2017 ISAKOS Biennial Congress ePoster #1526

 

Intraoperative Adjustment Of Alignment Under Valgus Stress Reduces Outliers In Patients Undergoing Medial Opening-Wedge High Tibial Osteotomy

Sueen Sohn, MD, Prof., Seoul KOREA, REPUBLIC OF
Man-Soo Kim, MD, PhD, Seoul KOREA, REPUBLIC OF
Yong In, MD, PhD, Seoul KOREA, REPUBLIC OF
In Jun Koh, MD, PhD, Prof., Seoul KOREA, REPUBLIC OF
Young Jun Choi, MD, Seoul KOREA, REPUBLIC OF
Keun Young Choi, MD, Seoul KOREA, REPUBLIC OF

Seoul St. Mary's Hospital, Seoul, Seoul, KOREA, Seoul, KOREA, REPUBLIC OF

FDA Status Cleared

Summary

Intraoperative adjustment of alignment under valgus stress significantly reduced outliers compared to a technique that corrected alignment using preoperative planning and cable method in patients undergoing medial opening-wedge high tibial osteotomy.

Abstract

Introduction

Satisfactory clinical outcomes are associated with proper correction of the deformity in medial opening wedge high tibial osteotomy (MOWHTO). Therefore, accurate preoperative planning and precise intraoperative adjustment are the key factors to achieve satisfactory alignment of the lower limb after MOWHTO. There have been various preoperative planning methods and surgical techniques to improve correction accuracy of MOWHTO. However, a considerable percentage of outliers with under- or over-correction continue to be reported despite precise preoperative planning and cautious intraoperative correction of lower limb alignment. The purpose of this study was to determine whether our novel technique of intraoperative assessment of alignment and adjustment under valgus stress reduces outliers in patients undergoing MOWHTO compared to the conventional technique, which corrects the alignment according to preoperative planning and cable method.

Methods

In this case-control study, 118 consecutive knees (112 patients) underwent MOWHTO and were enrolled. The first 53 knees (52 patients) were corrected according to preoperative planning using the Dugdale method with modification through intraoperative cable method (group 1: Control group). In the latter 65 knees (60 patients), the angle was corrected using the Dugdale method, and limb alignment was adjusted using intraoperative cable method by applying valgus stress to the knee joint (group 2: Case group). The postoperative weight bearing line (WBL) ratios and mechanical axis of the lower limb were measured and compared. The acceptable range of postoperative coronal alignment was defined as 55 - 70% of the WBL ratio from the medial margin of the tibia.

Results

Significant reduction in outliers was detected in group 2 compared to that in group 1 (outlier percentage: group 1 = 56.6%, group 2 = 15.4%, p < 0.001). Twenty of the 53 knees (37.7%) were under-corrected in group 1, whereas six of 65 knees (9.2%) were under-corrected in group 2 (p < 0.001). Ten of 53 knees (18.9%) were over-corrected in group 1, and four of 65 knees (6.2%) were over-corrected in group 2 (p < 0.001). After correcting the angle using the Dugdale method in group 2, 29 of 65 knees (44.6%) required additional adjustment of alignment under valgus stress. Additional opening of the correction angle was needed in 19 knees and further closing of the correction angle was needed in 10 knees. Fifteen of 19 knees (78.9%) that needed an increase in the correction angle obtained normo-correction postoperatively, whereas seven of 10 knees (70.0%) that needed a decrease in the correction angle acquired normo-correction postoperatively.

Discussion

& Conclusions: Intraoperative adjustment of alignment under valgus stress significantly reduced outliers compared to a technique that corrected alignment using preoperative planning and cable method in patients undergoing MOWHTO.