There are two mechanical problems in the spine that are of particular importance because they are amenable to surgical treatment: spondylolisthesis and spinal stenosis.
This condition arises because of a defect in the pars interarticularis of the vertebra, which may be either congenital or acquired. It gives rise to a slipping forward of one vertebra on another, most commonly at L4/L5. The acquired variety is usually the result of a fairly major traumatic episode that the patient will remember. A small spondylolisthesis is sometimes found in patients with degenerative disease of the lumbar spine and may contribute to the symptoms. The patients have mechanical pain that is not present on waking in the morning but develops as the day goes on and is aggravated by activities such as standing or walking. The pain may radiate to one or other leg and there may be signs of root irritation. More often there are no physical signs, though there may be some limitation of back movement. The diagnosis is confirmed by X-ray.
Small spondylolistheses are common, especially in patients with degenerative disease of the lumbar spine, and may be managed conservatively. It is appropriate to use simple analgesics to relieve the pain and there is no particular need for anti-inflammatory agents. A corset may provide support; this is one of the few indications for its use. A large spondylolisthesis causing severe pain,
especially in a younger patient without associated degenerative changes, requires spinal fusion. This is usually a very successful procedure.
This is sometimes called spinal claudication because of the resemblance of the symptoms to those of intermittent claudication due to vascular occlusion. The anatomical change in spinal stenosis is narrowing of the central canal, compressing the cauda equina. This can result from a variety of causes:
• Disc prolapse
• Degenerative osteophyte formation
• Congenital narrowing of the spinal canal
The patient typically presents with pain in one or sometimes both legs. The absence of back pain makes the diagnosis difficult. The pain comes after a period of walking and tends to diminish with the passage of time. The symptoms are relieved by rest and occasionally by leaning forward. Signs of root compression such as limitation of straight-leg raising or absent reflexes may be precipitated by exertion.
If spinal stenosis is suspected, CT or MRI scans will be required to confirm the diagnosis. Treatment is by surgical decompression.
Other mechanical problems
Bad posture is sometimes the cause of back pain. An exercise programme designed to improve posture will also therefore improve the pain. Such postural problems may be precipitated by congenital abnormalities of the spine such as a minor kyphoscoliosis. Obesity and presumably lack of activity sometimes appear to be relevant and weight-loss combined with an exercise programme may help.