The effect of distal tibial rotation during high tibial osteotomy on the contact pressures in the knee and ankle joints

Intraoperative fracture of the lateral cortex fractures of the tibia is a potential complication of high tibial osteotomy (HTO), which may result in inadequate rotational alignment of the distal tibia. Our aim was to determine how rotational malalignment of the distal tibial segment distal would affect intraarticular contact pressure distribution in the knee and ankle joints. A medial, L-shaped opening-wedge HTO was performed on seven human lower body specimens. A stainless steel device with integrated load cell was used to axially load the leg. Pressure-sensitive sensors were used to measure intraarticular contact pressures. Intraoperative changes in alignment were monitored in real time using computer navigation. Measurements were performed in the native knee alignment, after 10A degrees and 15A degrees of alignment correction and with the distal tibia fixed at 15A degrees of external rotation. Moderate-to-large alignment changes after medial opening-wedge HTO resulted in a shift in intraarticular contact pressures from the medial compartment of the knee towards the lateral compartment. However, fixation of the distal tibial segment at 15A degrees of external rotation neutralized this intended beneficial effect. In the ankle, external rotation of the distal tibia also caused a reduction in contact pressures and tibiotalar contact area. Malrotation of the distal tibial fragment negates the intended effect of offloading the diseased compartment of the knee, with the contact pressures remaining similar to those of the native knee. Furthermore, malrotation leads to abnormal ankle contact pressures. Care should be taken to ensure appropriate rotational alignment of the distal tibial segment during intraoperative fixation of HTO procedures.