The Presence or Absence of Cartilage Regeneration Following Medial Open-Wedge High Tibial Osteotomy Does Not Predict Long-term Outcomes.

Purpose: The study aims to assess the whether the patients who showed mature cartilage regeneration in the medial compartment in a second look arthroscopy have better clinical and radiologic long-term outcomes and survivorship compared to immature cartilage regeneration following medial open-wedge high tibial osteotomy (MOWHTO).

Methods: Patients who underwent MOWHTO using a medial locked plate system were retrospectively reviewed between February 2008 and December 2012. All included patients had no concomitant cartilage-restoring procedures, underwent second-look arthroscopy at 2 years postoperatively, and were followed for at least 10 years. Based on arthroscopic findings in the medial femoral condyle, patients were classified into mature and immature cartilage regeneration groups. Clinical outcomes, including the primary outcome of total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, were compared between the groups using patient-reported outcome measures. The minimal clinically important difference (MCID) was assessed to determine clinical significance. Radiologic progression of osteoarthritis was evaluated using serial changes in the Kellgren-Lawrence grade, and survivorship, defined as conversion to arthroplasty, was analyzed using the Kaplan-Meier method.

Results: A total of 83 consecutive knees were included, with 34 in the mature group and 49 in the immature group. The mean follow-up period was 12.1 years (range, 10-15.2 years). No significant differences were observed in clinical outcomes or the proportion of patients achieving minimal clinically important difference (MCID) on the WOMAC scale (MCID 9.1; Group M 93.9% vs. Group I 97.9%, P=.564). Radiologic progression showed a trend of progressing more slowly in the mature group than in the immature group without significance at the latest follow-up(P=.113). The 10-year survival rate was 100% in the mature group and 95.6% in the immature group (P = .099).

Conclusion: The presence or absence of cartilage regeneration in the medial compartment does not predict better long-term outcomes, including radiologic progression, the achievement of MCID in clinical outcomes, or survivorship following MOWHTO.

Level of evidence: IV, Retrospective comparative case series.