Purpose: A correlation between soft tissue thickness and osteoporosis has been suggested. We aimed to estimate if a low body mass index (BMI) and/or a decrease of skin thickness could estimate the risk of contra-lateral hip fracture.

Methods: First, we performed a retrospective analysis of 1268 patients treated for a hip fracture. The 146 patients who had a contra-lateral hip fractures-study group-were compared with the 1078 patients who did not-control group. Four BMI categories were considered: obese, overweight, normal weight and low weight. Second, we enrolled prospectively 1000 consecutive patients in the emergency department. History of fractures, BMI, and skin aspect on the dorsum of both hands-classified as severe decrease thickness, moderate decrease thickness or normal-were recorded.

Results: pt?>In the first part, we found that patients with contra-lateral fractures had a significantly lower BMI than those in the control group (22.2 Vs 26.5 kg/m², p = 0.01). In the second part, 48 on 1000 patients had a hip fracture. Among them, six had a contra-lateral fracture. BMI was 23.4 kg/m² in bilateral hip fractures, 33.68 kg/m² in the unilateral fracture group, and 28.04 kg/m² in the non-fracture group (p = 0.04). Finally, patients with contra-lateral hip fractures had a severe decrease thickness of the skin.

Conclusion: A low BMI and a decreased skin thickness increase independently the risk of fractures by three times. When associated, they increase the risk of fracture risk by five times. This combination had a sensitivity at 71 % and a specificity at 90 % for predicting hip fracture.