Background: Medial elbow injuries occur in approximately one-third of all young baseball players and are characterized by injuries to the bone and cartilaginous growth plates. Bone mineral mass, a representative of bone strength, may show individual differences during growth, and the bone strength can temporarily decrease depending on the stage of bone development. However, the relationship between bone mineral mass and medial elbow injuries in young baseball players has not yet been investigated.
Hypothesis: The bone mineral mass would be lower in players with medial elbow injuries, causing lower bone strength and increased susceptibility to injury.
Study design: Cross-sectional study.
Methods: We recruited 215 baseball players aged 9-12 years; the players completed a questionnaire regarding their age, height, weight, practice duration and frequency, baseball experience, and number of pitches per day. The injury and control groups were determined by ultrasonographic evaluation of the medial aspect of the elbow joint, and bone mineral mass was measured by bioelectric impedance analysis. The hip and shoulder ranges of motion were measured. Each variable was compared between the injury and control groups using the Student's t-test. Simultaneous multivariate logistic regression analysis was subsequently performed to identify the factors associated with medial elbow injuries.
Results: Bone mineral mass was significantly higher in the injury group than in the control group (2.02 ± 0.30 kg vs. 1.91 ± 0.26 kg, p = 0.003). However, it was not significantly associated with medial elbow injuries in multivariate logistic analysis. Baseball experience (OR, 1.03; 95% CI, 1.01-1.06; p = 0.009) were significantly associated with medial elbow injury.
Conclusion: Contrary to our hypothesis, bone mineral mass was higher in players with medial elbow injuries, but was not significantly associated with them. A one-time measurement of bone mineral mass is probably not specific enough to analyze the condition of the medial epicondyle. Baseball experience has been identified as a possible factor associated with medial elbow injuries in young players, and increases in experience should be used as an indicator to assess elbow joint health.
Keywords: Medial elbow injury; bioelectric impedance analysis; bone development; bone mineral mass; young baseball player.
What is known about the subject: Young baseball players who start their careers with low amounts of bone minerals may continue to have low amounts compared to their peers even after a growth spurt. Therefore, these players may be more susceptible to bone injuries, although all players are likely to experience similar amounts of mechanical stress in the body.What this study adds to existing knowledge: Although, the bone mineral mass is higher in those with medial elbow injuries, it is not significantly associated as an independent factor with the prevalence of medial elbow injuries in young baseball players. Baseball experience is a possible factor associated with medial elbow injuries in young baseball players, and increases in experience should be used as an indicator to assess elbow joint health.