athletes: A Correlational Study

Background

The overhead activity of throwing a baseball is arguably the most demanding athletic endeavor placed on the glenohumeral (GH) joint. Previous studies illustrate that 75-80% of baseball players will experience some degree of upper extremity (UE) pain. GH instability is thought to play a role.

Purpose

The purpose of this study was to investigate the relationship between GH joint hypermobility and instability with measures of arm pain and performance in overhead throwing athletes.

Methods

Actively competing baseball pitchers were recruited and evaluated once with the anterior-posterior Load and Shift examination procedure, the Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Questionnaire (KJOC), and the Functional Arm Scale for Throwers (FAST). Multivariate analysis was performed to identify correlation between severe GH capsular laxity (GH instability), mild capsular laxity (GH hypermobility), no capsular laxity (GH normal), and presence of shoulder pain when pitching.

Study Design

Cross-sectional Study.

Results

Forty-five pitchers were evaluated, 62.2% of throwing shoulders were classified normal stability, 26.7% were classified hypermobile, and 11.1% were classified unstable. Average KJOC scores for pitchers with the three mobility categories were 66.1 (normal), 59.7 (hypermobile), and 45.0 (unstable). Average FAST scores among the pitchers were 19.9 (normal), 34.2 (hypermobile), and 32.2 (unstable). Pitchers with GH instability and GH hypermobility demonstrated increased arm pain compared to athletes with normal GH joints; KJOC scores of 3.2, 5.5, and 7.4 (p = 0.0007), respectively.

Conclusion

Pitchers with GH instability and hypermobility demonstrated significantly increased ratings of arm pain compared to pitchers with no capsular laxity.

Level of Evidence

3b.

Identifying the underlying mechanisms responsible for glenohumeral internal rotation in professional baseball pitchers

Background and Hypothesis

Glenohumeral internal rotation deficit has been identified as a significant risk factor for upper-extremity injuries in pitchers across all ages. Humeral retroversion (HR), posterior capsule thickness (PCT), and posterior rotator cuff muscle pennation angle (PA) have been independently associated with internal rotation range of motion (IR ROM); however, these anatomic structures have not been collectively measured in baseball pitchers to determine the underlying mechanisms responsible for IR ROM. Therefore, the purpose of this study was to determine the contributions of HR, PCT, and posterior rotator cuff PA on IR ROM during a preseason evaluation in healthy professional baseball pitchers. The authors hypothesized that HR, PCT, and posterior rotator cuff PA would have a significant contribution to IR ROM.

Methods

This is a cross-sectional study. Healthy professional pitchers from a single organization were recruited at the beginning of the 2021 Major League Baseball Spring Training. Participants received bilateral IR ROM assessment while laying supine with the shoulder at 90 degrees of abduction and the scapula stabilized. Ultrasound imaging was also performed bilaterally to assess HR, PCT, infraspinatus (superficial + deep) PA, and teres minor (superficial + deep) PA. All ultrasound imaging processes were performed utilizing previously published, highly reliable techniques. A stepwise regression was performed, which included both arms to determine the mechanisms of IR ROM.

Results

Overall, 49 pitchers (88 shoulders) with an average age of 22.5 ± 2.2 years were included in the final data analysis. Stepwise linear regression found that only HR and PCT were associated with the preseason IR ROM. There was a moderate relationship between HR and PCT relative to IR ROM (R = 0.535, P < .001).

Conclusion

HR and PCT were found to be the primary mechanisms responsible for the preseason glenohumeral IR ROM. The posterior rotator cuff was not found to be significantly related to IR ROM. Future research evaluating these anatomic structures longitudinally-both acutely and chronically-will help clinicians optimize ROM management throughout the season. As glenohumeral internal rotation deficit can have harmful effects in baseball pitchers, understanding which anatomic structures are most responsible for IR ROM is important for injury prevention and treatment.

Posterior shoulder capsule of the dominant arm is stiffer in baseball players than that in nonthrowing population

BACKGROUND

Posterior shoulder capsule tightness is one of the factors for shoulder injuries in overhead athletes. Recent studies have shown the posterior capsule of the dominant arm to be stiffer than that of the nondominant arm in baseball players. However, whether posterior capsule tightness in the dominant arm is exclusive to overhead athletes remains unknown. This study aimed to investigate whether the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population.

METHODS

Fifteen male collegiate asymptomatic baseball players (baseball-player group) and fifteen male college students who did not partake in overhead sports (nonthrowing group) participated in this study. We measured the shear moduli of the middle and inferior posterior capsules, superior infraspinatus, inferior infraspinatus, teres minor, and posterior deltoid in the dominant arm by ultrasound shear wave elastography. We compared shear moduli between the two groups using an independent samples t-test and Mann-Whitney test. In addition, we investigated the correlation between the range of glenohumeral internal rotation and each shear modulus in each group using the Pearson correlation coefficient.

RESULTS

The shear moduli in the baseball-player group were significantly higher than those in the nonthrowing group in both the middle posterior capsule (baseball-player group: 36.1 ± 5.6 kPa vs. nonthrowing group: 29.0 ± 8.6 kPa; P = .018) and inferior posterior capsule (37.1 ± 9.6 kPa vs. 27.9 ± 6.8 kPa; P = .002). However, no difference in the shear moduli of individual muscle groups was identified. The glenohumeral internal rotation range exhibited a statistically significant negative correlation with the shear modulus of the inferior posterior capsule in the baseball-player group (Pearson correlation coefficient = -0.586, P = .022).

CONCLUSION

Our findings suggest that the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population.

Residual Effects of Glenohumeral Range of Motion, Strength, and Humeral Retroversion on Prior Overhead Athletes After Cessation of Sport

Background:

Research has shown that repetitive stress from playing an overhead (OH) sport can cause musculoskeletal and osseous adaptations to occur on the dominant side. Additionally, there are limited data about the residual effects of these adaptations after the cessation of sports participation.

Purpose:

To investigate the effects of prior participation in an OH sport versus not participating in an OH sport on glenohumeral range of motion (ROM), isometric strength, and humeral retroversion (HR).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Forty-eight college-aged individuals participated. Participants were split into 2 groups: (1) individuals who previously participated in an OH sport (n = 20; age, 20.3 ± 1.1 years; height, 166.3 ± 15.27 cm; weight, 72.2 ± 13.5 kg) and (2) individuals who previously did not play an OH sport (n = 28; age, 20.6 ± 0.9 years; height, 168.8 ± 6.3 cm; weight, 68.1 ± 15.1 kg). After completing a health history questionnaire, the following were measured: side-to-side shoulder internal rotation (IR) and external rotation (ER) ROM via an inclinometer, isometric shoulder strength via a handheld dynamometer, and HR using an ultrasound imaging machine. A Mann-Whitney U test was used to determine group differences, and a Wilcoxon t test was used to analyze side-to-side differences within each group.

Results:

The Mann-Whitney U test revealed a statistically significant group difference for dominant shoulder ER ROM (U = 162.00, P = .014). Specifically, the prior OH group had significantly more ER than the control group. Within the prior OH group, testing revealed that athletes had significantly more HR (Z =–2.782, P = .005), ER ROM (Z =–1.979, P = .048), and ER isometric strength (Z =–2.763, P = .006) on their dominant than nondominant shoulder and significantly less IR ROM (Z =–3.099, P = .002) on their dominant than nondominant shoulder.

Conclusion:

Prior OH sports participation may have residual osseous and musculoskeletal effects that remain after cessation of the sport.

Chronic adaptations of the long head of the biceps tendon and groove in professional baseball pitchers

BACKGROUND AND HYPOTHESIS

The long head of the biceps tendon (LHBT) plays a significant shoulder stabilizing role during pitching, with the large forces and repetitions involved in overhead throwing likely contributing to LHBT pathology. Determining whether the LHBT undergoes adaptive changes in baseball pitchers and how these changes relate to bicipital groove morphology can improve our understanding of the biceps function at the glenohumeral joint. Therefore, the purpose of this study was to determine the chronic adaptations of the bicipital groove morphology and the LHBT in professional baseball pitchers, with a secondary purpose of evaluating biceps integrity as it relates to torsional changes of the bicipital groove. We hypothesized that the throwing arm of professional baseball pitchers would exhibit chronic adaptations of the LHBT compared with their nonthrowing arm, and that these adaptations would be related to the bicipital groove morphology.

MATERIALS AND METHODS

Fifty-three professional baseball pitchers were enrolled at the beginning of the 2015 Major League Baseball spring training. Ultrasound was used to bilaterally measure humeral retroversion and to capture images of the bicipital groove and the LHBT. MATLAB software was used to calculate the area of the bicipital groove, and ImageJ software was used to quantify the area, echogenicity, and circularity of the LHBT.

RESULTS

The dominant arm LHBT cross-sectional area was significantly smaller than the nondominant arm (9 mm² vs. 10 mm²; P = .011), whereas the dominant arm LHBT echogenicity was significantly higher than the nondominant arm (65 optical density vs. 59 optical density; P = .002). Pitchers with more bicipital groove rotational adaptation (more retroversion) had significantly more LHBT echogenicity adaptation compared with pitchers with less bicipital groove rotational adaptation (12 vs. 2; P = .023).

CONCLUSION

There are significant bilateral differences in the LHBT of professional baseball pitchers. An adaptation in bony rotation was associated with a larger bilateral difference in LHBT echogenicity but was not related to bilateral differences in LHBT area or circularity. Therefore, the bilateral difference in echogenicity is impacted by bony morphology, whereas the bilateral difference in cross-sectional area may be independent of bony morphology in this healthy population.

Neurogenic thoracic outlet syndrome in the overhead and throwing athlete: A narrative review

Thoracic outlet syndrome is an important cause of shoulder pain and dysfunction due to compression of neurovascular structures as they traverse the thoracic outlet. Symptoms are most commonly due to compression of the brachial plexus called neurogenic thoracic outlet syndrome (nTOS). Throwing athletes are at increased risk of nTOS because of a variety of biomechanical factors. However, because nTOS symptoms are often nonspecific, delayed diagnosis is common. Neurogenic thoracic outlet largely remains a diagnosis of exclusion with advanced imaging ruling out vascular involvement and diagnostic injections gaining favor in helping localize sites of compression. Although rehabilitation alone may improve symptoms in some athletes, many require surgical treatment for long-term relief. This generally entails decompression of the thoracic outlet by some combination of muscle release, brachial plexus neurolysis, and first rib resection. Outcomes tend to be successful in athletes with most achieving resolution of symptoms and return to athletic activity. NTOS is an important cause of shoulder pain and dysfunction in throwing athletes. The history and physical examination should focus on activities that exacerbate symptoms. Treatment of nTOS generally requires surgical intervention and allows throwing athletes to return to sport.

The Contribution of Posterior Capsule Hypertrophy to Soft Tissue Glenohumeral Internal Rotation Deficit in Healthy Pitchers

BACKGROUND

The relationship between posterior capsule adaptations and soft tissue glenohumeral internal rotation deficit (GIRD) in healthy pitchers remains unclear.

PURPOSE/HYPOTHESIS

This study aimed to identify if posterior capsule thickness (PCT) was associated with soft tissue GIRD in healthy pitchers. We hypothesized that there would be a positive relationship between soft tissue GIRD and PCT in the dominant arm, no relationship between soft tissue GIRD and PCT in the nondominant arm, and a strong positive relationship between soft tissue GIRD and the bilateral difference in PCT (posterior capsule hypertrophy [PCH]).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 45 healthy collegiate and professional pitchers were included. Glenohumeral internal rotation and external rotation range of motion, humeral retroversion, and PCT were measured bilaterally. PCT was determined for unilateral posterior capsule measurements, and PCH of the throwing shoulder was calculated as the bilateral difference in PCT. Soft tissue GIRD was calculated as the sum of clinical GIRD and the bilateral difference in humeral retroversion. Pearson correlation coefficients were determined to evaluate the relationships between dominant arm PCT, nondominant arm PCT, and PCH and soft tissue GIRD.

RESULTS

Pearson correlations showed that both dominant arm PCT (R = -0.13; P = .378) and nondominant arm PCT (R = 0.21; P = .165) were not related to soft tissue GIRD. However, Pearson correlations did show that the amount of PCH was moderately related to soft tissue GIRD (R = 0.40; P = .007). Therefore, as the posterior capsule hypertrophied, soft tissue GIRD moderately increased.

CONCLUSION

Increased PCH was associated with an increase in soft tissue GIRD in healthy pitchers. If PCT measurements are feasible, clinicians should consider performing bilateral ultrasound assessments to isolate posterior capsule adaptations (ie, PCH). This will allow clinicians to identify pitchers with potentially maladaptive structural adaptations and optimize management strategies throughout the season to counteract them.

A Review of Upper Extremity Peripheral Nerve Injuries in Throwing Athletes

Peripheral nerve injuries in the upper extremities may be common in throwing athletes as the throwing motion places extreme stress on the dominant arm. The combination of extreme stress along with repetitive microtrauma from throwing uniquely places the throwing athlete at elevated risk of upper extremity peripheral nerve injury. However, because symptoms can be non-specific and frequent co-exist with pathology in the upper extremity, the diagnosis of peripheral nerve injury is often delayed. Diagnosis of peripheral nerve injuries may require a combination of history and physical exam, diagnostic imaging, electrodiagnostic testing, and diagnostic ultrasound guided injections. The primary management should include physical therapy focusing on throwing mechanics and kinetic chain evaluation. However, some athletes require surgical intervention if symptoms do not improve with conservative management. The purpose of this focused narrative review is to highlight upper extremity peripheral neuropathies reported in throwing athletes and to provide an overview of the appropriate clinical diagnosis and management of the throwing athlete with a peripheral nerve injury. This article is protected by copyright. All rights reserved.

Proximal humeral coordinate systems can predict humerothoracic and glenohumeral kinematics of a full bone system

BACKGROUND

Clinical imaging often excludes the distal humerus, confounding definition of common whole-bone coordinate systems. While proximal anatomy coordinate systems exist, no simple method transforms them to whole-bone systems. Their influence on humeral kinematics is unknown.

RESEARCH QUESTION

How do humeral kinematics vary based on proximal and whole-bone coordinate systems, and can average rotation matrices accurately convert kinematics between them?

METHODS

Three proximal coordinate systems were defined by the lesser and greater tuberosities (LT, GT), Crest of the greater tuberosity, and humeral shaft. Average rotation matrices derived from anatomic landmarks on cadaver humeri were generated between the proximal and whole-bone coordinate systems. Absolute angle of rotation was used to determine if anatomical variability within the cadaver population influenced the matrices. The matrices were applied to humerothoracic and glenohumeral motion (collected previously) and analyzed using the proximal coordinate systems, then expressed in the whole-bone system. RMSE was used to compare kinematics from the proximal and whole-bone systems.

RESULTS

A single average rotation matrix between a given proximal and whole-bone coordinate system achieved consistent error, regardless of landmarks. Elevation and plane of elevation had <2° mean error when proximal coordinate systems were transformed to whole-bone kinematics. Axial rotation had a mean 7° error, primarily due to variable humeral head retroversion. Absolute angles of rotation did not statistically differ between subgroups. The average rotation matrices were independent of sex, side, and motion.

SIGNIFICANCE

Proximal humerus coordinate systems can accurately predict whole-bone kinematics, with most error concentrated in axial rotation due to anatomic twist along the bone. These results enhance interpretability and reproducibility in expressing humerothoracic and glenohumeral motion data between laboratories by providing a simple means to convert data between common coordinate systems. This is necessitated by the lack of distal humerus anatomy present in most clinical imaging.

Relationship between glenohumeral internal rotation deficit and shoulder conditions in professional baseball pitchers

BACKGROUND

Previous studies have reported that glenohumeral internal rotation deficit (GIRD) may increase the risk of throwing-shoulder injuries. The purpose of this study was to analyze the conditions of the throwing shoulder in professional baseball pitchers with GIRD by comparing with those in pitchers without GIRD.

METHODS

In total, 26 male professional baseball pitchers participated in this study. We evaluated passive range of motion (ROM) and isometric muscle strength at internal rotation (IR) and external rotation (ER) at 90° of abduction, as well as the muscle thickness of the supraspinatus (SSP) and infraspinatus (ISP) by ultrasound. The pitchers were divided into 2 groups: those who exhibited a loss of IR of ≥20° in the throwing shoulder (GIRD group) and those who did not (non-GIRD group).

RESULTS

In the GIRD group, the total ROM deficit (throwing side - non-throwing side) (P < .001), the muscle thickness ratio (throwing to non-throwing) of the SSP and ISP (P = .017 and P = .014, respectively), and the muscle strength ratio (throwing to non-throwing) of ER (P = .028) were significantly lower than those in the non-GIRD group. In contrast, the muscle strength ratio (throwing to non-throwing) of IR was significantly higher in the GIRD group than in the non-GIRD group (P = .0064).

CONCLUSIONS

We have shown that GIRD has significant correlations with several conditions, such as atrophy of the SSP and ISP, weakness of ER strength, enhancement of IR strength, limitation of total ROM, and throwing side, all of which could be important factors for throwing-shoulder injuries.

Relationship of clinical measures with humeral torsion in young adults: a pilot study

PURPOSE

Humeral retroversion alters range of motion and has been linked to injury risk. Clinically,palpation of the bicipital groove is used to quantify humeral torsion, but the accuracy of this procedure has not been fully examined. The purpose of this study was to investigate the relationship between clinical and diagnostic ultrasound (US) assessment of humeral torsion while considering shoulder position of the participant and clinical expertise of the examiner.

METHODS

Seventeen participants (34 shoulders, 16/17 right handed, 10/17 history of throwing) were recruited. US was assessed by an experienced assessor. Two clinical assessments of humeral torsion were performed by two assessors of different experience (expert and novice). Humeral torsion was assessed at 90 degrees shoulder abduction (Palp90) and 45 degrees shoulder abduction (Palp45). Within assessor intraclass correlation coefficients (ICC (3, 1) were calculated. Correlation coefficients (Pearson's) were generated to determine relationship between clinical and US examination findings.

RESULTS

Intra-rater reliability for clinical tests were good (ICCs .73 - .92) for both raters. Of the palpation tests, only the expert assessor was significantly correlated to the US measurement (p<.001) at Palp45 (r = .64) and Palp90 (r = .62). For the expert, there was a significantly lower angle calculated for Palp45 compared to Palp90 (p<.001).

CONCLUSION

The accuracy of both palpation methods for assessing humeral retrotorsion may depend on the training background of the assessor. Further, the glenohumeral position of the patient during palpation should be consistent for the purposes of repeated testing.

Differences in Passive Shoulder Range of Motion Between Baseball Players With Neurogenic Thoracic Outlet Syndrome and Matched Healthy Controls

Background:

Neurogenic thoracic outlet syndrome (nTOS) is becoming more recognized as a diagnosis in the throwing athlete. Currently, there is limited information on the clinical presentation and development of nTOS in baseball players.

Purpose:

To compare passive shoulder range of motion (ROM) and anatomic humeral retrotorsion (HRT) of baseball players diagnosed with nTOS with a group of healthy, matched controls.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 53 adolescent baseball players diagnosed with nTOS (age, 17.2 ± 2.3 years; height, 180.9 ± 10.1 cm; weight, 80.0 ± 13.3 kg) were compared with 53 healthy baseball players (age, 17.2 ± 2.4 years; height, 183.9 ± 9.0 cm; weight, 83.8 ± 11.5 kg). Participants were measured for shoulder internal rotation (IR) and external rotation (ER) ROM and HRT. All measurements were taken bilaterally, and the differences (throwing to nonthrowing arm) were used to calculate mean values for glenohumeral internal rotation difference, glenohumeral external rotation difference (GERD), total rotational motion difference (TRM_diff), and anatomic humeral retrotorsion difference. Group comparisons were made between the nTOS and control players using multivariate analysis of variance, and descriptive comparisons were made with independent t tests.

Results:

There were no significant differences between groups in age, height, weight, or years of experience. Players in the nTOS group had significantly less throwing arm ER compared with controls (103.4° ± 10.4° vs 109.6° ± 7.5°, respectively; P = .001) and GERD (3.0° ± 9.2° vs 8.8° ± 9.2°, respectively; P = .002). TRM_diff was significantly greater in nTOS (–11.1° ± 11.1°) than in controls (–3.7° ± 9.4°) (P < .001).

Conclusion:

In the current study, adolescent baseball players diagnosed with nTOS were evaluated with shoulder ROM differences when compared with a matched healthy cohort. A loss of throwing arm ER appeared to be the main factor behind shoulder ROM changes in the nTOS group.

Shoulder Rotation Range of Motion and Serve Speed in Adolescent Male Volleyball Athletes: A Cross-Sectional Study

BACKGROUND

Throwing athletes present alterations in shoulder rotation range of motion (ROM), but not much is known about the relationship between these alterations and performance measurements in volleyball practitioners.

PURPOSE

To compare the passive ranges of motion of internal rotation (IR), external rotation (ER), and total rotation motion (TRM) of the shoulder in dominant and nondominant limbs of young volleyball athletes and to investigate their relationship with ball speed during serves with and without precision (inside and outside court, respectively). The possible association of anthropometrics and competitive practice time with these velocities was also investigated.

STUDY DESIGN

Cross-sectional study.

METHODS

Fifty-seven male volleyball athletes (mean age 17.11 ± 1.88 y; weight 74.68 ± 9.7 kg; height 1.87 ± 0.09 cm) were evaluated for shoulder IR and ER with a bubble goniometer and serve speed inside and outside court was measured with a radar gun. Simple and multiple regression analyses were applied to investigate associations of ROM, anthropometrics, and competitive practice time with serve speed.

RESULTS

Dominant shoulders had diminished IR ROM compared to nondominant shoulders (59.1º ± 16.7º vs 66.4º ± 16.9º; p < 0.001) as well as diminished TRM (173.5º ± 31.8º vs 179.1º ± 29.9º; p < 0.001). Simple regression showed negative association between dominant ER and serve speed outside the court (p = 0.004). Positive associations existed between age and serve speed in both conditions (p < 0.001), BMI and speed inside (p = 0.009) and outside the court (p = 0.008), and between competitive practice time and speed inside (p = 0.008) and outside court (p = 0.003). However, multiple analysis confirmed only age (p < 0.001) and BMI to be associated with ball velocities (inside court p = 0.034; outside court p = 0.031).

CONCLUSION

The results of this study demonstrated that young volleyball athletes presented lower IR and TRM of the shoulder in the dominant upper limb. Age and BMI were directly associated with ball velocities when serving. Passive rotation ROM did not have a relationship with this performance measurement.

LEVEL OF EVIDENCE

3b.

Effect of Younger Starting Pitching Age on Humeral Retrotorsion in Baseball Pitchers With an Ulnar Collateral Ligament Injury

BACKGROUND

Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development.

HYPOTHESIS

In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff).

RESULTS

There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P = .015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P = .007). No significant differences between groups were found for HRTdiff (P = .940).

CONCLUSION

Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries.

The Effect of Straight-Line Long-Toss Versus Ultra-Long-Toss Throwing on Passive Glenohumeral Range of Motion Recovery After Pitching

BACKGROUND

Repetitive throwing in baseball pitchers can lead to pathologic changes in shoulder anatomy, range of motion (notably glenohumeral internal rotation deficit), and subsequent injury; however, the ideal strengthening, recovery, and maintenance protocol of the throwing shoulder in baseball remains unclear. Two strategies for throwing shoulder recovery from pitching are straight-line long-toss (SLT) throwing and ultra-long-toss (ULT) throwing, although neither is preferentially supported by empirical data.

HYPOTHESIS

ULT will be more effective in returning baseline internal rotation as compared with SLT in collegiate pitchers after a pitching session.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 24 National Collegiate Athletic Association Division I baseball pitchers with mean age 20.0 ± 1.1 years were randomized to either the ULT group (n = 13; 9 right-hand dominant, 4 left-hand dominant) or SLT group (n = 11; 10 right-hand dominant, 1 left-hand dominant). Measurements (dominant and nondominant, 90° abducted external rotation [ER], internal rotation [IR], and total range of motion [TROM]) were taken at 5 time points across 3 days: before and immediately after a standardized bullpen session on day 1; before and immediately after a randomized standardized ULT or SLT session on day 2; and before practice on Day 3.

RESULTS

ULT demonstrated significantly greater final ER compared with baseline (+10°; P = 0.05), but did not demonstrate significant IR changes. Similarly, SLT demonstrated significantly greater post-SLT ER (+12°; P = 0.02) and TROM (+12°;P = 0.01) compared with baseline, but no significant IR changes. Final ER measurements were similar between ULT (135° ± 14°) and SLT (138° ± 10°) (P = 0.59). There was also no statistically significant difference in final IR between ULT (51° ± 14°) and SLT (56° ± 8°) (P = 0.27).

CONCLUSION

The routine use of postperformance, ULT throwing to recover from range of motion alterations, specifically IR loss, after a pitching session is not superior to standard, SLT throwing. Based on these findings, the choice of postpitching recovery throwing could be player specific based on experience and comfort.

CLINICAL RELEVANCE

The most effective throwing regimens for enhancing performance and reducing residual impairment are unclear, and ideal recovery and maintenance protocols are frequently debated with little supporting data. Two strategies for throwing shoulder recovery from pitching are SLT and ULT throwing. These are employed to help maintain range of motion and limit IR loss in pitchers. The routine use of ULT throwing for recovery and to limit range of motion alterations after a pitching session is not superior to SLT throwing.

Risk Factors of Overuse Shoulder Injuries in Overhead Athletes: A Systematic Review

CONTEXT

Shoulder injuries are highly prevalent in sports involving the upper extremity. Some risk factors have been identified in the literature, but consensus is still lacking.

OBJECTIVES

To identify risk factors of overuse shoulder injury in overhead athletes, as described in the literature.

DATA SOURCES

A systematic review of the literature from the years 1970 to 2018 was performed using 2 electronic databases: PubMed and Scopus.

STUDY SELECTION

Prospective studies, written in English, that described at least 1 risk factor associated with overuse shoulder injuries in overhead sports (volleyball, handball, basketball, swimming, water polo, badminton, baseball, and tennis) were considered for analysis.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

Data were extracted from 25 studies. Study methodology quality was evaluated using the Modified Coleman Methodology Score.

RESULTS

Intrinsic factors, previous injury, range of motion (lack or excess), and rotator cuff weakness (isometric and isokinetic) highly increase the risk of future injuries. Additionally, years of athletic practice, body mass index, sex, age, and level of play seem to have modest influence. As for the effect of scapular dysfunction on shoulder injuries, it is still controversial, though these are typically linked. Extrinsic factors, field position, condition of practice (match/training), time of season, and training load also have influence on the occurrence of shoulder injuries.

CONCLUSION

Range of motion, rotator cuff muscle weakness, and training load are important modifiable factors associated with shoulder injuries. Scapular dysfunction may also have influence. The preventive approach for shoulder injury should focus on these factors.

Does humeral torsion play a role in shoulder and elbow injury profiles of overhead athletes: a systematic review

BACKGROUND

Humeral retrotorsion (HRT) is one bony adaptation that occurs in overhead athletes. This bony adaptation often leads to bilateral changes in range of motion at the glenohumeral joint. Because HRT can create different stress environments on the surrounding tissue, it may play a role in upper-limb injury and pain profiles. Therefore, the aim of this review was to examine whether HRT plays a role in shoulder and elbow injury profiles.

METHODS

Two separate critical appraisal tools were administered: the Newcastle-Ottawa Scale (case control) and the Appraisal Tool for Cross-sectional Studies. The primary author extracted all data and obtained means and standard deviations for each outcome. Cohen d effect sizes (ESs) were calculated (ES [95% confidence interval]) for all HRT measurements including nondominant, dominant, and side-to-side differences. Finally, the Strength of Recommendation Taxonomy was used to evaluate the overall strength of the recommendation.

RESULTS

Nine articles were included in this review. Large ESs were present in 2 studies on examination of symptomatic and asymptomatic dominant HRT and ranged between 0.83 (0.08-1.55) and -2.57 (-3.66 to 1.99). The majority of all ESs for all HRT measurements were moderate or low, rendering comparisons between asymptomatic and symptomatic cohorts that were not clinically meaningful.

CONCLUSION

The Strength of Recommendation Taxonomy rating was C based on inconsistent findings. Differences in sports populations and definitions of injuries across studies may be one reason for the varying ESs. HRT does occur in the overhead population, but the degree to which this HRT starts to affect upper-limb injury is unknown and is more than likely player specific and multifactorial.

Posterior shoulder tightness; an intersession reliability study of 3 clinical tests

Background

Although posterior shoulder tightness (PST) has been associated with shoulder pathology and altered glenohumeral joint kinematics, uncertainty remains regarding its cause and definition. To understand the efficacy of treatments for PST, it must be possible to identify people with PST for the purposes of research and clinical decision-making. Clinical tests for PST must demonstrate acceptable levels of measurement reliability in order to identify the condition and to evaluate the response to intervention. There is currently a lack of research describing intersession reliability for measures of PST. The aim of this study was to quantify the inter-session reliability for three clinical tests used to identify PST over a 6-10 week interval.

Methods

A convenience sample of 26 asymptomatic adult participants (52 shoulders) were recruited from a university setting over a five-month duration. Participants attended the human movement laboratory for measurement of glenohumeral joint internal rotation, horizontal adduction and low flexion on two occasions separated by an interval of 6-10 weeks.Intra-class correlation coefficients were calculated from the mean square values derived from the within-subject, single factor (repeated measures) ANOVA. Test-retest measurement stability was evaluated by calculating the standard error of measurement and the minimum detectable change for each measurement.

Results

All 3 tests demonstrated good intersession intra-rater reliability (0.86-0.88), and the standard error of measurement (95%) were 7.3° for glenohumeral horizontal adduction, 9.4° for internal rotation, and 6.9° for low flexion. The minimum detectable change for glenohumeral horizontal adduction was 10.2°, internal rotation was 13.3°, and low flexion was 9.7°.

Conclusion

In this population of people without symptoms, the 3 measures of PST all demonstrated acceptable inter-session reliability. The standard error of measurement and minimum detectable change results can be used to determine if a change in measures of PST are due to measurement error or an actual change over time.

Human athletic paleobiology; using sport as a model to investigate human evolutionary adaptation

The use of sport as a conceptual framework offers unprecedented opportunities to improve our understanding of what the body does, shedding new light on our evolutionary trajectory, our capacity for adaptation, and the underlying biological mechanisms. This approach has gained traction over recent years. To date, sport has facilitated exploration not only of the evolutionary history of our species as a whole, but also of human variation and adaptation at the interindividual and intraindividual levels. At the species level, analysis of lower and upper limb biomechanics and energetics with respect to walking, running and throwing have led to significant advances in the understanding of human adaptations relative to other hominins. From an interindividual perspective, investigation of physical activity patterns and endurance running performance is affording greater understanding of evolved constraints of energy expenditure, thermoregulatory energetics, signaling theory, and morphological variation. Furthermore, ultra-endurance challenges provoke functional trade-offs, allowing new ground to be broken in the study of life history trade-offs and human adaptability. Human athletic paleobiology-the recruitment of athletes as study participants and the use of contemporary sports as a model for studying evolutionary theory-has great potential. Here, we draw from examples in the literature to provide a review of how the use of athletes as a model system is enhancing understanding of human evolutionary adaptation.

Geometrical analysis for assessing torsional alignment of humerus

BACKGROUND

Compared to other types of surgeries, minimally invasive surgeries (MISs) of humeral shaft fractures are associated with less radial nerve injury, less soft tissue injury and higher union rate. However, malrotation often occurs in MISs when closed reduction methods are used. This study aims to define specific palpable landmarks to help surgeons determine the correct torsional angle and reduce the incidence of malrotation.

METHODS

Twenty-eight normal humeral computed tomography scans were retrieved from our image database. One line was drawn through the vertices of the intertubercular sulcus of the humeral head in the coronal view, and another line was drawn through the longest axis between the medial and lateral condyles in the coronal view. The angle between these two lines was measured at least 3 times for each scan.

RESULTS

The profile of the intertubercular sulcus tangent line of the humeral head and the axis of the distal humerus was identified as the most accurate method for assessing the precision of torsion during MIS for humeral shaft fractures. The transepicondylar axis line is more internally rotated than the intertubercular sulcus tangent line. The mean angle was measured to be 41.1 degrees.

CONCLUSIONS

The axis of the distal humeral condyles is internally rotated by approximately 41.1 degrees compared with the intertubercular sulcus tangent line of the humeral head. Minimally invasive surgeries can be performed by using these palpable landmarks. The torsional deformities can be reduced with the proper angle adjustment without the need for fluoroscopy. It can also be used to treat unstable comminuted humeral fractures.

LEVEL OF EVIDENCE

Retrospective Study, Diagnostic study, Level III.

The Relationship Between Humeral Torsion and Arm Injury in Baseball Players: A Systematic Review and Meta-analysis

CONTEXT

Humeral torsion (HT) has been linked to various injuries and benefits. However, the exact interplay between HT, shoulder range of motion (ROM), competition level differences, and injury risk is unclear.

OBJECTIVE

To determine the relationship between HT, ROM, and injury risk in baseball players. Secondarily, to determine HT based on competition level.

DATA SOURCES

PubMed, Embase, Web of Science, CINAHL, and Cochrane databases were searched from inception until November 4, 2018.

STUDY SELECTION

Inclusion criteria consisted of (1) HT measurements and (2) arm injury or shoulder ROM.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

Two reviewers recorded patient demographics, competition level, HT, shoulder ROM, and injury data.

RESULTS

A total of 32 studies were included. There was no difference between baseball players with shoulder and elbow injuries and noninjured players (side-to-side HT difference: mean difference [MD], 1.75 [95% CI, -1.83 to 2.18]; dominant arm: MD, 0.17 [95% CI, -1.83 to 2.18]). Meta-regression determined that for every 1° increase in shoulder internal rotation (IR), there was a subsequent increase of 0.65° in HT (95% CI, 0.28 to 1.02). HT did not explain external rotation (ER ROM: 0.19 [95% CI, -0.24 to 0.61]) or horizontal adduction (HA ROM: 0.18 [95% CI, -0.46 to 0.82]). There were no differences between HT at the high school, college, or professional levels.

CONCLUSION

No relationship was found between HT and injury risk. However, HT explained 65% of IR ROM but did not explain ER ROM or HA ROM. There were no differences in HT pertaining to competition level. The majority of IR may be nonmodifiable. Treatment to restore and maintain clinical IR may be important, especially in players with naturally greater torsion. HT adaptation may occur prior to high school, which can assist in decisions regarding adolescent baseball participation.

Upper Extremity and Hip Range of Motion Changes Throughout a Season in Professional Baseball Players

BACKGROUND

Loss of upper and lower extremity range of motion (ROM) is a significant risk factor for injuries in professional baseball players.

PURPOSE/HYPOTHESIS

The purpose was to determine changes in ROM in professional baseball players over the course of a single season and their careers. We hypothesized that pitchers and position players would lose ROM, specifically total shoulder motion (total ROM [TROM]) and hip internal rotation (IR), over the course of a season and their careers.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Upper and lower extremity ROM measurements were recorded during pre-, mid-, and postseason on all professional baseball players for a single organization between 2011 and 2018. ROM measurements were compared for pitchers and position players over the course of the season and their careers. Also, ROM measurements over the pre-, mid-, and postseason were compared between pitchers and position players.

RESULTS

A total of 166 professional baseball players (98 pitchers, 68 position players) were included. Pitcher hip external rotation (ER; P < .001), IR (P = .010), and TROM (P < .001) for lead and trail legs decreased over the course of the season. Pitcher shoulder ER (P = .005), TROM (P = .042), and horizontal adduction (P < .001) significantly increased over the course of the season. Position player shoulder flexion (P = .046), hip ER (P < .001, lead leg; P < .001, trail leg), and hip TROM (P = .001; P = .002) decreased over the course of the season. Position player shoulder ER (P = .031) and humeral adduction (P < .001) significantly increased over the course of the season. Over the course of pitchers' careers, there was decreased shoulder IR (P = .014), increased shoulder horizontal adduction (P < .001), and hip IR (P = .042) and hip TROM (P = .027) for the lead leg. Position players experienced loss of hip TROM (P = .010, lead leg; P = .018, trail leg) over the course of their careers. Pitchers started with and maintained more shoulder ER and gained more shoulder TROM over a season as compared with position players.

CONCLUSION

Pitchers and position players saw overall decreases in hip ROM but increases in shoulder ROM over the course of the season and career.

Humeral Retroversion (Complexity of Assigning Reference Axes in 3D and Its Influence on Measurement): A Technical Note

Background

Humeral retroversion (RV) is important to the study of shoulder function and reconstruction. This study tests the hypothesis that clinically obtained computer tomography (CT) measurements for humeral RV (off-axis measurements) differ from those obtained after reformatting the image slice orientation so that the humeral shaft is perpendicular to the gantry (coaxial measurements) and explores deviations from true RV.

Materials and methods

A custom-built application created in Mathematica was used to explore the effect of altering the humeral orientation on slice angle acquisition by 3D imaging technologies, on the perceived angle of RV from the 2D-projection of the reference axes. The application allows for control of humeral axis orientation relative to image slice (3D) or plain of projection (2D) and humeral rotation. The effect of rotating a virtual model of one humerus around its own axis and in discrete anatomical directions on the measured RV angle was assessed.

Results

The coaxial measurement of humeral RV (31.2°) differed from off-axis measurement, with a maximum difference in measured RV of 50° in 45° of extension. The typical position of the humerus in a CT scan resulted in a difference in RV measurement up to 22°. Explorations of deviation led to the following outcomes, as divided by anatomic direction. Extension and abduction led to an underestimation, and flexion and adduction led to an overestimation of the RV-angle.

Conclusion

Measurements must be done consistently about the position and orientation of the humerus. Deviation in the humeral alignment of as little as 10° can distort the measurement of version up to 15°.

How to cite this article

van de Bunt F, Pearl ML, van Noort A. Humeral Retroversion (Complexity of Assigning Reference Axes in 3D and Its Influence on Measurement): A Technical Note. Strategies Trauma Limb Reconstr 2020;15(2):69-73.

Reduced shoulder strength and change in range of motion are risk factors for shoulder injury in water polo players

OBJECTIVE

To determine whether pre-season shoulder ROM and strength can be used to identify athletes at risk of future shoulder injury.

DESIGN

Prospective cohort.

SETTING

High performance sports institute.

PARTICIPANTS

76 sub-elite water polo players.

MAIN OUTCOME MEASURES

Mean pre-season shoulder internal (IR) and external rotation (ER) ROM and strength values compared by gender, dominance and prospective injury status.

RESULTS

14-dominant shoulder injuries were recorded. There was a significant difference (p = 0.05) in total ROM difference (TROM) between the prospectively injured and no injury groups (-17.2°(30.4);-0.8°(13.3)), and dominant side ER strength (11.7%(2.4) vs 14.5%(2.8), p = 0.03) and IR strength (16.5%(3.0) vs 21.6%(4.9) as a percentage body weight (PBW) were also significantly different (p ≤ 0.03). Separate significant associations were found between future episodes of shoulder injury and; dominant shoulder TROM difference of ≥7.5°(OR 3.6,95%CI 0.8-16.0), ER strength as a PBW≤12.5%(OR 5.2,95%CI 1.0-27.9), and IR strength as a PBW≤16.8%(OR 13.8,95%CI 2.2-88.0).

CONCLUSION

Pre-season dominant TROM difference, and reduced shoulder IR and ER strength relative to body weight were significant predictors for future shoulder injury. Although further investigation with a larger sample size is required, achieving optimal values on these measures may reduce future episodes of shoulder injury in water polo players.

Review of Shoulder Range of Motion in the Throwing Athlete: Distinguishing Normal Adaptations from Pathologic Deficits

PURPOSE OF REVIEW

Overhand (OH) throwers demonstrate a unique motion profile of the shoulder joint complex. This manuscript reviews normal adaptations in the OH thrower and contrast findings with pathologic motion deficits.

RECENT FINDINGS

Multiple adaptations in range of motion have been associated with increased risk for arm injury. The use of a more conservative cutoff value for glenohumeral internal rotation deficit and horizontal adduction in younger throwers may help reduce injury risk. Deficits in glenohumeral internal rotation, total range of motion, shoulder flexion, and external rotation insufficiency have all been proposed as means to identify OH throwers at risk for arm injury, but conflicting evidence exists. Understanding normal adaptation due to repetitive stress of throwing is essential to effective management of these athletes. Adaptive change in bone and soft tissues is normal and contributes to the unique motion profiles expected in throwers. The causative link between normal adaptation and shoulder and elbow injury remains uncertain.

Effect of Posterior Capsule Tightness and Humeral Retroversion on 5 Glenohumeral Joint Range of Motion Measurements: A Cadaveric Study

BACKGROUND

Altered glenohumeral joint range of motion can be caused by increased humeral retroversion (HR) and/or posterior capsule tightness (PCT). To make informed clinical decisions, it is vital to understand how HR and PCT alterations, individually and in combination, affect joint range of motion measurements.

PURPOSE

To evaluate the effect of experimental tissue alterations on clinical range of motion measures.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five clinical measurements were quantified in 8 fresh-frozen cadavers under 4 experimentally created conditions: baseline (no alterations), HR condition (20° increase in HR by transecting the bone), PCT condition (20% decrease in length via thermal energy), and PCT + HR combined. Clinical measurements included bicipital forearm angle, low flexion, glenohumeral internal and external rotation, and horizontal adduction. All measurements were taken by the same blinded tester. Separate 1-factor repeated measures analyses of variance were used to evaluate the effect of the alterations on each clinical measurement.

RESULTS

There was a significant main effect of condition for bicipital forearm angle ( P = .02, F = 4.03), low flexion ( P = .02, F = 3.86), internal rotation ( P = .03, F = 3.65), and external rotation ( P < .001, F = 15.15) but not for horizontal adduction ( P = .29, F = 1.33). The HR condition resulted in a decreased bicipital forearm angle of 16.1° and 15.8° as compared with the PCT and PCT + HR conditions, respectively. When compared with baseline, the PCT + HR condition decreased the low flexion test by 13.5°, and the HR condition decreased internal rotation range of motion by 14.2°. All conditions increased external rotation when compared with baseline.

CONCLUSION

Greater measurement changes were noted in both HR conditions, suggesting that bony alterations influence motion to a greater extent than posterior capsule alterations.

CLINICAL RELEVANCE

Clinicians should be aware that humeral retroversion will influence the measurement of posterior shoulder tightness.

Glenohumeral rotation deficits in high school, college, and professional baseball pitchers with and without a medial ulnar collateral ligament injury

BACKGROUND

It is unclear how a glenohumeral internal rotation (IR) loss (GIRLoss), a glenohumeral external rotation (ER) gain (GERGain), or a total rotational motion (TRM) deficit (TRMD) predict medial ulnar collateral ligament (MUCL) injury risk among high school (HS), college (COLL), and professional (PRO) baseball pitchers with and without MUCL injury. We hypothesized that pitchers with MUCL injury would have more GIRLoss and TRMD compared with pitchers without MUCL injury, with no differences in IR, ER, TRM, GIRLoss, GERGain, and TRMD.

METHODS

The study equally divided 216 male HS, COLL, and PRO pitchers into the MUCL injury group (n = 108) and a control group (n = 108) without MUCL injury. The control group was matched with the MUCL injury group according to number, level of play, and age. Bilateral shoulder passive IR/ER was measured and GIRLoss, GERGain, TRM, and TRMD calculated. A 2-way analysis of variance (P < .05) was used to assess shoulder rotational differences among the 2 groups and 3 pitching levels.

RESULTS

Compared with the control group, the MUCL injured group had more GIRLoss (21° ± 14° vs. 13° ± 8°; P < .001), GERGain (14° ± 9° vs. 10° ± 9°; P = .004), and TRMD (7° ± 13° vs. 3° ± 9°; P = .008). For all pitching levels, approximately 60% of pitchers in MUCL injury group had GIRLoss >18° compared with approximately 30% of those in the control group. Approximately 60% of pitchers in the MUCL injury group had TRMD >5° compared with 50% of pitchers in the control group. No differences were observed among HS, COLL, and PRO pitchers for GIRLoss (16° ± 12°, 17° ± 11°, 19° ± 13°, respectively; P = .131), GERGain (11° ± 9°, 11° ± 10°, 13° ± 10°, respectively; P = .171), TRMD (5° ± 11°, 6° ± 11°, 5° ± 14°, respectively; P = .711), and throwing shoulder ER (111° ± 10°, 111° ± 11°, 113° ± 9°, respectively; P = .427), IR (50° ± 11°, 49° ± 11°, 48° ± 10°, respectively; P = .121), and TRM (162° ± 14°, 160° ± 15°, 161° ± 14°, respectively; P = .770).

CONCLUSIONS

Greater GIRLoss, GERGain, and TRMD in MUCL injured pitchers compared with uninjured pitchers implies these variables may be related to increased MUCL injury risk, especially because GIRLoss >18° and TRMD >5° demonstrate an increased MUCL injury risk. Shoulder rotational motion and deficits do not vary among HS, COLL, and PRO levels of pitchers.

Risk factors for ulnar collateral ligament injury in professional and amateur baseball players: a systematic review with meta-analysis

BACKGROUND

Risk factors for ulnar collateral ligament injury (UCLI) are unclear despite increasing injury rates. We sought to summarize UCLI risk factors in baseball players.

METHODS

A computer-assisted search of 4 databases was performed using keywords related to UCLI risk factors. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used for study methodology. Odds ratios and 95% confidence intervals were calculated for dichotomous outcomes, and mean differences and 95% confidence intervals were calculated for continuous outcomes using a random-effects model.

RESULTS

Thirteen studies qualified for inclusion. A greater nondominant (ND) shoulder internal rotation (IR) range of motion (ROM) at 90° abduction arm demonstrated strong evidence as a significant risk factor for UCLI (P < .001) compared with a control group. Mean overall velocity (P < .001), fastball velocity (P < .001), changeup velocity (P = .03), and curveball velocity (P = .01), as well as fewer years of player experience (P < .001), less humeral retrotorsion in the ND arm (P < .001), and greater absolute side-to-side differences in retrotorsion (P = .006) were all moderate-evidence risk factors compared with control groups. Strong evidence suggests total ROM arc at 90° abduction in the dominant arm was not a risk factor for UCLI (P = .81).

CONCLUSIONS

Greater ND shoulder IR ROM and less humeral retrotorsion (in professional and amateur players) as well as pitching velocity (in professional players) demonstrated strong to moderate evidence as risk factors for UCLI. Dominant arm total arc of motion, external, or IR ROM were not risk factors for UCLI. Standardized collection and reporting of risk factors is recommended to more clearly elucidate definitive risk factors for UCLI.

Humeral retroversion and shoulder muscle changes in infants with internal rotation contractures following brachial plexus birth palsy

AIM

To examine humeral retroversion in infants who sustained brachial plexus birth palsy (BPBI) and suffered from an internal rotation contracture. Additionally, the role of the infraspinatus (IS) and subscapularis (SSc) muscles in the genesis of this bony deformation is explored.

METHODS

Bilateral magnetic resonance imaging (MRI) scans of 35 infants (age range: 2-7 mo old) with BPBI were retrospectively analyzed. Retroversion was measured according to two proximal axes and one distal axis (transepicondylar axis). The proximal axes were: (1) the perpendicular line to the borders of the articular surface (humeral centerline); and (2) the longest diameter through the humeral head. Muscle cross-sectional areas of the IS and SSc muscles were measured on the MRI-slides representing the largest muscle belly. The difference in retroversion was correlated with the ratio of muscle-sizes and passive external rotation measurements.

RESULTS

Retroversion on the involved side was significantly decreased, 1.0° vs 27.6° (1) and 8.5° vs 27.2° (2), (P < 0.01), as compared to the uninvolved side. The size of the SSc and IS muscles on the involved side was significantly decreased, 2.26 cm² vs 2.79 cm² and 1.53 cm² vs 2.19 cm², respectively (P < 0.05). Furthermore, the muscle ratio (SSc/IS) at the involved side was significantly smaller compared to the uninvolved side (P = 0.007).

CONCLUSION

Even in our youngest patient population, humeral retroversion has a high likelihood of being decreased. Altered humeral retroversion warrants attention as a structural change in any child being evaluated for the treatment of an internal rotation contracture.

Shoulder Range of Motion and Baseball Arm Injuries: A Systematic Review and Meta-Analysis

OBJECTIVE

Arm injuries in baseball players are a common problem. The identification of modifiable risk factors, including range of motion (ROM), is essential for injury prevention. The purpose of this review was to assess the methodologic quality and level of evidence in the literature and to investigate the relationship between shoulder ROM and the risk of arm injuries in baseball players.

DATA SOURCES

Relevant studies in PubMed, CINAHL, Embase, and SPORTDiscus published from inception to August 1, 2017.

STUDY SELECTION

Only studies that encompassed healthy baseball cohorts who were assessed for shoulder ROM and prospectively evaluated for injuries throughout a baseball season or seasons were included.

DATA EXTRACTION

Six articles met the search criteria. Only 3 studies were included in the meta-analysis due to disparate participant groups.

DATA SYNTHESIS

The modified Downs and Black scale (0-15 points) was used to analyze methodologic quality. Study quality ranged from 11 to 14. Four studies received high-quality (≥12) and 2 studies received moderate-quality (≥10) scores. The overall pooled analysis demonstrated that absolute and internal-rotation deficits (-5.93 [95% confidence interval {CI} = -9.43, -2.43], P < .001 and 4.28 [0.71, 7.86], P = .02, respectively) and absolute total ROM (TROM; -6.19 [95% CI = -10.28, -2.10]; P = .003) were predictors of injury, and these data exhibited homogeneity (absolute IR P value = .77, I² = 0%; IR deficit P value = .41, I² = 0%; absolute TROM P value = .78, I² = 0%). No significance was observed for absolute external rotation (-2.86 [95% CI = -6.56, 0.83], P = .13), which had data with high heterogeneity ( P = .003; I² = 83%). A deficit in horizontal adduction was a predictor of injury (-8.32 [95% CI = -12.08, -4.56]; P < .001); these data were homogeneous but yielded a moderate heterogenic effect ( P = .16; I² = 50%).

CONCLUSIONS

High-quality evidence demonstrated that deficits in throwing-arm TROM and IR were associated with upper extremity injury in baseball players. Heterogeneity across studies for horizontal adduction suggested that this may be a modifiable risk factor for injury, but it requires further research.

Effects of a six-week weighted-implement throwing program on baseball pitching velocity, kinematics, arm stress, and arm range of motion

BACKGROUND

Weighted-baseball training programs are used at the high school, collegiate, and professional levels of baseball. The purpose of this study was to evaluate the effects of a six-week training period consisting of weighted implements, manual therapy, weightlifting, and other modalities on shoulder external rotation, elbow valgus stress, pitching velocity, and kinematics.

HYPOTHESIS

A six-week training program that includes weighted implements will increase pitching velocity along with concomitant increases in arm angular velocities, joint kinetics, and shoulder external rotation.

METHODS

Seventeen collegiate and professional baseball pitchers (age range 18-23, average: 19.9 ± 1.3) training at Driveline Baseball were evaluated via a combination of an eight-camera motion-capture system, range-of-motion measurements and radar- and pitch-tracking equipment, both before and after a six-week training period. Each participant received individualized training programs, with significant overlap in training methods for all athletes. Twenty-eight biomechanical parameters were computed for each bullpen trial, four arm range-of-motion measurements were taken, and pitching velocities were recorded before and after the training period. Pre- and post-training period data were compared via post-hoc paired t tests.

RESULTS

There was no change in pitching velocity across the seventeen subjects. Four biomechanical parameters for the holistic group were significantly changed after the training period: internal rotational velocity was higher (from 4,527 ± 470 to 4,759 ± 542 degrees/second), shoulder abduction was lower at ball release (96 ± 7.6 to 93 ± 5.4°), the shoulder was less externally rotated at ball release (95 ± 15 to 86 ± 18°) and shoulder adduction torque was higher (from 103 ± 39 to 138 ± 53 N-m). Among the arm range of motion measurements, four were significantly different after the training period: the shoulder internal rotation range of motion and total range of motion for both the dominant and non-dominant arm. When the group was divided into those who gained pitching velocity and those who did not, neither group showed a significant increase in shoulder external rotation, or elbow valgus stress.

CONCLUSIONS

Following a six-week weighted implement program, pitchers did not show a significant change in velocity, joint kinetics, or shoulder external rotation range of motion. When comparing pitchers who gained velocity versus pitchers who did not, no statistically significant changes were seen in joint kinetics and shoulder range of motion.

Changes in humeral retrotorsion and the development of little league shoulder: A case study

OBJECTIVE

To present the case of a 15 year-old baseball player with Little League Shoulder (LLS) and describe how developmental changes in the angle of humeral retrotorsion (HRT) may contribute to the underlying pathology of this condition.

DESIGN

Case report.

SETTING

Two years earlier, the patient had participated in a healthy player screening program at which time measurements of height, weight, shoulder motion, and HRT were obtained. These same measures were obtained during the initial evaluation after injury. Between measurements, the patient grew more than 12 cm in height and demonstrated a large shift in proximal humeral torsional alignment with a change of 13° and 19° of HRT in the dominant and non-dominant sides respectively.

PARTICIPANT

15 year-old male (1.88 m, 79.8 kg), right hand dominant baseball pitcher and 3rd baseman diagnosed with right LLS.

CONCLUSION

The pathoanatomical factors contributing to LLS are not well understood. The degree of HRT is a developmental characteristic that changes over the course of physiological maturation. The large changes in HRT seen in this case, may implicate rapid changes in HRT angle create a window of increased susceptibility to physeal damage, and contribute to the development of LLS.

Differentiation of bony and soft-tissue adaptations of the shoulder in professional baseball pitchers

BACKGROUND

Baseball pitching places tremendous forces on the arm, which may lead to structural tissue adaptations that are represented by changes in rotational range of motion (ROM). These adaptations often include both bony and soft tissue; however, the contribution of each tissue to the change in motion is not always clinically attainable. The purposes of this study were to determine the adaptations of ROM, bone, and soft tissue bilaterally and to examine the correlation between clinical ROM and humeral retroversion (HR)-corrected ROM. We hypothesized that glenohumeral internal rotation (IR) and total motion would be decreased and glenohumeral external rotation (ER), posterior capsule thickness (PCT), and HR would be increased in the dominant arm; that HR-corrected ROM would be significantly different than clinical ROM; and that HR-corrected ROM would be correlated with total motion difference.

METHODS

Thirty professional baseball pitchers participated in this study. HR, PCT, and glenohumeral IR and ER were evaluated in the dominant and nondominant shoulders of each subject.

RESULTS

The dominant arm exhibited significantly more retroversion, ER, and PCT than the nondominant arm. The dominant arm also had significantly less IR and total motion than the nondominant arm. The total ROM difference was significantly correlated with both HR-corrected glenohumeral IR deficit and ER gain.

CONCLUSION

HR-corrected glenohumeral IR deficit and ER gain may more accurately reflect the contribution of soft-tissue changes to ROM. Unfortunately, measurement of HR is not always clinically attainable, making clinical management difficult.

Developing reliable measures of the passive torque-angle relationship for shoulder internal and external rotation: Implications for overhead athletics

OBJECTIVES

1) Thoroughly assess shoulder flexibility by establishing the passive torque-angle relationship for internal and external rotation with the arm in an overhead athletics position (abducted 90°) and 2) test the reliability of four passive torque-angle measures.

DESIGN

Reliability study.

SETTING

Data were collected in a university biomechanics laboratory.

PARTICIPANTS

Bilateral shoulder flexibility of 15 male college students (20.7 ± 1.1 y) was evaluated twice in two sessions over 7-10 days.

MAIN OUTCOME MEASURES

For both ER and IR, reliability was assessed bilaterally (intra-session, inter-session, and inter-tester) for the traditional range of motion measure and three novel kinetic measures: torque at end ROM, resistance onset angle, rotational stiffness. This resulted in 48 total assessments.

RESULTS

Thirty-four assessments had good to excellent reliability (ICC ≥ 0.8), 10 had fair reliability (0.7 ≤ ICC < 0.8), and 4 had poor reliability (ICC< 0.7). Three of the four flexibility measures had a good overall ICC score: ROM (0.83), torque at end ROM (0.84), and resistance onset angle (0.81). The fourth, stiffness, had a fair overall reliability score (0.74).

CONCLUSIONS

The passive torque-angle measures should be assimilated into clinical and research settings to determine the relevance to injury, rehabilitation, and performance.

Reliability and Validity of a 1-Person Technique to Measure Humeral Torsion Using Ultrasound

CONTEXT

  Knowledge of the bilateral difference in humeral torsion (HT) enables clinicians to implement appropriate interventions for soft tissue restrictions of the shoulder to restore rotational motion and reduce injury risk. Whereas the current ultrasound method for measuring HT requires 2 assessors, a more efficient 1-person technique (1PT) may be of value.

OBJECTIVE

  To determine if a 1PT is a reliable and valid alternative to the established 2-person technique (2PT) for indirectly measuring HT using ultrasound.

DESIGN

  Descriptive laboratory study.

SETTING

  Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

  A convenience sample of 16 volunteers (7 men, 9 women; age = 26.9 ± 6.8 years, height = 172.2 ± 10.7 cm, mass = 80.0 ± 13.3 kg).

MAIN OUTCOME MEASURE(S)

  We collected the HT data using both the 1PT and 2PT from a total of 30 upper extremities (16 left, 14 right). Within-session intrarater reliability (intraclass correlation coefficient; ICC [3,1]) and standard error of measurement (SEM) were assessed for both techniques. Simple linear regression and Bland-Altman analysis were used to examine the validity of the 1PT when compared with the established 2PT.

RESULTS

  The 1PT (ICC [3,1] = 0.992, SEM = 0.8°) and 2PT (ICC [3,1] = 0.979, SEM = 1.1°) demonstrated excellent within-session intrarater reliability. A strong linear relationship was demonstrated between the HT measurements collected with both techniques ( r = 0.963, r² = 0.928, F_1,28 = 361.753, P < .001). A bias of -1.2° ± 2.6° was revealed, and the 95% limits of agreement indicated the 2 techniques can be expected to vary from -6.3° to 3.8°.

CONCLUSIONS

  The 1PT for measuring HT using ultrasound was a reliable and valid alternative to the 2PT. By reducing the number of testers involved, the 1PT may provide clinicians with a more efficient and practical means of obtaining these valuable clinical data. ^a.

Humeral Retroversion and Capsule Thickening in the Overhead Throwing Athlete: A Systematic Review

PURPOSE

To investigate the humeral and soft-tissue adaptations, including humeral retroversion, range of motion, and posterior capsule changes, in overhead throwing athletes.

METHODS

We performed a systematic review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. PubMed, MEDLINE, CENTRAL (Cochrane Central Register of Controlled Trials), and Embase were searched from January 1, 2011, through April 23, 2017, by 2 reviewers independently and in duplicate. The methodologic quality of all included articles was assessed using the Methodological Index for Non-randomized Studies criteria. Interobserver agreement for assessments of eligibility was calculated with the Cohen κ statistic. Descriptive statistics and raw counts were used to summarize data.

RESULTS

We identified 14 studies (6 Level IV and 8 Level III) including 1,152 overhead throwing athletes. The mean age of the included athletes was 18.37 years (standard deviation, 1.52 years), with 59% of the athletes being pitchers and 41% being position players. Significantly greater humeral retroversion was found across all studies evaluating bony morphology in the dominant arm of overhead throwing athletes (range of mean differences, 9.6°-25.8°). Each of these studies also found decreased internal rotation in the dominant arm (range of mean internal rotation differences, -28° to -7.8°). Five studies found a significant negative correlation between the difference in humeral retroversion between the 2 arms and the difference in internal rotation (range of Pearson correlation coefficients, -0.56 to -0.35). Soft-tissue adaptations were assessed in 5 studies, with 4 identifying significantly thicker posterior capsules and 2 identifying significantly stiffer posterior capsules (P < .05).

CONCLUSIONS

Overhead throwing athletes consistently show several distinct changes in their dominant shoulder. These include increased humeral retroversion and the presence of a thickened and stiff posterior capsule. Concomitantly, there is often reduced internal rotation and increased external rotation of the dominant arm.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Effectiveness of a Posterior Shoulder Stretching Program on University-Level Overhead Athletes: Randomized Controlled Trial

OBJECTIVE

To determine whether a posterior shoulder stretch was effective in increasing internal rotation (IR) and horizontal adduction (HAd) range of motion (ROM) in overhead athletes identified as having reduced mobility.

DESIGN

Randomized controlled trial (parallel design).

SETTING

University-based sports medicine clinic.

PARTICIPANTS

Thirty-seven university-level athletes in volleyball, swimming, and tennis, with IR ROM deficits ≥15°, were randomized into intervention or control groups. No subjects withdrew or were lost to follow-up.

INTERVENTION

The intervention group performed the "sleeper stretch" daily for 8 weeks, whereas the control group performed usual activities.

MAIN OUTCOME MEASURES

Independent t tests determined whether IR and HAd ROM differences between groups were significant at 8 weeks and 2-way repeated-measures analysis of variance tests measured the rate of shoulder ROM change. Subject-reported shoulder pain and function were obtained at each evaluation.

RESULTS

Significant differences were found between the intervention and control groups' IR and HAd ROM at 8 weeks (P < 0.001 and P = 0.003, respectively) compared with baseline (zero weeks) (P = 0.19 and P = 0.82, respectively). Significant improvements in IR were detected in the intervention group at 4 weeks (P < 0.001), whereas HAd demonstrated significant changes only at 8 weeks (P = 0.003). Reported shoulder function (P = 0.002) was different between study groups at 8 weeks.

CONCLUSION

Overhead, university-level athletes with an IR deficit ≥15° significantly increased their IR and HAd ROM after performing a posterior shoulder stretch for 8 weeks.

CLINICAL RELEVANCE

Effective management of posterior shoulder tightness through stretching may reduce the incidence of shoulder pathology in overhead athletes.

Quantifying humeral retrotorsion in young swimmers and association with swim volume

OBJECTIVES

To compare the humeral retrotorsion (HRT) among non-athletes, amateur swimmers and competitive swimmers and to analyze the relationship between HRT and swim volume in competitive swimmers.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Ninety children and adolescents, both genders (30 non-athletes: 11.50 ± 1.94 years; 30 amateur swimmers: 11.56 ± 1.81 years; and 30 competitive swimmers: 12.63 ± 2.02 years).

MAIN OUTCOME MEASURES

HRT measurement through the bicipital forearm angle (BFA), by palpation, using an inclinometer to obtain the angle.

RESULTS

Competitive swimmers showed lower BFA (higher HRT) compared to the amateurs (mean difference: 8.3°; p = 0.013; effect size: 0.82) and to the non-athletes (mean difference: 8.5°; p = 0.010; effect size: 0.80). A significant fair negative relationship (r = -0.37; p = 0.04) was found between BFA and volume of swim.

CONCLUSION

Competitive young swimmers present increased HRT and a higher volume of swim is associated with a lower BFA (higher HRT) in these athletes. These results can help to improve the understanding of osseous adaptations in young swimmers.

Pitch Volume and Glenohumeral and Hip Motion and Strength in Youth Baseball Pitchers

CONTEXT

  Increased pitch volume and altered glenohumeral (GH) and hip range of motion (ROM) and strength contribute to injury risk in baseball pitchers. Although these factors affect one another, whether they are related is unknown.

OBJECTIVE

  To examine relationships among cumulative and seasonal pitch volume, ROM, and strength of the GH and hip joints in youth baseball pitchers.

DESIGN

  Cross-sectional study.

SETTING

  Baseball practice facilities.

PATIENTS OR OTHER PARTICIPANTS

  A total of 28 healthy baseball pitchers (age = 13.9 ± 2.9 years).

MAIN OUTCOME MEASURE(S)

  A demographic and pitching questionnaire was used to quantify pitch volume. Glenohumeral internal-rotation (IR) and external-rotation (ER) ROM and strength of the throwing arm; total arc of motion (IR + ER ROM); and bilateral hip IR, ER, and total arc of motion ROM and strength in IR, ER, and abduction were measured. A goniometer was used to assess ROM; a handheld dynamometer, to assess strength. Frequency analyses and bivariate correlations (age covariate) described data and identified relationships.

RESULTS

  Correlations between years of competitive play and increased strength in lead-leg hip IR ( r = 0.52, P = .02) and abduction ( r = 0.48, P = .04) and stance-leg hip IR ( r = 0.45, P = .05) were fair to good. The number of months played in the last year had a fair correlation with decreased GH IR strength ( r = -0.39, P = .04) and increased stance-leg hip IR strength ( r = 0.44, P = .05). Limited pitch time had a fair correlation with increased GH ER ROM ( r = 0.40, P = .04) and an excellent correlation with increased lead-leg hip IR ROM ( r = 0.79, P < .001). Increased innings pitched per game had a fair to good correlation with decreased GH IR strength ( r = -0.41, P = .04) and stance-leg hip ER ROM ( r = -0.53, P = .03). More pitches per game had a fair to good correlation with increased GH ER ROM ( r = 0.44, P = .05) and decreased stance-leg hip ER ROM ( r = -0.62, P = .008).

CONCLUSIONS

  The significant relationships identified in this study suggest the need to further examine youth and adolescent cumulative and seasonal pitch guidelines.

Shoulder Bone Geometry Affects the Active and Passive Axial Rotational Range of the Glenohumeral Joint

BACKGROUND

The range of motion of the glenohumeral joint varies substantially among individuals and is dependent on humeral position. How variation in shape of the humerus and scapula affects shoulder axial range of motion at various positions has not been established.

PURPOSE

To quantify variation in the shape of the glenohumeral joint and investigate whether the scapula and humerus geometries affect the axial rotational range of the glenohumeral joint.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The range of active and passive internal-external rotation of the glenohumeral joint was quantified for 10 asymptomatic participants with optical motion tracking at 60º, 90º, and 120º humeral elevations in the coronal, scapular, and sagittal planes. Bone geometrical parameters were acquired from shoulder magnetic resonance image scans, and correlations between geometrical parameters and maximum internal and external rotations were investigated. Three-dimensional participant-specific models of the humerus and scapula were used to identify collisions between bones at the end of range.

RESULTS

Maximum internal and external rotations of the glenohumeral joint were correlated to geometric parameters and were limited by bony collisions. Generally, the active axial rotational range was greater with increased articular cartilage and glenoid curvature, while a shorter acromion resulted in greater passive range. Greater internal rotation was correlated with a greater glenoid depth and curvature in the scapular plane ( r = 0.76, P < .01, at 60° of elevation), a greater subacromial depth in the coronal plane ( r = 0.74, P < .01, at 90° of elevation), and a greater articular cartilage curvature in the sagittal plane ( r = 0.75, P < .01, at 90° of elevation). At higher humeral elevations, a greater subacromial depth and shorter acromion allowed a greater range of motion.

CONCLUSION

The study strongly suggests that specific bony constraints restrict the maximum internal and external rotations achieved in active and passive glenohumeral movement.

CLINICAL RELEVANCE

This study identifies bony constraints that limit the range of motion of the glenohumeral joint. This information can be used to predict full range of motion and set patient-specific rehabilitation targets for those recovering from shoulder disorders. It can improve positioning and choice of shoulder implants during preoperative planning by considering points of collision that could limit range of motion.

Upper Extremity Range of Motion and Pitching Profile of Baseball Pitchers in Japan

BACKGROUND

Shoulder range of motion and pitch count in baseball pitchers have been linked to pitching-related upper extremity injury.

PURPOSE

To investigate upper extremity range of motion and pitching profiles in baseball pitchers in Japan as well as to make a comparison between injured and noninjured pitchers.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Forty-one Little League to college-level baseball pitchers were measured for bilateral shoulder and elbow range of motion, including shoulder internal rotation (IR), external rotation (ER), shoulder horizontal adduction (HAD), and elbow extension (EXT). They were also asked to answer a simple questionnaire regarding their past pitching-related medical history and pitching profile. Additionally, 28 participants with baseball-related upper extremity injuries (injury group) were compared with 13 participants without injury (no-injury group) for the same parameters. Collected data were analyzed using analysis of variance.

RESULTS

Significant limb differences (dominant vs nondominant side) were noted for ER (117.2° vs 109.8°, P = .02), IR (53.5° vs 61.9°, P = .007), HAD (28.3° vs 32.8°, P = .03), and EXT (1.0° vs 4.6°, P = .01). A significant between-group difference (injury vs no-injury group) was observed for IR in both the dominant (55.4° vs 45.6°, P = .03) and nondominant shoulder (65.3° vs 55.0°, P = .01). Participants in the injury group pitched more games in a season and more innings per game started.

CONCLUSION

Japanese baseball pitchers displayed adaptive changes in upper extremity range of motion similar to American pitchers when compared bilaterally. Injured pitchers exhibited greater IR range of motion in their pitching arm compared with noninjured pitchers.