Background Hip Structural Analysis (HSA) has been used to investigate the relationship between proximal femoral neck shape and femoral neck fracture risk; studies have reported contrasting findings. Although previous work has been carried out on the general population, it is not known if a particular proximal femur shape is associated with femoral neck fracture in patients with established osteoporosis (OP).
Objectives To investigate if HSA measurements differ between osteoporotic patients that have and have not sustained a femoral neck fracture.
Methods Data were collated from patients diagnosed with OP by DXA between 2006 and 2010 in a UK district general hospital. Two groups were identified: those with and without a previous femoral neck fracture. HSA measurements were compared between the two groups using a logistic regression model, unadjusted and adjusted for possible confounders - age, sex and body mass index (BMI). The following HSA measurements were collated: distance from center of femoral head to center of femoral neck (d1), distance from center of femoral head to inter-trochanteric line (d2), mean femoral neck diameter (d3), distance from center of mass of femoral neck to superior neck margin (y), hip axis length (HAL), cross-sectional moment of inertia (CSMI - theoretical measurement of femoral neck strength) and proximal femur strength index (SI). The previous fracture group’s HSA measurements were taken from the contra-lateral non-fractured hip.
Results Data of 632 (82.58% female) osteoporotic patients that had previously sustained a femoral neck fracture were compared to 11761 (82.50% female) osteoporotic patients that had not previously sustained a femoral neck fracture. The mean age of the fracture group was significantly lower compared to the non-fracture group: 69.21 years vs 70.24 years (p-value 0.01), respectively. Mean BMI did not significantly differ between the fracture and non-fracture groups: 25.86 kg/m2 vs 26.05 kg/m2 (p-value 0.29), respectively.
Following adjustment for age, sex and BMI, the odds ratios indicate that the fracture group had a significantly higher HAL, d2, d3 and y, and lower CSMI and CSA.
Conclusions Results indicate that, for osteoporotic individuals, femoral neck fracture is associated with a longer (HAL, d2), wider (d3, y) and theoretically weaker (CSA, CSMI) proximal femur. This study indicates that proximal femur shape is associated with femoral neck fracture risk in osteoporotic individuals. Measurement of proximal femur shape as well as BMD may more accurately quantify femoral neck fracture risk. Proximal femur remodeling following contra-lateral fracture can not be ruled out.
Disclosure of Interest None Declared
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