ISAKOS: 2019 Congress in Cancun, Mexico
ISAKOS

2019 ISAKOS Biennial Congress ePoster #1222

 

Survival Analysis of Medial Open Wedge High Tibial Osteotomy for Medial Unicompartment Knee Osteoarthritis

Seung-Min Na, MD, Gwangju KOREA, REPUBLIC OF
Eun-Kyoo Song, MD, PhD, Prof., Gwangju KOREA, REPUBLIC OF
Jong-Keun Seon, MD, PhD, Hwasun, Jeonnam KOREA, REPUBLIC OF
Hyeon-Wook Ahn, MD, Gwangju KOREA, REPUBLIC OF

Chonnam National University Hospital, Gwangju, KOREA, REPUBLIC OF

FDA Status Cleared

Summary

The MOWHTO provided good survival at mid- to long-term follow-up. Old age, high-grade cartilage injury on medial and lateral compartments, and under-correction of postoperative HKA angle appeared to be significant factors associated with failure after MOWHTO.

Abstract

Background

The purpose of this study was to evaluate the survival rates and analyze the factors that affect the survival rate after primary treatment with medial open wedge high tibial osteotomy (MOWHTO) for medial unicompartmental osteoarthritis of the knee.

Methods

In this retrospective study, 339 knees out of 391 knees treated with MOWHTO between October 2003 and December 2010 at our institute, were included after a minimum follow-up period of five years. Clinical evaluation using Knee Society Score (KSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and radiographic evaluation including mechanical axis (Hip-Knee-Ankle angle) were done preoperatively and postoperatively. The main failure criteria for survival included the conversion to total knee replacement or KSS<60 points. Further, risk factors that affected the survival after MOWHTO were analyzed.

Results

The mean KSS and WOMAC scores were significantly improved after surgery (87.3 and 18.5 at 5 years and 81.7 and 23.6 at 10 years, respectively). The mean HKA angle was corrected from 7.2° varus to 3.4° valgus after 1 year of surgery, which remained until 10 years after surgery without significant differences (2.9° valgus at 5 years and 2.3° valgus at 10 years, p>0.05). Using the Kaplan-Meier survival estimates, the probability of survival for MOWHTO was 96.8% at 5 years, 87.1% at 10 years, and 85.3% at 13 years. Multivariate regression analysis revealed that age=65 years (HR=2.52, p=0.034), medial compartment cartilage injury ICRS grade=4 (HR=3.13,24 p=0.004), lateral compartment cartilage injury ICRS grade=2 (HR=3.63, p=0.003), postoperative HKA angle<0° (HR=3.01, p=0.003) were associated with failure.

Conclusion

The MOWHTO provided good survival at mid- to long-term follow-up. Old age, high-grade cartilage injury on medial and lateral compartments, and under-correction of postoperative HKA angle appeared to be significant factors associated with failure after MOWHTO.