Risk factors associated with throwing injuries in young baseball players.

BACKGROUND: Few studies have retrospectively analyzed the relationship between joint range of motion (ROM) and muscle flexibility and shoulder and elbow throwing injuries in a large number of elementary school baseball players. The purpose of this study was to retrospectively identify the physical factors related to shoulder and elbow throwing injuries in younger baseball players. METHODS: A total of 2466 younger baseball players belonging to our Prefecture Rubber Baseball Federation who participated in medical check-ups from 2016 to 2019 were analyzed. Players completed a questionnaire and had a medical check-up that included a physical examination and ultrasonography. ROM (internal rotation [IR] angle and external rotation angle) of the shoulder and hip and the finger-to-floor distance and heel-to-buttock distance were measured. The straight leg raise was also performed. The results of two groups (normal group and injury group) were compared using the χ2 test, Mann-Whitney U test, and Student t test. Stepwise forward logistic regression models were developed to identify risk factors. RESULTS: On univariate analysis, nine of the 13 evaluated items showed significant decreases in ROM and muscle flexibility in the injury group. On multiple logistic regression analysis, grade, finger-to-floor distance, IR angle of the dominant side shoulder, and IR angle of the nondominant side hip were significantly associated with the occurrence of throwing injuries. Decreased total shoulder angle was observed not only on the dominant side but also on the nondominant side in the injury group. CONCLUSION: Decreased ROM and muscle flexibility were risk factors for baseball-related throwing injuries in elementary school baseball players. To prevent shoulder and elbow throwing injuries, players, coaches, medical staff, and parents need to be aware of these findings.

Remnant-Preserved Single-Bundle Anterior Cruciate Ligament Augmentation in Multi-ligamentous Knee Reconstruction.

This study was conducted to present remnant-preserving anterior cruciate ligament (ACL) augmentation as a useful option for partial ACL injury in multiligament knee injury (MLKI) cases, which may also contribute to conserving graft resources. The present study involved patients diagnosed with MLKI at our institute from Spring 2006 to February 2021. A total of 71 MLKI cases were provided surgery due to knee instability and disability. For every patient, an arthroscopic diagnostic was performed to ensure that ACL tear and a remnant were present. When the ACL remnant was classified into group 2, 3, or 4 of Nakamae's classification, remnant-preserved single bundle ACL augmentation was performed. Graft selection and the combination of injured ligaments were evaluated. The side-to-side difference under an anterior tibial load of 134 N with an arthrometer and the leg symmetry index at 60 degrees/s were measured. The present procedure was performed for five cases (male/female: 4/1, mean age: 33.6 years). The mean follow-up period was 26.4 months. The combination of torn ligaments was as follows: 3 cases of ACL + medial collateral ligament, one case of ACL + posterior cruciate ligament, and one case of ACL + posterolateral corner. An ACL augmentation graft was performed using an ipsilateral gracilis tendon in 2 cases, a contralateral full semitendinosus tendon in 2 cases, and the ipsilateral distal 1/2 of the semitendinosus tendon in 1 case. The mean side-to-side difference was 1.07 ± 0.4 mm. The mean leg symmetry index was 82.6 ± 12.2% in knee extension and 96.3 ± 9.9% in knee flexion. Although the present study was a small case series, the remnant-preserved single-bundle ACL augmentation for MLKI surgery provided good clinical outcome and conserved the graft resource. Even in the MLKI case, this technique is one of the useful surgical options. The level of evidence of this study is level IV (case series).

Does the contralateral healthy ankle of patient with ipsilateral mechanical lateral ankle laxity show greater lateral ankle laxity? Evaluation of the anterior talofibular ligament by stress ultrasonography.

BACKGROUND: A number of studies have evaluated risk factors for lateral ankle sprain (LAS) or chronic lateral ankle instability (CLAI). However, the definitive risk factors for LAS or CLAI remain controversial. The purpose of this study was to evaluate whether the contralateral healthy ankles of subjects with ipsilateral mechanical lateral ankle laxity (group I) show greater lateral ankle laxity in comparison to the healthy ankles of bilateral healthy controls (group B). METHODS: From March 2020, anterior talofibular ligament (ATFL) lengths of young adult volunteers were cross-sectionally measured in non-stress and stress positions using a previously reported stress ultrasonography (US) procedure. The ATFL ratio (the ratio of stress ATFL/non-stress ATFL length) was calculated as an indicator of lateral ankle laxity. The manual anterior drawer test (ADT) was also performed. The US findings of healthy ankles from groups I and B were compared. RESULTS: A total of 154 subjects in group B (mean age, 24.5 ± 2.8 years; male/female, 84/70) and 40 subjects in group I (mean age, 24.4 ± 2.3 years; male/female, 26/14) were included in the study. There was no significant difference in the ADT between the groups. There were no significant differences in the non-stress ATFL length (19.4 ± 1.8 vs. 19.3 ± 1.9, p = 0.84), stress ATFL length (20.8 ± 1.8 vs. 20.9 ± 1.9, p = 0.66), length change (1.5 ± 0.6 vs. 1.6 ± 0.6, p = 0.12) and ATFL ratio (1.08 ± 0.03 vs. 1.08 ± 0.03, p = 0.13) between the groups. CONCLUSION: No significant difference was detected between the contralateral healthy ankles of subjects with ipsilateral mechanical lateral ankle laxity and those of bilateral healthy controls.

The Ratio of Stress to Nonstress Anterior Talofibular Ligament Length on Ultrasonography: Normative Values.

BACKGROUND: Stress ultrasonography (US) has been shown to be a valid procedure for evaluating chronic anterior talofibular ligament (ATFL) injury. The ratio of stress/nonstress ATFL length (ATFL ratio) as measured on US is clinically useful; however, there are no published normative data concerning this ratio. PURPOSE: To report a normative value of the ATFL ratio on US and evaluate the relationships between sex, generalized joint laxity (GJL), and the grade of anterior drawer test (ADT). STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: The ATFL lengths were prospectively measured in the stress and nonstress positions (manual maximal anterior drawer position) for participants with noninjured ankles from March 2020 to March 2021. GJL was defined as a Beighton score ≥4. A manual ADT was also performed. The ATFL ratio was calculated, and the relationships between sex, GJL, and ADT grade were evaluated. RESULTS: A total of 333 ankles in 184 participants (mean age, 24.5 ± 2.7 years; range, 20-33 years) were eligible for the analysis. GJL was found in 69 ankles (20.7%). The mean ATFL ratio was 1.08 ± 0.04 (95% CI, 1.08-1.09; range, 1.01-1.24), and there was a significant difference between male (1.07 ± 0.04; 95% CI, 1.07-1.08; range, 1.02-1.23) and female (1.09 ± 0.04; 95% CI, 1.08-1.10; range, 1.01-1.24) ankles (P = .001). In male ankles, the ATFL ratio was significantly greater in participants with GJL (1.11 ± 0.06 vs 1.07 ± 0.03; P = .02) or a higher grade of ADT (grade 2 vs grade 1: 1.11 ± 0.06 vs 1.07 ± 0.03, P = .002). These findings were not observed in female ankles. CONCLUSION: The normative value of the ATFL ratio on stress US was 1.07 ± 0.04 in men and 1.09 ± 0.04 in women. The ATFL ratio was affected by the presence of GJL in men but not in women. These findings will be useful for future studies seeking to establish the cutoff value of the ATFL ratio for diagnosing chronic lateral ankle stability on stress US.