Longer hip axis length (HAL) has been shown to be associated with the risk of hip fracture. We examined whether HAL is associated with hip fracture risk in elderly community dwelling women in England, unselected for osteoporosis.

We undertook a case-controlled study of women aged ≥ 75 years enrolled to a large, randomised controlled study looking at the effect of a bisphosphonate, clodronate, in the prevention of hip fractures. Cases comprised those women who sustained a radiologically verified hip fracture during follow-up (median 3. 1 years). Two age, height and weight-matched controls were selected for each case. Baseline total hip bone mineral density (BMD) was measured using a Hologic 4500 QDR and the HAL was measured using the densitometer’s automated software.

92 of 4347 women (2. 1%) sustained a hip fracture, but two women had not received a baseline BMD assessment and were excluded, leaving 90 women with hip fractures and 180 matched controls.

The mean age of the cases and controls was 81. 9 ± 4. 9 years. The mean hip BMD was significantly lower (0. 65 ± 0. 31 vs 0. 72 ± 0. 13, P< 0. 001) and the mean HAL was significantly longer in the hip fracture women than the controls (11. 1 ± 0. 6 vs 10. 9 ± 0. 6, P=0. 03).

The increase in the HAL was significantly associated with the risk of hip fracture (Odds Ratio (OR) per 1 standard deviation increase was 1. 33, 95% CI 1. 02–1. 72; p=0. 03) remaining significant after adjustment for hip BMD (OR 1. 32, 95% CI 1. 01–1. 71; p=0. 04).

An increase in hip axis length is associated with an increased risk of hip fracture in elderly English women independent of hip BMD, although the odds ratio appears somewhat lower than that reported in other studies.