Artikel
Does soft tissue balancing in navigated TKA improve the in vivo kinematics?
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Veröffentlicht: | 21. Oktober 2010 |
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Objective: Previous in vivo kinematic studies have reported varying results even in patients with similar implant design. These findings suggest that surgical technique, especially soft tissue balancing, may play a role in postoperative kinematics. However, the uses of navigation systems have shown to improve the alignment and provide a helpful method for soft tissue balancing. The purpose of this study was to determine whether computer-assisted (CAOS+) total knee arthroplasties (TKA) is superior to the conventional surgical (CAOS-) method with regard to the postoperative in vivo kinematic.
Methods: Twenty subjects, with a posterior stabilized CAOS- (P.F.C. Sigma RP, DePuy, USA) and 20 with a CAOS+ posterior stabilized TKA (Emotion, Aesculap, Germany) were asked to perform maximum weight-bearing flexion, while under fluoroscopic surveillance. The 3D kinematics of the TKA`s was determined by analyzing fluoroscopic images at 10 degree increments from full extension to 90 degree knee flexion. We used the Kolmogorov-Smirnov test for normal distribution before further statistical analysis. The percentages of TKA with lift off were compared between groups with use of a chi-square test. As a twogroup comparison test we use the Mann-Whitney-Wilcoxon Test. P < 0.05 was considered to be the level of significance.
Results and conclusions: On average, the CAOS- TKA`s demonstrated medial 1.1 mm and lateral −2.1 mm of posterior femoral rollback, and 4.1° of axial rotation. The CAOS+ TKA`s averaged medial 1.4 mm and lateral −4.2 mm of posterior femoral rollback, and 7.3° of axial rotation. Sixteen subjects in the CAOS- and 4 in the CAOS+ group experienced greater than 1.0 mm of condylar lift-off. This was statistical significant.
We found in the CAOS+ TKA`s a more normal postoperative tibiofemoral kinematic than in the CAOS- knee arthroplasties. In addition, only 4 subjects having a CAOS+ TKA showed a condylar lift off greater than 1.0 mm. These data suggest that soft tissue balancing improve the postoperative kinematics.