The Arthrotic knee is frequently associated with several-pain and loosening of joint function often so important to need a total knee arthroplasty (TKA). Obviously, the aims of a TKA is to obtain no pain and restore a good joint function so to contribute to a good health and a better quality life. To realize ends like these it’s necessary a good selection of the patients first, an adequate preparation for the surgery, correct surgery technique and a specific post-operative rehabilitation until achieving the normal daily activities. In this way clinical biomechanical evaluations can contribute to quantify the achievement of the ends and they can get influence to modulate the “ways” used. Actually the dynamic evaluation more useful and reproducible in the gonartrhosis is the gait analysis.

Patients were selected from a group of subjects suffering from advanced gonartrhosis. Exclusion criteria from the study were: bilateral advanced arthrosis; previous surgery at the lower limbs or other disease that could influence the gait pattern. With these criteria a group of 7 males and 2 females, mean age 67,7 years old, participated at the study (after a known consensus). All subjects had clinical evaluation. For the dynamic analysis The knee society evaluation system for arthroplasty was used. The knee stability was evaluated on the frontal and mediolateralaxis. For evaluating the pain entity we used the V.A.S. score at rest and during gait, before and after taking the analgesic drug. In addition standard X-ray of the knees were evaluated. Gait Analysis was performed at the biomechanical laboratory “Let people move” of Perugia (Italy). Subjects walked on a track of 12,5 m., a 3Dcinematic evaluation was performed using the APAS system (ARIEL Dynamics, USA) with 4 high speed video cameras. 15 auto reflexed markers were applied on both lower limbs. The ground reaction forces during the gait were recorded at 500 Hz with Bertec platform placed at the centre of there cording area. At the subjects was asked to make 10 valid trials (5 for right and 5 for left knee). During gait was evaluated the range of motion of ankle and foot too.

The mean score obtained with the V.A.S. score for the pain during the first section was 3.3 (range 0–7). After taking the analgesic drug and 20 minutes of rest the range was 0–4 at the sequent trial. The results so obtained said that there’s no difference between the range of motion of the knee after taking the drug on the sagittal plane. In addition, no difference neither between the range of motion of the hip and the ankle, on the sagittal plane after the drug.

The mean score obtained with the V.A.S. score for the pain during the first section was 3.3 (range 0–7). After taking the analgesic drug and 20 minutes of rest the range was 0–4 at the sequent trial. The results so obtained said that there’s no difference between the range of motion of the knee after taking the drug on the sagittal plane. In addition, no difference neither between the range of motion of the hip and the ankle, on the sagittal plane after the drug.