[Early results of proximal interphalangeal joint replacement with pyrolytic carbon prosthesis (Ascension) in...

Surgical treatment of painful idiopathic and post-traumatic arthritis with joint replacement of the proximal interphalangeal joint has become increasingly important. Due to shortcomings of former constrained and partially constrained prostheses with regard to abrasion and durability we have been using an unconstrained prosthesis since April 2002. This model is an almost abrasion free, biocompatible 2-component prosthesis. The surface is shaped like the condyles and the position is secured in a press-fit technique. During October 2004 we reviewed the results of 20 out of 29 patients with idiopathic or post-traumatic arthritis who had been treated with a pyrolytic carbon proximal interphalangeal joint prosthesis from April 2002 to April 2004 retrospectively. Clinical, subjective and radiological parameters were studied. On follow-up after 0.5 to 2.5 years the patients were satisfied with the pain relief. The range of motion varied. However, with an average ROM of 50 degree it was equivalent to the results in literature. Signs of periprosthetic cysts, osteophytes and loosening of the proximal as well as of the distal component could be seen in the radiograms of some patients. There was no correlation between these radiological observations and range of motion, pain or grip strength. In three cases the joint prosthesis had to be converted to an arthrodesis of the proximal interphalangeal joint. Bearing in mind the correct indications (intact collateral ligaments, stable bone stock and sufficient extensor and flexor tendons), pyrocarbon prosthesis are a treatment option for idiopathic and posttraumatic arthritis preserving motion and reducing pain. Radiological results seem to indicate an absence of osteointegration and tension forces at the prosthesis/bone interface. Further investigation will be necessary to improve surface and design to increase radiological results in long-term follow-up. Additional surveys are required to improve indications, surgical approach and intraoperative control of correct component positioning.