Severe varus knees result in a high rate of undercorrection of lower limb alignment after opening wedge high tibial osteotomy.

Abstract

The purpose of this study was to clarify the indication for opening wedge high tibial osteotomy (OWHTO) in terms of lower limb alignment to achieve satisfactory clinical results. Ninety-two patients (98 knees) with medial compartment knee osteoarthritis were investigated in this study. The average follow-up period was 34 months (range, 24-68 months). The average age of the patients at the time of surgery was 63 years (range, 41-77 years). The patients were divided into the following two groups according to the preoperative femorotibial angle (FTA) on anteroposterior full-length radiographs of the lower limbs while weight bearing: 29 knees with a preoperative FTA of ≥185° were defined as those with severe varus (S group), and the remaining 69 knees with a preoperative FTA of <185° were defined as those with mild varus (M group). Knees with a postoperative FTA of >175° were defined as undercorrected. The Lysholm score was used to assess the clinical results. The average postoperative FTA was 175.7° ± 4.1° in the S group and 174.6° ± 3.1° in the M group ( p = 0.013). Significantly, more undercorrected knees were observed in the S than M group ( p = 0.00035). The postoperative Lysholm score was 85.6 ± 8.5 in the S group and 88.5 ± 5.7 in the M group at the last follow-up ( p = 0.0033). Based on these results, we recommend that a preoperative FTA of <185° should be included as a criterion for OWHTO alone.