Remodeling of Articular Cartilage and Subchondral Bone After Bone Grafting and Matrix-Associated Autologous Chondrocyte Implantation for Osteochondritis Dissecans of the Knee

Background: Osteochondritis dissecans (OCD) of the knee is a challenging problem. Previously, the authors implemented a novel 1-step surgical procedure for OCD treatment consisting of matrix-associated autologous chondrocyte implantation (ACI) and simultaneous bone reconstruction including the subchondral lamina. Purpose: This study presents the 2- to 5-year results after this technique, assessing correlations of clinical function and cartilage and bone remodeling processes. Study Design: Case series; Level of evidence, 4. Methods: Twenty-six patients with symptomatic condylar knee OCD (International Cartilage Repair Society OCD III/IV) were treated with matrix-associated ACI and monocortical cancellous cylinders for defect filling and subchondral bone plate reconstruction using cortical graft layers as novel subchondral lamina. Evaluations were performed with clinical rating scales and 1.5-T magnetic resonance imaging using the magnetic resonance observation of cartilage repair tissue (MOCART) score and a newly implemented subchondral lamina remodeling grade. Results: The defect size was 5.3 +/- 2.3 cm(2). The defect depth was 8.7 +/- 2.4 mm. After a follow-up of 39.8 +/- 12.0 months, all scores improved significantly. Nineteen patients (73%) reached good/excellent results in the Lysholm-Gillquist score (preoperatively: 53.2 +/- 18.0 points; latest follow-up: 88.5 +/- 9.5 points) and the Cincinnati knee rating score (preoperatively: 51.7 +/- 13.0 points; latest follow-up: 84.6 +/- 11.7 points) and significant improvements in the subjective International Knee Documentation Committee (IKDC) score by 27.9% (preoperatively: 50.5% +/- 16.1%; latest follow-up: 78.4% +/- 13.4%). The MOCART score reached 62.4 +/- 18.9 points. The clinical improvement and tissue remodeling occurred simultaneously and timed; thus, the cartilage defect filling and the lamina remodeling grades correlated significantly with each other, the follow-up time, and almost all clinical scores. Conclusion: The simultaneous reconstruction of deep osteochondral defects of the knee OCD with monocortical cancellous cylinders and matrix-associated ACI is a biological, 1-step alternative to osteochondral cylinder transfer or conventional ACI that leads to good clinical and magnetic resonance imaging results after an intermediate follow-up period. The present study demonstrated simultaneous remodeling processes of articular cartilage repair tissue and subchondral lamina; this synchronization is not yet understood and deserves further investigation.