[Management of posttraumatic osteoarthritis of the upper ankle joint by implantation of the S.T.A.R. ankle prosthesis].

OBJECTIVE: Treatment of posttraumatic osteoarthritis of the upper ankle joint by implantation of an uncemented total ankle joint prosthesis.

INDICATIONS: Painful osteoarthritis of any kind affecting the upper ankle joint with adequate joint stability, without significant bone deformity of the ankle axes (deviation of the lower leg axis in the distal third in the horizontal and sagittal planes < or = 20 degrees ), without manifest osteoporosis, with normal peripheral vascularity, correct alignment of the hindfoot, minimal sports expectations on the part of the patient, and good residual range of motion.

CONTRAINDICATIONS: Avascular talus necrosis > or = 25%. Degenerative neuropathic joint disease (Charcot's joint). Acute or chronic ankle joint infection. Sensory or motor dysfunction of the foot. Preceding arthrodesis of the ankle with resection of the malleoli. Medial instability of the upper ankle joint. Tibiotalar varus or valgus deformity > 20 degrees .

SURGICAL TECHNIQUE: Anterior approach to the upper ankle joint. Resection of the distal tibial joint surface and the cranial talar surface including the sides of the talus. Uncemented implantation of the talar cap, and the tibial component. Insertion of a polyethylene sliding core.

RESULTS: From January 2004 to March 2005, 13 patients with posttraumatic osteoarthritis were treated by implantation of an uncemented S.T.A.R. ankle prosthesis (Scandinavian Total Ankle Replacement). The indication for total joint replacement in all cases was advanced osteoarthritis of the upper ankle joint that could no longer be managed by conservative treatment. In one patient, the medial malleolus fractured intraoperatively and had to be stabilized with a screw. There was neither deep nor superficial infection. One patient developed persistent chronic regional pain syndrome without radiologic evidence. After an average follow-up period of 6.8 months (3-12 months), the range of motion had improved in all patients from 10-0-20 degrees to 15-0-30 degrees on average. The AOFAS (American Orthopaedic Foot and Ankle Society) Hindfoot Score improved from 53 to 89 points.