Osteoarthrosis is one of the 10 most disabling pathologies worldwide and today, the intra-articular injection of hyaluronic acid (viscosupplementation) is a therapeutic option. The principal limitation of this treatment is its limited efficacy, due among other reasons, to its rapid degradation. In order to develop more efficacious formulations, two strategies have been followed; the preparation of a hybrid hydrogel composed of hyaluronic acid and chitosan, a second chondroprotective biopolymer and, the covalent grafting of antioxidants in order to protect the hyaluronic acid from pathological oxidative stress. During this thesis, it has been demonstrated that such a hybrid hydrogels was biocompatible but that its therapeutic efficacy was poorly satisfactory in the tested conditions due to the high bone activity of chitosan. The second strategy showed more promising result; an antioxidant grafted hyaluronic acid was demonstrated biocompatible and it efficiently protected the synovial membrane from pathologic hypertrophy.