Abstract
Aims: Does CT-less navigation using the NAVITRACK-System improve post-operative rotational alignment of prosthesis compared to not-navigated implantation technique?
Methods: A total number of 250 patients was enrolled into a randomized mono-centre-study. Ninety patients received computer-aided-surgery (CAS), 160 patients received not-navigated implantation technique. Mechanical leg-/femur-/tibia-axes were identified using complete-leg-CT-scans. Rotational alignment was calculated measuring the angles formed between condylary and epicondylary axes (femoral), transverse tibia plateau axis and tibial tuberosity (tibial) respectively, by the use of coronar CT-scans. Knee Society – and SF-36-Scores were collected pre- and post-operatively at 6 weeks /6 months. Statistical analysis was performed by the chi-square-test.
Results: (All values in mean +− SEM (range)) A mechanical-axis-range of 180 +− 3 was achieved in 97,9% of navigated, and in 76,8% of the not-navigated patients. The tibial component was placed in a 2,1 +− 1,3 -varus-position in navigated patients. In the conventional patient group varus position was 1,8 +− 1,4. A 0,8 +− 1,5 femoral-valgus-position was found in navigated patients, respectively a 0,3 +− 2,7 varus-position in the not-navigated. The internal rotation (relative to epicondylar axis) of the femoral component was 2.8 +− 1,0 (0,7–3,8) in the CAS-group and 2.1 +− 1,5 (0–5,9) in the non-navigated. On the tibial side, the internal rotation of the plateau relative to tibial tuberosity was 20.5 +− 2.5 (16,8–24,8) in CAS- and 22.2 +− 7.5 (9,3–43,2) in the conventionally treated patients.
Conclusions: CT-less navigation using NAVITRACK was suitable to a.) reconstruct mechanical axis within the limits of 180° +− 3° and b.) reduce rotational malalign-ment especially on the tibia. The system may improve the survivorship of TKR as well as the functional outcome after implantation.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
