[DIGITOS-prosthesis for the proximal interphalangeal joint. A 2-year follow-up]

The treatment of osteoarthrosis of the proximal interphalangeal joint by prosthesis bears several specific problems. With the DIGITOS-prosthesis a new implant is now available. It is a cemented modular hinged prosthesis. We report our experiences with this implant from a prospective clinical trial. Seven patients with osteoarthrosis of the proximal interphalangeal joint had ten prosthetic middle joint replacements performed with DIGITOS-prostheses. Over an observation period of two years, the functional results were found to be good. The mean preoperative range of motion in the affected joints was 51.5 degrees. Three months after surgery, this had improved to 60.5 degrees, but then decreased to 53.0 degrees after one year and to 49.5 degrees, i.e. the original range of motion, by the end of the second postoperative year. No implant became loose. Nearly all patients were free from pain. The only serious complication was an iatrogenic lesion of the middle slip of the extensor aponeurosis resulting in a buttonhole deformity. In spite of these encouraging two-year results, the further follow-up has to be observed carefully.