Hormone Replacement Therapy in Postmenopausal Women Undergoing Total Hip Arthroplasty is Associated With Reduced 10-Year Periprosthetic Femoral Fracture Rate.

Background: In postmenopausal women who are estrogen deficient, hormone replacement therapy (HRT) has been shown to improve fragility fracture risk. However, few studies have examined the relationship between HRT and periprosthetic fracture (PPF) risk after total hip arthroplasty (THA). The purpose of this study was to determine the impact of HRT use on 10-year PPF risk following THA.

Methods: A retrospective cohort study was conducted using a large national database. Women who underwent elective THA were identified and stratified based on preoperative (< 6 months) HRT use. Those taking HRT were propensity score matched at a 1:2 ratio to those who do not have a history of HRT use based on age and Charlson Comorbidity Index score. Kaplan-Meier and Cox proportional hazards analyses were conducted to determine rates of PPF, revision, and aseptic loosening within 10 years of surgery. Regression analyses were performed to determine 90-day rates of venous thromboembolism (VTE) after controlling for perioperative VTE prophylaxis. In total, 21,220 patients were included.

Results: Patients who were taking HRT before THA demonstrated a lower risk of PPF (hazard ratio: 0.8; 95% confidence interval: 0.6 to 0.9) within 10 years of THA, but a similar risk of all-cause revision surgery and revision for aseptic loosening. The HRT cohort demonstrated lower odds of deep vein thrombosis (odds ratio: 0.7; 95% confidence interval: 0.6 to 1.0) and similar rates of pulmonary embolism.

Conclusions: In postmenopausal women, HRT use before elective THA was associated with lower rates of PPF within 10 years of surgery and was not associated with increased VTE risk. Given these results, appropriate HRT usage in patients may have a role in reducing PPF after THA.