Effect of Body Mass Index on Femur Fracture Location: A Retrospective Database Study.

OBJECTIVES

Use a large database design and multivariable analyses to assess the associations between body mass index (BMI) and femur fracture patterns after controlling for other risk factors.

DESIGN

Retrospective cohort study.

SETTING

National insurance claims database of patient records from 2010 to 2018.

PATIENTS/

PARTICIPANTS

Patients with femur fracture diagnoses were identified. Patients with multiple fractures within 1 week (polytrauma patients), patients without a BMI diagnosis code within 6 months of fracture, and patients with multiple BMI diagnosis codes (implying a substantial change in weight) were excluded.

INTERVENTION: N/A.

MAIN OUTCOME MEASUREMENTS: Patients were divided into groups based on fracture location: proximal (OTA/AO 31), shaft (OTA/AO 32), or distal (OTA/AO 33). The distribution of femur fractures was compared across BMI categories.

RESULTS

A total of 57,042 patients with femur fracture were identified: 45,586 proximal fractures, 4216 shaft fractures, and 7240 distal fractures. Patients with BMI <29.9 have increased odds ( P < 0.0001) of proximal fracture and decreased odds ( P < 0.0001) of shaft or distal fractures. Patients with BMI >30.0 have decreased odds ( P < 0.0001) of proximal fracture and increased odds ( P < 0.0001) of distal fractures.

CONCLUSIONS

Increasing BMI is associated with a decreased proportion of proximal femur fractures and a corresponding increase in the proportion of shaft and distal fractures. Regression analyses determined that age, sex, osteoporosis, diabetes, and tobacco use are not the cause of this trend.

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