Excessive movement between two vertebrae can be painful, or trap nerve roots and give rise to ‘referred’ pain. This pain, often like toothache, is associated with numbness and pins and needles, in the area that the nerve root subserves- for instance for a lumbar nerve root, it may radiate down to the foot, and sometimes be associated with weakness in the innervated muscles.
Typically the pain is worse on standing and walking, but relieved by sitting.
A CT or MR scan may show that bones have slipped, pinching the adjacent nerve root. The commonest causes are either facet joint wear, or a fracture. Symptoms need to be severe enough to limit quality of life, otherwise alternatives, such as physiotherapy and back strengthening exercises are preferable.
Either a single midline incision is used, or two smaller incisions, one either side, about 2-3 cm from the midline. The back of the vertebra is exposed, enabling any bone compressing the nerves to be removed, and placement of screws into the pedicles of the vertebrae. A rod is then placed between the two screws each side, and tightened in place. Bone graft is placed between the two vertebrae to enable a solid block of bone to join the two vertebrae together, so preventing further movement.
Some residual back pain and/or stiffness is not unusual after this procedure. A blood clot forming in the wound can sometimes prolong the local pain during the first two weeks after operation. An infection may occur in 2-3 per cent of patients, usually treated by a course of antibiotic tablets. More severe, deeper infections are rare, but may need hospital stay and intravenous antibiotics. Nerve root injury can occur during placement of the screws, occurring in about one in a hundred screw placements. This can give rise to persisting pain, numbness or weakness.
Patients usually remain in hospital for 2-3 days after operation, needing analgaesics. Sometimes a urinary catheter is necessary, and anti-embolism stockings are worn. Walking is then encouraged, starting with a short five minute walk, increasing to ten, then twenty minutes, two or three times a day, in the first few weeks. Physiotherapy follow up is usually arranged for three weeks, and an outpatient consultation at about six weeks. A phased return to work follows.