In this work the Authors have studied the efficacy of a standardized rehabilitative trial in patients with knee arthroplasty using an isokinetic technique and walking evaluation. 20 patients affected by gonarthrosis were evaluated: each of them underwent on one side an isokinetic evaluation before and 60 days after surgery, and on the other side a step evaluation, at the begin of limb charging and 60 days after surgery. The isokinetic parameters (strength, work, power) showed a sharp decrease of absolute values as compared to the preoperative situation, while in the walking evaluation the time reduction still remains in the first impact of the foot.