PRODUCT DESCRIPTION The medial knee arthrosis deteriorates more rapidly if the joint damage is associated with the varus tibia and insufficient lateral ligament. In such cases only the metaphyseal realignment, obtained through the tibia osteotomy, may relieve pain and reduce the pouring. If implemented early in the injury, the intervention significantly delays the progression of osteoarthritis. The PTA external fixation system is used for the correction of tibial varism acting through a gradual distraction. The goal of the intervention is to improve substantially the quality of physical life. The procedure is fast and easy, low invasive, with a short postoperative course, with rare and easy to manage complications. MAIN ADVANTAGES - Excellent mechanical strength, lightness, compact - Total modularity and great versatility - Quikly positioning of the screws thanks to the dedicated mask - Precise and modulated degree of correction - Minimally invasive - Reduced time to stay in hospital - Day hospital removing