# A Retrospective Study of Predictive Factors and Functional Outcomes of Medial Opening Wedge High Tibial Osteotomy for Varus Medial Compartment Knee Osteoarthritis: Insights From a Resource-Limited Setting

## TL;DR

This study evaluates the effectiveness of a surgical procedure for knee osteoarthritis in a resource-limited setting and identifies age and BMI as key factors affecting outcomes.

## Contribution

The study identifies age and BMI as significant predictors of failure in medial opening wedge high tibial osteotomy for knee osteoarthritis in a low-resource context.

## Key findings

- MOWHTO significantly improved knee function scores in patients with varus medial compartment knee osteoarthritis.
- Advanced age and higher BMI were found to be significant predictors of surgical failure.
- 90.2% of patients had successful outcomes, while 9.8% experienced failure requiring further surgery.

## Abstract

Introduction: Medial opening wedge high tibial osteotomy (MOWHTO) represents a well-established surgical intervention for varus malalignment associated with medial compartment knee osteoarthritis (KOA). Given the increasing prevalence of KOA, particularly within aging populations, a thorough evaluation of effective therapeutic strategies is paramount. This study aimed to identify predictors of MOWHTO failure and assess the functional outcomes of this procedure in a resource-limited setting, thereby informing clinical decision-making and optimizing patient care.

Materials and methods: This retrospective study analyzed the outcomes of MOWHTO performed on adult patients diagnosed with KOA and varus deformity at two hospitals in Sana'a, Yemen, between October 2019 and April 2023. Data pertaining to demographics, preoperative characteristics, intraoperative details, radiographic findings, and postoperative parameters were meticulously collected and analyzed. Clinical outcomes were evaluated using the American Knee Society Functional Score (AKSFS), the Clinical American Knee Society Score (CAKSS), and the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index. Multivariate regression analysis determined the associations between patient-specific factors and MOWHTO failure, defined as conversion to unicompartmental or total knee arthroplasty.

Results: A cohort of 102 patients underwent MOWHTO, with a mean follow-up duration of 24.4 ± 7.0 months. The mean age of the patient population was 42.6 ± 8.2 years, with a female predominance (n=69, 67.6%). Disease severity, as per the Kellgren-Lawrence classification, was graded as follows: grade 1 in 19 (18.6%) knees, grade 2 in 48 (47.1%) knees, grade 3 in 22 (21.6%) knees, and grade 4 in 13 (12.7%) knees. Postoperatively, statistically significant improvements were observed in the mean AKSFS, CAKSS, and WOMAC scores at the final follow-up compared to preoperative values (all p<0.05). Post-surgical complications included pin-tract infections (n=5, 4.9%) and lateral cortex fractures (n=4, 3.9%). Overall, 92 (90.2%) knees demonstrated successful outcomes, while 10 (9.8%) were classified as failures. Multivariate analysis revealed that advanced age (OR: 1.89; 95% CI: 1.02-3.50, p=0.043) and higher body mass index (BMI) (OR: 2.40; 95% CI: 1.13-5.10, p = 0.022) were significant predictors of surgical failure.

Conclusions: This study confirms that MOWHTO improves clinical outcomes for varus medial compartment KOA, especially in younger patients with a normal BMI, demonstrating its potential in resource-limited settings. These findings highlight the importance of considering age and BMI in treatment decisions; future prospective research is warranted to refine patient selection criteria and expand the applicability of MOWHTO.