What is Lumbar Degenerative Disc Disease?
Lumbar degenerative disc disease occurs in the lumbar spine, or lower back, refers to a syndrome in which a compromised disc causes low back pain.
Lumbar degenerative disc disease is quite common. At least 30% of people aged 30-50 years old are estimated to have some degree of disc space degeneration. All patients with the degenerated disc are not necessarily symptomatic.
Lumbar degenerative disc disease is common cause of low back pain. In fact, most of the episodes of low back pain are as a consequence of disc injury, rather than strain on muscles and ligaments.
Pain due to lumbar degenerative disc disease affects men and women equally. Usual affected group is middle-aged persons with peak incidence at approximately 40 years.
The cause of lumbar degenerative disc disease is not known. Acute annular tear is thought to be the inciting event. Causes appear to be multifactorial.
Surgeries like lumbar arthrodesis, lumbar discectomy, or lumbar laminectomy alter the biomechanics of lumbar spine resulting increased susceptibility to discogenic pain.
Degenerative cascade was described by Kirkaldy-Willis. It is widely accepted pathophysiologic model describing the degenerative process that occurs in 3 phases
The typical initiating event in the degenerative cascade is the loss of internal disc integrity. This could be due to congenital reasons or acquired insult and injury.
In congenital or genomic situations such as juvenile discogenic disease, disc nutrition may be poor because of the existing endplate abnormalities and premature disc collagen deterioration.
The collagen itself may have not formed normally at birth due to congenital enzymatic deficiencies.
In normal disc, progressively destruction may occur by acquired insult and/ or injury.
Following factors adversely affect the process
- Cigarette smoking
- Environmental pollutants
- Lack of exercise.
The disc becomes incompetent for segmental support [dysfunction] and progress to the point of true segmental instability
The process itself can cause discogenic pain or tears can coalesce and form a causing a herniated disc by protrusion of annulus.
Facet joints gets involved with instability and first react by effusion and become pain generator as the nerves get irritated by abnormal movement and inflammation.
With continued degeneration, facets become markedly degenerated, eroded and contain fluid.
Pain originating from facets as pain generator is referred to as facet syndrome [ as opposed to a discogenic pain syndrome]
Degenerative cascade is discussed in detail below.
Phase I -Dysfunction
- Repetitive trauma is the usual cause which results in circumferential tears or fissures in the outer annulus
- Accompanied by endplate separation or failure due to break blood supply to the disc. This affects nutrition and waste removal.
- Circumferential tears may coalesce to form radial tears.
- The nucleus pulposus may lose its normal water-imbibing abilities due to biochemical changes in aggregating proteoglycans and proteoglycan destruction
- Loss of nuclear hydrostatic pressure results in buckling of the annular lamellae.
- Leads to increased focal segmental mobility and shear stress to the annular wall.
- Delamination and fissuring within the annulus can result.
- Microfractures of collagen fibrils in the annulus have been demonstrated with electron microscopy.
MRI at this stage may reveal
- Disc desiccation
- Disc bulging without herniation
- High-intensity zone in the annulus
- Facet joints during the dysfunctional phase may include synovitis and hypomobility.
Tears or fissures in this area may be painful as outer part of the annulus is innervated. Moreover, muscles undergo spasm, contributing further to pain.
The facet joint may serve as a pain generator.
Phase II – Instability
- Progressive loss of mechanical integrity of the disc and facet joints.
- Multiple annular tears (eg, radial, circumferential)
- Internal disc disruption and resorption, leading to loss of disc-space height.
- Facet joint cartilage degeneration, capsular laxity, and subluxation.
The biomechanical result of these alterations leads to segmental instability. This phase of the cascade in clinical situations is diagnosed as segmental instability, internal disc disruption, and herniated disc.
Phase III- Restabilization
- Further disc resorption
- Disc-space narrowing
- Endplate destruction
- Disc fibrosis
- Osteophyte formation
Presentation of Lumbar Degenerative Disc Disease
Patient may present with back pain that could be related to a traumatic event that caused forced flexion and/or rotation. Spontaneous onset of symptoms could be also a presenting feature.
The pain is usually low lumbar region and buttocks. It can radiate to upper spinal regions, abdomen, flanks, groin, genitals and varying distances in lower limb [ thighs, knees, calves, ankles, feet, and toes] . Usually the involvement is unilateral.
The pain can range from aching to stabbing.
Typically, the pain is exacerbated by activities which load the disc
- Arising from a seated position
- Getting up in the morning
- Awaking in the morning
- Lumbar flexion with and without rotation/twisting
- Vibration (as in riding in a car)
Symptoms get better by lying on the side with hips and knees flexed or by changing positions frequently, and/or by engaging in activity.
On physical examination, inspection may reveal kyphotic or scoliotic deformity. Paraspinal muscles are tight and may be tender.
A step deformity may be present in spondylolisthesis.
These maneuvers reproduce symptoms
Flex both hips of the patient in supine position till the flexed knees approximate to the chest. Then, rotate the lower extremities from one side to the other.
Raise the patient’s extended lower extremities to approximately 60° and ask the patient to hold there.
Note if pain occurs in low lumbar buttock region.
Now lower the successively approximately 15°, and, at each point, note the reproduction and intensity of pain.
- Muscle strain
- Ligament/tendon injury
- Sacroiliac joint syndrome
- Lower lumbar zygapophyseal joint [facet joint] syndrome
- Hip joint pain
- Compression fracture
- Stress fracture
- Myofascial pain syndrome
- Spinal Stenosis
Generally not required for diagnosis. CBC, ESR, CRP, RF may be done to rule out infective or inflammatory processes.
Signs of degeneration on x-ray
- Loss of disc height revealed by decrease in disc space
- Endplate sclerosis
- Spondylolisthesis changes can be seen.
- Flexion/extension view [link] for assessing relative motion between two vertebral bodies.
Magnetic resonance imaging
MRI is the gold standard imaging modality for detecting disc condition. It can tell about disc height, hydration status of nucleus and intensity changes in annulus fibrosus, any protrusion and impingement of the nerve, presence or absence of nerve edema and status of end plate.
High intensity zones visible on MRI is considered to a marker for painful disc.
CT can be used to identify diffuse annular disc bulge, loss of disc height, endplate degenerative changes, including sclerosis and cortical irregularity with erosions.
But CT is not as detailed as MRI.
Discography is a provocative test where the disc is injected with contrast material and if pain is produced similar to symptoms, the disc being investigated is source of pain.
It is especially useful in cases with multiple levels of disc involvement on MRI.
It is the only available diagnostic intervention that identifies a symptomatic disc though some spinal physicians do not acknowledge its reliability or validity
Treatment of Lumbar Degenerative Disc Disease
The approach to treatment involves pain control and once the pain is controlled, patient is put on exercises and rehabilitation.
Most of the pain control measures are non operative, surgery being required in very few patients.
Exercise is best done under professional supervision.
Medications are an integral part of treatment of lumbar degenerative disc disease. Following medications are used
- NSAIDs or Non steroidal anti-inflammatory drugs like ibuprofen, ketorolac etc.
- Duloxetine – An antidepressant and potent inhibitor of neuronal serotonin and norepinephrine reuptake.
- Skeletal muscle relaxants
- Modest short-term benefit
Initial rest from all activities occupational or avocational should be carried for up to two days. In some cases, slight extension of the rest may be done but rest for longer periods has not been shown to be beneficial. Patient , in fact should be made independent as early as possible.
Conservative measures are tried first before epidural steroid injections are considered. But undue delay should not be made because the ongoing inflammatory process to result in fibrosis and possibly permanent damage.
After first injections, two weeks should be given for assessing response to injection and for possible reinjection.
Transforaminal route is considered best for injection as placing medication as close to the site of pathology provides best results.
Contraindications to epidural steroid injections
- pregnancy (because of the adverse effects of fluoroscopy on the fetus),
- Hypersensitivity to injection
- Bleeding diathesis.
- Diabetic with elevated serum glucose levels
- Elevated blood pressure
- Congestive heart failure with fluid retention
Epidural steroid injection have unfavorable response in following conditions.
- Long duration of symptoms
- Nonradicular pain
- Pain not relieved by medication
- Pain not increased by activity.
Patient Education, Exercises and Rehabilitation
Patient should be explained about natural history of the disease, body mechanics and lumbar ergonomics during activities.
Manual techniques may be applied in case of myofascial tightness.
In case, above measures are completed, dynamic rehabilitation may be started on an outpatient basis.
Dynamic lumbar-spine stabilization [DLSS] programs
This is aimed at maintaining a neutral spine position throughout various daily activities allowing for balanced segmental force distribution between the disc and facet joints. It is also called core strengthening or muscular fusion and aims at strengthening the core muscle which provides functional stability with axial
Cardiovascular training is an important adjunct training to prevent fatigue of the muscles.
Exercises should work on strength, endurance, and flexibility.
Work places should have proper ergonomics [link] at the work site, which might be as simple as changing chair and desk arrangement or be more complex.
Patient should continue through these exercises to reduce risk of further injury
Ice packs, heating pads, electrical stimulation, phonophoresis, iontophoresis, relaxation, and biofeedback.
Lifestyle changes aim at avoiding stress on the spine and inculcate habits of right posture and ergonomics.
Patient should avoid nicotine, excess alcohol, avoid staying in position for too long. It is better to stand up and stretch and walk around every 20 to 30 minutes instead of sitting for a prolonged period.
Patient should also maintain proper hydration.
The goal is to teach patients how to help themselves manage their back pain.
Patients should be taught about
- Basic body mechanics
- Correct posture for standing, standing at a desk or drawing board, sitting, brushing teeth, washing the face
- Pushing and pulling a weight
- Lifting a weight
- Getting in and out of bed
- Getting in and out of a car, and sitting in a car.
[Also read: Tips for managing Back Pain]
Different types of exercises are prescribed
- Floor exercises
- Swimming exercises
- Aerobic exercises
- Relaxation exercises are good for relieving muscular tension that may aggravate back pain.
Surgery for Lumbar Degenerative Disc Disease
Surgical treatment is used in about 5% of patients and includes lumbar surgeries and cervical surgeries.
Surgeries for degenerative disc need to decompress the nerve root by either removing the offending structure [disc] or create more space so that the disc does not impinge on the nerve root.
Second part of the surgery is fusion which aims at removal of motion between two vertebrae and thus decreasing the pain generated from the joint. This involves using a bone graft to fuse one or more vertebrae and stop motion at a painful vertebral segment.
Fusion is almost always accompanied by fixation surgery. In fact the actual procedure includes fixation first and fusion later.
The fixation is required to hold the vertebrae in immobilized position till they fuse.
Various implants used for fixation are pedicle screws, anterior and posterior body cages.
Usually the fusion and decompression are done in the same sitting, using same approach.
It involves removal of the affected disc through posterior approach. The offending structure is removed which relieves the nerve of the pressure.
Lumbar spinal posterolateral gutter fusion
This type of spinal fusion involves placing bone graft material in the posterolateral portion of the spine . Bone graft is harvested from the posterior iliac crest.
For better chances of fusion, immobilization is done and smoking should be stopped.
Posterior lumbar interbody fusion [PLIF]
Posterior lumbar interbody fusion achieves spinal fusion by inserting a bone graft directly into the disc space through posterior approach after removal of disc.
Anterior lumbar interbody fusion [ALIF]
Anterior lumbar interbody fusion is similar to posterior lumbar interbody fusion except that approach is anterior.
Transforaminal lumbar interbody fusion
Transforaminal lumbar interbody fusion (TLIF) has become an increasingly popular treatment for lumbar degenerative disk disease, spondylolisthesis, degenerative adult scoliosis, spinal stenosis, and recurrent disk herniation.
The approach to the spine is posterior.
TLIF is a modification of PLIF .
Total Disk Arthroplasty
This procedure has been used for lumbar discogenic pain, with and without radicular symptoms.
Artificial disk replacement has shown results similar to fusion in the short term, but long-term results are not known.
Intradiscal electrothermal therapy (IDET) or intradiscal electrothermal annuloplasty (IDEA) is a minimally invasive form of annuloplasty (repair of annulus fibrosus) that includes use of heat to seal any ruptures in the disc wall and probably burn nerve endings making the area less sensitive to pain.
New biological substances for injection therapies are underway.
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