Background Shoulder and hip rotational range of motion (ROM) have been reported to be associated with throwing-related shoulder and elbow injuries in baseball players. However, there is a lack of studies reporting the normal shoulder and hip rotational ROM in elementary school baseball players. The purpose of this study was to report the normal shoulder and hip rotational ROM in elementary school male baseball players based on field position, grade of elementary school, and baseball experience. Methods A large database of annual medical check-ups conducted for elementary school baseball players between 2019 and 2023 were reviewed. Shoulder internal rotation (IR) angle, shoulder external rotation (ER) angle, total shoulder rotational ROM (shoulder ER + IR), hip IR angle, hip ER angle, and total hip rotational ROM (hip ER + IR) of the uninjured baseball players were evaluated. All ROM angles were measured using a standard goniometer. The shoulder and hip rotational ROM were compared by the bilateral sides (throwing vs. nonthrowing side), field position (pitchers vs. nonpitchers), grade of the elementary school (between third to sixth grades), and pitching or baseball experience. Results A total of 1210 healthy elementary male baseball players (pitchers/nonpitchers, 590/620) with a mean age of 10.0 ± 0.9 (range, 8-12) years were finally included in this study. There were significant differences in all shoulder rotational ROM between the throwing and nonthrowing sides in all baseball players (p < 0.001). There were significant differences in shoulder ER angle (107.1 ± 13.4° vs. 104.2 ± 14.4°, p < 0.001) and total shoulder rotational ROM (164.7 ± 21.5° vs. 161.7 ± 21.7°, p = 0.02) of the throwing side between the pitchers and nonpitchers. There were significant differences in shoulder IR angle (p = 0.04) and total shoulder rotational ROM (p = 0.04) of the throwing side by grade of elementary school in pitchers, although no significant differences were found in any shoulder ROM in nonpitchers. There were significant differences in bilateral hip IR angles according to elementary school grade, regardless of field position. Finally, no significant differences in shoulder or hip rotational ROM were detected according to pitching experience or baseball experience. Conclusion The present study reported normal shoulder and hip rotational ROM in elementary school male baseball players based on field position, elementary school grade, and pitching or baseball experience using a large sample size. The findings of this study will serve as a reference for evaluating shoulder and hip rotational ROM in elementary baseball players.
Ganglion cysts arising from the posterior cruciate ligament (PCL) of the knee are rare, and their aetiology remains unknown. In this case, we found a ganglion cyst of the PCL concomitant with osteochondritis dissecans (OCD) of the medial femoral condyle (MFC). We presume that unstable OCD fragments of the MFC repeatedly irritate the PCL fibres connected to the lesion, and that this repetitive minor trauma and subsequent continuous tissue reaction may account for the development of a ganglion cyst of the PCL. We thus performed arthroscopic excision of the ganglion cyst of the PCL and OCD lesion, and osteochondral autograft transplantation. No ganglion recurrence was observed on magnetic resonance imaging at 12 months postoperatively and no symptom recurrence was observed during the final follow-up at 24 months postoperatively. We thus speculate that the pathogenesis of ganglion cysts in the cruciate ligament involves repetitive minor trauma and a subsequent continuous tissue reaction.
Background Bony posterior ankle impingement syndrome (PAIS) is associated with posterior talar morphology, including os trigonum and Stieda's process. However, whether these anatomical variations independently contribute to PAIS development remains unclear. This study aimed to investigate the independent association between posterior talar morphology and bony PAIS development using a propensity score-matched cohort design. Methods This retrospective cohort study included 752 lateral ankle radiographs of patients aged 13–65 years between April 2018 and April 2021. Posterior talar morphology was classified as Group Ⅰ (os trigonum), Group II (isolated Stieda's process), Group III (large Stieda's process without separation from the talus), and Group IV (no posterior deformity). To control for confounding by age and sex, 1:4 propensity score matching was performed. The association between posterior talar morphology and bony PAIS was evaluated using conditional logistic regression adjusted for sports participation. Interrater reliability was assessed using Cohen's kappa coefficient. Results Eighteen bony PAIS cases were matched to 72 controls. Adequate balance was achieved for age and sex (SMD<0.1). Interrater reliability was substantial (kappa = 0.633, p < 0.001). Os trigonum and isolated Stieda's process (Groups I and II) were significantly associated with bony PAIS (OR = 10.49, 95% CI 2.76–39.81, p < 0.001). Sports participation was not independently associated with bony PAIS (OR = 1.18, 95% CI 0.13–10.73, p = 0.884). Conclusions Os trigonum and isolated Stieda's process were independently associated with an approximately 10-fold increased risk of bony PAIS, though these findings should be interpreted with caution given the limited number of cases. Patients with these morphological variants engaging in repetitive plantar flexion activities should be carefully monitored.
Introduction In open reduction and hook plate fixation for high-grade acromioclavicular (AC) joint dislocation, proper placement of the hook plate is crucial in preventing subacromial osteolysis and improving clinical outcomes. This study aimed to identify the optimal sagittal plane positioning of the hook plate to minimize subacromial stress and erosion. Materials and methods Six pairs of artificial bone models, designed to mimic human clavicle and scapula anatomy, were used to assess the biomechanical effects of three hook plate positions: anterior (group A), neutral (group N), and posterior (group P). Each model was equipped with a 5-hole clavicle hook plate secured with 3.5-mm locking screws. A pressure sensor measured contact pressures and areas under sagittal rotations. The clavicle and scapula were fixed in customized jigs, and physiological loading conditions were simulated with a preload of 20 N and a 70 N upward force on the clavicle. Clavicular rotations of 15° internal and external were applied to evaluate their effect on contact pressures. Results Group P showed a significantly lower mean pressure (1.27 MPa) than group A (1.92 MPa, p < 0.01) and group N (1.83 MPa, p < 0.01). Maximum pressure in group P (1.37 MPa) was also significantly lower than in group A (2.75 MPa, p < 0.01) and group N (2.34 MPa, p < 0.01). The contact area was smallest in group P (11.00 mm2) compared to group A (19.00 mm2, p < 0.01) and group N (17.00 mm2, p < 0.01). Clavicular rotations significantly increased subacromial pressure and contact area at all plate positions compared to the neutral position (p < 0.01). Conclusion Posterior position of the hook plate in the sagittal plane significantly reduced subacromial pressure and contact area compared to neutral or anterior positions. Additionally, internal and external rotations of the clavicle further increased subacromial stress, indicating the importance of considering clavicular movement in clinical settings. Within the biomechanical test, these findings suggest that posterior positioning of the hook plate may help attenuate subacromial stress and could thereby have the potential to reduce the likelihood of subacromial bone erosion; however, further clinical or finite-element validation is warranted before this can be translated into a clinical recommendation for the surgical treatment of high-grade AC joint dislocations.
Purpose Medial open-wedge high tibial osteotomy (OWHTO) is widely performed for medial compartment pathology associated with varus malalignment. Although OWHTO corrects static alignment, its influence on dynamic knee stability remains unclear. This study aimed to evaluate changes in coronal and sagittal dynamic stability after OWHTO using intraoperative stress fluoroscopic assessment. Methods Thirty-eight knees in 35 patients undergoing OWHTO were retrospectively reviewed. Coronal stability was assessed using dynamic joint line convergence angle (dJLCA) and dynamic femorotibial angle (dFTA), and sagittal stability was evaluated using anterior tibial translation relative to Blumensaat's line (ATB). Alignment parameters included femorotibial angle (FTA), medial proximal tibial angle (MPTA), and posterior tibial slope (PTS). Clinical outcomes were assessed using Lysholm, IKDC, and KOOS scores up to 12 months postoperatively. Pre- and postoperative differences were analyzed using the Wilcoxon signed-rank test, and correlations were evaluated using Spearman's rank correlation. Results All alignment and stability parameters significantly improved postoperatively (p < 0.001). dJLCA and ATB showed marked reductions, indicating decreased stress-induced coronal and sagittal instability. Clinical scores significantly improved at 12 months (p < 0.001). Greater preoperative instability was strongly correlated with greater postoperative stabilization (dJLCA ρ = 0.794; dFTA ρ = 0.765; ATB ρ = −0.765; PTS ρ = 0.530). Conclusions OWHTO improves coronal and sagittal dynamic stability under stress conditions. These findings suggest that dynamic instability in varus knees is largely caused by malalignment and can be improved by osteotomy. Stress fluoroscopic assessment may aid in identifying correctable instability and guiding surgical planning. Level of evidence IV
