A COMPARISON OF RANGE OF MOTION AND OUTCOME IN FIXED AND MOBILE KNEE DESIGNS.

Aim: This study aims to establish whether or not mobile bearing TKR delivers the often stated benefits improved function and range of motion when compared to its fixed bearing equivalent. Methods and Results: A total of 357 patients undergoing TKR were randomly allocated to receive either a Mobile Bearing (181 knees) or a Fixed Bearing (176 knees) PSTKR. Further subrandomisation into patella resurfacing or retention was performed for both designs. All knees were scored using standard tools (Oxford, AKSS and SF12) preoperatively and at intervals postoperatively by independent observers. The range of motion increased from an average of 96 deg. (pre-op) to an average of 109 deg. at 1 year post-op for both the fixed and mobile bearing design. The management of the patella had no effect in either group. The knee society and knee function scores increased equally for both the fixed bearing and mobile bearing knees with no differences noted. Conclusion: There were no measurable differences in range of motion and clinical outcome scores at 1 year post-op for a mobile bearing design over its fixed bearing equivalent. It is likely that any potential advantages of a mobile bearing design will manifest in longevity rather than function.