Radiological changes ten years after St. Georg Sled unicompartmental knee replacement

Failure of a unicompartmental knee replacement (UKR) may be caused by progressive osteoarthritis of the knee and/or failure of the prosthesis. We have examined the fate of the other compartments of the knee by radiological assessment 10 years after operation. A total of 50 UKRs were performed on 45 carefully selected patients between 1989 and 1992. Fifteen patients died, two patients were lost to follow-up and two knees were revised. Standard long-leg weight-bearing anteroposterior views of the knee and skyline views of the patellofemoral joint were taken pre-operatively and at 8 months and 10 years after operation. The radiographs of the remaining 30 knees were reviewed three times by blind and randomized assessment to measure the progression of osteoarthritis within the joints. Two knees showed evidence of progression of osteoarthritis within the patellofemoral joint and three knees showed some progression of the opposite tibiofemoral compartment--but only on one of the radiological grading systems used for assessment. It is concluded that progression of arthritis in the unreplaced compartments is not a significant problem after fixed bearing UKR.