W. E. Harkin, A. T. Pennock, E. W. Edmonds, Department of Orthopedic Surgery, University of California, San Diego, CA, USA.
A T. Pennock, T. P. Bastrom, E. W. Edmonds, Pediatric Orthopedics & Scoliosis Center, Rady Children's Hospital, San Diego, CA, USA.
Clin Orthop Relat Res. 2021 Mar 1;479(3):623-631. doi: 10.1097/CORR.0000000000001468.
Stress from overhead throwing results in morphologic changes to the shoulder in youth baseball players. With greater valgus torque stresses, the elbow experiences injuries specifically attributed to throwing. However, no previous work that we know of has assessed throwing-related morphologic changes of the elbow without associated conditions.
QUESTIONS/PURPOSES: (1) Do children who play competitive baseball have enlargement or overgrowth of their radial head shape and/or capitellum compared with the nondominant elbow on MRI? (2) Do children who stop playing year-round baseball have less enlargement of the lateral elbow structures than children who maintain a high level of play?
A prospective study was conducted between 2015 and 2018 on preadolescent boys who underwent voluntary MRI of their bilateral elbows before the start of the spring baseball season. Twenty-six children agreed to participate out of a four-team league that was asked to participate; their first MRI was obtained at a mean (range) age of 12 years (10 to 13). We also obtained their history related to throwing and performed a physical examination. Players had a mean of 5.6 years of playing before their first MRI, and half the children (13 of 26) were year-round baseball players. Sixty-two percent (16 of 26) reported being either or both a pitcher or catcher as their primary position. No child was excluded from participation. Three years later, these boys were asked to return for repeat MRI and physical examinations. Fifty-eight percent (15 of 26) of players were still playing at the 3-year MRI. Continued play or new onset of pain was documented. Radiographic measurements were then compared between dominant and nondominant arms, and the differences of these changes were compared between those who had continued playing during the study period and those who had quit. The measurements were made in all three planes of the radial head and capitellum, both osseous and cartilaginous. Measurement intrarater and interrater reliability were in the good-to-excellent range (intraclass correlation coefficient 0.77 to 0.98).
When we compared dominant and nondominant arms, we found there was no dominant arm overgrowth (difference between baseline and 3-year measurements) in any measurement; for example, sagittal capitellum measurements in dominant arms were 2.5 ± 1.1 mm versus non-dominant arms: 2.8 ± 1.1 mm (mean difference -0.23 [95% CI -0.55 to 0.08]; p = 0.13). There was only undergrowth of the cartilaginous axial diameter of the radial head (change in dominant: 2.5 ± 1.3 mm; change in nondominant: 3.2 ± 1.7 mm; mean difference -0.64 mm [95% CI -1.2 to -0.06]; p = 0.03). There was no enlargement of the lateral elbow structures when children who continued to play were compared with children who stopped playing; for example, the difference in the bone-only growth ratio of the sagittal radial head to humerus of those still playing was 0.001 ± 0.03 and it was 0.01 ± 0.03 for those not playing (mean difference -0.01 [95% CI -0.04 to 0.01]; p = 0.29).
In healthy children who play baseball for multiple years between the ages of 6 to 11 years, continued torque at the elbow from throwing does not result in morphologic changes as it does in the shoulder. Despite evidence that injuries and surgery because of long-term participation in a throwing sport results in a larger radial head and capitellum, our study presents evidence that outside an injured elbow, throwing alone does not appear to change the morphology of the lateral elbow. Therefore, changes to the radial head size could presuppose other elbow pathology and future study could be performed to better evaluate the correlation.
Level I, prognostic study.
青少年棒球运动员在进行 overhead throwing 时会导致肩部形态发生变化。随着更大的外翻扭矩应力，肘部会受到专门归因于投掷的损伤。然而，据我们所知，以前没有任何工作评估过与投掷相关的肘外侧结构的形态变化，而没有相关的疾病。
问题/目的：（1）与非优势肘相比，参加竞技棒球的儿童在 MRI 上其桡骨头形状和/或肱骨小头是否有增大或过度生长？（2）与继续高水平比赛的儿童相比，停止全年参加棒球比赛的儿童肘部外侧结构的增大程度是否较小？
在 2015 年至 2018 年期间，对参加春季棒球赛季前自愿接受双侧肘 MRI 的未成年男孩进行了一项前瞻性研究。共有 26 名儿童同意参加，其中有 4 个队参加了比赛；他们的第一次 MRI 检查在平均（范围）年龄为 12 岁（10 至 13 岁）。我们还获取了他们与投掷有关的病史，并进行了体格检查。这些儿童在第一次 MRI 检查前的平均投掷年限为 5.6 年，其中一半（26 名儿童中有 13 名）是全年参加棒球比赛的儿童。62%（26 名儿童中有 16 名）报告说他们是投手或捕手，或者是他们的主要位置。没有儿童被排除在外。三年后，这些男孩被要求回来进行重复 MRI 和体格检查。58%（26 名儿童中有 15 名）的儿童仍在参加 3 年的 MRI。记录了继续参加或新出现疼痛的情况。然后在所有三个平面上比较桡骨头和肱骨小头的影像学测量值，并比较在研究期间继续参加的儿童和停止参加的儿童之间这些变化的差异。测量值在桡骨头和肱骨小头的所有三个平面上进行，包括骨和软骨。测量的组内和组间可靠性均在良好到极好范围内（组内相关系数 0.77 至 0.98）。
当我们比较优势臂和非优势臂时，我们发现在任何测量中都没有优势臂过度生长（基线和 3 年测量之间的差异）；例如，优势臂矢状位肱骨小头测量值为 2.5 ± 1.1mm，而非优势臂为 2.8 ± 1.1mm（平均差异-0.23[95%置信区间-0.55 至 0.08]；p = 0.13）。只有桡骨头的软骨轴向直径生长不足（优势变化：2.5 ± 1.3mm；非优势变化：3.2 ± 1.7mm；平均差异-0.64mm[95%置信区间-1.2 至-0.06]；p = 0.03）。与停止参加的儿童相比，继续参加的儿童肘部外侧结构没有增大；例如，仍在参加比赛的儿童矢状位桡骨头与肱骨的骨生长比例差值为 0.001 ± 0.03，而不参加比赛的儿童为 0.01 ± 0.03（平均差异-0.01[95%置信区间-0.04 至 0.01]；p = 0.29）。
在 6 至 11 岁之间多年参加棒球运动的健康儿童中，肘部持续的投掷扭矩不会导致肩部形态变化。尽管有证据表明，由于长期参加投掷运动而导致的损伤和手术会导致桡骨头和肱骨小头增大，但我们的研究表明，在受伤的肘部之外，单独投掷似乎不会改变肘外侧的形态。因此，桡骨头大小的变化可能预示着其他肘部病理，未来的研究可以更好地评估相关性。
I 级，预后研究。
