Biomechanical influence of hinge wire application and removal in medial opening wedge high tibial osteotomy: A...

To compare tensile strain changes on the lateral tibial cortex during the opening procedure of medial opening wedge high tibial osteotomy (MOWHTO) with and without hinge wire, and to evaluate strain changes after hinge wire removal.

MOWHTO was performed on five pairs of fresh-frozen human cadaveric knees (10 knees in total), which were allocated into two groups: with a hinge wire (n = 5) and without a hinge wire (n = 5). A uniaxial strain gauge was attached to the lateral tibial cortex to measure tensile strain, with negative values indicating compression and positive values indicating tension. All procedures were guided by a 3D-printed patient-specific cutting guide with a target opening gap of 9 mm, and fixation was completed using a locking plate. Tensile strain during the opening procedure was compared between groups, and strain before and after wire removal was assessed in the hinge wire group.

In four out of five matched pairs, the hinge wire group exhibited smaller tensile strain changes during opening than the contralateral group without a hinge wire. During the opening procedure, the median tensile strain change was -267 με (range: -2390 to -213 με) in the hinge wire group and -753 με (range: -1889 to -383 με) in the without hinge wire group (p = 0.345). Following hinge wire removal, the median strain change was minimal (44 με; range: 21-72 με).

The hinge wire group showed smaller tensile strain changes during the opening procedure in most specimens, though the difference was not statistically significant. These findings provide preliminary biomechanical evidence suggesting that the hinge wire may serve as a protective method against fracture of the lateral hinge during MOWHTO, and that its removal after the plate fixation does not compromise lateral cortex stability.

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