The Swanson ulnar head prosthesis for post-traumatic disorders of the distal radio-ulnar joint

20 Swanson ulnar head prostheses inserted for post-traumatic disorders of the distal radio-ulnar joint were reviewed at a mean of 44.2 months post-operatively (range 12-104 months). The indication for surgery was painful loss of forearm rotation with or without ulno-carpal impingement and ulno-carpal instability. Symptoms in 16 patients were the result of malunion following severe distal radial fractures (two Frykman 7 fractures and 14 Frykman 8 fractures), and in the remainder were due to unreduced dislocations in the distal radio-ulnar joint (two patients) or unsatisfactory Darrach procedures (two patients). 70% of patients achieved excellent or good clinical results despite the fact that radiographs showed bone resorption in all cases, tilting of the prosthesis in 40% and implant fractures in 15%.