Abstract: A dynamic hip screw comprises plate and a lag screw. The plate comprises a central ring portion from which a pair of oppositely directed wings extend, the plate having a concave medial surface and a convex lateral surface. The wings curve away from an axis transverse to a central axis of the ring portion. Each of the wings twists about the central axis as they extend away from the ring portion so that they extend in opposite directions away from the transverse axis. The lag screw comprises a shaft with a proximal end and a distal end for insertion into a bone. The distal end comprises a threaded section on which a main thread having a first thread depth is formed. A plurality of threads are defined on a leading surface of the main thread, each thread having a thread depth which is a fraction of the first thread depth.