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Background: The medial ulnar collateral ligament (UCL) of the elbow joint is the primary restraint to valgus stress during the throwing motion. The flexor pronator muscles (FPMs) also stabilize the elbow joint against valgus forces; however, assessment of FPM stiffness in baseball players has been limited., Purpose: To use ultrasound shear wave elastography (USWE) to evaluate the change in tissue elasticity of the FPMs due to pitching., Study Designs: Descriptive laboratory study., Methods: Included were 14 healthy male amateur baseball players (mean age, 28.0 ± 2.6 years) who had played intermediate-level high school or college baseball. The tissue elasticity of the flexor digitorum superficialis (FDS) in the superficial layer of the FPMs and the flexor digitorum profundus (FDP) in the deep layer of the FPMs were measured using USWE before, immediately after, and 24 hours after a throwing session of 100 pitches. The intra- and interrater reliability of the measurements were evaluated using the Pearson correlation coefficient and intraclass correlation coefficient (ICC). The elasticity of each muscle was analyzed using repeated-measures analysis of variance followed by post hoc analysis., Results: Reliability of the USWE measurements was good to excellent (intrarater ICCs, 0.78-0.94; interrater ICCs, 0.85-0.96). The mean tissue elasticity values before, immediately after, and 24 hours after pitching were 22.3 ± 4.4, 41.0 ± 13.8, and 38.3 ± 11.2 kPa, respectively, for the FDS and 27.1 ± 5.8, 48.0 ± 22.3, and 29.6 ± 11.5 kPa, respectively, for the FDP. For both the FDS and FDP, elasticity was significantly higher immediately after pitching than before pitching ( P < .001 and P = .0027, respectively). While the elasticity of the FDS at 24 hours after pitching remained significantly higher compared with before pitching ( P = .0011), the elasticity of the FDP at 24 hours decreased to the same level as before pitching ( P = .91)., Conclusion: Results using USWE indicated that the elasticity of the FDS did not decrease 24 hours after pitching and remained significantly higher than before pitching, suggesting that it may not be fully functioning as a dynamic stabilizer during this period., Clinical Relevance: Pitching in such a condition may result in greater stress on the UCL and increase the risk of UCL injury., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2024.)

Background: The optimal limb position during stress ultrasound (SUS) evaluation of elbow valgus laxity has not been standardized., Purpose: To compare 2 elbow positions (at 90° and 30° of flexion) and report which position method better represents the increased valgus laxity characteristics of baseball players., Study Design: Controlled laboratory study., Methods: Eighteen college baseball players with no history of elbow pain or elbow disorders who belonged to a college baseball club between April and November 2021 participated in this study. The medial elbow joint space (MEJS) was recorded by ultrasonography at rest and under valgus stress, and the difference in MEJS between the conditions was considered the valgus laxity. For all participants, the MEJS was recorded at 90° and 30° of elbow flexion. In the 90° of flexion position, the participant was positioned in the supine position with abduction and external rotation of the shoulder, and 2.5 kgf of valgus stress was applied proximally to the wrist. In the 30° of flexion position, the participant was positioned in the sitting position with abduction and external rotation of the shoulder, and 3.0 kgf of valgus stress was applied to the ulnar head. Valgus laxity on the throwing and nonthrowing sides was compared between the 2 elbow positions using paired t tests or Wilcoxon signed-rank tests after checking the normality., Results: There was a significant difference in valgus laxity on the throwing side between the 90° and 30° of flexion positions (1.9 vs 1.1 mm, respectively; P = .002), whereas no significant difference between positions was seen on the nonthrowing side ( P = .06)., Conclusion: SUS with the elbow flexed at 90° more clearly detected valgus laxity in the study participants than the 30° of flexion position., Clinical Relevance: The quantitative evaluation of valgus laxity is important for baseball players to assess the risk of ulnar collateral ligament injury., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2024.)

Background: Past research indicated that scapular malposition is related to the glenohumeral internal rotation deficit (GIRD). However, there is no research examining the effect of throwing-related pain on this relationship. This study investigated the relationship between scapular position and range of motion (ROM) and compared the difference in this relationship between with and without throwing-related pain., Methods: Forty male baseball players in high school were recruited for this study. The existence and degree of throwing-related pain were obtained from a questionnaire. Participants were divided into 2 groups according to the presence or absence of the pain. Glenohumeral internal and external rotation ROM (abduction internal rotation angle and abduction external rotation angle [ABER], respectively) were measured using a digital inclinometer. The pectoralis minor muscle length was measured using a vernier caliper and scapula index, which indicated the scapular position, measured using a measuring tape. All these measurements were taken on both dominant and nondominant sides. The GIRD and total motion arc (TMA) deficit were calculated from the ROM measurements. Groups were compared using a mixed-model analysis of variance., Results: There was a significant interaction between group and ABER dominance. Other variables were not seen as the interaction effect. There was a significant positive correlation between the scapula index and TMA (r = 0.47, P = .02) and a negative correlation between the scapula index and GIRD (r = -0.65, P < .01) in the dominant side of the pain group. In addition, in the nondominant side of the pain group, the scapula index and ABER were significantly correlated (r = 0.43, P = .04)., Conclusions: The results of this study indicate that the scapular position is associated with the glenohumeral ROM in high school baseball players. In addition, this study demonstrated that the scapular internally rotated position was correlated with the GIRD and TMA deficit in high school baseball players who had throwing-related pain. On the other hand, the scapular externally rotated position was correlated with increased ABER, mainly in the pain-free baseball players or on the nondominant side. These results indicated that the scapular position might affect the glenohumeral rotational ROM in high school baseball players., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Glenohumeral internal rotation deficit (GIRD) and total arc of motion difference (TAMD) have been associated with elbow injuries in throwing athletes., Hypothesis: Youth pitchers with elbow pain will have greater GIRD and TAMD compared with youth pitchers without elbow pain., Study Design: Cross-sectional study., Level of Evidence: Level 3., Methods: Glenohumeral range of motion of 25 consecutive throwing athletes presenting with elbow pain and that of a matched control group of 18 asymptomatic throwing athletes were compared. Bilateral glenohumeral internal rotation, external rotation, and horizontal adduction at 90° were measured and GIRD and TAMD were then calculated. An analysis of variance was performed to compare range of motion between throwers with and without elbow pain., Results: The average GIRD of the elbow pain group was 32.7° compared with 14.5° in the control group ( P < 0.05). The average TAMD in the elbow pain group was 28.3° compared with 6.7° in the control group ( P < 0.05). GIRD and TAMD were present in 88% (22 of 25) and 96% (24 of 25) of the elbow pain group versus 33.3% (6 of 18) and 55.6% (10 of 18) of the control group, respectively., Conclusion: Compared with asymptomatic youth pitchers, those presenting with elbow pain have a statistically significant GIRD and TAMD., Clinical Relevance: This study suggests that a GIRD and TAMD may predispose youth pitchers to present with symptomatic elbow pain.

Purpose: The objective of this study was to investigate the effects of plyometric training on physical fitness and muscle damage in high school baseball players., Methods: The participants in the study included 21 high school baseball players who are healthy and well-training. The participants were randomly allocated to the plyometric training (n=11) and control (n=10) groups. The plyometric training was applied 3 times a week for a total of 8 weeks and the control group took part in only regular baseball skills training without plyometric training. For physical fitness, measures included maximal strength (left and right hand-grip strength), muscle endurance (sit-up), agility (side-step), power (standing long jump), and balance (left and right Rhomberg test). For muscle damage, creatine kinase (CK) and lactate dehydrogenase (LDH) levels were measured., Results: The results showed a significant interaction effect between time and groups in left hand-grip strength (P = 0.022), side-step (P = 0.004), and standing long jump (P < 0.001) after the 8-week plyometric training, with greater improvement in the plyometric training group than the control group. On the other hand, there was no significant interaction effect between time and groups in right hand-grip strength, situp, left and right Rhomberg test, CK level, and LDH level (P > 0.05)., Conclusion: In conclusion, 8-week plyometric training had a positive effect on improving physical fitness, such as maximal strength, agility, and power, in high school baseball players without causing additional muscle damage.

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., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Improvements in ultrasound diagnostic equipment and techniques can enable muscle stiffness to be measured quantitatively as muscle elasticity using ultrasound shear wave elastography (USWE), where high muscle elasticity values represent muscle stiffness., Purpose: To use USWE to analyze the sequential changes in muscle elasticity in the posterior shoulder before and after pitching., Study Design: Descriptive laboratory study., Methods: The authors evaluated 14 baseball players who had played in high school or college at an intermediate level. The elasticity of the supraspinatus, infraspinatus (ISP), middle trapezius, lower trapezius (LT), rhomboideus, and serratus anterior muscles of the throwing shoulder was measured using USWE at 3 time points: before, immediately after, and 24 hours after a throwing session of 100 pitches. The authors analyzed the sequential changes in the mean elasticity values of the respective muscles at the 3 time points., Results: The mean elasticity values before, immediately after, and 24 hours after throwing were as follows: supraspinatus: 32.9, 53.4, 43.8 kPa; ISP: 22.7, 44.8, 43.7 kPa; middle trapezius: 45.1, 70.3, 59.9 kPa; LT: 32.8, 45.5, 46.5 kPa; rhomboideus: 29.1, 47.5, 38.8 kPa; and serratus anterior: 19.2, 36.9, 26.5 kPa, respectively. The mean elasticity values for all tested muscles were significantly higher immediately after throwing compared with before throwing ( P ≤ .0086 for all), and elasticity values in the ISP and LT remained significantly higher 24 hours after throwing compared with before throwing ( P ≤ .019 for both)., Conclusion: The study results indicated that pitching significantly increased ISP and LT muscle elasticity even after 24 hours., Competing Interests: The authors declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2021.)

Background: This study evaluated the effects of a 4-week initial rehabilitation program in middle and high school baseball players who underwent removal of a loose body from osteochondritis dissecans of the capitellum humerus., Methods: Middle and high school baseball players with osteochondritis dissecans of the capitellum humerus were enrolled in this study. Each had more than 3 yr of experience and had undergone arthroscopic removal of loose bodies from the same expert at Kim's Orthop Special Clinic in Seoul. The initial exercise rehabilitation program was based on a two-stage program. Body composition, range of motion of flexion and extension in the elbow and wrist joints, grip strength, and subjective pain scale were measured before and after rehabilitation. To assess the differences between groups, we used a two-way analysis of variance., Results: The range of motion for flexion and extension of the elbow and wrist joints, grip strength, and score on the visual analog scale each were significantly improved following the 4-week program ( P <0.001), had an interactive effect in time × group ( P <0.001), and had significance between groups ( P <0.05)., Conclusion: The 4-week initial rehabilitation exercise program might improve the overall range of motion of the elbow joint and has a positive therapeutic effect on grip strength and visual analog scores. However, future well-designed studies with more subjects and multicentric research groups are necessary for verification., Competing Interests: Conflict of interest The authors declare that there is no conflict of interest., (opyright © 2021 Seo et al. Published by Tehran University of Medical Sciences.)

Background: During shoulder abduction and external rotation, internal impingement can occur when compressive forces between the greater tuberosity and the posterior glenoid rim pinch the undersurface of the rotator cuff. Previous studies on internal impingement have focused on qualitative results such as pathological findings; however, few studies have quantified the area of impingement (AOI) of the rotator cuff muscles between the greater tuberosity and the posterior glenoid rim., Purpose: To compare the AOI between the throwing and nonthrowing shoulders of baseball players., Study Design: Controlled laboratory study., Methods: A total of 14 asymptomatic male collegiate baseball players participated in this study. The AOI in both the throwing and the nonthrowing shoulders was calculated using magnetic resonance imaging (MRI) scans. The MRI measurements were collected with the shoulder at 90° of abduction and at 90° and 100° of external rotation. The area, width, and depth of impingement as well as cystic changes in the greater tuberosity and degeneration in the posterior labrum were compared between the throwing and nonthrowing shoulders., Results: The AOI was significantly greater in the throwing shoulders than in the nonthrowing shoulders (90° of external rotation: 32.4 vs 19.1 mm 2 , respectively; 100° of external rotation, 28.0 vs 15.6 mm 2 , respectively; P < .001 for both). Compared with the nonthrowing shoulders, there were more positive findings in the throwing shoulders regarding greater tuberosity cystic changes (0 vs 7, respectively; P = .006) and posterior labral degeneration (3 vs 13, respectively; P < .001)., Conclusion: The AOI and the number of lesions in the greater tuberosity and posterior labrum were greater in throwing shoulders than in nonthrowing shoulders. Therefore, damage to the insertion of the rotator cuff muscles may affect internal impingement., Clinical Relevance: Lesions in the greater tuberosity and posterior labrum in throwing shoulders may increase the AOI by expanding the joint gap behind the glenohumeral joint. Impingement of the greater tuberosity and the posterior glenoid rim may lead to rotator cuff tears., Competing Interests: The authors declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2021.)

Background: The shoulder joint has a wide range of motion, but is vulnerable to sport-related injuries. We aimed to evaluate the differences in the proprioception of the shoulder should instability, and shoulder pain in high school baseball players with shoulder instability following a 12-week rehabilitation exercise program., Methods: We enrolled 13 baseball players with shoulder instability who visited the Orthopedics Department at Konkook University Hospital in Seoul, South Korea and 12 controls without shoulder instability. We examined the dominant shoulder and the non-dominant shoulder for both groups. We restricted participation to individuals who had no other orthomechanical disease in the past six months, except for instability of the shoulder, and no physical limitation to participate in the exercise. We measured the proprioception of the shoulder and shoulder instability, and we also evaluated pain with the Visual Analog Scale before and after the rehabilitation program. To verify the differences between groups, we used a two-way analysis of variance, and a two-way analysis of covariance was used when a significant difference was found at the pretest (baseline between groups)., Results: Proprioception was associated with shoulder instability. The Visual Analog Scale rating improved in the dominant shoulder with instability; and a positive change was found in the dominant shoulder without instability after the rehabilitation program ( P < 0.05)., Conclusion: The 12-week rehabilitation exercise program might improve the proprioception and pain of patients with shoulder instability. However, further studies with more participants and a rehabilitation exercise program should be undertaken., Competing Interests: Conflict of interest The authors declare that there is no conflict of interests., (Copyright© Iranian Public Health Association & Tehran University of Medical Sciences.)

Background: Limitations of shoulder range of motion (ROM) have been reported to be at high risk for shoulder disorders in baseball players. In this study, we assessed posterior shoulder muscle stiffness using shear wave elastography in baseball players with and without posterior shoulder tightness., Materials and Methods: In total, 21 college baseball players volunteered to participate in this study. Passive ROMs for shoulder abduction and horizontal adduction were measured using a goniometer. Subsequently, we divided all participants into 2 groups based on the differences between bilateral shoulder ROMs: STIFF+ and STIFF- groups. Thickness and elasticity of the posterior and inferior shoulder muscles were assessed using ultrasound., Results: Shoulder abduction ROM on the throwing side was 114.5° ± 5.3° and 131.3° ± 5.7° in the STIFF+ and STIFF- groups, respectively, which was significantly different between the 2 groups (P = .023). Horizontal adduction ROM on the throwing side was 96.6° ± 4.9° and 110.9° ± 4.8° in the STIFF+ and STIFF- groups, respectively, which was also significantly different between the 2 groups (P = .014). The elasticity of infraspinatus and lower trapezius in the STIFF+ group was significantly greater than that in the STIFF- group (P = .018 and .033, respectively)., Discussion: In this study, we found that the elasticity of infraspinatus and lower trapezius in stiff shoulders was significantly greater than that in nonstiff shoulders, which indicated that the infraspinatus and lower trapezius could be the key muscles in posterior shoulder tightness., (Copyright © 2019. Published by Elsevier Inc.)

Purpose of Review: With an increase in single-sport specialization, elbow injuries have become increasingly common in the pediatric and adolescent population. Osteochondritis dissecans (OCD) of the capitellum frequently requires intervention yet can be difficult to treat given high patient activity demands. The purpose of this paper is to review treatment options, understand failure rates, and provide strategies for successful revision surgery., Recent Findings: Patients at high risk for the development of this condition are involved in high-demand upper extremity activity such as baseball or gymnastics. Treatment options include non-operative management, drilling, fixation, loose body removal/microfracture, osteochondral autograft, and osteochondral allograft. Cartilage preservation procedures (i.e., osteochondral autograft) have a significant advantage in terms of clinical and radiographic healing compared with fixation or microfracture. Capitellar OCD lesions afflict a large number of adolescent athletes today and will likely continue increasing in number from sports-related injuries. It is critical to recognize and treat these lesions in a timely and appropriate fashion to optimize clinical outcomes. When faced with failure of healing, surgeons must critically analyze reasons for failure including post-operative compliance, return to high-demand sporting activity, fixation of non-viable fragments, utilization of microfracture, alignment, and concomitant pathology.

Background: Numerous studies have shown that baseball players develop range of motion adaptations in their throwing arm. While some of these shoulder range of motion adaptations can lead to greater throwing velocity, excessive changes in shoulder range of motion can increase the risk of injury to the ulnar collateral ligament (UCL)., Purpose/hypotheses: The purpose of this study was to compare the passive GH-ABD ROM measures of baseball players with a diagnosed UCL tear (UCL group) to a group of age, activity, and position matched healthy controls (CONT group). The primary hypothesis was that baseball players with an UCL tear would have a greater loss of passive glenohumeral abduction range of motion in their throwing shoulder than healthy controls. A secondary hypothesis was that baseball players with an UCL tear would demonstrate similar glenohumeral abduction range of motion in their non-throwing arm and increased side-to-side glenohumeral abduction differences compared to the healthy cohort., Study Design: Retrospective prospective case-control study., Results: The UCL group had significantly greater glenohumeral abduction range of motion on their throwing shoulder (132.5 °±8.3 °) than the CONT group (120.19 °±11.2 °, p = 0.000). Similarly, the UCL group had increased glenohumeral abduction range of motion on their non-throwing shoulder (141.2 °±9.5 °) compared to the CONT group (124.1 °±11.4 °, p = 0.000). Additionally, the UCL group had a greater glenohumeral abduction difference (-8.7 °±8.4 °) than the CONT group (-3.8 °±7.7 °, p = 0.001)., Conclusion: In contrast to the original hypotheses, high school and collegiate baseball players that sustained an UCL injury presented with greater glenohumeral abduction range of motion in both their throwing and non-throwing shoulders compared to healthy controls. However, the finding of greater side-to-side glenohumeral abduction range of motion deficits in the UCL group when compared to the matched healthy controls confirms the secondary hypothesis., Level of Evidence: Level 3., (© 2019 by the Sports Physical Therapy Section.)

Purpose of the Review: To review the most recent literature on osteochondritis dissecans (OCD) lesions of the capitellum in overhead athletes and describe a treatment algorithm based on current best evidence and surgeon experience., Recent Findings: Recent research has included larger cohort studies with longer follow-up as well as quality systematic reviews and meta-analyses. These studies have focused on understanding how lesion characteristics such as size, location, and appearance on advanced imaging can predict treatment success. Current literature continues to support nonoperative management for stable lesions. Operative intervention is generally required for unstable lesions and treatment strategies are largely dictated by lesion size and location: debridement or reparative techniques for small lesions while larger lesions or those in high-stress locations are better served by bone and/or cartilage restoration procedures. There has been a rising interest in the use of allograft materials and cell-based therapies. Overhead athletes are uniquely predisposed to capitellar OCD due to the nature of forces applied to the radiocapitellar joint during repeated activity in the overhead position. Despite improvements in operative techniques, successful use of alternative graft materials, and a better understanding of how lesion characteristics influence results, there is still much to learn about this challenging disorder. Future research should focus on comparing operative techniques, refining their indications, and further developing a reliable treatment algorithm that best serves the overhead athlete.

We aimed to investigate the structural neuroplasticity associated with different levels of sports experience and its effect on the corresponding resting-state functional circuitry. We recruited 18 skilled baseball batters (SB), 19 intermediate baseball batters (IB), and 17 healthy controls (HC), and used magnetic resonance imaging methods to compare their regional gray-matter volume (GMV) and seed-based resting-state functional connectivity (rsFC). Our results revealed that a quadratic function could better depict intergroup differences in regional GMV than a linear function. In particular, the IB showed lower or higher regional GMV than the other two groups. The difference in GMV in the supplementary motor area and areas belonging to the ventral stream, including the middle temporal gyrus and middle temporal pole, might be possibly related to baseball-specific motor and perceptual experience, such as inhibitory action control and pitch identification. On the other hand, the stronger rsFC seeded from the right middle temporal pole to the default mode network, particularly in the precuneus, in the SB and IB relative to that in the HC might be possibly associated with the theory of mind, such as deciding whether to swing or not against the pitcher by detecting the spatial information of pitches. In conclusion, our three-group design enabled the capture of the unique and transient changes that occur during the intermediate phase of expertise development. Our findings indicated that structural and functional brain changes do not necessarily linearly increase as a function of experience as previously suggested by the literature., (© 2018 Wiley Periodicals, Inc.)

Background: The diagnosis and treatment of Superior Labrum Anterior to Posterior (SLAP) tears have been evolving and controversial. The lack of clear diagnostic criteria on physical examination, Magnetic Resonance Imaging (MRI), and arthroscopic evaluation clouds the issue. The high rate of MRI diagnosed SLAP lesions in the asymptomatic population of athletes and non-athletes warrants consideration when planning treatment for those with shoulder pain., Objective: To provide information on the evaluation, diagnosis and management of SLAP tears in athletes., Methods: The results of a structured non-operative rehabilitation program are discussed and compared to traditional surgical techniques. The evolution of the author's treatment algorithm is presented. Results: The successful return to overhand throwing is more common with non-operative treatment than with surgical., Conclusion: A rehabilitation program focused on stretching the posterior capsule and correcting scapular posture is more successful than surgery for most throwers with SLAP lesions.

Background: Osteochondritis dissecans (OCD) lesions are often observed in the humeral capitellum both in young baseball players and gymnasts. It is generally believed that capitellar OCD in baseball players can be seen on an anteroposterior (AP) radiograph with the elbow in 45° of flexion. However, the mechanism of injury seems to be different in baseball players and gymnasts. Repetitive valgus overload with the elbow in flexion is believed to be the cause of capitellar OCD lesions in baseball players, whereas weightbearing with the elbow in extension may be the cause of OCD in gymnasts., Purpose: To determine the difference in capitellar OCD location between baseball players and gymnasts and to propose the optimal AP radiographic angle of the elbow for visualization of early-stage OCD lesions in adolescent gymnasts., Study Design: Cross-sectional study; Level of evidence, 3., Methods: Subjects consisted of 95 baseball players (95 elbows) and 21 gymnasts (24 elbows) with a mean age of 13.7 years (range, 11-18 years). To localize the lesion, inclination of the affected area in the humeral capitellum against the humeral axis was investigated using sagittal computed tomography images of the elbow. The inclination angle was defined as the angle between the long axis of the humerus and the line perpendicular to a line that connected the anterior and posterior margin of the lesion. The inclination angle in each group was compared and statistically analyzed., Results: The mean inclination angle was 57.6° ± 10.7° in baseball players and 28.0° ± 10.7° in gymnasts. Capitellar OCD lesions were located more anterior in baseball players when compared with gymnasts ( P < .01)., Conclusion: Due to differences in applied stress, capitellar OCD lesions in baseball players were located more anteriorly compared with those seen in gymnasts. Therefore, although AP radiographs with the elbow in 45° of flexion are optimal for detecting OCD lesions in baseball players, radiographs with less elbow flexion or full extension are more useful in gymnasts, especially in early-stage OCD., Competing Interests: The authors declared that they have no potential conflicts of interest in the authorship and publication of this contribution.

Background: The characteristics of scapular muscle activities in elevation and descent exercises have yet to be elucidated to assess scapular dyskinesis. The purpose of this study was to identify the adaptation of electromyograph (EMG) activities of the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and anterior deltoid (AD) muscles with different weight loads in flexion (FLX) and abduction (ABD) in collegiate baseball players., Materials and Methods: Twenty eight individuals, including 13 pitchers, were tested. Normalized EMG signals for the UT, LT, SA, AD muscle of the both the dominant (DOM) and nondominant (NON) side were blocked at every 1 second during each of the exercises. A 3-way repeated analysis of variance design was used to identify differences in the mean values between DOM and NON and between FLX and ABD for DOM., Results: The mean EMG value of the UT in the DOM was significantly less than that of the NON for all joint angles (P < .01), whereas the mean EMG value of the LT in the DOM was significantly greater than that of the NON (P < .01). In contrast, no difference in the SA EMG activity was determined between DOM and NON. However, the mean EMG value of SA in FLX was significantly greater than in ABD (P < .01)., Conclusion: This study identified an apparent adaptation of scapular muscle activities in the currently advocated scapular dyskinesis test for healthy active overhead athletes who are vulnerable to shoulder pathologies., (Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Hypothesis and Background: Humeral retroversion is defined as the orientation of the humeral head relative to the distal humerus. Because none of the previous methods used to measure humeral retroversion strictly follow this definition, values obtained by these techniques vary and may be biased by morphologic variations of the humerus. The purpose of this study was 2-fold: to validate a method to define the axis of the distal humerus with a virtual cylinder and to establish the reliability of 3-dimensional (3D) measurement of humeral retroversion by this cylinder fitting method., Methods: Humeral retroversion in 14 baseball players (28 humeri) was measured by the 3D cylinder fitting method. The root mean square error was calculated to compare values obtained by a single tester and by 2 different testers using the embedded coordinate system. To establish the reliability, intraclass correlation coefficient (ICC) and precision (standard error of measurement [SEM]) were calculated., Results: The root mean square errors for the humeral coordinate system were <1.0 mm/1.0° for comparison of all translations/rotations obtained by a single tester and <1.0 mm/2.0° for comparison obtained by 2 different testers. Assessment of reliability and precision of the 3D measurement of retroversion yielded an intratester ICC of 0.99 (SEM, 1.0°) and intertester ICC of 0.96 (SEM, 2.8°)., Discussion and Conclusion: The error in measurements obtained by a distal humerus cylinder fitting method was small enough not to affect retroversion measurement. The 3D measurement of retroversion by this method provides excellent intratester and intertester reliability., (Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Several studies have reported the clinical outcomes of medial ulnar collateral ligament (MUCL) reconstruction of the elbow joint in throwing athletes, including the rate of return to sports. However, little has been known about the imaging outcomes after MUCL reconstruction. The aim of this study is to report the clinical and imaging outcomes after MUCL reconstruction using figure of eight fashion in the elite and professional baseball players., Methods: This study included 17 baseball players, who underwent MUCL reconstruction between July 2007 and May 2010. The average follow-up period was 48.6 months. Imaging assessment consisted of preoperative plain and stress radiographs, magnetic resonance imaging, and postoperative serial ultrasonography. The clinical assessments were composed of visual analogue scale (VAS) for pain, range of motion, and the Conway scale., Results: The mean VAS score was 6.4 (range, 3 to 8) preoperatively and 2.2 (range, 0 to 4) postoperatively (p < 0.05). There were nine players (53%) classified as excellent who returned to sports at the same or higher level compared to preinjury. Serial ultrasonography revealed well-maintained grafts at 3 and 12 months in all of the players. Five out of 17 players showed decreased echogenecity in the common flexor tendon at 3 months, which was considered as remaining tissue swelling and resolved completely at 12 months., Conclusions: All grafts are well-maintained until 12-months based on the ultrasonographic findings, although only 53% of the players returned to preinjury level.