Intraoperative cutting errors in total knee arthroplasty

Introduction Precise reconstruction of leg alignment offers the best opportunity for achieving good long-term results in total knee arthroplasty (TKA). It was the aim of this study to evaluate the bone-cutting process as a potential source of inaccuracy in TKA. Materials and methods In a consecutive series of 50 computer-assisted TKAs, cutting errors, which were defined as a difference between the cutting block position before sawing and the achieved resection plane afterwards, were measured for the distal femur and proximal tibia resection. Measurements were performed using a CT-based navigation system. Results For the distal femoral cut, there was a mean varus/valgus deviation of 0.6 degrees (SD +/- 0.5 degrees) and a mean flexion/extension deviation of 1.4 degrees (SD +/- 1.3 degrees). For the proximal tibia, varus/valgus alignment showed a mean deviation of 0.5 degrees (SD +/- 0.5 degrees). The mean sagittal variability was 1.0 degrees (SD +/- 0.9 degrees). Differences between the frontal and the sagittal plane were significant. Conclusion To minimize cutting errors, techniques and instruments are needed which enable a more stable fixation of the cutting blocks or even more appropriate preparation instruments. Using a computer-assisted technique, the surgeon is aware of cutting errors occurring at each point of the operation and will therefore be able to correct these errors during surgery, while he is not aware of those errors with the conventional TKA technique.