A population of 100 patients randomised to rotating and fixed PE inlays in the Columbus knee prosthesis received a navigated TKR. Knee Society Score as primary endpoint, Oxford Score, and postoperative ROM after one year will be compared.

Mobile bearing tibial platform designs are advocated to improve functional results of total knee replacement (TKR), and to reduce wear in the longer term. This study investigates short term functional results with two patient groups who are systematically different in the fixed or mobile tibial bearing only.

Methods: 100 knees in 97 patients are stratified according to age and gender and randomized into two groups fixed bearing (FB) with 52 knees and mobile bearing (MB) with 48 knees. All receive the same posterior cruciate retaining implant but the tibial tray and bearing (B. Braun Aesculap Columbus CR and RP) by two experienced surgeons and follow an identical rehabilitation regime. Physical examinations are performed in a double-blinded manner before the operation and three, six and twelve months thereafter, using the Oxford and Knee Society scoring systems.

Inclusion Criteria:

• Indication for elective TKA
• agreement to participate in this study
• Patient age between 40 and 90 years

Exclusion Criteria:

• Malalignment of the knee to be operated of more than 20° varus or 15° valgus
• Former operations on the concerned knee (except diagnostic or therapeutic arthroscopy with only meniscus refixation or cartilage smoothing)
• Joint replacement of another joint of the same leg
• Infections in the operated joint during the follow-up period
• Thromboses during the follow-up period
• Preoperative classification according to ASA 4, 5 or 6