Computer navigation versus standard instrumentation for TKA: a single-surgeon experience.

UNLABELLED: Component alignment errors in total knee arthroplasty greater than 3 degrees can be associated with poorer outcomes. This retrospective study seeks to determine if computer navigation can improve accuracy of component alignment in comparable patient populations. The efficiency and safety of the navigated technique is also evaluated. Fifty total knee arthroplasties done using an imageless navigation system and 50 cases using standard instrumentation were compared. The same surgeon used a single system (Zimmer-Natural Knee) in all cases. Long-standing radiographs collected at 6-week followup were measured for component orientation. When the navigation system was used 98% (49 of 50 cases) of all femoral components and 100% (50 of 50 cases) of all tibial components were placed within +/- 3 degrees of the radiographic goal position. There was a decrease in the standard instrumentation group to 90% (45 of 50 cases) and 92% (46 of 50 cases) within +/- 3 degrees , respectively. There was a difference in the standard deviations observed for the navigated cases and the conventional cases when femoral and tibial component position was considered. Average tourniquet time was 68 minutes in the navigated group and 57 minutes in the conventional group. There were no technique specific complications associated with the navigation system. This system affords the surgeon the potential to reduce outliers with regard to component position without an increase in complications. Tourniquet times were increased with the use of the computer. LEVEL OF EVIDENCE: Therapeutic study, Level III-1 (retrospective comparative study). See the Guidelines for authors for a complete description of levels of evidence.