Navigated open-wedge high tibial osteotomy: advantages and disadvantages compared to the conventional technique in a cadaver study

High tibial osteotomy (HTO) is an established therapy for the treatment of symptomatic varus malaligned knees. A main reason for disappointing clinical results after HTO is the under- and overcorrection of the mechanical axis due to insufficient intraoperative visualisation. Twenty legs of fresh human cadaver were randomly assigned to navigated open-wedge HTO (n = 10) or conventional HTO using the cable method (n = 10). Regardless of the pre-existing alignment, the aim of all operations was to align the mechanical axis to pass through 80% of the tibial plateau (beginning with 0% at the medial edge of the tibial plateau and ending with 100% at the lateral edge). This overcorrection was chosen to ensure a sufficient amount of correction. Thus, the medial proximal tibia angle (MPTA) increased by 9.1 +/- 2.9 degrees (range 5.2 degrees-12.3 degrees) on the average after navigated HTO and by 8.9 +/- 2.9 degrees (range 4.7 degrees-12.6 degrees) after conventional HTO. After stabilization with a fixed angle implant, the alignment was measured by CT. After navigated HTO, the mechanical axis passed the tibial plateau through 79.7% (range 75.5-85.8%). In contrast, after conventional HTO, the average intersection of the mechanical axis was at 72.1% (range 60.4-82.4%) (P = 0.020). Additionally, the variability of the mean corrections was significantly lower in the navigated group (3.3% vs. 7.2%, P = 0.012). Total fluoroscopic radiation time was significantly lower in the navigated group (P = 0.038) whereas the mean dose area product was not significantly different (P = 0.231). The time of the operative procedure was 23 min shorter after conventional HTO (P < 0.001). Navigation systems provide intraoperative 3-dimensional real time control of the frontal, sagittal, and transverse axis and may increase the accuracy of open-wedge HTO. Future studies have to analyse the clinical effects of navigation on corrective osteotomies.