Increased medial laxity of the elbow in preadolescent baseball players with or without medial elbow apophysitis

Abstract

Background Medial elbow apophysitis is a traction apophysitis observed in the medial epicondyle of the elbow in preadolescent baseball players. The purpose of this study was to determine the relationship between medial elbow apophysitis and elbow valgus instability in preadolescent baseball players. Methods The participants were classified into a control group and an injury group; the injury group included participants diagnosed with a medial elbow injury (inclusion criteria were only symptoms of the elbow joint or positive findings on physical examinations, or both). Elbow valgus instability was assessed by measuring the differences in ulnohumeral joint gapping width, with and without gravity stress induced by weight loading of the forearm using ultrasonography. Results The control and injury groups consisted of 81 and 23 preadolescent baseball players, respectively. In the throwing elbow, valgus instability in the injury group was significantly greater than that in the control group (1.07 vs. 0.57 mm, P = .001). In the non-throwing elbow, valgus instability in the injury group was significantly greater than that in the control group (0.57 vs. 0.37 mm, P = .011). The area under the curve for valgus instability of the throwing elbow was 0.89 mm (95% confidence interval, 0.64-0.77), and the cut-off value for elbow pain appearance was 0.80 mm. Conclusion The increased elbow valgus instability in the injury group was associated with a medial elbow injury. For the elbow valgus instability of the non-throwing side in the injury group, we considered that players with medial elbow apophysitis inherently have elbow laxity.

Evaluation of flexor digitorum superficialis function in adolescent baseball players

“…Adolescent and college-aged baseball players with elbow pain have more medial elbow joint space than players without pain symptoms. 25 , 29 Recently, studies have reported that increasing FDS function increases the medial-side stability in valgus stress and helps to improve baseball players with ulnar collateral ligament injury. 9 , 18 , 22 , 24 Regarding finger movements during pitching motion, the force of the thumb and ring fingers is greatest just before the maximum shoulder external rotation, whereas the force produced from the index and middle fingers reaches the peak just before the maximum shoulder external rotation and ball release.…”

Optimal Limb Position for the Stress Ultrasound Evaluation of Elbow Valgus Laxity in Baseball Players

“…This limb position method for SUS was applied in similar studies. 10 , 11 , 22 , 24 However, it is unclear which limb position method more clearly detects valgus laxity in baseball players.…”