Lower Limb Length Discrepancy After High Tibial Osteotomy: Prospective Randomized Controlled Trial of Lateral Closing Versus Medial Opening Wedge Osteotomy

Abstract

Background: High tibial osteotomy (HTO) produces valgus limb alignment, and this change can affect lower limb length.

Purpose: To compare the change in lower limb length and the discrepancy compared with the contralateral limb after unilateral lateral closing wedge HTO (CWHTO) and medial opening wedge HTO (OWHTO).

Study design: Randomized controlled trial; Level of evidence, 1.

Methods: In this study, 30 knees undergoing unilateral CWHTO and 30 knees undergoing unilateral OWHTO for medial compartmental osteoarthritis were analyzed with 1-year follow-up. The tibial length, lower limb length, and lower limb length discrepancy were measured preoperatively and 1 year postoperatively. The patients' subjective sensation of, and discomfort due to, the lower limb length discrepancy were recorded 1 year postoperatively. Univariate and multivariate linear regression analyses were conducted to identify predictors related to the change in lower limb length.

Results: The mean lengths of the tibia and lower limb increased significantly after OWHTO (5.2 ± 3.7 and 7.6 ± 2.1 mm, respectively; P < .001). The mean tibial length decreased significantly after CWHTO (-6.0 ± 2.1 mm; P < .001); however, the mean lower limb length change was not significant (-0.8 ± 2.5 mm; P = .073). The mean lower limb length discrepancy increased significantly after OWHTO (-0.5 ± 0.7 to 7.2 ± 2.1 mm; P < .001) but not after CWHTO (-0.7 ± 0.6 to -1.0 ± 2.5 mm; P = .539). A significantly greater proportion of patients in the OWHTO group were aware of (70% vs 20%, respectively; P = .002), and uncomfortable because of (37% vs 7%, respectively; P = .010), the lower limb length discrepancy compared with those in the CWHTO group. The strongest predictor of a change in lower limb length was the wedge length in the OWHTO group and the preoperative hip-knee-ankle angle in the CWHTO group.

Conclusion: The lower limb length change and discrepancy were significant after unilateral OWHTO, whereas they were negligible after unilateral CWHTO. CWHTO was more beneficial in cases of unilateral HTO to minimize the discrepancy of lower limb length rather than OWHTO, particularly in knees requiring a large correction.

Registration: Clinical Trials Registry Platform (protocol number KCT00001684).

Keywords: closing wedge; high tibial osteotomy; lower limb length; lower limb length discrepancy; opening wedge.