H Bäthis1, L Perlick, M Tingart, C Perlick, C Lüring, J Grifka. 1. Department of Orthopaedic Surgery, University of Regensburg, Postbox 100662 , 93042, Regensburg, Germany. holger.baethis@klinik.uni-regensburg.de
Abstract
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.
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.
Authors: Markus Tingart; Christian Lüring; Holger Bäthis; Johannes Beckmann; Joachim Grifka; Lars Perlick Journal: Knee Surg Sports Traumatol Arthrosc Date: 2007-09-26 Impact factor: 4.342