Explanation:
In a Colles fracture, the distal radius fragment is displaced dorsally and radially. The extensor carpi radialis longus and brevis exert a dorsal pull on the distal fragment, contributing to the characteristic dorsal angulation. Additionally, the brachioradialis may cause proximal migration and radial shortening. The combination of muscle forces and fracture geometry leads to the classical 'dinner fork' deformity. Understanding these deforming forces helps guide reduction maneuvers and fixation strategies. Restoration of volar tilt and radial height is essential for optimal functional outcome. Reference: Jupiter JB. "Fractures of the Distal End of the Radius." Journal of Bone and Joint Surgery, 1991.