Spinal Instability And Progressive Deformity Syndromes

A significant number of patients with spondylotic disease will develop progressive spinal deformities. These are degenerative in nature for the majority, although congenital and traumatic instability certainly can occur and will be similar in presentation. Fortunately, the treatment is very much the same, so the aetiology makes very little difference ( Panjabi et al 1984 , Olerud et al 1986 , Dvorak et al 1991 ).
Degenerative spondylolisthesis
This is the most common of the apparent instability syndromes encountered ( Annertz et al 1990 ). However, the apparent movement expected because of the malalignment of adjacent vertebral bodies may not be seen on flexion-extension films. It may be slowly progressive and occasionally may be fixed. Patients typically complain of back pain in the lumbar area with or without associated root signs. Diagnosis is made by plain X-rays, which should include dynamic films to be certain whether the spine is moving actively.

Treatment should be symptomatic, unless pain is intractable or significant nerve root compression with neurological deficit is occurring. Symptomatic therapies include bracing, modification of lifestyle, and individualized active exercise for axial muscle strengthening, range of motion, and leg strength. Surgery should be considered when axial back pain, radicular pain, or both, are severe and disabling. Most patients with progressive listhesis or slowly progressive scoliotic deformities of any kind will require fixator use for stabilization and fusion. It is best to proceed when it is apparent that symptoms are serious enough to warrant surgery, but before extremely severe deformities occur. The surgeon should be experienced in the use of fixators and in this complex reconstructive spinal surgery. The goal of surgery is to restore or maintain lumbar lordosis in association with the decompression of individual lumbar roots and the stabilization of all required segments ( Turner et al 1992 , Zdeblick 1993 , Temple et al 1994 ).
The Faıled Back Syndrome
The failed back syndrome is an imprecise term usually used to categorize a large group of patients who have undergone one or more operations on the lumbar spine without benefit. It serves no useful purpose and should be abandoned. The patient who has not been benefited from one or more operations needs an evaluation which, if anything, is more complex than the patient who has not undergone surgery ( Fig. 23.6 ) ( Cherkin et al 1994 ). It may be possible to make a specific diagnosis about the cause of pain with greater frequency than in most idiopathic spondylitic back pain problems. The goal of the evaluation should be the most precise definition of abnormalities possible, so that an individualized treatment plan can be prescribed ( La Rocca 1990 ). Patients fall into broad categories within this heterogeneous group that are useful in order to guide the evaluation and the therapeutic plans. The first of these broad categories is a group of patients for whom surgery was probably not indicated in the first place ( Cherkin et al 1994 ). The second group of patients is those with clear indications for surgery, but in whom surgery did not correct the original abnormality. A third category of patients is those in whom some significant complication of surgery occurred and is now the pain generator ( Fager & Freidberg 1980 ). There is another very small group of patients in whom an intercurrent diagnosis has been missed. A typical example is the patient with chronic back pain who harbours a tumour, usually a schwannoma or ependymoma, of the cauda equina.

Whatever the proposed treatment plan, precise definition of the abnormalities which are likely to be generating the pain and which must be treated, is imperative. Specifically, if any reoperative surgery is to be done, it should be planned for abnormalities which are as well defined as for first surgery. It is still true in these patients that surgery will only benefit individuals who have nerve root compression or clearly demonstrable instability. Utility of surgery for removal of scar, which is not compressive, removal of tissues which potentially generate noxious substances in the inflammatory chain or the correction of micromovement in painful segments has not been proven and we do not use any of these concepts to justify reoperation.

In an extensive review of a small group of patients for whom all preoperative studies were available and complete records detailed status before failed lumbar surgery, we determined that the majority did not meet commonly accepted criteria for lumbar operation. Therefore, it is not surprising that surgery failed to relieve them. In a recent multicentre nationwide prospective study of the outcome of first-time-back surgery, we determined that over 90% of patients were improved when chosen for surgery by expert spinal surgeons. By contrast, in a small group of patients rejected for surgery by these same experts, only 10% were improved by operation carried out outside our study and worsening of symptoms following surgery was the rule. In examining patients who have failed lumbar surgery, it is important to determine the original indications for the procedure if possible. Of course, it is still quite possible for such patients to have had a surgical complication which now requires correction. Even though patients have not had appropriate indications for original surgery, they still require evaluation to determine the current cause of the problem. If symptoms remain the same and no new abnormalities are found, it is unlikely that any surgical procedure will be beneficial. However, the original surgeons may have failed to correct an abnormality or some complication may have occurred which will influence a decision about additional surgery. Therefore, whatever the original indications, complete evaluation of patients is required ( La Rocca 1990 ).

The first questions relate to the pain. Is it the same or has something new occurred? Does the pain suggest a mechanical back problem only or is there a radicular component? Does the radicular pain sound neuropathic, suggesting nerve root injury?

Physical examination is unlikely to be helpful in the diagnosis, but will record the patient’s current physical state.Imaging studies begin with plain films with flexion-extension. These should include obliques to evaluate the zygapophyseal joints. CT imaging, particularly with multidimensional reconstructions, will demonstrate bony detail, the effects of previous surgery, the status of zygapophyseal joints, the size of neural foramina and such common complications as pars fracture. MRI is more useful for the examination of discs, nerve root relations in the neural foramina, the size of the spinal canal and inflammation ( Ross et al 1987 , Hochhauser et al 1988 , Hueftle et al 1988 , Cavanagh et al 1993 ). If fixators are in place, 3D reconstruction will eliminate the metallic artefact and provide a view of the placement of the fixator as well ( Firooznia et al 1987 ). CT myelography is sometimes required, particularly when fixators are in place ( Hashimoto et al 1990 ).
Alternatives For Care Of Chronic Low Back Pain
It is not surprising that a clinical problem as poorly understood as low back pain should generate a huge number of therapies which are devised to be helpful. Most are as yet unproven, although many are supported by long-standing practice ( Bigos et al 1994 ).

The first general category comprises all those adjuncts which claim to make people more comfortable. The list is long: adjustable beds, firm mattresses, chairs, pillows, supports and whirlpools to name a few. Patients may try the ones that seem attractive to them, and use those that are comfortable. I tend to discourage use of those that are excessively expensive and will not prescribe any.

Many patients are in long-term programmes of passive therapy measures such as heat, massage, electrical stimulation, or active programmes of massage, electrical stimulation, or active programmes of massage plus manipulation. The value of any of these is not supported by strong evidence in chronic back pain. I tell patients to continue if they are convinced they are symptomatically better ( Wiesel et al 1980 , Bell & Rothman 1984 , Heliovaara 1987 ).

Patients also seek accupuncture, and a variety of related and unrelated therapies such as are available from mail-order
catalogues. None are supported by scientific data on chronic back pain, and I do not recommend any. This is also true of the many herbal remedies patients bring.

A large number of books, tapes and videos are available on the topic of back pain. Most are helpful; a few could be dangerous. It is best to find some you like and recommend them, rather than allowing the patient to choose indiscriminantly.

Many minimally invasive techniques have and are appearing which promise patients no risk relief. Some of the most popular were and are chymopapain intradiscal injection, steroid in epidural or intradiscal spaces, percutaneous discectomy, endoscopic laser discectomy, endoscopic discectomy, endoscopic fusion and microdiscectomy. All are techniques for experts. Some have come and gone. Some are being evaluated. None are clearly established to have an important role in chronic low back and leg pain ( Martins et al 1978 , Choy et al 1987 , Kambin 1988 , 1991a , b , Kahanovitz et al 1990 , Onik et al 1990 , Nordby et al 1993 , Revel et al 1993 , Regan et al 1995 ).

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