Intramedullary nailing in opening wedge high tibial osteotomy-in vitro test for validation of a method of fixation.

PURPOSE: Opening wedge high tibial osteotomy (HTO) as a treatment in unicompartimental osteoarthritis of the knee can significantly relieve pain and prevent or at least delay an early joint replacement. The fixation of the osteotomy has undergone development and refinements during the last years. The angle-stable plate fixator is currently one of the most commonly used plates in HTOs. The angular stable fixation between screws and the plate offers a high primary stability to retain the correction with early weight-bearing protocols. This surgical technique is performed as a standard of care and generally well tolerated by the patients. Nevertheless, some studies observed that many patients complained about discomfort related to the implant.

METHODS: Therefore, the stability of two different intramedullary nails, a short implant used in humeral fractures and a long device used in tibial fractures for stabilization in valgus HTOs, was investigated as an alternative fixation technique. The plate fixator was defined as reference standard. Nine synthetic tibia models were standardly osteotomized and stabilized by one of the fixation devices. Axial compression was realized using a special testing machine and two protocols were performed: a multi-step fatigue test and a load-to-failure test.

RESULTS: Overall motion, medial, and lateral displacements were documented. Fractures always occurred at the lateral cortex. Axial cyclic loading up to 800 N was tolerated by all implants without failure. The tibia nail provided highest fatigue strength under the load-to-failure conditions.

CONCLUSIONS: The results suggest that intramedullary nailing might be used as an alternative concept in HTO.