Wrist drop after a fall onto the shoulder

A man in his 70s presented to the emergency department with severe pain in his left shoulder and inability to move his left arm, immediately after falling onto his left side. He had a history of three previous right shoulder dislocations. On examination, he had obvious left shoulder joint swelling and shoulder contour deformity with pain on movement. He had notable weakness of forearm extensors of the wrist and fingers, Medical Research Council grade 2/5, with intact strength of wrist and finger flexion. He described diffuse paraesthesia over the dorsal hand, including the anatomical snuffbox and the lateral three and a half digits (radial nerve distribution) but also over the dorsal surface of the medial one and a half digits (ulnar nerve distribution). Plain radiography showed severe injury (fig 1). The arm was immobilised with a poly-sling, …