Hip Replacements Come with More Complications in Ankylosing Spondylitis

As many as half of patients with ankylosing spondylitis have involvement of the hip, the treatment for which is total hip replacement. But a new study presented on March 3 at the annual meeting of the American Academy of Orthopaedic Surgeons in Orlando, Florida, finds an elevated risk of complications from this surgery in ankylosing spondylitis patients.

The research, presented by Duke University School of Medicine orthopedic surgery resident Daniel Blizzard, M.D., drew from a 2005-2012 Medicare sample of patients. There were 1,026 patients in the sample with ankylosing spondylitis who underwent total hip replacements.

Compared with a control-group, patients with ankylosing spondylitis were more likely to experience breakage of a component of the prostheses within two years of surgery, Dr. Blizzard and his colleagues found. The relative risk of this complication was 2.49 (C.I.: 1.04-5.98) at 90 days post-surgery and 1.99 (C.I.: 1.10-3.58) two years after surgery. The relative risk of hip dislocation was significantly higher than controls a year after surgery, with a relative risk of 1.45 (C.I.: 0.97-2.18) and two years after surgery, with a relative risk of 1.67 (C.I.: 1.25-2.23).[[{"type":"media","view_mode":"media_crop","fid":"46548","attributes":{"alt":"©Alarico/Shutterstock.com","class":"media-image media-image-right","id":"media_crop_9209128958173","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"5411","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"font-size: 13.008px; line-height: 1.538em; float: right;","title":"©Alarico/Shutterstock.com","typeof":"foaf:Image"}}]]

Patients with ankylosing spondylitis (AS) were also more likely to have to undergo revision of the hip replacement, with significantly increased relative risks of 1.72 (C.I.: 1.31-2.26) at one year and 1.51 (C.I.: 1.23-1.85) at two years post-operation.

"AS patients also had a significantly higher risk ratios at all time points for medical complications including heart failure, pulmonary embolism, pneumonia and acute renal failure," the researchers wrote. Infections and wound complications were also elevated in these patients, they reported.

The increased rates of immunosuppressant drugs and elevated rates of cardiopulmonary disease, put ankylosing spondylitis patients at increased risk, the researchers found. Kyphosis of the spine can also add stress to the hip joints. While total hip arthroplasty remains the gold standard, the researchers wrote, "the elevated peri- and postoperative risks should be discussed preoperatively and these patients may require increased preoperative medical optimization as well as possible changes in component selection and position to compensate for altered spinopelvic biomechanics."

References:

“Ankylosing Spondylitis Increases Peri- and Postoperative Complications After Total Hip Arthroplasty,” Daniel J. Blizzard, MD, Duke University School of Medicine. American Academy of Orthopaedic Surgeons, 2016 Annual Meeting.  March 3, 2016.