Imaging Institute, Cleveland Clinic, 9500 Euclid Avenue, A21, Cleveland, OH 44195, USA.
Am J Sports Med. 2013 Sep;41(9):2015-21. doi: 10.1177/0363546513493249. Epub 2013 Jun 20.
High levels of humeral torsion allow baseball pitchers to achieve maximum external rotation in the late cocking phase of pitching with lower twisting and shear forces on the long head of the biceps tendon and rotator cuff tendons.
Humeral torsion is inversely related to the incidence and severity of shoulder injuries and other upper extremity injuries in professional baseball pitchers.
Case-control study; Level of evidence, 3.
A total of 25 professional pitchers from a single Major League Baseball organization were prospectively recruited into this study. Computed tomography (CT) was performed on dominant and nondominant humeri, and image data were processed with a 3-dimensional volume-rendering postprocessing program. The software program was then modified to model a simplified throwing motion and to measure potential internal impingement distances in a small subset of players. Players were followed for 2 years after CT, and the number of days missed from pitching activities was recorded as a measure of injury severity and incidence.
The mean dominant humeral torsion was 38.5° ± 8.9°; the mean nondominant humeral torsion was 27.6° ± 8.0°. The difference between dominant and nondominant torsions was significant (P < .0001). Among the 11 pitchers (44%) injured during follow-up, 5 players had shoulder injuries, 7 had elbow injuries, and 2 had finger injuries. Dominant humeral torsion was a statistically significant predictor of severe injuries (≥30 days; P = .048) but not of milder injuries. Among injured players, higher numbers of days missed because of injury were strongly correlated with lower degrees of dominant humeral torsion (r = -0.78; P = .005) and smaller differences between dominant and nondominant humeral torsions (r = -0.59; P = .055). There was no significant association between the incidence of shoulder injury and minimum glenoid-tuberosity distance in the dominant or nondominant shoulder or degree of dominant glenoid version.
A strong relationship was found between lower degrees of dominant humeral torsion and more severe upper extremity injuries as well as a trend relating lower side-to-side differences in torsion with more severe dominant upper extremity injuries. In addition, there was a higher incidence of severe injuries in players with lower degrees of dominant torsion. If future studies confirm these results, humeral torsion measurements could play a role in risk assessment in pitchers.
高水平的肱骨扭转使棒球投手在投球的后期扣球阶段能够实现最大的外旋，同时减少肱二头肌长头肌腱和肩袖肌腱的扭转和剪切力。
肱骨扭转与职业棒球投手中肩伤和其他上肢伤的发生率和严重程度呈负相关。
病例对照研究；证据水平，3 级。
从一个大联盟棒球队中前瞻性地招募了 25 名职业投手参与本研究。对优势侧和非优势侧肱骨进行计算机断层扫描（CT），并使用三维容积渲染后处理程序处理图像数据。然后，该软件程序被修改为模拟简化的投掷运动，并测量一小部分运动员的潜在内部撞击距离。在 CT 后对运动员进行了 2 年的随访，记录因伤错过投球活动的天数作为伤严重程度和发生率的衡量标准。
平均优势侧肱骨扭转为 38.5°±8.9°；平均非优势侧肱骨扭转为 27.6°±8.0°。优势侧和非优势侧扭转之间的差异具有统计学意义（P＜0.0001）。在随访期间受伤的 11 名投手中（44%），5 名患有肩部损伤，7 名患有肘部损伤，2 名患有手指损伤。优势侧肱骨扭转是严重损伤（≥30 天；P=0.048）的统计学显著预测因子，但不是轻度损伤的预测因子。在受伤运动员中，因伤错过的天数与优势侧肱骨扭转程度较低（r=-0.78；P=0.005）和优势侧与非优势侧肱骨扭转差异较小（r=-0.59；P=0.055）呈强烈相关。在优势或非优势肩的最小关节盂结节距离或优势侧关节盂版本程度方面，肩伤的发生率与肱骨扭转之间没有显著相关性。
发现较低的优势侧肱骨扭转程度与更严重的上肢损伤之间存在很强的关系，并且扭转的侧侧差异与更严重的优势侧上肢损伤之间存在趋势关系。此外，扭转程度较低的运动员发生严重损伤的发生率更高。如果未来的研究证实了这些结果，肱骨扭转测量可能在投手的风险评估中发挥作用。
