HIGH TIBIAL OSTEOTOMY AND ALTERATION OF THE TIBIAL SLOPE, IS THERE A CORRELATION?

High tibial osteotomies are commonly performed for varus/valgus malalignment of the knee. In the past we have been well aware that a high tibial osteotomy corrects the coronal plane but we did not consider changes of the tibial slope. Altering the slope has an impact on the in situ forces of the cruciate ligaments and influences the stability of the knee. The purpose of this study was to investigate the amount of alteration of the tibial slope by a closed wedge osteotomy. From January 2001 to September 2001 we reviewed retrospectively all Xrays of patients that underwent a high tibial osteotomy or were admitted for removal of hardware. 80 patients were included. 67 patients could be followed up. The slope on the preoperative xrays was 6,1 degrees (0–12). A closed wedge osteotomy decreased the slope by a mean of 4,88 degrees. A high tibial osteotomy of six degrees in the coronal plane decreased the slope by 4.29 degrees, a HTO of eight degrees decreased the slope by 7 degrees, a HTO of ten degrees by altered the slope by 4.75 and of twelve degrees by decreased the slope by 6.5 degrees. A closed wedge osteotomy decreases the tibial slope. It is the preferred technique when a combined procedure (HTO and ACL reconstruction) is planned. There is no correlation between the degree of correction of the coronal plane by a closed wedge high tibial osteotomy and changes of the tibial slope.