Postoperative brachial plexus neuropathy after total knee replacement under spinal anaesthesia.

We describe a case of idiopathic postoperative brachial plexus neuropathy. A 68-yr-old man underwent elective total knee replacement under spinal anaesthesia. Two days after surgery, there was sensory loss and weakness in the right forearm and hand, which suggested an ulnar nerve neuropathy. Two weeks later the patient complained of a dull ache between the scapulae, followed by a burning sensation in the forearm and severe pain in the elbow. A diagnosis of brachial plexus neuropathy was made based on clinical examination and nerve conduction studies. The pain disappeared after a few months, although weakness of the right arm persisted 9 months later. The differential diagnosis between brachial plexus neuropathy and ulnar nerve neuropathy is important, as the prognosis of brachial plexus neuropathy is generally good.