Purpose: Limited literature reports on internal and external rotation of the distal fragment in the context of valgus open wedge (OW) high tibial osteotomy (HTO). In the authors clinical observation, the distal fragment was always rotated internally in relation to the proximal fragment by the end of the surgical procedure. The purpose was to evaluate the influence of valgus OW-HTO on post-operative tibial torsion.
Study design: Prospective case series.
Methods: Fifty patients (10 female, 40 male; mean age 42.1 ± 9.4 years) underwent valgus OW- HTO. The osteotomy was spread and fixed with a locking plate at the posteromedial aspect of the proximal tibia. The osteotomy of the tibial tuberosity was performed either proximally or distally dependent on the patello-femoral findings. Two independent observers measured axial tibial rotation using K-wires placed into the anterior margin of the tibia proximal and distal to the osteotomy.
Results: An overall mean of 4.4 ± 2.8° internal rotation of the distal tibia has been shown. In four patients with additional single step double bundle ACL-replacement after harvesting ipsilateral autologous hamstring grafts, the distal tibia rotated internally by 0.1 ± 0.3°, accordingly in the other 46 patients by 4.8 ± 2.6°.
Conclusions: Valgus OW-HTO produces significant internal axial rotation of the distal tibia. This might be caused by soft tissue tension of the medial hamstrings/soft tissue structures and the location of the lateral tibial hinge.
Clinical relevance: Surgeons have to take into consideration that valgus OW HTO might result in significant 3D changes of the tibia. Higher degrees of internal torsion of the tibia might influence overall gait mechanics and specifically alternate patellofemoral kinematics.
Keywords: High tibial osteotomy; Open wedge; Tibial torsion.