Medial Opening Wedge High Tibial Osteotomy for Medial Compartment Overload/Arthritis in the Varus Knee Prognostic Factors

Background: Medial opening wedge high tibial osteotomy (OWHTO) is a widely accepted procedure for the treatment of medial compartment arthritis of the knee. Compared with closing wedge HTO, however, the outcomes of OWHTO reported in the literature are incomplete. Purpose: To identify the positive and negative prognostic factors related to the outcomes of OWHTO through an evaluation of midterm study results and survivorship analysis. Study Design: Case series; Level of evidence, 4. Methods: From January 2001 to December 2009, a total of 141 consecutive OWHTOs were performed in 123 patients. Only patients with symptomatic medial knee overload/arthritis were included. The patients were evaluated preoperatively and at every follow-up visit with (1) the Knee Society score, (2) the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, (3) another self-evaluation scale, (4) long-leg radiographs, and (5) plain radiographs. Preoperative, intraoperative, and postoperative variables were investigated to find an association with the outcomes. Results: Of the 123 patients, 15 were lost to follow-up, and 24 were excluded from the study, leaving 84 patients (99 OWHTOs) for the present study. The mean age of the patients at the time of surgery was 54.5 9.2 years. The mean follow-up was 51.5 +/- 23.8 months. The Knee Society and WOMAC scores significantly improved after surgery (P < .001). The variables significantly related to a poor outcome were (1) age >56 years (P = .008) and (2) postoperative knee flexion <120 degrees (P < .001); the variables significantly related to a good outcome were (1) Ahlback grade 0 arthritis of the medial compartment (P < .001) and (2) excellent preoperative Knee Society score (P < .001). The Kaplan-Meier analysis showed a survival rate of 98.7% at 5 years and 75.9% at 7.5 years. Conclusion: With correct indications, OWHTO is a reliable procedure for medial knee arthritis/overload. The outcomes reported are similar to those from other studies, although the variables related to outcomes are slightly different.