Background: Throwing-related shoulder and elbow injuries are common among collegiate baseball pitchers; however, prospective evidence on scapulothoracic (ST) joint function as a risk factor is limited. This study prospectively investigated whether ST joint stability was associated with throwing-related injuries. Methods: Twenty-seven collegiate pitchers were prospectively categorized into injury and noninjury groups during the 12-month follow-up. Scapular and trunk positional coordinates were recorded using a 3D scanner during preseason screening under 2 conditions: (1) 90° scapularplane abduction with the elbow flexed and palm on the head (elevation trial) and (2) the same position with manual resistance applied to the distal forearm (resistance trial). ST joint Euler angles were calculated, and ΔST angles between trials were derived to quantify scapular stability, with larger ΔST joint angle along X-axis values indicating excessive upward rotation during the resistance trial. Time-to-event analysis using Cox proportional hazards regression was performed with ΔST and age as predictors. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated. Results: A greater ΔST joint angle along X-axis was significantly associated with increased injury hazard; each 1° increase corresponded to a 34% higher risk (HR = 1.34, 95% CI: 1.04-1.72, P = .02). Age was also a significant predictor (HR = 3.60, 95% CI: 1.33-9.74, P = .01). Conclusion: Excessive scapular upward rotation during a throwing resistance posture, quantified by the ΔST joint angle along X-axis, was significantly associated with an increased risk of throwing-related shoulder and elbow injuries in collegiate pitchers.

Comparative data on markerless motion capture systems for upper-extremity kinematics during high-speed movements remain limited. We aimed to examine inter-system modelling differences in shoulder joint kinematics between a markerless motion capture system (Theia3D) and a marker-based system during baseball pitching, focusing on a wide range of shoulder joint motion throughout baseball pitching. Six collegiate pitchers completed 117 trials recorded simultaneously by both systems. Shoulder joint angles and joint centre positions were compared using nested Bland-Altman analysis, intraclass correlation coefficients (ICC (3,1)), and statistical parametric mapping (SPM). At maximum external rotation (MER), inter-system differences were small for external rotation (bias: -0.3°; ICC = 0.77), whereas the horizontal angle demonstrated a pronounced fixed bias (bias: -19.1°). At ball release (BR), inter-system differences increased across all joint angles, with the largest discrepancy for external rotation (bias: -8.5°; ICC = 0.33). Proportional bias was evident for most variables at BR. Between-participant variance exceeded within-participant variance at MER, indicating that participant-specific offsets were primary contributors to the limits of agreement. SPM identified significant inter-system differences during the acceleration phase. These findings highlight the importance of understanding the characteristics of each modelling approach for appropriate interpretation and application of markerless motion capture in overhead athletes.

Abstract Shoulder dislocations frequently occur during rugby tackles, often associated with hazardous "arm tackle" techniques. Although pre-tackle footwork has traditionally been emphasized, its dynamic influence on shoulder kinematics remains poorly understood. This study aimed to analyze how the pre-tackle sidestepping influences the temporal evolution of trunk and shoulder joint kinematics using markerless motion capture and Statistical Parametric Mapping (SPM). Fifty-one collegiate rugby players performed right shoulder tackles against a static bag. The trials were categorized into Normal (ipsilateral step, n=28) and Opposite-leg (contralateral step, n=23) groups. An 8-camera markerless motion capture system (250 Hz) and Theia3D software were used to estimate the 3D kinematics. SPM was used to compare the continuous trajectories of the trunk and shoulder from the two steps before impact. SPM identified a significant cluster (30.4%–100% of the movement cycle) where the Opposite-leg group exhibited greater trunk lateral flexion away from the target (p<0.05). Discrete analysis showed that the Opposite-leg group had a significantly larger total shoulder horizontal range of motion compared to the Normal group (45.1±23.7° vs. 31.9±18.8°, p=0.030). No significant differences were observed in the shoulder angles, specifically at the moment of impact. Stepping with the contralateral foot initiates a "failed kinetic chain" characterized by early-onset trunk collapse. This postural deviation increases the distance from the target, forcing athletes to perform a wider compensatory arm sweep to ensure contact. These findings suggest that injury prevention should prioritize pre-tackle footwork instructions to maintain trunk alignment and prevent high-risk reaching motions.

BACKGROUND:Frozen shoulder (FS) is a common condition characterized by pain and restricted range of motion (ROM); however, its definition varies widely across randomized controlled trials (RCTs). This variability in eligibility criteria may compromise comparability across studies and hinder evidence synthesis. In this scoping review, we aimed to systematically map how FS has been defined in RCTs and identify key elements requiring standardization. METHODS:We searched the CENTRAL, MEDLINE, and Embase databases from their inception to December 2024. RCTs involving adults with FS or adhesive capsulitis were included. Two independent reviewer pairs screened the studies based on eligibility criteria. We extracted data from the included studies and categorized them into 5 domains based on definitional components, including age-related criteria, pain characteristics, ROM limitations, symptom duration, and imaging requirements. Reporting patterns were summarized descriptively and visualized using frequency plots and heat maps. This scoping review was performed in accordance with the Extended Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement for Scoping Reviews. RESULTS:Of 4,426 records identified, 310 RCTs were included. Use of terminology was inconsistent across studies, with 57.7% employing the term "adhesive capsulitis" and 42.3% using "frozen shoulder." Across domains, age-related criteria showed the greatest convergence; most trials targeted middle-aged adults, typically setting a lower age limit of approximately 40 years and an upper limit between 60 and 70 years. Conversely, the pain criterion was poorly aligned; nearly half of the studies omitted pain thresholds, and those that used diverse visual analog scale/numerical rating scale cutoffs infrequently specified night pain and functional disturbances. For ROM, most studies required loss in at least 2 or 3 planes (commonly flexion, abduction, and external rotation); however, quantitative cutoffs and movement combinations varied, and many trials provided ambiguous thresholds. Symptom duration was unreported in approximately 40% of RCTs; among those that reported it, a minimum duration of ≥3 months was the most common, but it was not universal. Similarly, imaging requirements were inconsistent; plain radiographs were the most frequently used modality, with magnetic resonance imaging and ultrasound used in a minority of trials, and >60% of the studies did not cite reference literature to justify their diagnostic criteria. CONCLUSION:The definition of FS in RCTs differs substantially across diagnostic domains, which may affect the comparability of study populations and the interpretation of treatment outcomes. The development of standardized, clearly described eligibility criteria, particularly regarding terminology, disease stage, pain and ROM criteria, symptom duration, and exclusion of other shoulder pathologies, will help strengthen methodological rigor and improve the interpretability of future clinical trials.

OBJECTIVE:This study aimed to examine the characteristics and clinical outcomes of high-level athletes with acute lumbar spondylolysis (ALS) treated with a progressive rehabilitation (PR) approach without rigid bracing or activity restriction. METHODS:This retrospective consecutive case series included seven high school or collegiate athletes competing at the national level who underwent a PR approach for ALS at our institution between January 2023 and December 2024. One athlete was excluded due to loss to follow-up, leaving six athletes for analysis. The intervention consisted of a PR program without rigid bracing or activity restriction, emphasizing stepwise mobility, stability, strengthening, and pain-based progression of functional movements. Main outcomes included MRI findings, pain status, return-to-sport (RTS) rate and period, and follow-up duration. RESULTS:Traumatic episodes were the most common etiological factor (66.7%), involving high ground reaction force movements or excessive lateral bending. MRI improvement was observed in five patients (83.3%), and pain resolution occurred in all six patients (100%). The RTS rate was 100%, with a median RTS period of 65 days (range, 54-112), which was shorter than previously reported for conservative treatment. No recurrence occurred during follow-up (median, 109 days). CONCLUSIONS:A PR approach without rigid bracing or activity restriction enabled early RTS in high-level athletes with ALS, with symptom improvement and no recurrence. This approach may allow modification of pain-provoking or injury-related movements and help minimize declines in physical fitness and body composition associated with activity restriction. It may be suitable for post-growth high-level athletes who understand the risks related to bone healing and require timely RTS, although further research is needed to clarify stage-specific indications and long-term outcomes.

Background: The posterosuperior humeral head contacts the glenoid during pitching. While magnetic resonance imaging often detects abnormalities in the posterosuperior humeral head of baseball pitchers, ultrasonography may also be effective in identifying these abnormalities. However, studies on such abnormalities in asymptomatic players are limited. Thus, this study aimed to determine the prevalence of abnormal findings in the humeral head using ultrasonography in asymptomatic collegiate baseball pitchers. Methods: We utilized ultrasonography to assess abnormal findings in the humeral head, defined as a break in continuity or an irregular surface around the infraspinatus insertion, in 33 college baseball pitchers (pitcher group) and 30 college students without experience in overhead sports (control group). For 11 of the 33 pitchers, computed tomography-like images were used to locate the abnormalities. The location was quantitatively identified in the axial plane using a clock system, with the bicipital groove designated as 12 o'clock, and qualitatively assessed in the sagittal plane. Shoulder internal and external rotation ranges of motion (IR and ER ROMs) and humeral retroversion were measured using an inclinometer. The prevalence of abnormalities among the 4 subgroups (throwing and nonthrowing shoulders of the pitcher group and dominant and nondominant shoulders of the control group) was compared using the Fisher's exact test. A paired t-test was also performed to compare the IR and ER ROMs, as well as the humeral retroversion between each group's throwing (dominant) and nonthrowing (nondominant) sides. Results: The prevalence of abnormalities was significantly higher (76%) in the throwing shoulder of the pitcher group than in the other shoulder groups (<.001). The mean position of the humeral head abnormalities in the axial plane was 8:32 +/- 0:21 in the clock system, with all abnormalities located at the infraspinatus insertion on the greater tuberosity in the sagittal plane according to CT-like image analysis. While ER ROM and humeral retroversion were greater in the throwing shoulder, IR ROM was less than that in the non- throwing shoulder in the pitcher group (<.001). Conclusion: Ultrasonographic assessments revealed a higher prevalence of abnormalities in humeral head for asymptomatic collegiate baseball pitchers. Repetitive throwing motions may lead not only to adaptations in the ROM of the shoulder joint but also to abnormalities in the humeral head. Thus, ultrasonography may help identify asymptomatic baseball players with physiological internal impingement. Level of evidence: Level III; Cross-Sectional Design; Epidemiology Study (c) 2024 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

BACKGROUND:Dysfunctional features of distal ulnar collateral ligament (UCL) tears remain unclear. We aimed to clarify the characteristics of valgus and rotational alignment of the ulnohumeral joint at rest in distal UCL tears compared with those in proximal tears. METHODS:The participants were baseball and softball players diagnosed with UCL tears, classified as proximal, middle, or distal. Valgus and rotation alignment of ulnohumeral joint were measured using computed tomography-like images and a 3-dimensional image analysis system. For valgus alignment, the medial joint space was measured as the distance between the medial epicondyle and the ulnar coronoid processes. For rotational alignment, the medial distance (MD) and lateral distance (LD) of the ulnohumeral joint were measured in the reconstructed axial views at the medial epicondyle and trochlear levels. MD was measured as the distance between the medial edges of the olecranon fossa and trochlear notch, whereas LD was measured as the distance between the lateral edges of the olecranon fossa and trochlear notch. RESULTS:Of the 20 included cases, 6 (30%) were distal and 14 (70%) were proximal UCL tears. The medial joint space results showed no significant difference between the 2 groups. The MD was significantly higher in the distal tear than the proximal tear only at the trochlea level. The LD showed no significant difference at either level. CONCLUSION:Distal tears did not show hypervalgus malalignment compared to proximal tears using conventional measurements. In contrast, distal tears showed hyperinternal rotation malalignment of the ulnohumeral joint only at the distal side of the joint compared to proximal tears.

Background: Risk factors for throwing injuries related to pitching mechanics are unknown. Insufficient pelvic rotation during pitching may be a risk factor for shoulder and elbow injury. This cohort study aimed to identify biomechanics risk factors for throwing injuries in young baseball players. We hypothesized that excessive mechanical load and motion errors would be risk factors for throwing injuries. Methods: Young baseball pitchers (aged 8-9 years) were recruited from regional baseball leagues between December 2016 and December 2019. Pitching measurements were performed before the start of each season and after the end of the last season in December 2019. The trunk tilt angular displacement, pelvic rotation angular displacement, and forearm rotation angle were calculated using a markerless motion capture system. We also measured elbow varus torque using an accelerometer. After the initial test session, each participant was followed up for 3 years to determine the occurrence of throwing injuries. Players with throwing shoulder and elbow injuries were categorized into the throwing injury group, and those without shoulder and elbow pain for 3 years were categorized into the noninjured group. Results: In this study, 97 baseball pitchers completed a 3-year follow-up. Among those participants, 66 (68.0%) had throwing injuries. A significant difference was observed between the throwing injury and noninjured groups, whereby the injured players had less pelvic rotation angular displacement. Conclusion: Insufficient pelvic rotation during pitching is a newly discovered risk factor related to throwing injuries. Level of evidence: Level I; Prospective Cohort Design; Prognosis Study (c) 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

[Purpose] The purpose of this study was to clarify the characteristics of posture control of young patients with low back pain (LBP) in unstable sitting and standing. [Participants and Methods] The subjects were 46 young patients with non-specific LBP and 47 healthy university students. Each subject performed the sitting and standing tasks on unstable surfaces with a balance cushion. The total locus length (LNG), outer peripheral area (ENV. AREA), and length per unit area (LNG/ENV.AREA) of the center of pressure were measured using a stabilometer. [Results] In the sitting position, LNG and ENV. AREA were significantly greater and LNG/ENV.AREA was significantly smaller in the LBP group than in the healthy group. In the standing position, there was no significant difference between the two groups in any parameter. [Conclusion] The results suggest that the patients with LBP had decreased postural control function of the trunk.

[Purpose] The purpose of this study was to identify the characteristics of injuries that occur while playing volleyball, based on the positions of the players, to help with their prevention. [Subjects and Methods] We searched players’ electronic medical records, counted the number of diagnoses, and surveyed a total of 290 players’ (638 injuries). We classified the positions into three categories, spiker, setter, and receiver, and analyzed the injuries. [Results] The incidence rates of knee and ankle joint injuries were high for spikers and setters, and the incidence rate of low back injuries was high for spikers and receivers. The incidence rate of foot injuries was high for receivers. [Conclusion] The results suggest that to prevent injuries, we should consider the characteristics of injuries that occur while playing volleyball based on the positions of the players.

The purpose of this study was to identify a gender-specific pattern of volleyball injuries. We surveyed a total of 469 patients (1046 injuries). We divided injuries into seven parts, shoulder, low back, knee, lower leg, ankle, foot, and others. There were significant differences in disease-specific injury incidence of foot, low back, shoulder, lower leg (P <0.01). The incidence of metatarsal stress fracture was found to be higher in women, whereas myofascial low back pain was common in both men and women. However, the incidence of discogenic low back pain was higher in men. Further, the incidence of shoulder impingement syndrome was higher in men, whereas that of loose shoulder was higher in women. The incidence of shin splints was found to be higher in women. The injuries occurred in the foot, low back, shoulder, lower leg was found to differ between men and women who play volleyball. Therefore, instructions given to volleyball players during conditioning should take gender differences into consideration.

〔目的〕バレーボールのポジションによる傷害発生の特徴を明らかにし,傷害予防やコンディショニング指導の一助とすることを目的とした.〔対象と方法〕対象は30歳未満の女性バレーボール競技者290人638件とした.電子カルテ上から検索し,診断名の件数をカウントした.それらをスパイカー,セッター,レシーバーの3つのポジションに分類し分析した.〔結果〕スパイカーとセッターでは膝関節と足関節の割合が高かった.また,スパイカーとレシーバーでは腰部の割合が高かった.レシーバーでは足部の割合が高かった.疾患もポジションで異なっており,ポジションにより特徴がみられた.〔結語〕傷害予防やコンディショニング指導の際には,ポジションによる傷害発生の特徴を考慮する必要性が示唆された.

〔目的〕我々が考案したSingle Leg Up Downテスト（以下SLUDテスト）と体重支持指数（以下WBI）の関連について検討すること．〔対象と方法〕中学野球選手202名にSLUDテストおよびWBI（等尺性最大膝伸展筋力を体重で除した値）を測定した．非投球側のSLUDテスト遂行可能な高さで群分けし，各群間のWBIをKruskal-Wallis検定，多重比較法を用いて比較した．〔結果〕SLUDテスト40 cm，30 cm，20 cm，10 cmのWBIの平均はそれぞれ0.79±0.18，0.87±0.20，1.00±0.19，1.04±0.24であり，40 cmと30 cmの各群に対して，20 cm，10 cmの各群が高値を示した．〔結語〕スポーツ選手に必要な筋力はWBI 1.0以上とされていることからも，20 cm台からのSLUDテスト遂行の可否が下肢筋力のスクリーニングテストとして有用であることが示された．

Recently, the problem of the high incidence of throwing injuries in young people has been gaining attention. Identifying high-risk players before the onset of the throwing injury is important for prevention. One of the most widely used screening tests for sports-related injuries is the Functional Movement Screen (FMS), which assesses the quality of movement; however, its correlation with throwing injuries has not been established. The purpose of this study was to investigate the correlation between the FMS score and throwing injuries. The FMS was used during the medical check for two hundred and thirty junior high school baseball players. We allotted those who had experienced throwing injuries multiple times to the injury group and those who had never experienced throwing injury to the control group. We then calculated the FMS cutoff value using the receiver operating characteristic curve. In addition, we investigated differences in the incidence of throwing injury between above and below the cutoff value using chi-square test. The FMS cutoff score was 17. Players who scored ≤17 had a significantly higher incidence of throwing injuries than those who scored ≥18. Conclusion: We believe that FMS score is correlated to throwing injuries. In addition, the results suggest that throwing injuries might be prevented in junior high school baseball players who scored ≤17 on the FMS if they undergo training in the correct movement patterns. Jpn J Phys Fitness Sports Med, 65(2): 237-242 (2016)