Introduction: Many types of prosthesis are currently used for total knee arthroplasty. Controversy exists as to whether mobile-bearing or fixed-bearing implants make any difference in achieving earlier or better movement, resulting in earlier patient discharge.

Aim: The purpose of our study was to compare the post-operative recovery and early results of 4 different mobile- and fixed-bearing knee implants.

Method: Between 19/7/05 and 15/6/07 202 knees were implanted into 190 patients. Patients were randomly selected for 1 of 4 implants (2 mobile-bearing, 2 fixed-bearing). Outcomes were assessed using the American Knee Society Score (AKSS) and range-of-movement, both pre-operatively and at 1 year post-operatively. Range-of-movement was also recorded on discharge.

Results: No significant difference was shown between the individual implant groups and the actual mean pre-operative and 1 year post-operative AKSS knee or functional scores or the change in knee score. A difference was noted however in the change in functional score between the 2 mobile-bearing knees (p=0.03). No significant difference was found between the 4 individual implants or the type of bearing used (mobile- or fixed-bearing) with regards to gender, age, length of stay or range-of-movement.

Conclusion: The type of implant used does not affect the early or 12 month outcomes in relation to range-of-movement, length of stay or AKSS knee scores.