Summary

Novel Safety Device Eliminates Neurovascular Injury in Medial-Opening Wedge High Tibial Osteotomy

Abstract

Introduction

Medial open wedge high tibial osteotomy (OWHTO) is an effective treatment for knee osteoarthritis. However, the proximity (15-20 mm) of the neurovascular (NV) structures, specifically the anterior tibial arteriovenous bundle and deep peroneal nerve, to the lateral tibial cortex poses a risk of injury during drilling of the distal hole of the plate for osteosynthesis. We developed the Drill Stopper (DS) to prevent excessive drill penetration beyond the contralateral cortical bone. This study aimed to evaluate the clinical performance of DS, hypothesizing that it would eliminate the risk of NV injury.

Methods

The DS is a small device that attaches to a drill and is used in combination with spacers of various thicknesses. The operation of the DS is as follows: (a) When the drill tip penetrates the medial cortical bone of the tibia and contacts the inner surface of the lateral cortical bone, a spacer is placed on the drill. (b) The DS is moved along the drill until it contacts the spacer and is fixed in place. Then, the spacer is removed from the drill. (c) When drilling through the lateral cortical bone, the drill tip can only advance by the thickness of the spacer, preventing it from reaching the NV bundle. We retrospectively evaluated 332 drillings in four distal holes of a long locking plate in 83 consecutive patients who underwent OWHTO with DS at our institution. The distance "D" (mm) between the drill tip and the lateral cortical bone surface was measured using intraoperative fluoroscopy in the tangential direction of the lateral cortical bone of the tibia. D in the four distal holes was defined as D1, D2, D3, and D4, respectively, from proximal to distal. The primary endpoint was the occurrence of any D value exceeding 15 mm. A value of D > 15 mm indicates possible NV damage and inadequate DS performance. Continuous variables were described as mean (SD) if normally distributed, or median [interquartile range] if not normally distributed. The Shapiro-Wilk test was used to assess for normality. P < 0.05 was considered statistically significant.

Results

Of the 83 cases, 50.6% (42 cases) were female. The median age was 59 [51, 65] years. For the primary endpoint, no cases had D > 15mm (0/332 drillings). There were no clinical findings of NV injury. The overall D value (mm) was 2.1 [1.5, 2.7], with a maximum value of 4.9, which was significantly below 15 mm. The D values (mm) for the four distal holes were: D1 = 1.5 [1.0, 2.1], D2 = 2.0 [1.4, 2.7], D3 = 2.3 (0.9), and D4 = 2.5 (0.8).

Discussion

Our hypothesis was confirmed as the DS effectively prevented deep drilling beyond the contralateral cortical bone. This allows secure bicortical fixation of all four distal screws without NV injury risk, and potentially improves surgical outcomes and provides additional initial stability for high-risk patients, including those who are obese, osteoporotic, or highly active.

Conclusion

The DS demonstrated safety and efficacy in OWHTO, successfully eliminating the risk of injury to the anterior tibial arteriovenous bundle and deep peroneal nerve.