Background/Purpose:

Total Joint Replacement in rheumatoid arthritis (RA) patients is a marker of disease severity. Whilst the rate of total hip (THA) and total knee arthroplasties (TKA) are increasing in Australia, this may not be the case for those patients with rheumatoid arthritis. Currently, there are no published data examining the rates of hip and knee joint replacement surgery, revision rates and mortality following total joint arthroplasty in rheumatoid arthritis over time in Australia. The aim of the study was to determine if the rate of THA and TKA undertaken for RA in Australia has changed since 2003. A secondary aim was to assess the outcome of both THA and TKA undertaken for RA versus Osteoarthritis (OA) during the study period.

Methods:

The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) collects validated data on all THA and TKA procedures throughout Australia. Registry data include patient demographics, diagnosis, prosthesis type and features, method of fixation and surgical technique. Patient specific outcomes are determined by linking the primary procedure to any subsequent revision or death. Data collection commenced in 1999 and full national data collection was achieved in mid-2002. All hospitals in Australia that perform joint replacement surgery contribute to this registry. A Chi-Square test was used to compare the distribution of RA and OA in THA and TKA. Kaplan-Meier estimates of survivorship and Cox Proportional hazards models were used to compare revision rates and mortality.

Results:

The proportion of both THA and TKA undertaken for RA decreased significantly between 2003 and 2011, THA; 1.74% vs 0.84% (chi²=71.9, p<0.0001) and TKA; 2.38% vs 1.15% (chi²=135.7, p< 0.0001).

There was no significant difference in the overall rate of revision for primary THA undertaken for RA and OA (HR=1.20, 95CI, 0.98-1.48, p=0.074) but revision rates were higher for dislocation in RA  (HR=2.36, 95CI, 1.68-3.31, p<0.001). There is a significantly higher rate of mortality in RA following THA (HR=2.03, 95CI, 1.76-2.33, p<0.001).

There was a significantly lower rate of revision for primary TKA undertaken for RA compared to OA after 9 months (9mths-2yrs: HR=0.38, 95CI, 0.25-0.58, p<0.001, 2-2.5yrs: HR=0.27, 95CI, 0.10-0.72, p=0.009 and 2.5+yrs: HR=0.67, 95CI, 0.48-0.93, p=0.016). TKA for RA has a significantly higher rate of mortality than patients with OA in TKA (HR=2.07, 95CI, 1.84-2.32, p<0.001).

Conclusion:

A reduction in the total numbers of THA and TKA in RA patients across Australia has occurred over the last 9 years.  The lesser numbers may be the result of improvements in disease control but further studies are needed to clarify.  Outcomes of both THA and TKA undertaken for RA appear different when compared to OA.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/hip-and-knee-arthroplasty-in-patients-with-rheumatoid-arthritis-results-from-the-australian-orthopaedic-association-national-joint-replacement-registry-2003-to-2011/