Abstract

Purpose:

This study aimed to evaluate the relationship between post-operative knee adduction moment (KAM) and patient-reported outcome measures (PROMs) after medial opening wedge high tibial osteotomy (MOWHTO).

Methods:

A retrospective analysis was conducted on 40 patients who underwent MOWHTO. Radiographic assessments, including hip–knee–ankle angle, were performed pre-operatively and 6 months post-operatively. Dynamic three-dimensional gait analysis was conducted pre-operatively and at 6 months to measure KAM 1st peak. PROMs were evaluated using the WOMAC total score pre-operatively and at 12 months. Pearson correlation analysis examined the relationship between post-operative KAM 1st peak and ΔWOMAC total score. Receiver operating characteristic (ROC) analysis was performed as an exploratory analysis to assess the relationship with the minimal clinically important difference (MCID).

Results:

KAM 1st peak significantly decreased by 53% post-operatively (p < 0.001). A significant positive correlation was observed between post-operative KAM 1st peak and ΔWOMAC total score (r = 0.325, p = 0.020). Exploratory ROC analysis suggested a potential threshold of 25.7 Nm for achieving the MCID.

Conclusion:

While reducing KAM is a primary goal of MOWHTO, excessively low post-operative KAM values may be associated with reduced improvements in PROMs. These findings suggest that achieving an optimal range of correction, rather than simply minimizing KAM, may be important for optimizing post-operative outcomes and highlight the potential value of incorporating dynamic biomechanical assessment.

What are the new findings?

• Post-operative knee adduction moment (KAM) was significantly associated with improvements in patient-reported outcomes following medial opening wedge high tibial osteotomy (MOWHTO).

• KAM was reduced by 53% after surgery, demonstrating effective unloading of the medial compartment during walking.

• Greater correction was not always associated with better outcomes. Patients with excessively low post-operative KAM showed smaller improvements in pain and function, suggesting that overcorrection may be detrimental.

• An optimal range of correction may be more important than maximising correction, supporting a personalised approach to alignment rather than a "more is better" philosophy.

• Dynamic gait analysis may complement conventional radiographic assessment, providing additional insight into post-operative biomechanics and patient outcomes after MOWHTO.

*Corresponding author.

Sydney Orthopaedic Research Institute
Level 2, 500 Pacific Highway
St Leonards, Sydney, 2065
Australia
Tel: +61 2 9904 7182
E-mail address: koumei.01.13@gmail.com (T. Hiranaka).

https://doi.org/10.1016/j.jjoisr.2026.05.003

Received 22 January 2026; Received in revised form 8 May 2026; Accepted 31 May 2026 2949-7051/© 2026 The Author(s).

Published by Elsevier B.V. on behalf of The Japanese Hip Society, The Japanese Society for Replacement Arthroplasty and The Japanese Knee Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).