Abstract
Introduction and Aims: Fixed bearing and mobile bearing knee designs are currently used in clinical practice with little evidence based research available to determine superiority of one system. The purpose of this study was to compare the results between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.
Method: We performed a prospective, randomised, blinded clinical trial to compare a mobile bearing to two standard fixed-bearing implants. We evaluated the short- and long-term outcomes of the SAL® (Sulzer) mobile bearing versus the AMK® (Depuy) and Genesis II® (Smith & Nephew) fixed bearing, total knee joint replacements. Ninety patients were randomised to receive one of the three prostheses. Patients were evaluated pre-operatively, at three, 12 months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated. A single observer was used to measure range of motion scores.
Results and Discussion: No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two-year follow-up, and one patient was revised for infection at six months, leaving 87 patients at an average follow-up of 3.37 years (range 2.91–4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL – 167, AMK – 158, GenesisII – 166 ). There were no differences in WOMAC scores or SF-12 survey scores. There were no differences in knee flexion at two years (SAL – 117°, AMK – 115°, GenesisII – 118°). Therefore, no differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.
Conclusion: In this prospective randomised clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
