Focal osteoporosis defects play a key role in hip fracture by Poole, K, Skingle, L, Gee, A, Turmezei, T, Johannesdottir, F, Blesic, K, Rose, C, Vindlacheruvu, M, Donell, S, Vaculik, J, Dungl, P, Horak, M, Stepan, J, Reeve, J, Treece, G