Radiographic assessment of factors associated with poor outcomes after osteochondral autograft transplantation for capitellar osteochondritis dissecans

OBJECTIVES: Osteochondral autograft transplantation (OAT) is a treatment option for large, inviable osteochondritis dissecans (OCD) lesions. Many papers have reported good clinical outcomes after OAT; however, we sometimes experience elbows with poor outcomes that show pain and restricted range of motion. Few articles have investigated factor associated with poor outcomes after OAT. The purpose of this study was to retrospectively investigate the clinical outcome and radiographic findings after OAT in elbows with a large capitellar OCD lesion and to elucidate radiographic factors associated with poor clinical outcomes. METHODS: Sixty-nine elbows that underwent OAT for large osteochondral dissecans lesions of the capitellum with a minimum of 2-years follow-up were included in this study. They consisted of 65 males and 4 females with a mean age of 14 (range, 12-15) years at surgery. The mean follow-up was 48 months (range, 24-144). Cylindrical osteochondral grafts were harvested from the lateral condyle of the ipsilateral knee. We usually transplant an 8-mm graft in the lateral part of a lesion and add two 6-mm grafts medial to the initial graft. Clinical outcomes, including elbow range of motion and Timmerman and Andrews clinical rating score (T-A score), were retrospectively investigated. We measured cranial migration of the radial head on the preoperative tangential views. We also evaluated the location and orientation of the most lateral graft on the tangential views at 1 month after OAT: 1) the tilting angle (the angle between the graft axis and the vertical line to the radial articular surface), 2) the distance between the most lateral edge of the graft and the center of radial head, 3) protrusion of the graft from the articular surface of the medial capitellum. The paired t-test and Student’s t-test were used for statistical analysis, and the level of significance was set at p<0.05. RESULTS: The mean elbow extension/flexion significantly improve from preoperative -10/125 to postoperative -5/133 (p<0.001 for each). The mean T-A score significantly improved from preoperative 125±43 to 170±34 at 2 years after surgery (p<0.001). We compared the radiographic findings between good outcomes elbows (T-A score >190, n=33) and poor outcomes elbows (T-A score <150, n=18). The cranial migration of the radial head was 0.2mm and 2.1mm, respectively (p<0.001). The tilting angle was larger in the poor group (18±11 degrees) than the good group (9±8 degrees, p=0.002). The graft was significantly located laterally in the good group (6.8±1.6 mm) than the poor group (3.8±2.3 mm, p<0.001). The protrusion tended to be larger in the poor group (0.2±2.7mm) than the good group (-0.7±1.8mm), but the difference was not significant (p=0.17). CONCLUSION: The outcomes after OAT was good with significant improvement of range of motion and clinical score, but a quarter of patients showed poorer outcomes. The results of this study indicated that the radial head migration before surgery and the location and orientation of the graft were associated with the clinical outcomes. For better surgical outcomes, OAT should be performed before the radiographic changes progress, and surgeons should be careful about the location and orientation of osteochondral grafts.