Appropriate hinge position to prevent hinge fracture in open wedge distal tuberosity tibial osteotomy.

PURPOSE

Open wedge distal tuberosity tibial osteotomy (owDTO) is an effective treatment for varus knee osteoarthritis. Hinge fracture is a major complication, and hinge position is a contributing factor. This study aimed to investigate the relationship between hinge position and fractures.

METHODS

This study examined 42 knees that underwent owDTO. The level of the proximal tibiofibular joint (PTFJ) hinge fracture was investigated on postoperative computed tomography (CT) images measuring the distances and angles around hinge area. Based on previous reports, the hinge position was classified, and hinge fractures were assessed.

RESULTS

No cases were found with a hinge position above PTFJ, 41 cases were within PTFJ, and one case was distal to PTFJ. Hinge fractures were observed in 10 patients (23.8%). According to the hinge position classification, seven cases were type I (a fracture within PTFJ), three were type II (a fracture that reaches the distal portion of PTFJ), and no cases were type III (intra-articular fracture). The anteroposterior hinge width measured perpendicular to the descending cut of the flange on axial CT images at the proximal level of the PTFJ was significantly shorter in the hinge fracture group ( = 0.03).

DISCUSSION

The owDTO hinge fracture rate in our study was comparable to that in previous reports on open wedge high tibial osteotomy. As the risk of hinge fracture increases with the shortening of the anterior-posterior hinge width, our results indicate that preservation of the anterior-posterior hinge width may help reduce hinge fractures.

LEVEL OF EVIDENCE

Level III, Retrospective study.