Minimally invasive imageless computer-navigated knee surgery: initial results.

The combination of imageless computer-aided surgery (CAS) and minimally invasive surgery (MIS) for total knee arthroplasty (TKA) has not been reported. This study presents the initial 30 procedures in which imageless CAS was combined with MIS for TKA by the senior author. Coronal alignment of femoral and tibial components with respect to the mechanical axis of the lower limb was measured when patients could achieve full extension. Component position was acceptable for all implants. The mean coronal tibial alignment was 90.35 degrees (range, 88 degrees -93 degrees ) and mean coronal femoral alignment 90.10 degrees (range, 88 degrees -93 degrees ) to the mechanical axis. Tourniquet time averaged 90 minutes (range, 60-118 minutes). There was no significant reduction in tourniquet time with increasing familiarity with the technique. Our results demonstrate that CAS combined with MIS for TKA maintains the accuracy of component alignment despite the minimally invasive approach. These initial results demonstrate no significant learning curve associated with the technique.