Different Pattern of T-Score Discordance between Patients with Atypical Femoral Fracture and Femur Neck Fracture

BACKGROUND: Our study evaluated the prevalence and pattern of T-score discordance between the spine and hip in Korean patients with atypical femoral fracture (AFF) and femur neck fracture (FNF). METHODS: A total of 49 patients (all women) who were treated for AFF and 1:3 matched 147 female patients with FNF were included from January 2012 to August 2022. A discordance of more than 1.5 between lumbar spine and femur neck bone mineral density (BMD) was defined as a difference and divided into 3 groups: lumbar low (LL; lumbar BMD is less than femur neck BMD), no discordance (ND), and femur neck low (FL; femur neck BMD is less than lumbar BMD). We compared the prevalence and pattern of discordance between 2 groups, and the associated risk factors of T-score discordance among the subjects were evaluated using regression analysis. RESULTS: The prevalence of discordance was significantly higher in patients with AFF (51%) than in those with FNF (25.2%; P<0.001). LL discordance was found in 46.9% of the patients with AFF but only 4.8% in those with FNF. Conversely, FL discordance was found in 4.1% of the patients with AFF and 20.4% in those with FNF, respectively. No specific risk factor was found as T-score discordance in the 2 groups. CONCLUSIONS: Clinicians should be aware that the pattern of T-score discordance can vary depending on the location of osteoporotic fractures. In addition, a longitudinal study would be necessary to verify the pattern of T-score discordance related to the osteoporotic fracture location.