Complications of Total Hip Arthroplasty in Patients With Ankylosing Spondylitis

Objective To compare the risks of complications of primary total hip arthroplasty ( THA ) between patients with ankylosing spondylitis ( AS ) and those without AS . Methods In this population‐based study, we examined data from 1999 to 2013 of US Medicare beneficiaries (ages <75 years old) with AS and a comparison group without AS who had undergone primary THA . Complications were based on the Centers for Medicare & Medicaid Services 2013 THA Complication Measure, which included myocardial infarction, pneumonia, or sepsis within 7 days; surgical site bleeding, pulmonary embolus, or venous thrombosis within 30 days; or mechanical complications or local infection within 90 days. Mortality within 90 days, revision arthroplasty within 1 year, long length of stay, discharge to a care facility, and readmission within 90 days were also examined. Results The study included 2,773 patients with AS and 107,341 patients without AS who had THA . Perioperative complications, 30‐day complications, and local infections were rare in both groups (<1%). Mechanical complications and revision arthroplasty were uncommon in both groups. Ninety‐day mortality was lower among patients with AS than those without AS (0.36% versus 0.7%). Patients with AS were more likely to be discharged to a care facility, and slightly more likely to have a long length of stay. Likelihood of a long stay was lower at hospitals that performed ≥100 THA s per year, but other complications were not associated with hospital volume. Conclusion Complications after primary THA are uncommon in patients with AS and similar in frequency to those without AS . Ninety‐day mortality was lower among patients with AS .