No Increased Risk of Nonunion with Bisphosphonate Use in a Medicare Claims Cohort Following Operatively Treated Long-Bone Fractures

Background: The diagnosis of a fragility fracture represents an important intervention event for the initiation of medical osteoporosis treatments. However, it is unclear if osteoporosis medications increase the risk of nonunion if administered in the setting of acute fracture. The purpose of the present study was to investigate whether bisphosphonates or selective estrogen receptor modulators/hormone replacement therapy (SERM/HRT) are associated with nonunion following fracture in a Medicare population.

Methods: A retrospective analysis of Medicare claims from 2016 to 2019 was performed to identify patients ≥65 years of age who had a surgically treated long-bone fracture as identified with Current Procedural Terminology (CPT) codes and International Classification of Diseases, 10th Revision (ICD-10) codes. Successive claims were linked for each beneficiary through 1 year following the fracture to determine fracture union status. Multivariable logistic regression models were specified to identify the association between medications and fracture union status while controlling for age, sex, race, Charlson Comorbidity Index (CCI), and fracture type.

Results: Of the 111,343 included fractures, 10,452 (9.4%) were associated with a diagnosis of nonunion within 1 year. The nonunion group was younger (79.8 ± 8.3 versus 80.6 ± 8.4 years; p < 0.001), more likely to be White (92.4% versus 90.9%; p < 0.001), and more likely to have a CCI of ≥2 (50.9% versus 49.4%; p < 0.001). Bisphosphonate use was more common in the nonunion group (12.2% versus 11.4%; p = 0.017). When controlling for race, age, sex, and CCI, neither bisphosphonates (OR, 1.06 [95% CI, 0.99 to 1.12]; p = 0.101) nor SERM/HRT (OR, 1.13 [0.93 to 1.36]; p = 0.218) were associated with nonunion. Bisphosphonate use within 90 days post-fracture was not significantly associated with nonunion (OR, 0.94 [95% CI, 0.86 to 1.03]; p = 0.175), and the timing of medication administration did not influence fracture union status.

Conclusions: The rate of nonunion after operatively treated long-bone fractures was 9.4%. In this cohort, use of a bisphosphonate or SERM/HRT was not associated with fracture union status at 1 year. Orthopaedic surgeons should not withhold or delay initiating medical therapies for osteoporosis in the setting of acute fracture out of concern for nonunion.

Level of evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.