Lumbar Instability

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Original Editors - Bruno Luca, Anke Jughters

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Search Strategy

It was not easy to find searchterms that referred to functional instability of the lower back. Databases such as pubmed and web of knowledge were very usefull. Then I found a very recent review, which was really useful and put me in the right direction to search for more information.   

Definition/Description

The spinal system has three basic functions to perform, namely carrying loads, protection of spinal cord and nerve roots and allowing movement between body parts. To make sure that the spinal system can fulfill these tasks, there needs to be a spinal stabilizing system. [Panjabi, 1992 a]
The stabilizing system can be represented by means of three subsystems. The passive subsystem consisting of vertebrae, facet joints, intervertebral discs, spinal ligaments, joint capsules and passive muscle support. Then there is the neural feedback system containing force and motion transducers and the neural control centers. The third system is the active subsystem including the muscles and tendons surrounding the spinal column. Thus the spine needs the integrated function of the three subsystems, mentioned above, to control stability and movement. Instability is found when one of the systems fails to fulfill his task, and disturbs the balance. [Panjabi, 1992 a]
Muscles are one of the three important factors contributing to stability of the spine. But is there one muscle that deserves more attention than all the others? At a given time, there can be one muscle that is more important than another one. Only, the importance of the individual muscles change when there are alterations in body movements and positions. This change will happen by changes and adjustment in relative muscle activation. All muscles are important, a clinical focus on one muscle and not the whole system will be pernicious. [McGill et al., 2003] Thus, Lumbar Multifidus for example, has the ability to control and restore motion of an uninjured segment. Nevertheless is it important to consider that all lumbar muscles contribute to stability of the lumbar spine. [McGill et al., 2003; MacDonald2006]

Clinically Relevant Anatomy

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Epidemiology /Etiology

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Characteristics/Clinical Presentation

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Differential Diagnosis

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Diagnostic Procedures

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Outcome Measures

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Examination

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Medical Management

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Physical Therapy Management

Why is there so much ado about the Transversus Abdominis and Lumbar Multifidus? They are both primary stabilizers, meaning they are responsible for stabilizing and approximating joints. The most important things that characterize them are following qualities: they are located close to the joint, they lie deep, are slow twitch, consist of short fibers and reasonable fatigue resistant. With muscle imbalance they tend to weaken and lengthen. [Norris, 2008]
Often, it has been assumed that Lumbar Multifidus and Transversus Abdominis co-contraction is required for lumbar stability and that it has to be maintained with patients suffering from low back pain. [Taylor and Twomey, 2000] Co-contraction occurs in periods of time but it is not necessary for stability. In preparation for the disruption to the spine from a movement of an extremity (ex. arm movement). Transversus Abdominis and Lumbar Multifidus are active but in a non-direction-specific feed forward manner. The contraction does not happen simultaneously, however the mechanical effects occur roughly at the same time. This can be explained by the fact that the Transversus Abdominis has a longer electromechanical delay than that of the Lumbar Multifidus, because of its long elastic anterior fascias. Transversus Abdominis is earlier active, so that compensates for the longer delay. So the two discussed muscles don’t maintain tonic co-contraction. Therapeutic exercise programs which involve training co-contraction of the Transversus Abdominis and Lumbar Multifidus, are not going to be capable of restoring typical activation patterns. Nonetheless, the co-contraction training may be necessary to restore intervertebral control which can be caused by an underlying osseoligamentous deficiency. [Mosely et al., 2002; Hodges and Richardson, 1997]
And what about the relationship between these two muscles and the prognostic factors that predict clinical success with stabilizing programs? There are five useful factors, namely age<40y, average straight leg raise range of motion >91°, presence of aberrant movement with lumbar spine flexion, a positive prone instability test [Hicks et al., 2005] and at last the existence of segmental hypermobility. [Fritz et al., 2005] The connection between the prognostic factors and clinical success with stabilizing programs was supported through their relationship with Lumbar Multifidus activation. Even after controlling for the effects of sex, current pain level, BMI, fear-avoidance beliefs and prior history of low back pain, the relationship kept upright. In addition to this, there was no significant relation found between the factors and Transversus Abdominis muscle activation. You have to take notice of the fact that the study, which investigated this relation, has not examined the feed forward behavior of Transversus Abdominis. The relationship between the prognostic factors and this aspect of Transversus Abdominis function remains unknown. Thus the findings of this study provide evidence that shows the importance of restoring Lumbar Multifidus function in patients with low back pain. However, examination of other muscle functions (ex. feed forward behavior) may cause a more extensive understanding. [Herbert, 2010]

Therapy Exercises for Lumbar Instability

Key Research

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Resources

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Clinical Bottom Line

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Recent Related Research (from Pubmed)

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References

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All sources mentioned below have a weak level of evidence (level C) because none of them is a controlled study. But they all have the same opinion. 

• Panjabi M. The stabilizing system of the spine. Part I. Function, dysfunction, adaption, and enhancement, Journal of Spinal Disorders 1992; 4; 383-389 

• McGill SM., Grenier S., Kavcic N., Cholewicki J.. Coordination of muscle activity to assure stability of the lumbar spine, Journal of Electromyography and Kinesiologie 2003; 13; 353-359

• MacDonald DA., Moseley GL., Hodges PW. The lumbar Multifidus: does evidence support clinical beliefs?, Manual Therapy 2006; 11; 254-263

• Norris CM. Back stability, integrating science and therapy, human kinetics, second edition; 2008; 62

• Taylor J., Twomey L. Physical Therapy of the low back, Churchill, third edition; 2000; 201-247

• Moseley G., Hodges PW., Gandevia S. deep and superficial fibers of the lumbar multifidus are differentially active during voluntary arm movements, Spine 2002; 27; 29-36

• Hodges PW., Richardson CA. Feed forward contraction of transversus abdominis is not influenced by the direction of arm movement, Experimental Brain research 1997; 114; 262-270

• Hicks GE., Fritz JM., Delitto A., McGill SM. Preliminary development of a clinical prediction rule for determining which patients with low back pain will respond to a stabilization exercise program, Arch Phys Med Rehabilitation 2005; 86; 1753-1762

• Fritz JM., Whitman JM., Childs JD. Lumbar spine segmental mobility assessment: an examination of validity for determining intervention strategies in patients with low back pain. Arch Phys Med rehabilitation 2005; 86; 1745-1752

• Herbert JJ., Koppenhaver SL., Magel JS., Fritz JM. The relationship of transversus abdominis and lumbar multifidus activation and prognostic factors for clinical success with a stabilization exercise program: a cross-sectional study. Arch Phys Med Rehabilitation 2010; 91; 78-85