Comparative Study of Opening-Wedge High Tibial Osteotomy With and Without a Combined Computed Tomography-Based and Image-Free Navigation System

Purpose: To assess whether a combined computed tomography (CT) ebased and image-free navigation system results in better coronal and sagittal alignment than the conventional method for performing opening-wedge high tibial osteotomy (OWHTO) and whether CT-based navigation results in acquisition of an accurate osteotomy plane. Methods: Sixty-two consecutive knees were randomly divided into navigated and conventional groups. The intraoperative correction angle was determined by the change in hip-knee-ankle angle in the navigated group and by the predicted medial opening width in the conventional group. Outliers of femorotibial angle (FTA) and tibial posterior slope (TPS) were defined as angles of > 175 degrees or < 165 degrees and angles of > 2.5 degrees or < -2.5 degrees, respectively. Radiographic and clinical data were compared between the 2 groups at 2 years postoperatively. Results: Mean postoperative FTAs were 168.5 degrees in the navigated group and 168.1 degrees in the conventional group. Mean change in TPS of -0.2 degrees in the navigated group was significantly lower than that of 1.6 degrees in the conventional group (P =.005). On postoperative CT, mean angle between the tibial plateau and osteotomy planes in the sagittal plane showed a significantly higher anterior opening of 12 degrees in the conventional than in the navigated group (P <.001). There was a significantly greater proportion of TPS outliers in the conventional (51.6%) than in the navigated group (12.9%) (P =.001), and a significantly greater proportion within the normal range in both planes in the navigated (74.2%) than in the conventional group (48.4%) (P =.037). Conclusions: Combined CT-based and image-free navigation in OWHTO better preserves the original TPS and more frequently restores normal coronal and sagittal plane knee joint alignment. CT-based navigation also enabled acquisition of our target osteotomy plane in the sagittal plan. The navigation system in OWHTO was helpful for simultaneous control of the alignment in 2 planes. Level of Evidence: Level II, lesser-quality prospective randomized trial.