Spinal decompression surgery. Surgeon operating on a 76 year old female patient's spine. This patient has spinal stenosis of the third lumbar (lower) vertebra, where a narrowing of the spinal canal has put pressure on the spinal cord. This is usually due to the natural spinal degeneration that occurs with aging. It can also be caused by the displacement of the vertebrae, osteoporosis or a tumour. The surgery will remove parts of the lumbar vertebra in order to relieve the pressure (decompression).