Rotational forces and combined motions, particularly forward flexion with rotation, have been shown to be the high risk to the disc.

Causes

Deterioration of the spinal structures is a fact of ageing. The intervertebral disc is part of a 3-joint complex with the functioning unit suseptible to damage at the level of either the zygapophyseal joints or the disc.The two basic causes are then internal derangement of the disc or deterioration of articulation at the zygapophyseal joints. The debate rages on as to which is the initiator and which is secondary. The commonly accepted wisdom these days is that discal changes are first with compensatory changes and degeneration in the apophyseal articulations as a consequence to this.

The deteriorative process most likely begins with the intervertebral disc. Tiny blood vessels originating in the vertebral end-plates enter and exit the disc in the early decades of life. Eventually  these vessels become obliterated and thereby the intervertebral disc becomes an avascular (without blood supply) structure in any direct sense. Thereafter, nutrition of the disc is supported only through extracellular fluid osmosis. Water is drawn into the disc, and, with motion, the water is partially expelled. This constant movement of water into and out of the disc is thought to allow the disc to remain healthy by bringing in needed nutrients. With the ageing process, there is a loss of some of the connective tissue fibers within the disc and an alteration in the properties of the nucleus pulposus. This causes less water to be drawn into the disc and, ultimately, may lead to impairment of nutrition. The water content of a disc in young persons is 88%, but it is reduced to less that 70% in elderly persons.

The deterioration process leads to a stiffening of the intervertebral disc and a change in its shape, causing the disc to lose its ability to distribute load uniformly. The fibres of the annulus run in different directions at different depths to allow the annulus to accommodate complex 3-D motions. Axial rotation of the spine or rotation of a flexed spine may isolate some of the annular fibers and cause small annular tears. These annular tears may or may not be symptomatic; however, in time, they may coalesce to weaken the annulus fibrosus. This can lead to disc bulging, disc space narrowing, or even frank herniation.

In addition, the loss of disc space height may lead to intervertebral segment instability and increased forces on zygapophyseal joints. Sclerosis and hypertrophy of these joints is the likely result since they are more suited to acting as guides rather than weight-bearers. The loss of disc height also causes posterior bulging of the annulus into the spinal canal and buckling of the ligamentum flavum that forms part of the posterior spinal canal architecture. Singlely or combined these changes can lead to a narrowing of the foramen of the spinal canal and create an acquired spinal stenosis.

These degenerative changes can begin as early as the second to third decade of life and progress with advancing age. The clinical consequences of this deterioration vary with the age of the patient.

In persons aged 30-50 years, degenerative changes and tears in the annulus of the disc may cause frank herniation of the disc material. This population usually has incurred some compromiseof disc integrity, yet the nucleus is still malleable enough to be extrudable, and the spine is mobile enough to produce the required forces for herniation.

With aging of the spine, the nucleus pulposus becomes firmer, spinal motion generally decreases and boney degenerative processes increase. Thefore the  intervertebral discs have far less capacity to extrude and herniate but the foramen will be compromised. Spinal stenosis becomes the likely clinical presentation

Athletes and nonathletes alike are subject to these progressive degenerative changes. However, it is not completely clear how the potentially beneficial effects of training interact with the potentially harmful effects of loading experienced by athletes. Does one outweigh the other? The greatest incidence of discogenic disease would be expected to be found in those athletes participating in sports with the greatest axial (those in the line of the spine) stresses.

• Hellstrom et al found that disc height reduction was much more common in athletes than nonathletes, and, specifically, it is most prevalent in wrestlers and male gymnasts.
• Horne et al found a high frequency of disc space narrowing in the thoracolumbar spines of water-ski jumpers.
• Other studies have failed to show a correlation between physical loading and increased spinal pathology or low back symptoms, and some evidence suggests that certain types of loading may slow down the degenerative process.
• Videman et al reported that former elite athletes overall reported less back pain than control groups in later adulthood. However, they did find an increase in the degenerative changes throughout the entire spine in former weight lifters and in the lower lumbar levels in soccer players when compared to controls. Despite these increased degenerative findings, the former weight lifters and soccer players still had less reported back pain than those in the control groups. This study and others provide some evidence that certain forceful athletic activities may accelerate the degenerative process, but that the degenerative changes seen on imaging studies do not correlate well with clinical symptoms.

  Treatment

  Acute Phase

 

Physical Therapy

During the acute phase of a rehabilitation program for discogenic LBP (lower back pain), the focus of treatment is on reducing pain symptoms and halting disease progression. Some or all of the following will be implemented depending on the case.

•  Instruction in posture and body mechanics in activities of daily living is aimed at protecting injured structures, reducing symptoms, and preventing further injury. Using leveraged tools such as a broom or vacuum are hazardous for example. 
• Educate patients to avoid positions that increase intradiscal pressure such as sitting, bending, and lifting.
• A short course of intermittent bed rest (not more than 2 days) may provide some beneficial effects via pain modulation and reduction of intradiscal pressure, but longer courses of bed rest yield detrimental effects on bone, connective tissue, muscle, and cardiovascular fitness.
• Emphasis on activity modification, rather than strict bed rest, is recommended to avoid the unwanted effects of immobilization. For example it is OK to walk but it may only be to the front gate and back.
• Ice therapy
• Anti-inflammatory medication may be considerd adjunctively. Talk to those who know you. Your health professional or pharmacist can help you.
• Eat fibrous foods and keep hydrated. Constipation is never any fun but far less so if you have discogenic LBP. Be aware that codeine-based painkillers such as panadeine can have a constipating effect.
• Gentle and relevant mobilizing can be done once all safety procedures have been carried out.

 

Surgical Intervention

 

There are a number of situations where conservative measures need to be supplanted by surgical opinion. Surgical consultation is warranted in patients with acute discogenic back or leg pain when there is progressive neurologic deterioration. Significant and thecal deforming postero-central disc protrusions with cauda equina syndrome, characterized by saddle anesthesia (ie, perineal numbness) and bowel or bladder dysfunction, require urgent surgical decompression within 12 hours if permanent damage is to be avoided.  No ifs, buts or maybe's.

 Other indications for surgical intervention are less clear-cut. Research to this point does not conclusively state that operative intervention restores neurological function more rapidly than nonoperative treatment. Saal, in his description of the natural history of lumbar disc herniation, notes that patients who recover without surgery usually demonstrate signs of improvement in the first 3-6 weeks from the time of onset. Many authors suggest that it is reasonable to operate on patients with significant neurologic loss (eg, a foot drop) that has not improved by 6 weeks postinception.

Steroids

 

Lumbar epidural steroid injections (LESIs) have been used to treat a variety of low back conditions. Controlled studies have evaluated the effectiveness of epidurals in the treatment of lumbar conditions, with some studies showing success in certain subgroups of patients with discogenic back pain. LESIs appear to provide short-term benefits for patients with lumbar radiculopathy and can be an important component to an overall treatment approach. Meta-analyses however have failed to show a long-term benefit from these injections.

Nonradicular pain (LBP but no leg pain) does not appear to respond well to LESIs.

 

Recovery and Rehabilitation Phase

Once the painful symptoms of the acute phase of treatment are over, the strengthening of the lumbar spine and associated muscles can be initiated.

IMPORTANT; There is no "one-size-fits-all". Every rehabilitation program has to be drawn up recognizing the individuals history, aetiology, presentation and lifestyle, amongst other factors relevant to the case. Just because an exercise is great for Aunty Jill does not make it good for you. You shouldn't take her medicine, nor her exercises. Talk to the professionals. 

Comprehensive spinal rehabilitation programs  include spine stabilization exercises.

With spine stabilization exercises, the object is to teach the patient how to find and maintain a neutral spine during everyday activities. The neutral spine position is specific to the individual and is determined by the pelvic and spine posture that places the least stress on the elements of the spine and supporting structures. In classic discogenic pain, the neutral spine is likely to have an extension bias (lumbar curve is straightened out). In classic posterior element pain or spinal stenosis, which may both result from the ongoing degenerative cascade initiated by disc degeneration, the neutral spine may have a mild flexion bias (lumbar curve is increased). Dynamic lumbar stabilization is used to provide dynamic muscular control and to protect the spine from biomechanical stresses of your lifestyle that include tension, compression, torsion, and shear. This occurs with even simple activities such as getting in and out of a motor vehicle. Spinal stabilization provides this control and protection by emphasizing the synergistic activation of the trunk and spinal musculature in the midrange position. That is to say that the muscles work when they are supposed to.

This can get a little complicated. Much emphasis these days is placed on the "mirror muscles", both for men and women alike. With this comes emphasis on sit-ups and various devices that will give these mirror muscles to you in only 3 minutes a day. The reality is that the obvious stomach muscles form a very small part of the spinal and trunk stabilization complex. To decrease the stress on the intervertebral disc we need to strengthen and coordinate the muscles of the back, abdomen, pelvis and upper leg. Thus any attempt to stabilize the trunk needs lots of different muscle attention.

Muscles do not work in isolation. Muscles and life are not a series of individual muscle contractions. The muscles work in a complex and coordinated manner relative to our position in space and the various mechanical advantages and disadvantages relevant to that moment in time. For example the joint positions of the lower back, hip, knee and ankle are different getting out of our car versus getting off a toilet seat. The kinetic chain of action is different and our exercises need to reflect that.

The same needs to be said about the individuals joint history. The development of protective exercises of a 60 kg gymnast with exceptional joint flexibility will have to be different to a 90 kg bricklayer who has degenerative hip joints. The kinetic chain is not the same and their programs should acknowledge that.

 

Maintenance Phase

The maintenance phase represents the final phase of the rehabilitation process. Eccentric muscle strengthening exercises are becoming increasingly well recognized as a safe and effective form of training. Eccentric exercises are those where the muscle is contracting but the muscle is still lengthening in a controlled manner (cf concentric contraction).

In this phase we can add dynamic conditioning exercises (eg, with a large gym ball). Sport-specific training should be incorporated so that the mature athlete can maintain a neutral spine in all recreational activities.

The goals of a comprehensive spinal rehabilitation program have been met when the mature athlete no longer demonstrates the original symptoms, full range of motion of the spine is present, strength and flexibility are within normal limits, and good sport-specific mechanics are demonstrated.

 

Surgical Intervention

Lumbar fusion

A general lack of consensus exists regarding the indications for lumbar fusion in patients with DDD. The natural history of DDD has not been shown in scientific studies to be treatable with great success by any method of lumbar fusion.

An updated Cochrane review from 2005 of surgical interventions for degenerative lumbar disease found inconclusive results for a firm conclusion on the effectiveness of fusion surgery. Two new randomized clinical trials comparing spinal fusion with conservative treatment have emerged in the literature since 1999. The first such trial is the Swedish trial reported by Fritzell et al, which found that patients who underwent surgery had significant improvements in pain and significantly higher rates of return to work. In contrast, the second such trial, the Norwegian trial reported by Brox et al and Keller et al found no significant differences in outcomes in surgery compared with a conservative rehabilitation approach.

Kwon et al, Spine 2006-Jan; vol 31 (issue 2) : pp 245-9, criticized the Fritzell study for not making a true comparison of the operative and nonoperative study groups that reduced the validation of the 2001 study.

A significant morbidity associated with lumbar fusions involves juxtafusional degeneration, which may require reoperation within approximately 10 years of a successful fusion surgery. Some studies have suggested hastening of degeneration of spinal functional units adjacent to the fused vertebrae. Furthermore, fusion causes limited range of motion, a consequence that has become less acceptable as a treatment outcome.

Disc arthroplasty

Disc arthroplasty (total disc replacement) in the lumbar spine is an alternative to fusion when treating discogenic pain. Its theoretical benefits include preservation of the motion segment and the potential prevention of adjacent-segment degeneration. Manufacturers and proponents cite the ability of these devices to relieve pain while preserving motion at the disc space. However, the devices are expensive and their use is associated with the potential for significant complications above and beyond those seen with lumbar fusion. At the present time, there is no evidence to suggest that the use of disc arthroplasty results in better short- or long-term functional outcomes than fusion in properly selected patients.Candidates for disc arthroplasty are limited to patients without significant facet joint dysfunction because this has been associated with poor outcomes.

To date in the United States, 1 lumbar disc replacement device has received approval from the US Food and Drug Administration, the SB Charite III, while the 3 other devices (the ProDisc II, Maverick and Flexicore) are currently undergoing investigative trials. The SB Charite III, which is commercially available in the United States, was limited to disease of L4-L5 or L5-S1. European data with complication rates of lumbar disc arthroplasty give pause to the use of this intervention, as does the overall limited long-term follow-up and randomized clinical trials currently available. Furthermore, the average age of patients who are candidates for total disc replacement are typically younger than those who are candidates for total joint replacements, further highlighting the need for longevity of the implanted devices.

At this stage the medical literature does not yet provide sufficient data to support or refute firm conclusions on the safety and applicability of disc arthroplasty in the many candidates. These devices require further long-term study in a controlled environment before widespread application.

Nucleus pulposus replacement

An emerging technology is nucleus pulposus replacement. Coric et al, Journal of neurosurgery, 2008-Feb; vol 8 (issue 2) : pp 115-20 reports that nucleus replacement offers a less invasive alternative to traditional fusion or total disc replacement techniques in the treatment of symptomatic lumbar degenerative disc disease (DDD). This surgical intervention is designed to increase disc space height in the degenerating disc and decrease the transmission of forces onto the remaining annulus, facet joints, and other stabilizing structures. Compared with total disc replacement, this surgical option involves less surgical exposure, potentially provides biomechanics similar to native discs, and the advantage that a failure of nucleus pulposus replacement still allows for revision with fusion if necessary. The implants currently under investigation are primarily composed of hydrogels that an absorb water and release water when loaded.

Limitations in implant materials include toxicity of the materials and the danger of their extrusion from the disc space. One such implant under development with the most thorough studies yet is the Prosthetic Disc Nucleus, which is designed to absorb 80% of its weight in water. It has been shown in a small study by Schonmayr et al to restore disc space height and normal motion. A multicenter clinical study of the Prosthetic Disc Nucleus by the US Food and Drug Administration is currently under review.

Coric concludes that nucleus replacement remains investigational with some encouraging  early clinical results.

Ma et al, Chinese journal of surgery, 2008-Mar; vol 46 (issue 5) : pp 350-3,concluded that the mid- or long-term outcome of PDN replacement in the treatment of degenerative lumbar disc disease is not as encouraging as that of the short-term follow-up. It is neither effective in term of restoration of the intervertebral disc height nor increase of the ROM of the operative segment, complication rates are significantly higher, and inferior results are to be expected.

Further clinical investigation with well-designed prospective, randomized pivotal trials is needed to determine the efficacy of nucleus replacement in the treatment of lumbar DDD, as well as its ideal indications

 

IDET

IDET, or Intradiscal Electrothermal Therapy, is a procedure that is being done to treat discogenic back pain. It involves the insertion of an electrothermal catheter (heat probe) into a painful intervertebral disc under fluoroscopic (a type of imaging) guidance. Thermal energy to about 85 degrees celcius is delivered by the catheter for around 5 minutes and with the patient only under mild sedation and local anaethetic.

It is believed to result in breakdown and restructuring of collagen fibers in the disc. Several mechanisms by which IDET might relieve discogenic pain have been proposed, including an sealing of annular tears through collagen denaturation, stiffening of the intervertebral disc, or simple ablation of nerve endings in the annulus.

Proponents of the procedure believe that IDET may be indicated for patients who have degenerative disc changes with concordant pain on discography and a chronicity of LBP for all conservative management techniques have failed. A preliminary nonrandomized study by Saal and Saal on a small number of patients who had IDET revealed an improvement in function by a visual analog scale and sitting tolerance time. Ergün et al, Neurological Research, 2008-May; vol 30 (issue 4) : pp 411-6, has concluded that the IDET procedure may become a intervening step for carefully selected group of patients who failed non-operative treatment before surgical intervention. One important pre-selection criteria was that disc height loss was not more than 50%.

 Maurer et al, Journal of Spinal Disorders & Techniques, 2008-Feb; vol 21 (issue 1) : pp 55-62,supports these findings of his study that suggested durable clinical improvements can be realized after IDET in highly selected patients with mild disc degeneration.

As with all techniques a lot of investigation is still to be done to assess which patients with which type of back problem will benefit from IDET.

Medication

Drugs used to treat lower back pain include paracetemol, non-steroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, opioid analgesics, oral corticosteroids, and antidepressants. As with all drugs we need to be aware of the contraindications, common adverse effects, and mode of action of each agent.

Nonsteroidal anti-inflammatory drugs or NSAIDs

Offer additional anti-inflammatory effects compared with paracetemol. The dose to produce anti-inflammatory effects differs substantially from that for analgesic effects. Most NSAIDs achieve only analgesic effects because the dose prescribed is too small and too infrequent to produce an anti-inflammatory effect. Risks are associated with NSAIDs, especially in the elderly population and in those with a history of peptic ulcer disease, hypertension, or renal insufficiency. Newer generation NSAIDs selectively interact with the COX-2 receptors and have a lower gastrointestinal risk. Prolonged use of these medications generally is not recommended for most patients with low back problems.

 

Ibuprofen (Motrin, Ibuprin)

DOC for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

 

Interactions; ACE inhibitors, alcohol, aspirin, corticosteroids, diuretics, heparin, lithium, methotrexate, and warfarin

Contraindications; Documented hypersensitivity; aspirin/NSAID-induced asthma; bleeding disorders; patients on coumadin; patients with a history of GI bleed

Pregnancy

C - Safety for use during pregnancy has not been established.

Precautions

Patients with a history of nasal polyps, CHF, hypertension, and/or GI complaints

Celecoxib (Celebrex)

Inhibits primarily COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and by inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited, thus GI toxicity may be decreased. Seek lowest dose of celecoxib for each patient.

Contraindications; Documented hypersensitivity