Internal Fixation of Unstable In Situ Osteochondritis Dissecans Lesions of the Capitellum

Background: Limited data exist regarding the indications and expected outcomes of internal fixation of unstable in situ osteochondritis dissecans (OCD) lesions of the capitellum. The objective of this investigation was to characterize healing rates, clinical results, and functional outcomes of internal fixation of unstable in situ OCD lesions in adolescents. Methods: Retrospective analysis was performed of 26 elbows in 24 patients who underwent internal fixation for unstable in situ OCD. Mean age at surgery was 14.1 years; 7 patients had open physes. Mean lesion width and thickness were 12.0 and 5.4 mm, respectively. Demographic, clinical, and radiographic variables of patients who went on to healing versus revision procedures were compared with univariate analysis. Classification and regression tree analysis identified optimal threshold values associated with healing. Functional outcomes were assessed with the Mayo Elbow Performance Score, Timmerman, and Pediatric Outcomes Data Collection Instrument scores. Mean clinical follow-up was 39 months (range, 12 to 96 mo). Results: Twenty of 26 elbows healed. Patients who healed were younger (P=0.01) and had smaller sagittal plane lesion widths (P=0.03) than patients who underwent revision. Classification and regression tree analysis identified 15.3 years and 13mm as the threshold values distinguishing patients who did and did not heal. Overall, mean arc of elbow motion improved from 109 degrees preoperatively to 127 degrees at last follow-up (P=0.001). Mean Mayo Elbow Performance Score improved from 68 to 92 (P<0.001). Of 18 questionnaire respondents, two thirds reported full return to their prior level of sports participation without elbow complaint; 9 had excellent final Timmerman scores, 5 good, and 4 fair. Mean Pediatric Outcomes Data Collection Instrument upper extremity and sports scores were 98 and 93, respectively. Conclusions: Healing, return to sports, and good to excellent functional outcomes may be expected in the majority of patients undergoing internal fixation of unstable in situ OCD lesions of the capitellum, particularly in younger patients with lesions <13mm in sagittal width. Higher levels of evidence must further differentiate the optimal surgical treatments of unstable OCD. Level of Evidence: Level IV.