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Spinal Stabilization

A review of low-back anatomy and careful study of current literature can guide treatment decisions

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Vol. 24 • Issue 15 • Page 24

Low-Back Pain

Many factors are responsible for the onset and progression of low back pain. Type of acute injury, chronicity, failed surgery, level of conditioning, and lack of adherence to physical therapy recommendations are all compelling reasons why we as clinicians must be prepared to address this very common condition.

In our experience, we've treated the elderly female patient with spinal stenosis and bilateral foot drop who will need braces and balance training. We'll probably see the football player who developed a spondylolysis progressing to a spondylolisthesis, and does not understand the pathology of his condition.

We will even treat patients that have had spinal surgery for a stability problem related to a failure of bony architecture requiring internal fixation. We may also treat problems related to osteoporosis and degenerative arthritis of the spine, along with postural anomalies.

With the prevalence of low back pain hovering at 80% in the general population, and a recurring episode rate between 48% to 90% -along with a $50 billion price tag to treat these cases - it's no wonder that today's physical therapist is facing a monumental challenge.1

The one common malady present in all the examples above is a loss of stability and strength of the deep stabilizing muscles of the spine. The lack of strength and endurance that affects the stabilizer function of these specific muscles is based upon our clinical acumen and a careful review of specific literature.

Review of Pertinent Anatomy

As we recall from our anatomy, the lumbar spine is composed of anterior and posterior functional elements supported by bony alignment of the facet joints, capsule, ligaments, and deep stabilizing muscles. The posterior aspect of the lumbar spine is reinforced by the posterior longitudinal ligament, and anteriorly by the anterior longitudinal ligament.

Of critical importance is the multifidis muscle, originating from the transverse processes of the C4-5 vertebra, posterior superior iliac spine and sacroiliac ligaments, and inserting onto the spinous process of a vertebra above the origin. The multifidus is an extender and rotator of the spine, and is noted for stiffness and stability of the spine, along with sustenance of the lumbar lordotic curve.

The multifidus has been shown to demonstrate atrophy in the presence of instability. Manipulation of the high velocity, low amplitude type has been shown to increase the thickness of the multifidus muscle, as well as provide relief from pain and disability at one week follow-up as reported on the Oswestry Disability Index and other measures.2

The transverse abdominis has an origin from the costal margin, lumbar fascia, anterior two thirds of the iliac crest, and lateral half of the inguinal ligament. The multifidis is made up of fasciculi arising in the sacral, lumbar, thoracic, and cervical region. These fasculi will vary in length from the most superficial and longest - and likened to a staircase, as the muscle passes one vertebra to the third or fourth above - and those next, running from one vertebra to the second or third above.

This latter muscle, referred to as the transversus abdominis (TA), inserts onto the aponeurosis of the posterior and anterior rectus sheath and conjoint tendon, to the pubic crest and pectineal line.

The TA functions like a cylinder, as it spreads itself across the anterior trunk, providing support to the abdominal wall. The TA also provides a feed-forward mechanism of the lumbar spine, which assists in prevention of potential injury to the lumbar back. Other key muscles that assist the spine and trunk for support include the rotators, obliques, and quadratus lumborum.1,3

Review of Current Research

The experience of working with patients that require stabilization training has shown that endurance, flexibility and strength of muscles are not the only facets of optimal function, and that any exercise program must also use coordination training along with balance training.

If the patient has not used proper motor training on how to selectively recruit these very important muscles, the program may become expedient at best. Patients suffering from lumbar instability, regardless of the grade of severity, often require closer supervision for home program application as well as in-clinic treatment. A study by Stanton and Fritz et al indicated that a quality algorithm existed for treatment of low back pain with four components - one of which is stabilization.4

SLR testing is not always accurately performed by clinicians, and improvement rating questionnaires sometimes have a ceiling effect, along with variations from one test date to the next. Specific testing unrelated to the algorithm approach may be necessary to get a more accurate clinical picture.

Trunk muscle stabilization and exercise was reported on by Koumantakis and colleagues for low back pain. Their results supported the hypothesis that in the absence of lumbar instability, a patient having subacute or chronic low back pain may not benefit additionally by the use of stabilization training.5

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Patients having chronic lumbar instability with a grade 1 spondylolisthesis, and who can maintain a strict exercise program of lumbar stability without having surgery, are rare. Patients who try exercises as a conservative measure often reinjure their lumbar spine and require surgery.

Many patients with low back pain and instability are treated by physical therapists. One common denominator is weakness and lack of motor control in working these very important stabilizer muscles - namely the multifidus and TA.

Clinical Tests for Instability

Clinically, a patient with lumbar spine instability will often complain of a "giving out" feeling. Often the patient will feel better after having cracked their back. Some patients will have trouble tolerating the prone position.

Other patients may have symptoms brought on by specific ROM movements, such as standing and leaning backward, or combining rotation with backward bending. During the examination you may be confronted with instability testing of the lumbar spine.5

There are more than 10 tests to diagnose segmental instability of the lumbar spine. Common ones are the posterior shear test, prone instability test, Beighton Hypermobility scale, prone leg extension test, instability catch sign, painful catch sign, and apprehension sign.6

Each patient's uniqueness for pain and instability through the examination can guide you on which test would be most provocative. One study indicated that the passive lumbar extension test was the most sensitive (84%) and was 90% specific for testing patients.7

Also important during the physical exam is to identify hypermobile segments that correlate radiographically and use them to develop a strategy for neuromuscular stabilization. Help them to learn how to isolate specific muscles for recruitment, control and function.

Have the patient undergo staged rehabilitation for enhancement of appropriate muscle function, and inhibit global muscle substitution. Observe for signs of step-off in the midline, muscle atrophy and spasm.

Is Surgery Warranted?

The decision of whether surgery is warranted is based upon pain, mobility and function, along with interpretation of radiographic findings and recommendation of the neurosurgeon.

Allograft bone use has been recommended when immediate structural support is warranted, as the strength of this graft has been reliable. Difficulties with allograph can be attributed to the patient's size, age, previous graft harvesting, donor site pathologic processes, or presence of neoplastic disease, infection, or metabolic conditions. Allograft surgery can be used to augment existing autologous bone, and can be a good option when revision surgery is needed.8

The decision on which procedure to use is based upon whether the patient will need a posterior lateral fusion alone, or also another procedure such as an anterior interbody fusion. Our experience has shown that depending upon the patient and disease process, choice of technique is predicated upon the pathology and amount of disease present, as well as the patient's motivation.

Our primary experience has been with patients who have made a decision on having a posterior lateral fusion or a posterior lateral interbody fusion with screw fixation. Some of these surgeries are conducted in conjunction with a lumbar laminectomy or laminotomy procedure, and again, depending upon the amount of degenerative arthritis, facet joint loading and disease process, the procedure for each patient presents a unique set of circumstances for the neurosurgeon.

For patients that have opted out of surgery, success is often based upon completion of a successful rehab program and not having the insecurity of instability in the posture and ROM of the spine. We've treated several workers with what was referred to as spinal instability, when it was in fact posterior lateral disc herniation giving rise to postural list, leg pain, and limited mobility.

Returning to Activity

For patients that have undergone one-level fusion, the mean number of days from surgery to driving a car is 31 days, while unlimited walking requires 30 days. Sitting 1 hour involves 29 days.

Recovery times can vary based on the surgeon's experience and clinical markers, as well as by the patient's motivation, surgical technique, and clinical acumen of the physical therapist.

Use your clinical experience when treating lumbar segmental instability. Progressive treatment using the principles of stabilization training for the selected muscles of the lumbar spine and trunk is justified. Patients with segmental instability may also benefit from biofeedback, TENS, swim conditioning, walking, behavioral intervention in select cases, and home exercise.

A diagnosis of lumbar instability does not determine how a patient will respond to treatment. The MRI study, as well as prudent X-ray examination and appropriate treatment with the aid of recent research on clinical prediction rules, can indicate how successful a specific treatment approach will be.

References are available at www.advanceweb.com/pt under the Toolbox tab.

Lou Grant has been a physical therapist for 40 years and has special interest in vestibular, geriatrics, manual therapy and orthopedics. He currently works at Physiotherapy Associates in Grand Rapids, Mich. Tony Schuster is clinic director at Physiotherapy Associates of Grandville, Mich.




     

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