Bisphosphonates after Hip Replacement Reduce Revision Risk

Surgeons and endocrinologists have wondered if bisphosphonate use might reduce revision hip replacements, and a new study indicates they may help.

Most (but not all) patients who receive a hip replacement are elderly and can be expected to retain the prosthesis for 15 to 20 years. While many retain their first hip replacement for life, patients who have hip replacement surgery at a young age or have very active physical lifestyles may need revisions. In the United States, 18 of every 100 hip replacements are revisions and the most common cause is aseptic loosening.

A multinational team of researchers conducted this retrospective cohort study using Danish registries that follow 5.5 million individuals. They identified 80,342 adults older than 40 years of age undergoing total joint replacement between 1998 and 2007 and excluded patients with diagnoses that would confound the results. They classified participants as bisphosphonate users if they had been on treatment for more than 6 months. They examined duration of use, medication possession ratio, timing of therapy initiation (pre/post-op), and implant survival.

Approximately 2% of participants (1,590) were bisphosphonate users. The researchers paired 1,558 of them to 8,966 non-users to evaluate revision risk over the 2.61-year study period. Among the bisphosphonate users 27, or 1.73%, underwent revision surgery. Among the matched cohort, 399, or 4.45%, needed revisions.

Data analysis showed that bisphosphonate use reduced the risk of revision by 59%. Patients with the longest bisphosphonate treatment durations and/or best adherence rates had the lowest risk of revision. Using sensitivity analysis, the researchers demonstrated their findings were unlikely to be confounded by patient co-morbidity or health-seeking behavior.

The authors concluded that oral bisphosphonate users are at 59% reduced risk of revision, but noted their findings only applied in patients who initiated bisphosphonates after arthroplasty surgery. They postulated that bisphosphonates initiated after arthroplasty surgery could reduce inflammation-mediated osteolysis around the implant and reduce related loosening.