Benign hydroarthrosis of knee in patients with spinal cord injury.

Swelling of the knee joint occurred in 8 of 35 patients with spinal cord injury; in seven of the eight patients the swelling developed within the first eight months after injury. Six of the eight patients had flaccid paraplegia. None of the patients showed any constitutional or local changes other than swelling. No laboratory evidence of inflammation could be detected. Swelling disappeared in two to six weeks and no sequelae were noted. Although trauma appeared to be the most likely cause of the swelling. Only one of four joints showed hemarthrosis on aspiration.