The definition of atypical femoral fractures should include periprosthetic femoral fractures (PAFFs).

Periprosthetic hip fractures may have features of atypical femoral fractures.

Purpose: Atypical femoral fracture (AFF) is a rare complication of treatment with bisphosphonates (BPs) or denosumab. The American Society for Bone and Mineral Research (ASBMR) Task Force definition for AFFs excludes periprosthetic fractures. The purpose of this study was to determine prodromal symptoms, frequency, treatment, and outcomes of periprosthetic AFFs (PAFFs) in persons prescribed a BP or denosumab for osteoporosis and later diagnosed with a periprosthetic hip fracture.

Methods: Participants were all veterans (age ≥ 50) from the VA Corporate Data Warehouse with at least one filled prescription for an oral or intravenous BP or denosumab from October 1999 through December 2022, prior to an ICD code for a periprosthetic fracture around a hip joint. Radiographs were reviewed for features of AFF. In those with a PAFF, the presence of a contralateral AFF was sought. Medical records of those with a PAFF were reviewed to identify prodromal symptoms, treatments, and outcomes.

Results: Among approximately 400,000 veterans who received a BP or denosumab, there were 76 ICD-coded periprosthetic hip fractures, including one AFF. This fracture met all five ASMBR-defined AFF criteria. The PAFF, a Vancouver C cemented periprosthetic femur fracture, occurred in a man with > 7 years of BP therapy. There was no contralateral AFF. The BP was discontinued and the fracture was treated with an interlocking plate with cerclage wires. In the 12 months following PAFF, there were no infectious complications, but the fracture had a chronic nonunion.

Conclusion: Periprosthetic hip fractures may rarely have features of AFFs. Fracture nonunion may complicate PAFFs.