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DOES A MANUFACTURER’S CHANGE IN DESIGN INFLUENCE THE OUTCOME IN TOTAL KNEE ARTHROPLASTY?



Abstract

In 2000 the Nuffield and Rotaglide Knee prostheses were combined into the Rotaglide+ system. This allowed a choice of either mobile or fixed meniscal bearing in the same prosthesis.

Between 1988 and 2000 460 primary Nuffield knee prostheses were implanted and between September 2000 and September 2005 185 primary Rotaglide+ prostheses have been used. A Prospective review using a pain score, range of movement, time walked, and the American Knee Surgeons score was performed. The Rotaglide+ cases have been age, sex, and diagnosis matched with 185 Nuffield knees. All prostheses have been implanted by one surgical team, using the same technique and the same instruments. All are inserted cementless with patella replacement if possible.

Statistical analysis was performed on the first 5 years of follow-up for both sets of prostheses (STATA).

The Nuffield prostheses was significantly better at relieving pain in all years post-operatively. The Rota-glide+ has a slightly better range of flexion, but this is significant only at the 2nd year. There is no significant difference in the walking time, and the AKSS is significantly better for the Nuffield prosthesis only at the first year. Statistical significance is difficult to obtain in years 4 and 5 due to the small numbers of Rotaglide+ prosthe-ses that have reached this stage of review.

Conclusion: A change in design has not improved the short term outcome of these prostheses, and may have worsened the results especially in terms of pain relief. This could be due to the change in stem size and the tibial fins. It is recommended that all changes in prostheses should undergo a limited controlled clinical trial before being released onto the open market

Correspondence should be addressed to: Tim Wilton, BASK, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.