Comparison of the outcome between unilateral and bilateral open wedge high tibial osteotomy in the bilateral varus knees.

INTRODUCTION: Bilateral open wedge high tibial osteotomy (OWHTO) can be performed in a staged manner to enable the healing and rehabilitation of each limb separately after surgery. However, the effects of staged bilateral OWHTO on the pattern of recovery and changes over time for each limb have not been established. Additionally, there is a lack of information regarding the optimal timing for staged surgery.

METHODS: Twenty-two patients (44 knees) in the bilateral OWHTO group and 42 patients (42 knees) in the unilateral OWHTO group were analyzed. Clinical and radiological results were evaluated and compared between the two groups. For the alignment change assessment, the hip-knee-ankle (HKA) angle and weight-bearing line (WBL) ratio were measured preoperatively and at postoperative 6 weeks, 3 months, 6 months, and 1 year.

RESULTS: The correction loss of HKA angle in the bilateral OWHTO group was significantly larger than that in the unilateral OWHTO group (0.5° ± 1.4° vs 1.3° ± 2.0°, p = 0.049). The correction loss of WBL ratio was significantly greater in the patients with staged bilateral OWHTO within a 3-month interval compared to those with staged bilateral OWHTO in an interval longer than 3 months (WBL ratio; 7.5% vs 2.1%, p = 0.01). There was no significant difference in the clinical scores and range of motion at the last follow-up.

CONCLUSION: The smaller loss of correction in the unilateral OWHTO group occurred compared to the bilateral OWHTO group. Additionally, surgeons should keep in mind that the amount of correction loss may be greater if staged bilateral OWHTO is performed at intervals of 3 months or less.