Background: Acetabular fractures following a fall from a standing height or less are increasing in older adults. The role of osteoporosis is unclear as, compared to hip fractures, acetabular fractures are more common in men. This suggests other factors are likely involved. We explored if differences in hip geometry may influence the type of fracture sustained.
Methods: The database of two acute care hospitals in London, Ontario from 2013 to 2015 was reviewed for acetabular and hip fracture patients aged 75 years and older. Thirty patients with acetabular fracture were age and gender matched with 30 hip fracture patients. Digital X-rays were used to measure hip geometry in all patients using previously defined methods. Measurements included hip axis length, neck shaft angle, acetabular thickness, femoral shaft width, femoral neck width and femoral neck axis length.
Results: Patients (35 women, 25 men) had a mean age of 86 years (range 75 to 98). Compared to those with hip fracture, patients with acetabular fracture had narrower neck shaft angle (126.7° vs. 129.6°, p = 0.029) and larger femoral shaft width (36.4 mm vs. 34.7 mm, p = 0.049). Hip axis length, femoral neck length, and femoral neck width measurements were similar between groups.
Conclusion: Hip geometry differs between patients with acetabular fracture and hip fracture. The narrower neck shaft angle, indicating that the femoral neck is approaching a right angle, may increase the propensity to sustain an acetabular fracture. The role of the wider femoral shaft is unclear. It may suggest increased femoral bone strength, which could explain the higher incidence in men. Future studies incorporating bone mineral density are needed to improve our understanding of factors associated with acetabular fractures.