Mobile and fixed bearing in total knee replacement are still discussed controversially. In a retrospective, matched-pair study, we investigated 40 patients with computer-assisted (BrainLAB) primary total knee replacement (PFC Sigma, DePuy) performed two years before. Twenty patients each received a mobile bearing and a fixed bearing. We compared Womac Score, Knee Society Score, postoperative ROM, fluoroscopic measurement of knee stability in flexion and extension and isokinetic muscle strength using a Biodex-3 dynamometer. Both groups showed similar results concerning WOMAC Score (total rotating bearing: 23.05; fixed bearing: 22.57), KSS (rotating bearing: 174.89; fixed bearing: 176.1). Isokinetic muscle force demonstrated statistically significant superior results for knee flexion in the rotating bearing group. Medio-lateral stability revealed statistically significant superior results for the rotating bearing compared to fixed bearing in extension (P>0.05). In flexion only lateral stability was superior (P>0.05). Two-year clinical follow-up after computer-assisted total knee replacement resulted in good clinical outcome with high patient satisfaction. Statistically significant better values for the rotating platform group were found for the medio-lateral stability in extension and the peak flexion torque.

Soft-tissue management is a critical factor in total knee arthroplasty, especially in valgus knees. The stepwise release has been based upon surgeon's experience. Computer-assisted surgery has gained increasing scientific interest in recent times and allows the intraoperative measurement of leg axis and gap size in extension and flexion. We therefore aimed to analyse the effect of sequential lateral soft-tissue release and the resulting change in the a.p. limb axis on the one hand and the tibiofemoral gaps on the other hand in extension as well as in flexion in eight cadaveric knees. Measurements were obtained using a CT-free navigation system. In extension the highest increase compared to the previous release step was found for the first (iliotibial band, P=0.002), second (popliteus muscle, P=0.0003), third (LCL, 0.007) and the sixth (entire PCL, P=0.001) release step. In 90°flexion all differences of the lateral release steps were statistically significant (P<0.004). Massive progression of the lateral gap in flexion was found after the second (popliteus muscle, P=0.004) and third (LCL, 0.007) release step. Computer-assisted surgery allows measurement of the effect of each release step of the sequential lateral release sequence and helps the surgeon to better assess the result.Résumé La libération des tissus mous lors de la réalisation d'une prothèse totale du genou est un facteur important notamment dans les génu valgum. Les techniques de «releases» sont bien connues des chirurgiens. La chirurgie assistée par ordinateur permet de mesurer en peropératoire les axes et les espaces en flexion et en extension. Pour cela nous avons mesuré tous ces paramètres lors d'une expér-imentation sur 8 genoux de cadavre, utilisant un système de navigation avec en extension, libération de la bandelette iliotibiale (P=0.002) puis du muscle poplité (P=0.003) et enfin, du ligament collatéral (P=0.007), en sixième position libération du ligament croisé postérieur (P=0.001). A 90°d e flexion toutes les étapes de la libération tissulaire sont importantes. L'étape importante pour redonner de l'espace est atteinte après libération du muscle poplité puis du ligament collatéral. La chirurgie assistée par ordinateur permet de mesurer les effets de chaque étape de cette libération tissulaire et permet donc aux chirurgiens d'améliorer leurs résultats.

Computer assisted (CAS) knee surgery has been established in clinical routine. There is still no study that investigates clinical outcome. Fifty patients who received a primary total knee replacement 2 years before were investigated. These patients were divided into two groups of matched-pairs; group A was operated in the freehand technique and group B with support of a computer system. We compared Womac score, Knee Society score, range of motion, leg alignment, knee stability and isokinetic muscle strength. We found similar results for WOMAC, Knee Society score and isokinetic muscle force. Stability and range of motion revealed slightly better values for the CAS group. A statistically significant difference could only be demonstrated for postoperative leg alignment. Two years after freehand versus computer assisted TKR we found slightly better values for range of motion and ligamentous stability. Only postoperative leg alignment was statistically better in the CAS group.

The knee subscore appears to be an efficient method for staging the clinical progression of osteoarthritis of the knee for clinical practice as well as for clinical trials. The Womac score especially serves to record the level of pain. We were able to confirm that the presence of osteophytes is the most significant radiographic feature of osteoarthritis of the knee. The Kellgren score turned out to be a reliable method for monitoring the radiographic progression of osteoarthritis of the knee.

Our survey shows that most of the surgeons perform prevention of deep vein thrombosis according to the official guidelines.