Holt Joshua B, Stearns Philip H, Bastrom Tracey P, Dennis M Morgan, Dwek Jerry R, Pennock Andrew T
Pediatric Orthopedics & Scoliosis Center.
Department of Radiology, Rady Children's Hospital.
J Pediatr Orthop. 2020 Jan;40(1):e19-e24. doi: 10.1097/BPO.0000000000001391.
Throwing guidelines have been implemented in Little League baseball in an attempt to minimize injuries in young baseball players. We hypothesized that playing pitcher or catcher and increased innings played during the season would result in dominant shoulder magnetic resonance imaging (MRI) abnormalities.
A prospective evaluation of Little League players aged 10 to 12 years was performed. Players recruited before the start of the season underwent bilateral preseason and dominant shoulder postseason MRI, physical examination, and questionnaires addressing their playing history and arm pain. Innings played, player position, pitch counts, and all-star team selection were recorded.
In total, 23 players were enrolled. The majority (19/23, 82.6%) were right-handed and 16 of 23 (69.6%) played at least 10 innings as pitcher or catcher. Sixteen were selected for the all-star team. Fourteen players (60.9%) had positive dominant shoulder MRI findings not present in their nondominant shoulder. Eight players (34.8%) had new or worsening postseason MRI findings. Thirteen players (81.3%) selected to the all-star team had abnormal MRI findings whereas only one (14.3%) player not selected as an all-star had MRI abnormalities (P=0.005). Year-round play (P=0.016), innings pitched (P=0.046), innings catcher (P=0.039), and number of pitches (P=0.033) were associated with any postseason MRI abnormality, but not for new or worsening MRI changes. Single sport athletes and players playing for multiple teams were significantly more likely to have abnormal MRI findings (P=0.043 and 0.040, respectively) when compared with multisport athletes playing on a single team.
MRI abnormalities involving the dominant shoulder are common in Little League baseball players and often develop or worsen during the season. Contrary to our hypothesis, MRI abnormalities were not associated with player position and pitch counts. Instead, they were most closely associated with year round play, single sports participation, and all-star team selection. The increased demands required for all-star selection comes at a price to the young athlete as the majority of players selected for this honor had abnormal MRI findings in their throwing shoulder while few non all-stars demonstrated such pathology.
Level II.
小联盟棒球已实施投球指导方针，试图将年轻棒球运动员的受伤风险降至最低。我们假设担任投手或捕手以及赛季中增加投球局数会导致优势肩磁共振成像（MRI）异常。
对10至12岁的小联盟球员进行前瞻性评估。在赛季开始前招募的球员接受了双侧季前和优势肩季后MRI检查、体格检查，并填写了关于他们比赛历史和手臂疼痛的问卷。记录投球局数、球员位置、投球次数和全明星队选拔情况。
共招募了23名球员。大多数（19/23，82.6%）为右撇子，23名中有16名（69.6%）作为投手或捕手至少投了10局。16名球员入选全明星队。14名球员（60.9%）优势肩MRI检查结果为阳性，而非优势肩未出现此类情况。8名球员（34.8%）季后MRI检查结果出现新的异常或加重。入选全明星队的13名球员（81.3%）MRI检查结果异常，而未入选全明星队的球员中只有1名（14.3%）MRI检查结果异常（P=0.005）。全年参赛（P=0.016）、投球局数（P=0.046）、接球局数（P=0.039）和投球次数（P=0.033）与任何季后MRI异常相关，但与新的或加重的MRI变化无关。与在单一球队参赛的多项运动运动员相比，单项运动运动员和为多支球队效力的球员MRI检查结果异常的可能性显著更高（分别为P=0.043和0.040）。
小联盟棒球运动员中优势肩MRI异常很常见，且在赛季中常出现或加重。与我们的假设相反，MRI异常与球员位置和投球次数无关。相反，它们与全年参赛、单项运动参与和全明星队选拔密切相关。入选全明星队所需的更高要求给年轻运动员带来了代价，因为大多数获得此荣誉的球员其投球肩MRI检查结果异常，而很少有非全明星球员出现此类病变。
二级。
