Magnetic Resonance Imaging and Clinical Evaluation of Patellar Resurfacing with Press-Fit Osteochondral Autograft Plugs

Abstract

Background Autologous osteochondral transplantation (AOT) has been successfully used in the femoral condyle and trochlea and is an attractive treatment option for full-thickness patellar cartilage lesions. Hypothesis Patients treated with AOT for the repair of symptomatic, isolated patellar cartilage lesions will demonstrate improvement in functional outcomes and postoperative magnetic resonance imaging appearance. Study Design Case series; Level of evidence, 4. Methods Between 2002 and 2006, patients with focal patellar cartilage lesions treated with AOT were prospectively followed. The mean age at the time of surgery was 30 years. Clinical assessment was performed with the International Knee Documentation Committee (IKDC), activities of daily living of the Knee Outcome Survey (ADL), and Short Form-36 (SF-36) at baseline and most recent follow-up. Magnetic resonance imaging was used to evaluate the cartilage repair morphologic characteristics in 14 cases. Results Twenty-two patients met the study criteria with a mean follow-up of 28.7 months (range, 17.7–57.8 months). The mean Patellar lesion size was 165.6 ± 127.8 mm and the mean size of the donor plug was 9.7 ± 1.1 mm in diameter with 1.8 ± 1.4 Plugs/defect. The mean preoperative IKDC score was 47.2 ± 14.0 and improved to 74.4 ± 12.3 ( P = .028). The mean preoperative ADL score was 60.1 ± 16.9 and increased to 84.7 ± 8.3 ( P = .022). The mean SF-36 also demonstrated an improvement, from 64.0 ± 14.8 at baseline to 79.4 ± 15.4 ( P = .059). Nine patients underwent concomitant distal realignment and demonstrated improvement between preoperative and postoperative outcomes scores, but these differences were not statistically significant. Magnetic resonance imaging appearance demonstrated that all plugs demonstrated good (67%–100%) cartilage fill, 64% with fissures <2 mm at the articular cartilage interface, 71 % with complete trabecular incorporation, and 71 % with flush plug appearance. Conclusion Patellar AOT is an effective treatment for focal patellar chondral lesions, with significant improvement in clinical follow-up. This study suggests that patients with patellar malalignment may represent a subset of patients who have a poor Prognostic outlook compared with patients with normal alignment.