Doi Orthopaedic Clinic, Takatsuki, Osaka, Japan.
Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
Am J Sports Med. 2019 Nov;47(13):3100-3106. doi: 10.1177/0363546519876060. Epub 2019 Oct 4.
The increased humeral retroversion on the dominant side of throwing athletes is thought to result from repetitive throwing motion. Little Leaguer's shoulder-a rotational stress fracture of the proximal humeral epiphyseal plate-may influence the risk of humeral retroversion and injury of the shoulder or elbow joint.
To investigate the effect of Little Leaguer's shoulder on humeral retroversion and the rates of shoulder and elbow injuries.
Cohort study; Level of evidence, 3.
10 high school baseball players (average age, 16.6 years; range, 16-18 years) who had experienced Little Leaguer's shoulder during elementary or junior high school (average age, 12.6 years; range, 11-15 years) were enrolled in the study. As a control group, 22 high school baseball players (average age, 16.9 years; range, 16-18 years) who had never had any shoulder or elbow injury during elementary and junior high school were included. Humeral retroversion on ultrasonographic measurement, shoulder range of motion, and rates of shoulder and elbow injuries were evaluated.
Humeral retroversion was significantly greater on the dominant side than on the nondominant side in both players with Little Leaguer's shoulder (dominant, 104°± 8°; nondominant, 84°± 12°; < .001) and controls (dominant, 91°± 13°; nondominant, 81°± 10°; < .001). In the dominant shoulder, humeral retroversion was greater in the Little Leaguer's shoulder group than in the control group ( = .008). When the effects of humeral retroversion were excluded, maximal external rotation was significantly less in the dominant shoulder than in the nondominant shoulder in the Little Leaguer's shoulder group (by 11°± 12°, = .02), whereas no significant difference was found between dominant (110°± 11°) and nondominant (111°± 13°) shoulders in the control group ( = .64). The rates of shoulder and elbow pain were significantly higher in the Little Leaguer's shoulder group (shoulder pain 80%, elbow pain 70%) than in the control group (shoulder pain 9%, < .001; elbow pain 32%, = .04).
Humeral retroversion was increased in baseball players without any history of shoulder or elbow injury during elementary and junior high school and was further increased in players who had had Little Leaguer's shoulder. Increased humeral retroversion after Little Leaguer's shoulder may be a risk factor for future shoulder or elbow injury.
投掷运动员惯用侧肱骨后倾增加被认为是由于重复性投掷运动所致。Little Leaguer 肩——肱骨近端骺板旋转性应力骨折——可能会影响肱骨后倾的风险以及肩部或肘部关节的损伤。
探讨 Little Leaguer 肩对肱骨后倾的影响以及肩部和肘部损伤的发生率。
队列研究；证据水平，3 级。
纳入 10 名高中棒球运动员（平均年龄 16.6 岁；范围，16-18 岁），他们在小学或初中时经历过 Little Leaguer 肩（平均年龄 12.6 岁；范围，11-15 岁）。作为对照组，纳入 22 名高中棒球运动员（平均年龄 16.9 岁；范围，16-18 岁），他们在小学和初中期间从未有过任何肩部或肘部损伤。评估肱骨后倾在超声测量、肩部活动范围以及肩部和肘部损伤的发生率。
Little Leaguer 肩患者（优势侧 104°±8°；非优势侧 84°±12°；<.001）和对照组（优势侧 91°±13°；非优势侧 81°±10°；<.001）的优势侧肱骨后倾明显大于非优势侧。在优势侧，Little Leaguer 肩组的肱骨后倾大于对照组（=.008）。当排除肱骨后倾的影响时，Little Leaguer 肩组的优势侧外旋明显小于非优势侧（11°±12°，=.02），而对照组的优势侧（110°±11°）和非优势侧（111°±13°）之间无显著差异（=.64）。Little Leaguer 肩组肩部和肘部疼痛的发生率明显高于对照组（肩部疼痛 80%，肘部疼痛 70%）（<.001；肘部疼痛 32%，=.04）。
在小学和初中期间没有任何肩部或肘部损伤史的棒球运动员中，肱骨后倾增加，而经历过 Little Leaguer 肩的运动员中，肱骨后倾进一步增加。Little Leaguer 肩后肱骨后倾增加可能是未来肩部或肘部损伤的危险因素。
