Big-Data News About Inflammatory Arthritis and Joint Replacements

March 30, 2015

(AAOS2015) Patients with inflammatory arthritis appear to be at less risk for complications from knee or hip replacement than those with osteoarthritis, a large national database reveals. But those with ankylosing spondylitis have greater risk.

The first nationwide study to assess the effects of inflammatory disease on the outcomes of knee and hip replacement surgery offers a paradox and a caution.

In general, patients with rheumatoid arthritis (RA) and psoriatic arthritis fare even better as inpatients than those with osteoarthritis (OA) undergoing total hip arthroscopy (THA) or total knee arthroscopy (TKA).

People who have anylosing spondylitis (AS) do significantly worse, however, with significantly greater mortality risk than OA patients having the same procedures.

The researchers speculate that patients who have inflammatory arthritis may get extra medical attention at the time of surgery, but those with AS may demand more vigilance thant they've been getting before the operation and afterwards.

At the American Academy of Orthopaedic Surgeons annual meeting in Las Vegas, Erik Schnaser of Desert Orthopedic Center in Rancho Mirage CA presented results of the analysis by surgeons from four US orthopedic facilities. They used data from the Nationwide Inpatient Sample, the largest publicly available inpatient care database in the US. Altogether they analyzed outcomes for 278,844 patients with inflammatory arthritis disorders undergoing TKA and for 86,671 who had THA between 2002 and 2011.

The major findings:

- Patients with lupus are at increased risk for hip dislocations during or shortly after either TKA or THA. “There is little published literature regarding this specific situation,” the team observes. “However, in our experience these patients tend to have compliant soft tissue and excellent range of motion preoperatively which is a plausible explanation” for the finding.

- Despite having more medical comorbidities, people with rheumatoid arthritis (RA) are at less risk of many medical complications and perioperative death than patients who have TKA or THA for osteoarthritis. This paradox has been reported before, said Schnaser and coauthors, speculating that RA patients may get better medical attention because of their inflammatory condition.

- Patients with ankylosing spondylitis had more cardiac, peripheral vascular, respiratory, gastrointestinal and central nervous system complications with knee or hip replacement than patients with OA, and were also more likely to die in the hospital. Perhaps both patients and doctors underestimate the gravity of their subclinical cardiovascular and respiratory symptoms, the researchers suggest.

- Blood-related complications (hematomas, seromas, acute hemorrhagic anemia, and wound healing problems) were increased among patients with RA, juvenile idiopathic arthritis, and lupus (but not for those with AS or psoriatic arthritis), probably due to long-term treatment with immunosuppressive medications.

- The risk for periprosthetic fracture is increased (perhaps unsurprisingly) for those with ankylosing spondylitis, due to their fragile bones, and for young patients with JIA, probably because of difficulties reconciling their growing bones with the prosthetics.

Two other reports at AAOS2015 added information about the risks of hip replacement among patients with rheumatic disease.

Researchers at Hospital for Special Surgery in New York added lupus to the list of conditions they have analyzed for THA outcomes, also comparing it to outcomes from patients undergoing the procedure for OA. Their assessment of 58 SLE patients and 116 OA controls showed significantly increased rates of falls, revisions, and deep vein thrombosis in the former group.

The study revealed no differences related to the medications they were taking. “There is not much more to say except, ‘Be vigilant,’” team member Susan Goodman MD said in an email.

A smaller registry study from the Mayo Clinic, involving 4,713 patients who had revisions of hip replacements between 1987 and 2007, found that patients with a preoperative diagnosis of RA were at increased risk for further revisions, due to repeat aseptic loosening and osteolysis.