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° (P < .001); the variables significantly related to a good outcome were (1) Ahlbäck 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.