Midterm follow-up results of two different types of implants in opening wedge high tibia osteotomy

Background This retrospective study investigated the midterm results of medial opening wedge high tibia osteotomy, with a monoplanar or a biplanar osteotomy using two types of implant system. Methods Osteotomies were performed on 241 knees (231 patients). The mean follow-up period was 6.0 years (SD 3.0, range 0.2–12.8 years). Two types of implant system were used, a precountered non-locking plate (PP) (n = 74) and a precountered locking plate (LP) (n = 167). A Kaplan-Meier cumulative survival curve and a Cox regression model were used to analyse and revise survival and risk factors. Results Cumulative survival estimates for LP were 80% at 5 years, and 64% at 10 years (SE = 0.4, CI 95%: 9.0–10.5), and for PP, they were 68% at 5 years and 49% at 10 years (SE = 0.5, CI: 95% 6.3–8.2) (p = 0.024). The revision rate was 26% (44/167) for the LP group, and 47% (35/74) for the PP group (p = 0.001). Reoperations on LP osteotomies occurred for the tibial monoplanar cut and biplanar cut groups, in 19/52 (37%) and 25/167 (16%) osteotomies, respectively (p = 0.04). Our Cox regression model showed that PP had a higher risks (RR = 1.7; CI: 95% 1.1–2.6) of revision, when compared with LP (p = 0.026). Conclusions The risk of revision for any reason and that of early conversion to total knee arthroplasty (TKA) after high tibia osteotomy were significantly increased for PP, when compared with LP.