Two balances occur within the disc:

Lumbar disc degeneration (dysfunction) is the result of deterioration of the mechanical and chemical properties of the disc. The cause is the universal phenomenon of the aging process and aggravated by environmental factors such as trauma, high-impact activity, type of work, and smoking. Genetics with a predisposition also plays a role. The deterioration in physical and chemical properties leads to the loss of low back function manifest as mechanical disorders (“my back hurts when I bend and lift”) and/or neurologic compressive disorders [“my leg(s) hurt(s) when I sit or walk”]. We
all get older and by default we all deteriorate our discs yet we are not all symptomatic (6). It is a constant theme throughout this book that degenerative disc disease routinely occurs without symptoms, or when it does become symptomatic there is a powerful natural tendency toward self-healing.

The actual physical and chemical changes that occur with aging are loss of water in the nucleus and the annulus (the conversion of a grape to a raisin!), the end stage of which is intradiscal fibrosis. The body does an autofusion with fibrous tissue replacing the nucleus and annulus reducing movement in the segment. This explains why we get stiffer as we get older and why the vast majority of individuals grow older without back pain.

The reason for these chemical changes centers around an understanding of disc nutrition (Fig. 10-2). The intervertebral disc is avascular after age 8 years and receives its nutrition through transport across the cartilaginous endplate and through the annulus. With aging these vascular channels start to fail and diffusion of nutrients decreases. The result is a decrease in the number of fibroblasts and chondrocytes and a decrease in formation of collagen and proteoglycans. The end result is failure of the disc to absorb mechanical forces because of failure of the swelling pressure balance.

Kirkaldy-Willis and Farfan (31) described three phases of disc degeneration (Fig. 10-3).

Kuslich and coworkers (32) have carried out the best clinical work in this field. While doing microdiscectomies for disc ruptures under local anesthesia in more than 700 patients, these researchers took the opportunity to stimulate various tissues and record the patient’s response. They found that muscle, fascia, and bone were largely insensitive structures, whereas the facet joint capsule was painful in half of the patients. The outer annulus was the most consistent structure to produce back pain when stimulated. The inner annulus and nucleus were largely insensitive structures. The surgery for the patients in this study was being done for the symptom of sciatica and the disease of disc rupture. The researchers found that stretching the already stretched, compressed, and inflamed nerve root reproduced or exacerbated the patients’ leg pain.

Instability may be demonstrated on flexion/extension lateral x-rays (Figs. 10-6 and 10-7). In those patients in whom instability cannot be demonstrated on radiograph, some investigators have used provocative/ablation testing. Examples of the latter are bracing or the external fixator (11,43) to see if back pain can be decreased. Bracing does not work because to immobilize the lower lumbar

spine, where most instability occurs, the thigh must be included in the brace (Fig. 10-8), which severely strains patient compliance. There is controversy about the usefulness of this test in identifying the source of low back pain.

An example of provocative testing is lumbar discography, a discussion of which splits the orthopedic community into naysayers and enthusiasts. For most neurosurgeons performing spine surgery there is no controversy: discography is a useless test (26).

Most scientists, aware of the pros and cons of discography, would agree on the following points:

The other two parameters of discography, namely volume of test material and the pressure of injections, have largely been abandoned.

Like anything else, the choices for treatment of instability causing back pain are either conservative or surgical. Conservative measures include short terms of bed rest, anti-inflammatories, modification of activity, exercise, and back school.

Surgical methods to stabilize the spine are most commonly accomplished by fusion (Fig. 10-12). Artificial discs are an alternative to fusions in select patients.

There are not many people who have lived for a half century who have not, at some time in their lives, been smitten by an acute episode of incapacitating backache. Perversely, this is encouraging. These people do not remain incapacitated: they get better, perhaps despite treatment rather than because of it. They are visiting with Kirkaldy-Willis and Farfan’s (31) Phase 1 of spinal dysfunction.

Characteristically, the patient, while engaged in some trivial activity, is suddenly seized with back pain and cannot move. “I was paralyzed with pain.” The lumbar spine is splinted rigidly and the patient can only move with painful caution, clutching his or her back and walking with the trunk leaning forward, keeping the hips and knees slightly bent.

Examination reveals that all movements of the spine are limited by pain and muscle spasm, but there is no evidence of root tension, irritation, or compression. In some of these patients, there is so much back spasm and muscle splinting that attempting to perform the straight leg raising (SLR) test will cause back pain and leave the examiner with the false impression that a disc rupture may be present. A useful examination is the sitting SLR test. Most of these patients can sit in a few moments of comfort; in this sitting position, gentle SLR testing (Fig. 10-14) will reveal good SLR.

The clinical picture is explosively dramatic and threatening to the patient, if he or she has not been through a previous episode. The physician must not overreact. The physician must constantly remind himself or herself that even if the elected treatment involved rubbing peanut butter on each of the patient’s buttocks, in the balance of probabilities, the patient would get well fairly quickly.

In the majority of such cases the patient is suffering from painful dysfunction of the disc space or a “sprain” of one of the zygapophyseal joints. When trying to rationalize treatment, one should compare the lesion with a severely sprained ankle in a patient who has only one leg and who is unable to wear a prosthesis. There is only one way to treat a severely sprained ankle in such a patient: the patient has to be put to bed. Theoretically, the patient with an acute severe low back strain should also be considered for bed rest. However, theoretical treatment must be tempered by reason. If your patient is a young married woman who is responsible for care of the children and getting
the meals, how are these responsibilities going to be met? What about the responsibilities of functioning in the office for the dentist with acute back pain?

Let us repeat: you are treating a patient and not a spine, and the experience of the lay world is that many, in fact, the majority, will get better by just creeping around, with their pain mollified by analgesics.

Some patients, however, cannot cope. The pain is too severe. In such instances, if they cannot do their normal daily work, they should be sent to bed. A patient with pneumonia is ill and may feel defeated; that person is happy to go to bed. A patient with severe low back pain feels well except for his or her back and does not want to go to bed. This patient is hopping mad at the affliction, and your insistence on bed rest will increase the frustration, unless you take care and time to explain in detail the purpose of this apparently neglectful form of management. It is advisable to give the low back pain patient some literature explaining in detail the probable underlying pathology and the rationale of
treatment by bed rest (Table 10-2). You must advise the patient regarding the use of toilet facilities. Using a bedpan at home is impractical. The use of crutches makes it easier for the patient to get to the bathroom, and the purchase of a high toilet seat is sometimes essential.

Although analgesics are rarely needed once the patient is in bed, in the majority, sedatives such as tranquilizers are essential. At present there is no specific medication to speed the resolution of the symptoms, although anti-inflammatory drugs may help some patients (3).

The question of the role of manipulation is always raised. The “locking” of the back by spasm of the paraspinal muscles may tend to perpetuate the problem, and gentle flexion of the spine into the fetal position of rest appears to release the muscle by hyperactivity. This is best accomplished initially by getting the patient to flex the knees and hips and then use the hands to pull the knees against the chest repetitively (Fig. 10-15). Later, a passive flexion manipulation can be carried out. The patient lies on his or her back with hips and knees flexed. The heels are grasped so that feet point toward the ceiling. The feet are then pushed gently over the patient’s head. The movement is repeated slowly and rhythmically. This repetitive rocking must be carried out with slow, simple harmonic motion with each swing of the legs flexing the spine a little further. This rhythmical swinging is continued for approximately 2 minutes (Fig. 10-16). This is a much more effective maneuver for the occasional manipulator than the specific manipulation of spinous processes or the commonly employed flexion rotation manipulation of the lumbosacral joint.

To be effective, however, this manipulative therapy must continue on a daily basis and, therefore, the patient must learn how to perform these maneuvers independently. The patient should be taught specific steps. The manipulation exercises are carried out on a bed, not on the floor. The neck is kept slightly flexed by a pillow to minimize the effects of the inevitable contraction of the sternomastoids when the patient first makes an attempt to kick his or her feet up in the air.

The hips and knees are first flexed to a right angle. The legs are then raised toward the ceiling, keeping the knees slightly bent. The feet are then moved over the patient’s head. This movement must not be in the form of a sudden kick. The buttocks must be raised slowly and smoothly off the bed by contraction of the trunk flexors and then, just as slowly, the legs are lowered. This movement is repeated several times, each time lowering the legs just to the starting position with the hips flexed at 90 degrees. The legs must not be lowered to the bed.

After five “kickups,” the patient rests by lowering his or her legs, with the knees fully flexed, thereby putting the feet onto the bed, soles first (Fig. 10-17). This routine, at this stage in the treatment of an acute back pain, is not designed to be an exercise program. It is really an active flexion manipulation of the spine. The duration of these flexion manipulations should be restricted to 10 kickups only and these should be repeated three times a day.

If you are uncomfortable describing this regime to the patient and you think the patient can be driven to a professional’s office, refer them to a skilled practitioner of the manipulative arts. Chiropractors are the most skilled, and many osteopaths are pursuing more “traditional” methods of medical care. Some physical therapists also include manipulation (in addition to mobilization) in their armamentarium (19).

Bed rest should be continued until the patient can make journeys to the toilet in relative comfort without the aid of crutches (usually no more than a few days). After this period of time, the patient
gradually increases activities within the limits set by his or her own tolerance of decreasing discomforts. The time of return to work is determined largely by the demands made on the patient’s need to return to the job.

Well-designed braces and corsets may also be helpful during the active phase. When considering a brace, remember that most of these patients will be better in a few days, and a brace is not indicated thereafter.

The treatment program previously described has been officially blessed by the Agency for Health Care Policy and Research (5), an arm of the American Government (U.S. Department of Health and Human Services). The agency has, with great fanfare including media exposure, recommended a few days of bed rest, nonsteroidal anti-inflammatory drugs (NSAIDs), a brace for return to work, physical therapy, and manipulation for acute low back pain of less than 3 months’ duration. They did not recommend acupuncture, transcutaneous electrical stimulation, trigger point injections, epidural injections, or traction.

This is probably the most common manifestation of disc degeneration and is the phase leading from dysfunction to instability. Rowe (45,46), studying the incidence of low back pain in workers at the Kodak Company, found that 85% of the patients with backache had intermittent attacks of disabling pain every 3 months to 3 years, each attack lasting 3 days to 3 weeks. Between the attacks, the patients were relatively free from backache. The posterior joints are vulnerable to extension strains because degenerative changes in one or more discs may give rise to segmental hyperextension or persistent posterior joint subluxation. The facets of the involved segment or segments in these conditions are held at the extreme limit of extension; they have no safety factor of movement. A simple analogy can be drawn with the wrist. If a moderate blow is applied to the palm of the hand with the wrist in the neutral position, no pain results because the force of the blow is absorbed by the movement that occurs. If, however, the hand is hit with the same force, with the wrist in full extension, then this is painful because there is no safety factor of movement and the full brunt of the injury is transmitted to the capsule of the wrist (Fig. 10-18).

The same mechanical principle applies to the spine. In the neutral position moderate extension strains are not painful, but if a segment is held in hyperextension, there is no safety factor
in movement and the extension strains of everyday living give rise to painful capsular lesions. The significance of extension strains is noted both in the history and examination of the patient.

Working with the hands above the head, such as in hanging up laundry, reaching, and so on, applies extension strains to the back and is painful. When the forward stooped position is maintained, the sacrospinales have to contract to hold the spine. With an unstable lumbar disc segment in this position, the sacrospinales act as a bowstring producing hyperextension at the involved segment (Fig. 10-19). These patients complain of pain on stooping over the wash basin in the morning and when maintaining the bent forward position, as when making beds, and so on.

Sitting in a soft chair will allow the lumbar spine to become concertina-like and sag into hyperlordosis. These patients find it more comfortable to sit on a hard seat. Sitting in a theater with the knees out straight and the floor sloping away will apply a significant extension strain to the spine, and the patients tend to irritate the patrons in the row in front by putting their feet on the back of their seat to keep knees and hips flexed. Similarly, sitting in a car with the knees held straight hyperextends the spine and makes prolonged driving uncomfortable.

When these patients stand for long periods of time, the lumbar spine sags into extension, and the patients automatically try to flatten the lumbar spine by flexing one hip and knee, as in the act of putting one foot on the seat of a chair or on a bar rail. Emotional tensions and frustrations will make the patient adopt the fight position, tightening up the sacrospinales. This posture will aggravate the pain, and the patient’s increase in pain will aggravate his or her frustrations.

The pain experienced is commonly localized to the lumbosacral junction radiating out to one or both sacroiliac joints. If the pain intensifies it may radiate down one or both posterior thighs as far as the knee, which may be confused with sciatica. On occasion, the pain may radiate into the groin and can be mistaken for hip disease.

On examination, the patients may demonstrate an increase in the normal lumbar lordosis, but more commonly they do not demonstrate any postural spinal abnormalities. They may, however, show many mechanical features that tend to aggravate hyperextension of the lumbar spine.

The bête noire of orthopedic surgeons is the syndrome of chronic, persistent discogenic low back pain, easily made intolerable by modest activity. These patients are in the midst of chronic spinal instability and have yet to advance into Kirkaldy-Willis’s third phase of spontaneous stabilization.

Patients with a chronic persistent daily backache generally report a history of having been plagued by intermittent episodes of back pain for several years. Eventually, they reach the stage when the back pain never really leaves them. By pushing themselves, they may get through the average day with barely tolerable nagging discomfort in their backs. They are very vulnerable to the traumatic insults of everyday life and, on minimal provocation, may get a “flare-up” of back pain. They have to be careful about everything they do and gradually, almost imperceptibly, their activities grind to a halt. They become the subjects of spinal rule, with their spine acting as a malevolent dictator, determining what they can do and what they cannot do. These patients then report the history of a back pain that seriously interferes with their ability to do their work and their capacity to enjoy themselves in their leisure hours.

When assessing such patients, it must be remembered that, although a chronic back pain may make the patient’s life very miserable, persistent incapacitating back pain is most unusual. For example, if a woman presents with these complaints, the first question that the physician has to ask is “Why is this patient so disabled by the back pain she experiences?” It must be remembered that pain and disability are not synonymous. “The pain in my back is so severe I can’t stoop to make the beds.” This seems to be a perfectly reasonable complaint, but, nevertheless, it must be remembered that the patient is not describing the pain: she is describing her own reaction to the pain. Her next-door neighbor with the same degree of pain may be out playing tennis. In chronic depressive states when the patient’s emotional state is affected, the patient may describe an obviously unreasonable decrease of activities: “For the last 2 years the pain has been so bad that I have had to use two canes to get around the house, and I haven’t slept for more than 1 or 2 hours any night,” “I got a sudden severe attack of pain in the middle of the symphony concert and they had to carry me out on a stretcher.” This grossly exaggerated degree of disability is obviously divorced from reality. Discogenic back pain never gives rise to this degree of physical impairment for this length of time. The magnification of the disability may be less bizarre. “I spend at least half the day lying down.” “I can’t walk a block.”

Emotional problems commonly play a significant role in the disability resulting from chronic persistent low back pain. A patient with an hysterical personality tends to react hysterically to any pain, including a backache, but the histrionics generally subside as the pain abates. When the disability represents just one small facet of a general emotional breakdown, the symptoms will be intensified and perpetuated if too much attention is paid to them and too little attention is paid to the patient as a whole.

In the management of these patients, then, the important questions to answer are: “Why is this patient so disabled by the pain he or she experiences?” “Where has the breakdown occurred: in the patient, or in the spine, or in both?”

Examination of the spine will reveal the features described in patients suffering from recurrent back pain due to segmental instability: pain on extension of the spine, reversal of normal spinal rhythm, pain on bilateral active SLR, and tenderness on palpation and manipulation of the lower lumbar spinous processes. It is frequently observed that the lower lumbar spine moves very little on forward flexion, a fact that can be measured by noting that the spinous processes do not separate very much on forward flexion. There are no signs of root tension, root irritation, or root compression.

Other factors contributing to the persistence of the pain may be noted: excessive weight, flabby abdominal muscles, a tight tensor fascia femoris. Radiographs will show the stigmata of degenerative disc disease at one or more segments (Fig. 10-23).

No form of therapy will alter the degenerative changes that have occurred. Manipulation of the spine may result in a short-lived amelioration of symptoms but rarely, if ever, gives rise to permanent relief. Manipulation is most useful to break the pain cycle and allow a patient to pursue an appropriate exercise program.

In trying to outline a rational form of management of these patients, the following points must be remembered: (a) the natural tendency of the disease is eventually toward subsidence of symptoms and, occasionally, recovery; (b) no specific treatment alters the changes in the disc; and (c) treatment perforce must be directed at making the patient comfortable while nature affects the control of symptoms by stabilizing the painful motion segment.

When considering the means to make the patient comfortable, it must be remembered that (a) the pain is relieved by lying down, by unloading the spine, and (b) any activity that puts an extension strain on the spine increases the pain. Bearing these two points in mind, patients can be managed by unloading the spine in the following manner:

Extension strains are common: reaching, pushing, sitting with the legs out straight, prolonged standing, walking with big strides, and so on. In the act of lifting with the knees straight, the sacrospinales act as a bowstring and extend the spine (Fig. 10-19).

The patients must be taught to modify activities and assume postures that maintain the lumbar spine in the neutral position. They must be given written instructions in this regard (Table 10-3).

Extension strains are more liable to occur if the trunk flexors are weak, and a prolonged program to build up the trunk flexors is an essential part of treatment. The kickup exercise-manipulation program is the simplest to learn and the one most readily accomplished and persevered with by the patient.

A corset should not be prescribed early in treatment. Flexion exercises and the flexion routine should be tried first and, as long as the patient shows some measure of improvement, they should be continued. If the patient reaches a plateau in recovery and is still plagued by back pain, a corset should be ordered (Fig. 10-24).