In this study, 54 patients with a unicompartmental knee arthroplasty (UKA) were compared with 54 patients who had a total knee replacement (TKR). A UKA replaces just one side of the knee joint. Usually the medial or side closest to the other knee is replaced.
Measures used to compare results included range of motion (ROM), function, and survivorship of the implant. The patients in the two groups were matched (same or similar) in age, body mass index (BMI), and gender. ROM and function before surgery were also about the same in both groups.
All patients were followed for up to five years. Results showed greater motion in the UKA group. Function was the same in both groups. The UKA had a lower survivorship. This means the implant was removed or revised for some reason. In this study, none of the TKAs failed or had to be revised.
The authors report that good results with the UKA has resulted in an increased use of these implants. However, this study showed a high failure rate in the UKA group. They suggest when all things are equal (age, gender, health, severity of arthritis), the TKA was a more reliable choice for knee osteoarthritis.