A Navigated 8-in-1 Femoral Cutting Guide for Total Knee Arthroplasty : Technical Development and Cadaveric Evaluation

The goals of this study were to determine the precision of femoral component placement using a novel computes assisted surgery (CAS)-enabled 8-in-1 cutting guide in cadaver limbs and to identify errors generated at various stages of the cutting process. The cutting guide placement was on average within 1° or millimeter of the target position in the varus/valgus, axial rotation, and cut height directions and within 2° or millimeters, in all other directions. The difference between the desired femoral component and the impacted trial component position, defined as the execution error, averaged 0.9° ± 1.7° of varus rotation, 0.8 ± 2.3 mm of lateral translation, and 0.3 ± 1 mm of proximal translation in the coronal plane (±SD). In the sagittal and axial planes, the execution error averaged 2.8° ± 2.5° of flexion, 3.4 ± 1.3 mm of anterior translation, and 0.7° ± 2.7° of external rotation. CAS permits accurate placement of 8-in-1 jigs for valgus/varus, axial rotation, and cut height but is less accurate in the sagittal plane. Care should be taken when executing the cuts, which can affect precision in the sagittal plane more than actual positioning of the jig.