Summary
Regardless of the type of previous CR, additional bone grafting in secondary M-ACI improves clinical outcome, response rate and survival at 36 months compared with M-ACI alone.
Abstract
Purpose
To evaluate whether additive autologous bone grafting improves clinical outcome and survival in secondary matrix-associated autologous chondrocyte implantation (M-ACI) after failed cartilage repair (CR).
Methods
A retrospective, registry-based, matched-pair analysis was performed to compare patient-reported outcomes (PRO) and survival in secondary M-ACI with or without additional bone grafting for focal full-thickness cartilage defects of the knee and to compare it with those in primary M-ACI. Patients were matched for age, sex, body mass index, defect size and localization, and number of previous CRs. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was assessed over a follow-up period of 36 months. The Patient Acceptable Symptomatic State (PASS), the Clinical Response Rate (CRR), and the survival of the subgroups were determined.
Results
A total of 409 patients were matched. Patients with previous CR failure had a significantly higher PRO as measured by KOOS (80.8±16.8 vs. 72.0±17.5, p=0.03) and a higher CRR (81.4% vs. 52.0%, p=0.01) at 36 months when secondary M-ACI was performed with concomitant bone grafting. KOOS and KOOS improvement in these patients did not differ from those who underwent primary M-ACI (p=n.s.). The combination of M-ACI and autologous bone grafting resulted in a significantly higher KOOS at 36 months than M-ACI alone, regardless of whether bone marrow stimulation (89.6±12.5 vs. 68.1±17.9, p<0.01) or ACI (82.6±17.0 vs. 72.8±16.0, p=0.02) was performed before. Additional bone grafting results in equivalent survival rates at 7 years in secondary compared to primary M-ACI (83% vs. 84%, p=n.s.).
Conclusions
Regardless of the type of previous CR, additional bone grafting in secondary M-ACI improves clinical outcome, response rate and survival at 36 months compared with M-ACI alone. Secondary M-ACI with bone grafting had comparable clinical response and survival rates to primary M-ACI. Therefore, in secondary M-ACI, subchondral bone should be treated generously.