Osteochondral Lesions of the Capitellum Do Not Affect Elbow Kinematics and Stability With Intact Collateral Ligaments: An In Vitro Biomechanical Study

PURPOSE: Osteochondritis dissecans (OCD) of the capitellum most commonly affects adolescent pitchers and gymnasts, who present with pain and mechanical symptoms. Patients with larger lesions have poorer outcomes, possibly related to increased contact pressures on the surrounding articular surface with or without instability. The purpose of this in vitro study was to determine whether displaced OCD lesions of the capitellum lead to altered kinematics and stability of the elbow. METHODS: We mounted 9 fresh-frozen cadaveric arms in an upper extremity joint testing system, with cables attaching the tendons of the major muscles to motors and pneumatic actuators. An electromagnetic receiver on the ulna enabled quantification of the kinematics of the radius and ulna with respect to the humerus. We used 3-dimensional computed tomography scans and computer-assisted techniques to navigate sequential osteochondral defects ranging in size from 12.5% to 100% of the capitellum. The arms were subjected to active and passive flexion in both the vertical and valgus positions with the forearm in both pronation and supination. RESULTS: We found no significant differences in valgus angulation or ulnar rotation between any of the OCD lesions and the intact elbow during flexion, regardless of arm position or forearm rotation. CONCLUSIONS: Osteochondritis dissecans lesions of the capitellum, both small and large, did not alter the ulnohumeral kinematics and stability with intact collateral ligaments. Therefore, excision of unfixable osteochondral fragments of the capitellum in the setting of intact collateral ligaments can be considered without the risk of creating instability.