Biomechanical comparison between high tibial osteotomy (HTO) and combined HTO and fibular osteotomy

The ojectives of this study were to determine the changes in the lateral ligamentous stability of knee joint that occur after performing high tibial osteotomy with and without fibular osteotomy. Utilizing cadaveric specimens, lateral ligamentous stability was assessed by calculating the length of the lateral collateral ligament, and the lateral opening at different flexion angles when varus stress was applied to the tibia. The Polhemus 3-SPACE system was used to collect motion data describing the six-degrees-of-freedom three-dimensional tibiofemoral motions. It was found that the separation distance between the two attachment points of the lateral collateral ligament decreased by an average of 5 mm at all flexion angles after performing a 5-degree valgus high tibial osteotomy. Performing an additional 5-degrees of osteotomy caused this distance to further decrease. It was further found that performing a fibular osteotomy following a 5-degree valgus high tibial osteotomy produced no changes in the length of the lateral collateral ligament. It was also found that the lateral opening increased an average of 5 mm at all flexion angles after performing a 5-degree valgus high tibial osteotomy. Performing a 10-degree osteotomy caused a further increase in the lateral opening. It was further found that performing a fibular osteotomy following a 5-degree valgus high tibial osteotomy caused the lateral opening to return to its original value. That is to say, the fibular osteotomy negated the lateral opening caused by the tibial osteotomy and produced a pattern of lateral opening similar to the one found in the intact knee.