Disparity between Preoperative Target Correction Amount and Postoperative Correction Amount in Open Wedge High Tibial Osteotomy

Abstract

Purpose: The purpose of this study was to evaluate the disparity between the preoperative target correction amount and the postoperative correction amount in open wedge high tibial osteotomy (OWHTO) in patients divided according to the planned osteotomy gap.

Materials and methods: Seventy-two patients were divided into two groups (group 1 with the planned opening gap lager than the mean opening gap length of total patients and group 2 with a smaller opening gap). The opening gap was determined according to the target weight bearing line (WBL) ratio on the preoperative whole leg radiograph. Absolute and relative values of the disparity between the target and postoperative WBL ratios were compared between groups in order to clarify whether the disparity was deviated toward over- or under-correction.

Results: The absolute value of disparity between the target and postoperative WBL ratios in group 1 was significantly larger than that in group 2 (6.01%±5.68% vs. 3.32%±3.38%; p=0.02). However, there was no statistically significant difference in relative values between groups (p=0.54).

Conclusions: The postoperative WBL ratio after OWHTO was different from the preoperative target WBL ratio if the planned osteotomy gap was large. This mismatch was not deviated toward one side, either over- or under-correction.

Keywords: Knee; Osteoarthritis; Osteotomy; Varus deformity.

Fig. 1

Preoperative target weight bearing line (WBL) ratios (55.0%, 57.5%, 60.0%, 62.5%, 65.0%, and 67.5%) and the heights of opening gap at the osteotomy sites.

Fig. 2

The height of the opening gap was adjusted according to the preoperative plan and intraoperative status of the medial compartment.

Fig. 3

Radiographs of a 59-year-old male showing a difference of 5.3% between the preoperative target weight bearing line (WBL) ratio and postoperative WBL ratio (65.0%–59.7%).