Unicompartmental prosthesis for gonarthrosis. A nine-year series of 575 knees from a Swedish hospital.

From 1980 to 1989, 575 unicompartmental prostheses were implanted for gonarthrosis in 415 patients. More than half of the prostheses were operated in cases of arthrosis of both knees. In 115 patients, both knees were operated on the same day. Pain relief was very good, and the patients were generally satisfied. There was no loss in follow-up evaluation, even deaths were registered. Clinical and roentgenographic examination was performed at three, six, and ten years, according to the Swedish Knee Project. Of the 575 cases, 1.2% had a change of component during revision surgery, and generally, the same type of prosthesis could be used at revision. In 2.4% of the cases, other secondary procedures were used. More than 90% of the candidates for prosthesis surgery in gonarthrosis had unicompartmental arthroplasty. That included cases with pyrophosphate synovitis, absence of the anterior cruciate ligament, and severe degree of the disease. The status of the ligaments after correction was crucial for a good result. Secondary wear of the contralateral compartment was not a problem. A roentgenographic assessment of the follow-up evaluation by an independent radiologist was considered important, because the material is retrospective.