Although the design features of the Medial Pivot fixed-bearing prosthesis reportedly improve kinematics compared with TKAs
using fixed-bearings, clinical improvements have not been reported. We asked whether the clinical and radiographic outcomes,
ranges of motion of the knee, patient satisfaction, and complication rates would be better in knees with a Medial Pivot fixed-bearing
prosthesis than in those with a PFC Sigma mobile-bearing prosthesis. We compared the results of 92 patients who had a Medial
Pivot fixed-bearing prosthesis implanted in one knee and a PFC Sigma mobile-bearing prosthesis implanted in the other. There
were 85 women and seven men with a mean age of 69.5 years (range, 55–81 years). The minimum followup was 2 years (mean, 2.6 years;
range, 2–3 years). The patients were assessed clinically and radiographically using the rating systems of the Hospital for
Special Surgery and the Knee Society at 3 months, 1 year, and annually thereafter. Contrary to expectations, we found worse
early clinical outcomes, smaller ranges of knee motion, less patient satisfaction, and a higher complication rate for the
Medial Pivot fixed-bearing prosthesis than for the PFC Sigma mobile-bearing prosthesis.
Level of Evidence: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
Each author certifies that he or she has no commercial association (eg, consultancies, stock ownership, equity interest, patent/licensing
arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the human protocol for this investigation, that all investigations
were conducted in conformity with ethical principles of research, and that informed consent for participation in the study
was obtained.