Less risk of conversion to total knee arthroplasty without significant clinical and survivorship difference for opening-wedge high tibial osteotomies in varus knee deformities at 10-year minimum follow-up compared to closing-wedge high tibial osteotomies

Purpose The purpose of this study was to evaluate the clinical outcomes and survivorship at minimum 10-year follow-up of patients undergoing primary valgisation high tibial osteotomy (HTO) for medial osteoarthritis (OA), treated by Opening-Wedge HTO (OW-HTO) or Closing-Wedge HTO (CW-HTO). Methods This was a retrospective cohort study of consecutive patients presenting to a single institution undergoing HTO for isolated medial compartment OA. Two hundred and twenty three HTOs for isolated medial tibio-femoral OA were performed between January 2002 and December 2010. Patients were eligible if they had minimum 10-year follow-up and received either a CW or OW-HTO. Fifteen (6.7%) patients died and twenty-five (11.2%) were lost to follow-up. One hundred and eighty three (82.1%) patients were included in the final analysis and divided into two groups: OW-HTO (96/183; 52.4%) and CW-HTO (87/183; 47.6%). Range of motion, KSS, KOOS scores, and conversion to TKA rate were analyzed between groups. Both groups were comparable regarding age, arthrosis stage, gender, ASA score and BMI at the time of HTO. Survival analysis was conducted with re-intervention for TKA as the end point. Results At the time of HTO, mean age was 55 years +/- 7.9 (27-73.9) with 72.7% of patients being male. The mean follow-up was 13.3 years +/- 2.7 (10-19). Sixty-four (34.9%) patients underwent TKA at a mean delay of 9.3 years +/- 3 (3-16). The conversion to TKA rate was significantly higher in the CW-HTO group versus the OW-HTO group: 42.5% (37/87) versus 28.1% (27/96) (p = 0.04). The survival at 15-year follow-up was 59.2% in the OW-HTO group versus 54.6% in the CW-HTO group (n.s.). At 13-year follow-up, KSS Function score was significantly better in the OW-HTO (90.9 versus 82.4; p = 0.007). No significant difference was observed between the two groups regarding the KOOS score, KSS Knee Score and complication rate. Conclusion At mean follow-up of 13 years, no significant clinical and survivorship difference was observed between the two groups. The conversion to TKA was significantly lower following OW-HTO. Minor correction was associated with risk of requiring subsequent TKA.