Background/Purpose: Atypical femoral fractures (AFF) are low energy femoral fractures with a specific radiographic pattern and subtrochanteric / diaphyseal localization that have been related to long-term bisphosphonate therapy. Glucocorticoid and rheumatic diseases, mainly rheumatoid arthritis has also been implicated in this comorbidity. Therefore, the aim of this study was to evaluate a cohort of patients with AFF from a Tertiary Rheumatology Center, including clinical presentation, radiographic data and findings of bone histomorphometry.

Methods: From January 2007 to May 2017, all patients from the Outpatient Clinic (Osteometabolic Disease) of a Tertiary Rheumatology Service, Clinics Hospital- School of Medicine who fulfilled the American Society of Bone Mineral Research (ASBMR, 2010) criteria for atypical fracture were included in this study. Clinical-epidemiological data were obtained from electronic chart review. Anteroposterior radiographs of bilateral hip were analyzed, according to ASBMR. Confirmation of bilateral AFF was performed by magnetic resonance imaging or scintigraphy. Serum markers of bone remodeling, C-terminal telopeptide of type 1 collagen (CTX) and alkaline phosphatase (AP) were also evaluated. Iliac crest bone biopsy and static and dynamic bone parameters (compared to reference values of healthy controls matched by sex and age) were performed by histomorphometric analysis (Osteomeasure® software).

Results: Eighteen patients presented AFF, mostly women (94.4%), Caucasian (72.2%), mean age of 64.9 ± 13.3 years and all had prodromal pain in the anterolateral region of the thigh before the clinical fracture. Seventeen used bisphosphonate (5.83 ± 2.74 years), mostly alendronate (83.3%) at the time of fracture. One patient was taking denosumab, but had previously received bisphosphonate for 6 years. Presence of any inflammatory rheumatic disease was observed in 9 (50%) patients: rheumatoid arthritis (n=4), systemic lupus erythematosus (n=1), Sjögren’s syndrome (n=1), Behçet´s disease (n=1), inclusion body myositis (n=1) and adult-onset Still’s disease (n=1). Eight patients (44.4%) were using oral glucocorticoid at a median dose of 5 mg/day (ranged 5-15mg/day). All fractures presented diaphyseal localization, 16 (88.8%) were complete fracture and 4 (22.2%) bilateral. Bone markers were in the normal range (CTX: 0.28±0.18ng/mL and AP: 76.11± 30.22 U/L). Bone biopsy performed in 6 patients revealed suppression of bone turnover (100%), with reduction of osteoid tissue, as well as decreasing of resorption, osteoclastic and osteoblastic surfaces and impairment of bone mineralization. Sixteen patients underwent surgical treatment and 2 only clinical treatment (teriparatide). In total, 14 patients received teriparatide, 1 strontium ranelate and 3 remained without medication.

Conclusion: Our study alerts the rheumatologist about the possibility of AFF in those patients with bisphosphonate above 5 years, mainly with inflammatory rheumatic diseases and glucocorticoid use. Bone biopsy revealed a bone turnover suppression. Attention should be aware of the prodromal thigh or groin pain and subclinical imaging changes in the lateral femur, both associated with AFF.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/atypical-femoral-fracture-in-patients-of-a-rheumatology-service-clinical-radiographic-and-bone-histomorphometric-data/