2023 ISAKOS Biennial Congress ePoster
What is an Acceptable Limit of Weight Bearing Line Ratio Following Medial Open Wedge High Tibial Osteotomy. (2015.2 ~ 2020.3)
Ryu Kyoung Cho, MD, Seoul KOREA, REPUBLIC OF
Man-Soo Kim, MD, PhD, Seoul KOREA, REPUBLIC OF
Keun Young Choi, MD, Seoul KOREA, REPUBLIC OF
Dongho Kwak, MD, Seoul KOREA, REPUBLIC OF
Sungcheol Yang, MD, Seoul KOREA, REPUBLIC OF
Hyukjin Jang, MD, Seoul KOREA, REPUBLIC OF
Yong In, MD, PhD, Seoul KOREA, REPUBLIC OF
The Catholic University of Korea Seoul ST. MARY`s Hospital, Seoul, KOREA, REPUBLIC OF
FDA Status Not Applicable
Summary
The acceptable range of WBL ratio of MOWHTO can be more flexible than 55-70%. The WBL ratio did not have a negative effect on the PROMs 2 years after MOWHTO, up to 49.3% using MCID and 51.1% using SCB
ePosters will be available shortly before Congress
Abstract
What is an acceptable limit of weight bearing line ratio following medial open wedge high tibial osteotomy. (2015.2 ~ 2020.3)
Background
It is well known that accuracy of correction is the most important factor in determining successful results after medial open wedge high tibial osteotomy (MOWHTO). Undercorrection and overcorrection are associated with poor clinical outcomes. However, in various studies, the target range of postoperative alignment has been reported in various ways. In the case of weight bearing line (WBL), it is generally reported that the Fujisawa point of 62.5% is the target. Acceptable ranges vary from study to study. The target range is sometimes defined as 50-70% or more strict and set to 55-70%, but there is still a lack of research on this. The purpose of this study is to investigate the effect of postoperative WBL ratio on patient reported outcome measures (PROMs) after MOWHTO and to determine an acceptable range of WBL ratio based on PROMs.
Methods
Among patients with medial compartment knee OA who underwent MOWHTO, 226 patients who were followed-up for 2 years were retrospectively reviewed. The acceptable range of the postoperative WBL ratio was divided into two categories: 50-70% and 55 - 70%, respectively. According to the WBL ratio, it is divided into three groups: undercorrection, normocorrection, and overcorrection. The clinical outcomes of each group were compared by evaluating Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores. The achievement rates of WOMAC the minimal clinically important differences (MCID) and substantial clinical benefit (SCB) were also compared. The receiver operating characteristics (ROC) curve was used to evaluate whether the WBL ratio could discriminate the achievement of WOMAC MCID and SCB, which means the acceptable limit of WBL ratio.
Results
As a result of dividing the acceptable range as a WBL ratio by 50-70% and 55-70%, there was no difference in the preoperative WOMAC subscores between the three groups. However, there was a significant difference in WOMAC subscores (pain, function, and total) between the three groups at 2 years after surgery (all p < 0.05). The under- and overcorrection group showed significantly inferior WOMAC pain, function, and total scores compared to the normocorrection groups (all p < 0.05). There was no significant difference of WOMAC scores between the under- and overcorrection groups. The under- and overcorrection group showed significantly inferior results than the normocorrection groups in MCID and SCB achievement rates (all p < 0.05). The lower limit of WBL ratio of the ROC curve using MCID was 49.3% (AUC 0.674, p < 0.01) and the cut-off value using SCB was 51.1% (AUC 0.644, p < 0.01).
Conclusions
The acceptable range of WBL ratio of MOWHTO can be more flexible than 55-70%. The WBL ratio did not have a negative effect on the PROMs 2 years after MOWHTO, up to 49.3% using MCID and 51.1% using SCB.