It is difficult to identify objective parameters for assessing the joint function when evaluating the outcome of orthopaedic procedures, especially endoprosthetic replacement. Spatial and temporal parameters of gait have clinical relevance in the assessment of motor pathologies, particularly in orthopaedics. However, the influence of gait speed on these biomechanical parameters has been difficult to be taken into consideration so far. The objective of the present study was to analyse the impact of gait speed on gait parameters and to set a standard walking speed for patients with osteoarthritis by means of a special treadmill control mechanism. The second objective is to compare the gait patterns in patients with unilateral osteoarthritis of the hip joint or of the knee joint to the gait pattern of healthy control subjects. A total of 20 patients with severe unilateral osteoarthritis of the hip, 20 patients with severe unilateral osteoarthritis of the knee and 20 healthy elderly subjects without any history of lower extremity joint pathology were investigated at four different gait speeds. The gait analysis equipment used consisted of an infinitely adjustable force-instrumented treadmill and an ultrasound-based motion analyser system with electromyography. Our data suggest that most of the biomechanical parameters depend on gait speed. The highest gait speed that all our patients with severe osteoarthritis were suitable with, without pain and loss of coordination, was 2.00 km/h. Our findings indicate that the changes in gait parameters may occur in patients with unilateral osteoarthritis of the hip joint or the knee joint compared to the gait pattern of healthy control subjects. Hip joint or knee joint degeneration was compensated for in part by the pelvis and other joints in the lower limb. Reduced motion of the hip joint or knee joint leads to an increased pelvic motion, which should affect the natural mobility of the lumbar spine and cause pain in the lumbar region of the spine because of their kinematic interaction.

II.

the results of the study confirm that navigation does not influence the length of rehabilitation. However, in case of minimal invasive surgery, rehabilitation is faster than in Groups I and II.

The successful outcome of total knee arthroplasty (TKA) is very much dependent on precise positioning of the components. Inaccuracy may result in complaints as well as in early mechanical failure. Between March 2003 and September 2005, 69 TKA procedures were performed by the computer navigated technique. The postoperative outcome of this cohort was compared with the same number of TKAs done by the traditional technique. The lower limb anatomical axis was determined in all cases preand postoperatively by weight-bearing anteroposterior (AP) and lateral full length X-rays. The positions of femoral and tibial components were recorded. Comparing the data in the navigation group on the AP view, 96.6% of femoral and 96.9% of tibial components and on the lateral view in 95.4% of femoral and in 95.4% of tibial components, the overall postoperative axis in 95.4% fell in the range considered in the literature as optimal. In the traditional group on the AP view, 75.7% of femoral and 68.1% of tibial components and on the lateral view 81.8% of femoral and 63.6% of tibial components, the overall postoperative axis in 60.6% fell between the values considered optimal in the literature. It seems to be proven that the computer navigated total knee arthroplasty technique ensures positioning of components significantly more precisely compared with the traditional surgical method. Accuracy of navigation depends on the software used, on the correct detection of anatomical reference points, and on a potentially uneven thickness of the cement layer during final insertion of the components. The computer navigated technique does not substitute professional skill and experience, since it merely transmits information for the surgeon. The decision is in the hands of the doctor during the entire procedure. The real benefits of the computer navigated technique require further research and can be determined only after long-term analyses. Résumé Le succés de l'arthroplastie totale de genou dépend beaucoup du positionnement des implants. Entre mars 2003 et septembre 2005, 69 athroplasties étaient réalisées avec une technique de navigation informatique. Le devenir de ce groupe était comparé avec le même nombre d'arthroplasties faites avec la technique traditionnelle. L'axe anatomique du membre inférieur était déterminé par des radiographies antéro-postérieures en charge et de profil en extension. Dans le groupe navigué, la position des implants était optimale sur les radio de face pour 96,6% des pièces fémorales, 96,9% des pièces tibiales, sur les radio de profil pour 95,4% des pièces fémorales et tibiales, avec un bon axe dans 95,4% des cas. Dans le groupe traditionnel, les chiffres étaient: 75,7% pour les pièces fémorales, 68,1% pour les pièces tibiales sur les radio de face et 81,8% pour les pièces fémorales, 63,6% pour les pièces tibiales sur les radio de profil avec un bon axe dans 60,6% des cas. Il semble prouvé que l'utilisation de la navigation informatique permette un meilleur positionnement des implants que la méthode convention...

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