The effect of rotational fixation error of the tibial cutting guide and the distance between the guide and the bone on the tibial osteotomy in total knee arthroplasty.

Computed tomography based computer simulation studies were made on fifty consecutive patients with osteoarthritis scheduled for TKA. Proximal tibial cutting was simulated with the cutting guide placed at different rotational errors (-10°, 0°, 10° and 20° of internal rotation) and different distances (4 cm and 8 cm) between the alignment rod and the bone. Only ten degrees of rotation error with 8 cm of distance resulted in over 3° of varus or valgus tibial cut. Our study demonstrated that rotational mismatch between the proximal and distal part of the tibia should be avoided and the distance between the alignment rod and the bone should be as short as possible to achieve proper tibial alignment.