Adding a protective K-wire during opening high tibial osteotomy increases lateral hinge resistance to fracture

Abstract

Purpose It was hypothesized in this in-vitro study that positioning a K-wire intersecting the cutting plane at the theoretical lateral hinge location would limit the cut depth and help preserve the lateral hinge during the opening of the osteotomy. Objectives were (1) to compare the mechanical resistance of the hinge and the protective effect of leaving the K-wire during the opening procedure (2) to check if the K-wire would limit the depth of the osteotomy. Methods An ex-vivo mechanical study, testing 5 pairs of fresh-frozen tibias, was designed. CT-scan based Patientspecific cutting guides were obtained to define the cutting plane and the location of the K-wire at the hinge, using standardized 3D planning protocol. In each pair, OWHTO was performed either with or without the K-wire. To evaluate the hinge's resistance to fracture, the specimens were rigidly fixed at the proximal tibia and a direct load was applied on the free tibial diaphysis to open the osteotomy. The maximum load at breakage, maximum permissible displacement and maximal angulation of the osteotomy before hinge failure was measured. To assess the preservation of an unscathed hinge (protected by the K-wire), the distance from the end of the osteotomy cut to the lateral tibial cortical was measured in mm. Results The maximum load to hinge breakage in the K-wires PsCG knees compared to the control group (48.3 N vs 5.5 N, p = 0.004), the maximum permissible displacement (19.8 mm vs 7.5 mm, p = 0.005) and the maximal angulation of the osteotomy before hinge breakage (9.9° vs 2.9°, p = 0.002) were all statistically superior in the K-wires PsCG knees compared to the control group. A mean distance of 10 ± 1 mm between cut-bone (saw-print) and lateral hinge cortical bone was found post-performing the osteotomy and the hinge failing. ConclusionThe maximum load to breakage and the maximum permissible displacement were, respectively, 880% and 260% higher during the opening of the OWHTO in using K-wires compared to the non-K-wire control group. This confirms the mechanical advantage of using a K-wire for both stabilization and protecting the Hinge during OWHTO. This comparative cadaveric study shows an improvement of the lateral hinges resistance to failing during the opening of the osteotomy. This can be achieved by the placement of a K-wire intersecting the cutting plane at the theoretical location of the lateral hinge.

Hinge location and apical drill holes in opening wedge high tibial osteotomy: A finite element analysis

“…Vertical crack propagation (Type III fractures) is particularly serious as it creates intra‐articular incongruity of the lateral plateau onto which the mechanical axis is being shifted. The risk of lateral fracture at medial opening wedge HTO has been shown to be reduced by inserting K‐wires which cross at the desired hinge location in an experimental cadaveric study 11 . Others have suggested using an apical drill hole for the same purpose 12 .…”

“…The risk of lateral fracture at medial opening wedge HTO has been shown to be reduced by inserting K-wires which cross at the desired hinge location in an experimental cadaveric study. 11 Others have suggested using an apical drill hole for the same purpose. 12 Apical drill holes have been incorporated into the design of proprietary HTO jigs, which can be patient specific, to minimize the risk of iatrogenic fracture in addition to aiding osteotomy accuracy and precision.…”

Adding a protective screw improves hinge's axial and torsional stability in High Tibial Osteotomy

“…The axis of the screw was then defined with an angle of 54°compared to this plane and passing through the middle of hinge fractures during OWHTO, half occurring during the procedure. The main causes seem to be related to a technical error due to a too deep cut decreasing hinge 's thickness (Lee and Moon, 2015)or to an uncontrolled aperture of the osteotomy propagating bone cracks from the end of the osteotomy site to the lateral cortex (Dessyn et al, 2019). The other half fractures occurred post-operatively during the 6 weeks of follow-up despite the use of modern locking plates (Lee et al, 2019)To date, the only hypothesis mentioned in the literature is an increase in the stresses induced by the full weight bearing on an area whose surface has been reduced by the opening-wedge (Schröter et al, 2011), receiving compression and torsion forces, even in the rehabilitation phase.…”

Hinge Location and Apical Drill Holes in Opening Wedge High Tibial Osteotomy: A Finite Element Analysis

“…Vertical crack propagation (Type III fractures) is particularly serious as it creates intra-articular incongruity of the lateral plateau onto which the mechanical axis is being shifted. The risk of lateral fracture at medial opening wedge HTO has been shown to be reduced by inserting K-wires which cross at the desired hinge location in an experimental cadaveric study 12 . Others have suggested using an apical drill hole for the same purpose 13 .…”