Comprehensive Elbow Joint Morphology Changes in Surgically Treated Osteochondritis Dissecans of the Capitellum: Clinical Implications.

Background: Capitellar osteochondritis dissecans (OCD) frequently results in radial head enlargement. However, due to the elbow joint's complex anatomy, deformities likely extend beyond just the radial head.

Hypothesis/purpose: It was hypothesized that in patients with OCD treated with surgery, imbalances in bone morphology during growth would affect the entire joint, leading to postoperative clinical symptoms. The purpose of this study was to test this hypothesis through a 3-dimensional evaluation of morphological changes.

Study Design: Cross-sectional study; Level of evidence, 3.

Methods: After retrospective identification, this study enrolled 47 patients who had undergone surgery, with a mean postoperative follow-up of 6.8 years. After in-person evaluation and bilateral computed tomography scanning, 3-dimensional bone models of the affected and contralateral elbows were created. The bone morphology of the radial head, the distal humerus, and the proximal ulna at the anatomic points were evaluated and compared between affected and contralateral sides. These measurements were correlated with clinical symptoms, and risk factors for these changes were identified.

Results: The mean age at examination was 20.6 ± 3.3 years and at surgery was 13.9 ± 1.3 years, with a mean follow-up of 6.8 ± 3.2 years. In the radial head, morphological enlargement was observed for radioulnar diameter (26.3 ± 1.9 vs 22.9 ± 1.5 mm; < .001) and dorsovolar diameter (26.5 ± 1.9 vs 24.2 ± 1.5 mm; < .001). In the humeral trochlea, enlargement was noted at the lateral trochlea (28.2 ± 1.7 vs 25.0 ± 1.3 mm; < .001), trochlear groove (20.4 ± 1.7 vs 17.9 ± 1.6 mm; < .001), and medial trochlea (30.5 ± 2.1 vs 25.5 ± 1.6 mm; < .001) as well as the ulnar trochlear notch (28.2 ± 1.7 vs 25.0 ± 1.3 mm; < .001). Restricted elbow flexion was associated with radial head enlargement in radioulnar and dorsovolar diameters ( = 0.60, < .001; = 0.44, = .002). Lesion size was identified as a risk factor for these changes (odds ratio [OR], 1.36; = .019), as was development of OCD during skeletal growth (OR, 0.82; = .006).

Conclusion: Over mid- to long-term follow-up, the entire elbow joint underwent cylindrical-like morphological changes, leading to restricted motion. Enlargement typically developed during skeletal growth, with larger lesions resulting in more severe enlargement. Awareness of these natural postoperative changes is crucial, and it is clinically important to provide appropriate treatment during skeletal growth when treating OCD.