Abstract
We thank Qin et al.1 for the thoughtful and constructive letter regarding our recent study, in which we prospectively examined the association between elbow valgus torque during pitching and medial elbow injuries in young baseball pitchers.2 We appreciate the opportunity to clarify and expand on several important points raised by the authors. We agree that chronological age alone may not represent biological mechanisms underlying the risk of medial elbow injuries in young baseball pitchers. Rather, age may partly reflect maturational vulnerability during the growth period. Tariq et al.3 reported that skeletally immature symptomatic baseball players showed a higher prevalence of medial epicondyle marrow edema and avulsion fractures than skeletally mature players. Costa e Silva et al.4 revealed that injury patterns in young athletes differ according to maturation status, with upper-limb injuries in boys occurring more frequently before peak height velocity. In our original article, we discussed that the apophysis may be particularly vulnerable during growth because bones grow rapidly and growth cartilage is less resistant to repetitive microtrauma than mature cartilage.5, 6 However, our study did not directly assess maturity-related variables, such as peak height velocity, recent growth velocity, bone age, skeletal age, or apophyseal maturation status. Therefore, age should be interpreted as an indirect marker. Additionally, we agree that preseason asymptomatic ultrasonographic abnormalities of the medial elbow may represent a clinically meaningful preclinical susceptibility state. Shitara et al.7 reported that asymptomatic medial epicondylar abnormalities were associated with subsequent elbow injuries in young baseball players. In our study, baseline ultrasonographic assessment of the elbow joint was performed before passive elbow extension range of motion and elbow valgus torque measurements.2 Although this point may not have been described with sufficient clarity in the exclusion criteria, young pitchers with medial elbow ultrasonographic abnormalities at baseline were excluded regardless of the presence or absence of elbow pain. Therefore, the analyzed cohort included pitchers without baseline structural medial elbow abnormalities, and the possibility that asymptomatic structurally susceptible elbows were pooled with normal elbows was reduced. At 1-year follow-up, medial elbow injury was evaluated based on elbow pain during pitching and ultrasonographic abnormalities in the elbow joint.2 We appreciate the thoughtful comments by Qin et al. that highlighted the importance of a multifactorial interpretation of the risk of elbow injury in young baseball pitchers, encompassing growth and maturation, baseline elbow morphology, and biomechanical loading. Further studies using multifactorial models may clarify the mechanisms of medial elbow injury and improve prevention strategies for young baseball players. The author (A.S.) declares the following financial interests/personal relationships which may be considered as potential competing interests: A.S. reports financial support was provided by the Japan Society for the Promotion of Science. The other authors (T.K., K.S., H.S., Y.N., Y.T., M.H.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.