A Comparative Evaluation of Conventional Instrumentation and Accelerometer-Based Navigation in the Practice of a High-Volume Unicompartmental Knee Arthroplasty (UKA) Surgeon

Background: Component malpositioning and joint malalignment following unicompartmental knee arthroplasty (UKA) increase the risk for revision. This study investigates whether accelerometer-based navigation (NAV) decreases radiographic outliers with respect to component placement and joint alignment in comparison to conventional instrumentation in UKA. Methods: A radiographic review of UKAs was performed by a single surgeon following adoption of an accelerometry-guided navigation system (OrthAlign, Aliso Viejo, CA). This cohort was then compared to previous patients undergoing UKA with conventional instrumentation. Six-week postoperative radiographs were used to compare femoral coronal and sagittal angles, tibial coronal and sagittal angles, the net coronal angle, tibial component rotation, and medial tibial overhang. Outliers in implant positioning were compared between groups. Patient variables including age, gender, body mass index, American Society of Anesthesiology, and surgical time (incision until the start of closure) were also compared between groups. Results: Eighty-eight UKA’s were reviewed (49 conventional instrumentation [CI] patients; 39 NAV patients). Using 2-sample t-tests, no significant differences were found in patient demographics, radiographic parameters, and operative times between the CI and NAV cohorts. Using chi-squared tests, no significant difference was found in the number of radiographic outliers between the CI and NAV cohorts. Conclusions: Our study found that a high-volume UKA surgeon achieved a low rate of radiographic outliers in both NAV and CI cohorts. This data suggests that NAV is no different from conventional instrumentation with respect to implant positioning, overall joint alignment, and operative time when used by a high-volume UKA surgeon.