2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Matrix-Associated Autologous Chondrocyte Implantation of the Knee Shows Superior Clinical Results and Survival When Combined With Bone Grafting for Failed Cartilage Repair: Findings From the German Cartilage Registry (KnorpelRegister DGOU)

Johannes Weishorn, MD, Heidelberg GERMANY
Thomas Tischer, Prof. Dr., Erlangen GERMANY
Tilman Walker, Heidelberg GERMANY
Tobias Renkawitz, Prof., Heidelberg GERMANY

Department of Orthopaedics, Heidelberg University Hospital, Ruprecht-Karls University, Heidelberg, GERMANY

FDA Status Cleared

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.