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Friday, March 2, 2001

Risk of TKA revision higher for OA than RA

A report on the outcome of 22,445 total knee arthroplasties (TKA) in patients with osteoarthrosis (OA), and 4,309 TKA in patients with rheumatoid arthritis (RA) found that when the age of patients was taken into consideration, the risk of revision for any reason was higher for OA than RA. Also, the risk of being revised for infection was higher for patients with RA than those with OA.

The outcome after 41,233 primary knee arthroplasties performed in Sweden in the 10-year period of 1988-1997 is reported in scientific exhibit 17. The researchers report on the structure of the register, demographic data and separately analyze the survivorship after the TKAs in patients with OA and RA, as well as 12,282 unicompartmental arthroplasties (UKA) for OA. They also describe the 3,198 primary revisions that were performed during the period when one-third were revisions of arthroplasties performed earlier (1975-1987).

In UKA, the risk of revision did not change over the years while for TKA the risk significantly diminished with time, even after taking into account the increased age of patients. During 1988-1997, primary UKA for OA had higher risk of revision than TKA, while the risk of revision for infection was lower after UKA than TKA.

Using uncemented fixation of the tibial plateau in TKA was associated with increased risk of revision, but researchers could not find a correlation between use of cement, in general, and the risk of becoming revised for infection. Resurfacing of the patella during TKA was not found to affect the revision rate.

When analyzing different brands of implants, they found that newer TKA implants by the same manufacturer often had better results than the ones they replaced, at least in a short-term. The most commonly used TKA and UKA implants in Sweden also were among those with the lowest risk of revision.

Half of the revisions performed during 1988-1997 were performed within 45 months after the primary operation. Loosening, the most commonly stated cause of primary revision, was reported in 44 percent of cases.

Coauthors of the study were Otto Robertsson, MD; Kaj Knutzon, PhD; Stefan Lewold, PhD; and Lars Lidgren, MD, PhD, all of the University Hospital, Lund, Sweden.

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Last modified 15/February/2001 by IS