Summary

Although the TomoFix plate provides biomechanically stable fixation but its too large and long size can be result in local irritation and superficial wound problem frequently. So under special condition, OhtoFix plate which is slightly thin and more anatomically pre-contoured to fit the anteromedial proximal tibia seems to be a good alternative choice in using HTO for small patients

Abstract

Background

A stable initial fixation and maintenance of its stability are very important for safe healing of the osteotomy site to minimize the risk of nonunion and loss of correction. TomoFix plate has been widely used due to its superior biochemical stability and various studies have reported favorable outcomes of HTO using the TomoFix plate. Although the TomoFix plate provides biomechanically stable fixation, it is too long, large and thick than other implants, so it can be relatively bulky long fixative device for small patients.

Purpose

The purpose of this study was to evaluate a retrospective clinical and radiographic outcomes after opening wedge HTO using two different locking plates, OhtoFix (Ohtomedical Co.Ltd., Goyang, Korea) and TomoFix (DePuy Synthesis, West Chester, PA, USA)

Methods

From March 2014 to April 2015, a total 64 patients with medial osteoarthritis who underwent a HTO were retrospectively reviewed. We performed 31 HTOs with the Ohtofix plate (group A) and 33 HTOs with the TomoFix plate (group B). The minimum follow-up period was 15 months. The clinical functional outcomes were assessed by Lysholm, IKDC score and severity of pain was assessed on a VAS score. Radiographic results were examined by measuring mechanical tibiofemoral angle (mTFA) preoperatively and at the time of final follow-up. And the time to bone union was assessed. In addition, we evaluated the complications related to the implant in each group. Implant-related complications included metal irritation by pressing on nearby structure, superficial wound healing problem, loss of correction, nonunion , and fracture of the lateral hinge.

Results

The demographic features and preoperative degree of varus deformity(mTFA: group A, -8.4º±2.8º vs group B, -8.2º±3.1º; P=.235) did not differ significantly between the 2 groups. At the latest follow-up, the mean mTFA was 1.4º±2.2ºin group A and 1.6º±2.3ºin group B (P=.367). All clinical parameters including VAS score, Lysholm and IKDC scores improved significantly postoperatively, but there were no differences between two groups.
We found a total complication rates of 13% in group A and 18% in group B. (P=.024) and implant-related complication rates of 6.4% in group A and 15.1% in group B (P=.039).
Implant-related complications included 2 correction loss in group A and 3 implant irritation and 1 wound healing problem, 1 correction loss in group B. Other complications included 1 sensory nerve injury, 1 flexion contracture in group A and 1 mal-alignment(valgus deformity) in group B. The average time to bone union was 10.8 weeks in group A and 11.3 weeks in group B(p=.452)

Conclusions

We have shown a more high plate-related complication rate during a short-term follow-up period after opening-wedge HTO using the TomoFix plate compared with OhtoFix plate. Although the TomoFix plate provides biomechanically stable fixation but its too large and long size can be result in local irritation and superficial wound problem frequently. So under special condition, OhtoFix plate which is slightly thin and more anatomically pre-contoured to fit the anteromedial proximal tibia seems to be a good alternative choice in using HTO for small patients.