The role of autologous bone grafting in matrix‐associated autologous chondrocyte implantation at the knee: Results from the German Cartilage Registry (KnorpelRegister DGOU)

Self Cite

PurposeThe aim of this study was to evaluate the role of leg alignment on long‐term clinical outcome after matrix‐associated autologous chondrocyte implantation (M‐ACI) and to define an individualized target range to optimize clinical outcome.MethodsThe present study examined patients who underwent M‐ACI of the femoral condyle. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) were used to assess the results. Clinical outcomes were related to Patient Acceptable Symptomatic State (PASS). For intra‐ and interobserver reliability of mechanical tibiofemoral angle, mechanical medial proximal tibial angle and mechanical lateral distal femoral angle, we calculated intraclass correlation coefficients using a two‐way mixed model with absolute agreement. A regression model and receiver‐operating characteristics curve were used to identify an individual range of alignment where a favourable clinical outcome could be expected in the long term.ResultsAdditional osteotomy was performed in 50% of patients with similar clinical outcomes as physiologically aligned patients (p > 0.05). The curve‐fitting regression model identified a target range of −2.5° valgus to 4.5° varus for ideal postoperative alignment (R2 = 0.12, p = 0.01). Patients within this range were more likely to achieve PASS (70% vs. 27%, p = 0.001). In medially treated defects, a refined range of −2.5° valgus to 4° varus alignment was found (R2 = 0.15, p = 0.01). These patients were more likely to achieve PASS (67% vs. 30%, p = 0.01) and showed favourable postoperative KOOS and MOCART scores (p = 0.02). Patients with lateral defects were more likely to achieve PASS within a range of −2° valgus and 0.5° varus (90% vs. 45%, p = 0.03) and showed favourable postoperative KOOS and MOCART scores (p = not significant).ConclusionsAn individual range of leg alignment—whether achieved by osteotomy or physiologic alignment—should be respected in M‐ACI treatment. A neutral to slightly undercorrected alignment favours the postoperative outcome after M‐ACI. When planning surgery for patients with focal cartilage defects of the femoral condyle, these ranges should be recognized as critical factors.Level of EvidenceLevel III.

Section: Outcome Measures and Radiographic Evaluationmentioning

confidence: 99%

Neutral to slightly undercorrected mechanical leg alignment provides superior long‐term results in patients undergoing matrix‐associated autologous chondrocyte implantation

Weishorn,

Koch,

Zietzschmann

et al. 2024

Self Cite

Favourable clinical outcomes and low revision rate after M‐ACI in adolescents with immature cartilage compared to adult controls: Results at 10 years

Weishorn,

Wiegand,

Koch

et al. 2024

PurposeThe purpose of this study was to evaluate long‐term survival, patient‐reported outcomes (PROs) and radiographic results of matrix‐associated autologous chondrocyte implantation (M‐ACI) in adolescents with immature cartilage and compare them to adult controls.MethodsA retrospective matched‐pair analysis was performed comparing the PRO after M‐ACI for focal cartilage defect of the knee in cartilaginous immature adolescents to mature adults. Groups were matched for sex, body mass index, defect site and size, symptom duration and the number of previous knee surgeries. Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART 2.0) scores were assessed at least 60 months postoperatively. Patient acceptable symptomatic state (PASS) and clinical response rate in KOOS and KOOS subscores were calculated.ResultsA total of 54 patients were matched. At a mean of 96 months (65–144 months), no surgical complications, graft hypertrophy or reoperations were noted in the cohorts studied. Adolescents showed superior PROs at the final follow‐up (76.9 ± 14.1 vs. 66.4 ± 15.0, p = 0.03) and were significantly more likely to achieve PASS (74.1% vs. 55.6%; p = 0.02) compared to the adult cohort. The KOOS subscale analysis showed long‐term benefits for adolescents in terms of symptom improvement, pain reduction, activities of daily living, sports and quality of life (p < 0.05). None of the patients in the adolescent group showed graft hypertrophy on magnet resonance imaging or signs of osteoarthritis on radiographs at long‐term follow‐ups.ConclusionsM‐ACI is an effective treatment for chondral defects of the knee in patients with immature cartilage with low revision rates and high patient satisfaction over the long term. Adolescents showed comparable clinical and radiographic results in the short and medium term, with slightly more favourable, clinically relevant functional results in adolescents in the long term. M‐ACI can be safely used in adolescents, and consideration should be given to expanding the indication to include these patients.Level of EvidenceLevel III.

Secondary matrix‐associated autologous chondrocyte implantation after failed cartilage repair shows superior results when combined with autologous bone grafting: Findings from the German Cartilage Registry (KnorpelRegister DGOU)

Weishorn,

Niemeyer,

Angele

et al. 2024

PurposeThe aim of this study was to evaluate whether additive autologous bone grafting (ABG) improves clinical outcome and survival in revision matrix‐associated autologous chondrocyte implantation (M‐ACI) after failed cartilage repair (CR).MethodsA retrospective, registry‐based, matched‐pair analysis was performed to compare patient‐reported outcomes 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, the clinical response rate and the survival of the subgroups were determined.ResultsA total of 818 patients were matched. Revision M‐ACI (n = 238) with concomitant bone grafting was associated with significantly higher PRO as measured by KOOS (80.8 ± 16.8 vs. 72.0 ± 17.5, p = 0.032) and higher CRR (81.4% vs. 52.0%, p = 0.018) at 36 months compared to patients with revision M‐ACI alone. 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 ABG 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 = 0.003) or ACI (82.6 ± 17.0 vs. 72.8 ± 16.0, p = 0.021) 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.).ConclusionsRegardless of the type of previous CR, additional bone grafting in secondary M‐ACI improves the clinical outcome, response rate and survival at 36 months compared to M‐ACI alone. Secondary M‐ACI with ABG had comparable clinical response and survival rates to primary M‐ACI. Therefore, subchondral bone should be treated even in cases of mild bone involvement in revision M‐ACI.Level of evidenceLevel III.