Meta-analyses showed no clinical ly relevant differences in terms of revision rates , clinical outcome scores or patient-reported outcome measures between MB and FB TKRs .
It appears that theoretical assumptions of superiority of MB over FB TKR are not borne out in clinical practice
Mobile-bearing ( MB ) total knee replacement ( TKR ) was introduced to reduce the risk of aseptic loosening and wear of polyethylene inserts .
However , no consistent clinical advantages of mobile- over fixed-bearing ( FB ) TKR have been found .
In this study we evaluated whether mobile bearings have an advantage over fixed bearings with regard to revision rates and clinical outcome scores .
Furthermore , we determined which modifying variables affected the outcome .
A comparison of fixed-bearing and mobile-bearing total knee arthroplasty at a minimum follow-up of 4.5 years.
BACKGROUND Durable long-term independent results with the Low Contact Stress rotating-platform ( mobile-bearing ) and the Insall Burstein-II ( fixed-bearing ) total knee prostheses have been reported , but no studies describing either the mid-term or long-term results and comparing the two prostheses are available , to our knowledge . METHODS Thirty-two patients who had bilateral arthritis of the knee with similar deformity and preoperative range of motion on both sides and who agreed to have one knee replaced with a mobile-bearing total knee design and the other with a fixed-bearing design were prospect ively evaluated . Comparative analysis of both design s was done at a mean follow-up period of six years , minimizing patient , surgeon , and observer-related bias . Clinical and radiographic outcome , survival , and complication rates were compared . RESULTS Patients with osteoarthritis had better function scores and range of motion compared with patients with rheumatoid arthritis . However , with the numbers available , no benefit of mobile-bearing over fixed-bearing design s could be demonstrated with respect to Knee Society scores , range of flexion , subject preference , or patellofemoral complication rates . Radiographs showed no difference in prosthetic alignment . Two knees with a mobile-bearing prosthesis required a reoperation : one had an early revision because of bearing dislocation and another required conversion to an arthrodesis to treat a deep infection . CONCLUSIONS We found no advantage of the mobile-bearing arthroplasty over the fixed-bearing arthroplasty with regard to the clinical results at mid-term follow-up . The risk of bearing subluxation and dislocation in knees with the mobile-bearing prosthesis is a cause for concern and may necessitate early revision . LEVEL OF EVIDENCE Therapeutic Level II
Meta-analyses showed no clinical ly relevant differences in terms of revision rates , clinical outcome scores or patient-reported outcome measures between MB and FB TKRs .
It appears that theoretical assumptions of superiority of MB over FB TKR are not borne out in clinical practice
Mobile-bearing ( MB ) total knee replacement ( TKR ) was introduced to reduce the risk of aseptic loosening and wear of polyethylene inserts .
However , no consistent clinical advantages of mobile- over fixed-bearing ( FB ) TKR have been found .
In this study we evaluated whether mobile bearings have an advantage over fixed bearings with regard to revision rates and clinical outcome scores .
Furthermore , we determined which modifying variables affected the outcome .