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The Role of the Lumbar Multifidus in Chronic Low Back Pain: A Review

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Low back pain (LBP), a highly prevalent problem in society, is often a recurrent condition. Recent advances in the understanding of the biomechanics of LBP have highlighted the importance of muscular stabilization of the "neutral zone" range of motion in the low back. The lumbar multifidus muscles (LMM) are important stabilizers of this neutral zone, and dysfunction in these muscles is strongly associated with LBP. The dysfunction is a result of pain inhibition from the spine, and it tends to continue even after the pain has resolved, likely contributing to the high recurrence rate of LBP. Persisting LMM dysfunction is identified by atrophic replacement of multifidus muscle with fat, a condition that is best seen on magnetic resonance imaging. Muscle training directed at teaching patients to activate their LMM is an important feature of any clinical approach to the LBP patient with demonstrated LMM dysfunction or atrophy.
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Clinical Review: Focused
The Role of the Lumbar Multifidus in Chronic Low
Back Pain: A Review
Michael D. Freeman, PhD, MPH, DC, Mark A. Woodham, DC,
Andrew W. Woodham, BA
Low back pain (LBP), a highly prevalent problem in society, is often a recurrent condition.
Recent advances in the understanding of the biomechanics of LBP have highlighted the
importance of muscular stabilization of the “neutral zone” range of motion in the low back.
The lumbar multifidus muscles (LMM) are important stabilizers of this neutral zone, and
dysfunction in these muscles is strongly associated with LBP. The dysfunction is a result of
pain inhibition from the spine, and it tends to continue even after the pain has resolved,
likely contributing to the high recurrence rate of LBP. Persisting LMM dysfunction is
identified by atrophic replacement of multifidus muscle with fat, a condition that is best
seen on magnetic resonance imaging. Muscle training directed at teaching patients to
activate their LMM is an important feature of any clinical approach to the LBP patient with
demonstrated LMM dysfunction or atrophy.
PM R 2010;2:142-146
INTRODUCTION
Low back pain (LBP) is a highly prevalent problem in society; approximately 60% to 80% of
the population will experience an episode of LBP during their lifetime, and 60% to 86% of
these people will have more than one episode of LBP [1,2]. A relatively recent shift in the
view of LBP has gone from classifying it as a self-limited acute condition to a recurrent
syndrome [3]. The purpose of this review is to discuss the role of the lumbar multifidus
muscles (LMM) in recurrent LBP, as well as to discuss literature-based clinical approaches to
assessment and treatment of multifidus dysfunction.
Spinal stabilization therapy has been observed to be more effective over time in treating
LBP than minimal intervention and exercise therapy alone, and has also been observed to
reduce pain, disability, and medication intake, as well as recurrence rates [4,5].Asa
consequence, treatment focus has shifted to reactivation and strengthening of the smaller
muscles of the spine to improve long-term stabilization of the vertebral column.
Biomechanical research has increased the understanding of mechanisms of low back
injury and pain, specifically regarding the ability to stabilize the “neutral zone” of the lumbar
spine with tonic muscle control. Panjabi [6] has described the neutral zone as the part of the
range of intervertebral motion, measured from the neutral position, in which spinal motion
can occur with minimal nonmuscular passive resistance from the spine. Suni and colleagues
[2] described a randomized controlled trial of a neuromuscular training program directed at
neutral zone stabilization on a population of patients with recent back injury. These authors
demonstrated a significant decrease in the intensity of LBP in the treatment group that was
not seen in the control group, and concluded that control of the lumbar neutral zone was an
important component of LBP and disability prevention.
MULTIFIDUS FUNCTION
It is well established that the LMM are important stabilizers of the lumbar neutral zone; Wilke et
al [7] found that the actions of the multifidi account for more than two thirds of the stiffness of
the spine when in the neutral zone. In comparison with all lumbar muscles, the LMM are short
and stout, with a high cross-sectional area (CSA) and short muscle fibers. Furthermore, these
M.D.F. Department of Public Health and Pre-
ventive Medicine, Oregon Health and Science
University School of Medicine 1234 SW 18
th
Ave, Portland, OR 97205. Address correspon-
dence to: M.F.; e-mail: forensictrauma@
gmail.com
Disclosure: nothing to disclose
M.A.W. Private practice, Tacoma, WA
Disclosure: nothing to disclose
A.W.W. Department of Genetic, Molecular,
and Cellular Biology, University of Southern
California, Los Angeles, CA
Disclosure: nothing to disclose
Disclosure Key can be found on the Table of
Contents and at www.pmrjournal.org
Submitted for publication May 15, 2009;
accepted November 19.
PM&R © 2010 by the American Academy of Physical Medicine and Rehabilitation
1934-1482/10/$36.00 Vol. 2, 142-146, February 2010
Printed in U.S.A. DOI: 10.1016/j.pmrj.2009.11.006
142
authors found that at the foundation of this high CSA was a high
mass, which allows for packing of a large number of muscle
fibers into relatively small space. This morphology allows the
LMM to produce very large forces over a small operating range,
and makes the LMM ideally suited for stability as opposed to
motion [8,9]. Functionally, the LMM are divided into deep and
superficial fibers, with deep fibers spanning 2 vertebral seg-
ments and functioning tonically, and the superficial fibers span-
ning 3 to 5 levels and functioning phasically [10,11]. This
arrangement makes the deep fibers of the LMM anatomically
and biomechanically well suited for stabilization.
MULTIFIDUS ATROPHY AND LOW BACK
PAIN
A number of prior investigations have described the LMM
atrophy and replacement by fat after low back injury, a patho-
logic process that is closely correlated with LBP. Kjaer and
colleagues [12] evaluated the lumbar magnetic resonance imag-
ing (MRI) results for 412 adult and 442 adolescent subjects in a
cross-sectional study of LMM atrophy. These authors catego-
rized the degree of observed atrophy in the LMM as none, slight,
and severe, and correlated the findings with complaints of LBP.
They found that fat infiltrations of the LMM were strongly
associated with LBP in adults, and that the association was
independent of body mass index (BMI).
Kader et al [13] performed a retrospective study of 78
patients with LBP and either with or without leg pain. The
authors assessed the correlation between MRI changes in the
LMM and leg pain. It was reported that LMM atrophy was
present in 80% of the patients with LBP and that there was a
significant correlation between LMM atrophy and referred
leg pain. The authors theorized that LMM atrophy may be
caused by dorsal ramus syndrome, which has been described
as LBP with referred leg pain, produced by irritation of
anatomic structures supplied by the dorsal ramus nerve, ie,
the facet joints and LMM. The authors further concluded that
abnormalities of the LMM may explain referred leg pain in
the absence of other MRI abnormalities.
Hides et al [14] described a study of 26 subjects with unilat-
eral LBP, some with referred lower extremity pain. The authors
assessed LMM atrophy among the subjects using ultrasound
imaging, noting marked asymmetry of the LMM that was local-
ized to a single vertebral level in most cases. The authors noted
that the level of LMM asymmetry correlated with the neurologic
level of the symptoms in 24 of the 26 subjects in the study.
IMAGING OF MULTIFIDUS ATROPHY
There are numerous publications describing the morpho-
logic assessment of the LMM using MRI, computed tomog-
raphy (CT), and ultrasound (US).
Kader et al [13] used MRI in evaluating LMM atrophy,
which they defined as muscular replacement with fat and
fibrous tissues. The authors established a ranked grading
scale for LMM atrophy consisting of mild, moderate, and
severe, corresponding to atrophy in less than 10% of CSA of
the LMM, more than 10% and less than 50%, and more than
50%, respectively (Figures 1-3). Two readers assessed the
degree of LMM atrophy among the subjects, with good inter-
observer agreement noted.
Kjaer et al [12] described the blinded assessment of LMM
atrophy in 854 MRI scans of adults and adolescents using a
grading scale similar to that used by Kader et al [13]. The
authors found good intraobserver and interobserver agree-
ment among the readers for the adult group. The authors
noted that fatty infiltration after LMM atrophy could be
measured in a noninvasive manner using MRI.
Barker et al [15] performed MRI on 50 patients presenting
to a back pain clinic with unilateral persisting LBP. The
authors measured the CSAs of the left and right psoas and
LMM and correlated their findings with the distribution and
duration of symptoms among the subjects. A significant
positive correlation between the side of LMM atrophy and the
distribution of the LBP was found, as well as between the
degree of atrophy and the duration of the symptoms.
CT has been evaluated as a relatively lower-cost and more
accessible alternative to MRI for assessment of LMM atrophy.
Danneels et al [16] described a study of CT assessment of 32 LBP
patients and 23 active volunteers. The study design included CT
of the CSA of the LMM at 3 levels. The authors found macro-
scopic atrophic changes in the LMM in 80% of the patients with
LBP, and that the atrophy in the LMM at the lowest levels of the
lumbar spine correlated significantly with LBP status. The au-
thors concluded that the most important finding from their
study was the finding of a significant correlation between LMM
atrophy and radicular and nonradicular leg pain.
The utility and reliability of US relative to MRI scanning,
have also been evaluated as a means of assessing LMM CSA.
Hides et al [17] compared the CSA assessment of the LMM
among healthy young adults using MRI and US, following a
strict protocol The authors determined that LMM CSA could
be measured as accurately with US as with MRI, although
they did not assess the ability of US to discriminate the degree
of atrophy in the LMM.
REFLEX INHIBITION MODEL OF LOCALIZED
MULTIFIDUS ATROPHY
Macintosh et al [11] described the morphology of the LMM
by means of the dissection of 12 adult cadaver spines. In
contrast to previous determinations that each LMM is inner-
vated by a number of spinal nerves, these authors found that
the LMM is divided into 5 distinct myotomes that are each
innervated by a single spinal segment. They found that all
muscle fibers attaching to the spinous process or lamina of a
particular vertebra are segmentally innervated by the same
nerve; the medial branch of the dorsal ramus that originates
143PM&R Vol. 2, Iss. 2, 2010
inferior to the respective vertebra (Figure 4). Thus, the mus-
cle that moves a given spinal segment is supplied by the nerve
for that segment. The authors postulated that from an ana-
tomic perspective, the shared innervation of the zygapophy-
seal joints means that pain emanating from these joints could
result in a reflex inhibition of the LMM at the same level.
Indahl et al [18] noted that the injection of saline into the
zygapophyseal joint in a porcine model resulted in decreased
activity of the multifidus muscle. They concluded that the
effect of the injection was to activate a stretch reflex in the
joint capsule, which in turn excited inhibitory interneurons
in the spinal cord, which in turn inhibited the motor neurons
and decreased the muscle response. The authors inferred that
LMM atrophy seen in the human spine is a result of reflex
inhibition caused by afferent feedback from the zygapophy-
seal joint, which in turn impedes the voluntary activation of
the LMM. The authors pointed to their results as evidence
that multifidus atrophy seen in back pain patients is more
likely a result of dysfunction rather than disuse. The authors
postulated that inhibitory discharges from the zygapophyseal
joints may explain the efficacy of manual medical approaches
to back pain such as manipulation and mobilization directed
at the zygapophyseal joints.
Hodges et al [19] demonstrated, also in a porcine model,
the rapid onset of LMM atrophy within 3 days after an
experimentally induced nerve root injury. After transection
of the medial branch of the L3 nerve root, the ipsilateral LMM
CSA adjacent to the L4, L5, and L6 spinous processes was
reduced by 13%, 20%, and 12%, respectively, by 72 hours
after injury. The changes were isolated to the side of injury;
there were no differences in the CSA or muscular activity
levels of the contralateral LMM, as determined by US assess-
ment. The authors also investigated the changes in the LMM
after experimentally induced disk injury in the porcine
model. A stab wound was introduced to the left anterolateral
aspect of the L3-4 intervertebral disk, and this was followed
by focal atrophy and a reduction of the CSA of the left LMM
by 17%. The authors opined that it was unlikely that the
injury resulted from LMM denervation (owing to nerve root
injury) as the atrophy was only at the level of the disk,
whereas single nerve roots innervate three levels of LMM. The
authors noted that the posttraumatic changes in the LMM
noted in their study were undoubtedly attributable to a
reduction in neural drive to the muscle, but that the mecha-
nism that accounted for the reduction was unclear.
Hides et al [20] provided further evidence that the pattern
of LMM atrophy is local rather than general in a study that
compared multifidus size and bilateral symmetry between
chronic LBP patients and healthy asymptomatic subjects. The
authors reported that at the L4 and L5 levels, asymptomatic
subjects were found to have significantly larger multifidus
muscles in comparison with chronic LBP patients. They also
found that the greatest asymmetry was seen at the L5 verte-
bral level in patients with unilateral pain presentations. The
authors concluded that their findings support a clinical ap-
proach to LBP that uses exercise therapy that focuses on
localized muscle impairments.
Wallwork et al [21] demonstrated that LMM atrophy was
associated with a reduction in the ability to voluntarily con-
tract the muscle. The authors used diagnostic US to measure
contractions of the LMM by comparing the thickness of the
muscle at rest to when it was contracted. Study subjects with
chronic LBP and LMM atrophy demonstrated significantly
decreased ability to perform isometric contractions of their
LMM. These study results reinforced the findings of prior
authors and emphasized the clinical perspective that rehabil-
itation in LBP patients may need to target localized impair-
ments in motor control.
MULTIFIDUS ATROPHY TREATMENT
Danneels et al [4] assessed the efficacy of 3 different treat-
ment modalities on multifidus CSA in chronic LBP patients.
A group of 59 patients were randomly allocated to one of 3
programs: stabilization training, stabilization training com-
bined with dynamic resistance, and stabilization training
combined with dynamic-static resistance. Using CT scan-
ning, LMM CSAs were measured before and after 10 weeks of
training. The CSA of the LMM muscle was significantly
increased at all vertebral levels only in the dynamic-static
resistance training group. The authors concluded that the
static holding component between concentric and eccentric
contraction phases was critical to induction of muscle re-
growth.
A randomized controlled trial performed by Van et al [22]
used real-time visual feedback by means of US to improve the
isometric contraction capability of the LMM in healthy sub-
Figure 1. Mild multifidus muscle atrophy, per Kader et al [13]
grading criteria (less than 10% of CSA of muscle replaced with
fat).
144 Freeman et al ROLE OF THE LUMBAR MULTIFIDUS IN CHRONIC LOW BACK PAIN
jects. The authors applied motor learning principles to train
the subjects in voluntary contraction of the multifidus and
gave verbal feedback to one group, and verbal and visual
feedback to the other. They found that providing the subjects
with visual feedback of their performance resulted in better
quality muscle contraction of the LMM as well as better
memory of how to contract the multifidi after reassessment a
week later.
Sung [23] evaluated the question of whether an exercise
program designed to increase the ability to contract the LMM
improves functional status or reduces LBP. This author de-
scribed a short-term cohort study that assessed the effect of a
4-week spinal stabilization exercise program in a group of
LBP patients, reporting a significant improvement in LMM
function, as well as a reduction in LBP disability.
Hides et al [5] described the effects of stabilization training
on LMM CSA among elite athletes (cricketers) with LBP,
concluding that LMM atrophy can exist in highly active, elite
athletes. The authors demonstrated that the stabilization
training increased the CSA of the LMM, and that the training
was associated with a decrease in symptoms of LBP. Their
results showed that specific training that aims at activation of
the LMM is associated with both an increase in functional
status and a reduction in LBP.
In an earlier study by Hides et al [24], the authors dem-
onstrated that LMM function recovery is not necessarily
associated with the resolution of painful symptoms in LBP
patients. The authors studied a group of 39 patients with a
first episode of acute unilateral LBP and corresponding uni-
lateral segmental inhibition of the LMM. The patients were
randomly allocated to 2 groups, only one of which performed
specific exercises designed to reactivate the LMM through
facilitating an isometric contraction of these muscles. The
group that did not perform the exercises had decreased LMM
size at a 10-week follow-up examination even though they
had resumed normal levels of activity and had a remission of
painful symptoms, whereas the group that performed the
isometric contractions showed more rapid and complete
LMM recovery. The authors suggested that the continued
dysfunction of the LMM in such patients may be one reason
for the high recurrence rates of LBP after an initial episode.
MacDonald et al [25] assessed muscular control of long
and short LMM fibers in 15 recurrent LBP patients and 19
control subjects. The authors used EMG to determine
whether LMM control at the L5 level differed between the
groups. They found that there were changes in motor control
of the LMM among the patients that primarily affected the
shorter fibers, and that these changes were greater on the
previously painful side of the low back. These findings sup-
port the use of a specifically designed stabilization exercise
program directed toward the LMM and specifically the
deeper shorter fibers that serve to stabilize the spine. The
authors concluded that the abnormal pattern of muscle con-
trol they observed may leave the spine vulnerable to reinjury,
thus predisposing the spine to recurrent episodes of LBP. The
authors postulated that the observed motor control problem
among the recurrent LBP patients implied that pain and
functional performance should not be the only outcome
measures after an acute episode of LBP.
CONCLUSIONS
The LMM are important stabilizers of the lumbar spine neu-
tral zone, and atrophy of the muscle decreases the ability to
Figure 2. Moderate multifidus muscle atrophy, per Kader et al
[13] grading criteria (more than 10% but less than 50% of CSA
of muscle replaced with fat).
Figure 3. Severe multifidus atrophy, per Kader et al [13] grad-
ing criteria (more than 50% of CSA of muscle replaced with
fat).
145PM&R Vol. 2, Iss. 2, 2010
control the neutral zone and is strongly associated with LBP.
This atrophy appears to help perpetuate an inhibitory feed-
back loop that begins with pain in the spine, possibly stem-
ming from the intervertebral disks or zygapophyseal joints,
followed by reflex inhibition of the multifidus, and then
atrophy and fatty replacement of the muscle. Amelioration of
the LBP does not necessarily result in resumption of normal
LMM function, and decreased LMM function is likely impli-
cated in recurrent LBP. Muscle training directed at teaching
patients to activate their LMM is an important feature of any
clinical approach to the patient with LBP who demonstrates
LMM dysfunction or atrophy.
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Transverse Process
Spinous Process
Intervertebral Disc
Facet Joint
Medial Branch of
The Dorsal Ramus
Multifidus Muscle
Figure 4. Schematic representation of orientation and inner-
vation of a lumbar multifidus muscle.
146 Freeman et al ROLE OF THE LUMBAR MULTIFIDUS IN CHRONIC LOW BACK PAIN
... Recent research highlights the crucial stabilizing role of the multifidus muscles in LBP biomechanics, particularly during spine motion and neutral positioning [29]. Dysfunction and degeneration of these muscles, often due to reflexive inhibition from shared innervation with zygapophyseal joints, are strongly associated with LBP [30]. ...
... The FDA approved multifidus muscle stimulation ( Fig. 4) for chronic LBP, supported by Level-1B evidence, by stimulating the L2 medial branch of the dorsal ramus at the L3 transverse process. It is designed for patients who have not found relief from conventional treatments and are not candidates for or have opted against spine surgery [29,30]. Contraindications include active implanted cardiac or electrical stimulation devices, pregnancy, active infections, allergies to device materials, severe psychiatric disorders, or individuals unable or unwilling to operate the device. ...
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... 2,12 Other muscles that have been implicated as dysfunctional in LBP include the posterior spinal muscles, including the erector spinae and multifidi. 13,14 Olympic-style rifle shooting requires strength in the trunk muscles for uses that are atypical compared to other sports. 9 Rifle athletes utilize their trunk in a static manner, requiring these muscles to provide stabilization and static control for optimal performance, rather than coordination with arm and leg movement as seen in other sports. ...
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... In the lumbar spine, these muscles include the multifidus, erector spinae, interspinales, intertransversarii, psoas major and quadratus lumborum (1). The multifidus muscles are important stabilizers of the lumbar spine (2). ...
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... 9,10 Because CSA and FI of the LMM play major roles in lumbar spine stabilization and functionality, 17,24 the severity of these factors should be taken into account in the component decision-making process when a patient is a candidate to undergo a lumbar spine procedure, particularly if they are consulting for lower back pain, leg pain, and/or chronic disability. 30,34,[40][41][42][43][44][45] This study has several limitations, including inherent limitations due to the study's retrospective nature, such as potential observer and reporting biases. Because a standardized methodology to evaluate LMM and PMM properties was lacking, our team used a thresholding technique (ImageJ) that was found to be highly reliable. ...
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Background Recurrence is common in chronic low back pain (CLBP). However, predicting the recurrence risk remains a challenge. The aim is to develop and validate a machine learning tool to predict the recurrence risk in patients with CLBP by using multidimensional medical information. Methods This prospective cohort study consecutively enrolled 341 patients with CLBP from two hospitals between 1 January 2021 and 31 December 2021. Patients from both centres were used for model development and internal validation, employing multivariate logistic regression (MRL) along with three additional machine learning algorithms. The multidimensional model (MDM) was used to predict recurrence in the next 2 years and was compared with the widely used prognostic tool, the STarT BACK Tool (SBT). The models' performance in detecting recurrence was evaluated using several metrics, including the area under the receiver operating characteristic curve (AUC), decision curve analysis, accuracy, sensitivity and specificity. Results A total of 131 patients (38.42%) experienced recurrence. In the MRL model, factors linked to recurrence odds included progressive lower limb weakness, anxiety, mechanical pressure test, number of previous episodes, Oswestry disability index and multifidus proton density fat fraction. For recurrence prediction, the MRL‐MDM achieved an AUC of 0.813 (95% CI, 0.765–0.862), sensitivity of 85.2% and specificity of 70.2% in internal validation. In comparison, the SBT for recurrence had an AUC of 0.555 (95% CI, 0.518–0.592), sensitivity of 93.3% and specificity of 17.6%. Conclusion The MDM may predict recurrence in patients with CLBP over a 2‐year period, surpassing the performance of SBT. Significance Statement This study found that the STarT BACK tool is suboptimal in predicting the 2‐year recurrence of chronic low back pain (CLBP). Our proposed multidimensional machine learning model aids clinicians in identifying patients at high risk for future recurrence of CLBP and in implementing appropriate preventive measures. Given the considerable healthcare resource utilisation associated with the frequent recurrence of CLBP, our novel model provides significant assistance in addressing this issue, demonstrating substantial clinical relevance.
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Study design Low back pain (LBP) is a widespread clinical symptom affecting nearly all age groups and is a leading cause of disability worldwide. Degenerative changes in the spine and paraspinal tissues primarily contribute to the etiology of LBP. Objectives We conducted this systematic review of animal models of paraspinal muscle (PSM) degeneration secondary to degenerative intervertebral disc (IVD), providing a comprehensive evaluation of PSM structural changes observed in these models at both macroscopic and microscopic levels. Methods PubMed, EMBASE, Web of Science, Cochrane Library, and MEDLINE Ovid databases were searched through November 2023. Literature was sequentially screened based on titles, abstracts, inclusion of animal models and full texts. A manual search of reference lists from all eligible studies was also performed to identify any eligible article. Two independent reviewers screened the articles according to inclusion and exclusion criteria. The risk of bias was assessed using the Systematic Review Centre for Laboratory Animal Experimentation's Risk of Bias tool. Results A total of nine studies were included in the final analysis after a comprehensive screening process. The included studies were assessed for various aspects of the multifidus muscle. Given the limited number of studies and the substantial heterogeneity among them, a quantitative meta-analysis was deemed inappropriate. Conclusions This systematic review shows a comprehensive analysis of structural changes in the multifidus muscle in animal models of IVD degeneration and offers crucial insights for developing improved rodent models of IVD degeneration and assessing a battery of approaches for multifidus degeneration.
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ABSTRACTBackground: Chronic lumbar radiculopathy, often caused by lumbosacral disc herniation, leads tosignificant muscle changes and back pain. Previous studies have demonstrated that specific muscles,such as lumbar multifidus (LM) and transversus abdominis (TrA), are preferentially affected inindividuals with low back pain. Objective: This study aimed to evaluate maximal concentric isokinetictrunk extension and flexion torque in patients with unilateral chronic lumbar radiculopathy in comparisonto healthy subjects. Methodology: Sixty-two male participants aged 35 to 45 years were included anddivided into two groups: 31 male patients with chronic unilateral lumbar radiculopathy and 31 healthymatched controls. Lumbar flexion and extension muscles strength were assessed using an isokineticdynamometer. Results: Patients with chronic lumbar radiculopathy exhibited a significant reduction inlumbar flexion and extension strength compared to healthy controls. Conclusion: There is a significantreduction in trunk muscle strength at 60 ̊/s and 120 ̊/s velocities in chronic low back pain (CLBP) patientscompared to healthy controls indicating an imbalance that may contribute to the persistence of chronicback pain.Keywords: Chronic Lumbar Radiculopathy – Muscle Strength – Lumbar Multifidus – TransversusAbdominis –Isokinetic Dynamometer. Page 2
Article
Study Design. A multicenter, randomized, controlled trial with 1-year follow-up. Objectives. To compare the effect of manual therapy to exercise therapy in sick-listed patients with chronic low back pain ( > 8 wks). Summary and Background Data. The effect of exercise therapy and manual therapy on chronic low back pain with respect to pain, function, and sick leave have been investigated in a number of studies. The results are, however, conflicting. Methods. Patients with chronic low back pain or radicular pain sick-listed for more than 8 weeks and less than 6 months were included. A total of 49 patients were randomized to either manual therapy (n = 27) or to exercise therapy ( n = 22). Sixteen treatments were given over the course of 2 months. Pain intensity, functional disability (Oswestry disability index), general health ( Dartmouth COOP function charts), and return to work were recorded before, immediately after, at 4 weeks, 6 months, and 12 months after the treatment period. Spinal range of motion (Schober test) was measured before and immediately after the treatment period only. Results. Although significant improvements were observed in both groups, the manual therapy group showed significantly larger improvements than the exercise therapy group on all outcome variables throughout the entire experimental period. Immediately after the 2-month treatment period, 67% in the manual therapy and 27% in the exercise therapy group had returned to work ( P < 0.01), a relative difference that was maintained throughout the follow-up period. Conclusions. Improvements were found in both intervention groups, but manual therapy showed significantly greater improvement than exercise therapy in patients with chronic low back pain. The effects were reflected on all outcome measures, both on short and long-term follow-up.
Article
Increasing documentation on the size and appearance of muscles in the lumbar spine of low back pain (LBP) patients is available in the literature. However, a comparative study between unoperated chronic low back pain (CLBP) patients and matched (age, gender, physical activity, height and weight) healthy controls with regard to muscle cross-sectional area (CSA) and the amount of fat deposits at different levels has never been undertaken. Moreover, since a recent focus in the physiotherapy management of patients with LBP has been the specific training of the stabilizing muscles, there is a need for quantifying and qualifying the multifidus. A comparative study between unoperated CLBP patients and matched control subjects was conducted. Twenty-three healthy volunteers and 32 patients were studied. The muscle and fat CSAs were derived from standard computed tomography (CT) images at three different levels, using computerized image analysis techniques. The muscles studied were: the total paraspinal muscle mass, the isolated multifidus and the psoas. The results showed that only the CSA of the multifidus and only at the lowest level (lower end-plate of L4) was found to be statistically smaller in LBP patients. As regards amount of fat, in none of the three studied muscles was a significant difference found between the two groups. An aetiological relationship between atrophy of the multifidus and the occurrence of LBP can not be ruled out as a possible explanation. Alternatively, atrophy may be the consequence of LBP: after the onset of pain and possible long-loop inhibition of the multifidus a combination of reflex inhibition and substitution patterns of the trunk muscles may work together and could cause a selective atrophy of the multifidus. Since this muscle is considered important for lumbar segmental stability, the phenomenon of atrophy may be a reason for the high recurrence rate of LBP.
Article
Study design: This study investigated the influence of five different muscle groups on the monosegmental motion (L4-L5) during pure flexion/extension, lateral bending, and axial rotation moments. Objectives. The results showed and compared the effect of different muscle groups acting in different directions on the stability of a single motion segment to find loading conditions of in vitro experiments that simulate more physiologically reasonable loads. Summary of Background Data. In spine biomechanics research, most in vitro experiments have been carried out without applying muscle forces, even though these forces stabilize the spinal column in vivo. Methods. Seven human lumbosacral spines were tested in a spine tester that allows simulation of up to five symmetrical muscle forces. Changing pure flexion/extention, lateral binding, and axial rotation moments up to +/-3.75 Nm were applied without muscle forces, with different muscle groups and combinations. The three-dimensional monosegmental motion was determined using an instrumented spatial linkage system. Results. Simulated muscle forces were found to strongly influence load-deformation characteristics. Muscle action generally increased the range of motion and the natural zone of the motion segments. This was most evident for flexion and extension. After five pairs of symmetrical, constant muscle forces were applied (80 N per pair) the range of motion decreased about 93% in flexion and 85% in extension. The total natural zone for flexion and extension was decreased by 83% muscle action. The multifluids muscle group had the strongest influence. Conclusion. This experiment showed the important of including at least some of the most important muscle groups in invitro experiments in lumbar spine specimens.
Article
Dissection studies revealed that the fibres of the lumbar multifidus are divided by distinct cleavage planes into five bands. Each band arises from a lumbar spinous process, and is innervated unisegmentally. The lumbar multifidus is therefore composed of five myotomes arranged such that the fibres that move a particular segment are innervated by the nerve of that segment. Target points are described that enable electromyography to be performed on paraspinal muscles of known unisegmental innervation.
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The lack of control of lumbar stability is thought to be a major factor in the aetiology and chronicity of low back pain. The lumbar multifidus muscle is considered to play a significant role in maintaining lumbar stability and stiffness. The aim of this study was to use clinical measures to compare lumbar multifidus muscle in chronic low back pain patients and unimpaired subjects. Sixteen subjects with chronic low back pain and 16 unimpaired subjects were assessed in the study. Cross-sectional area (CSA) and contraction size of multifidus were measured on both sides and at individual vertebral levels, from L2 – L5, using realtime ultrasound. The differences between the chronic back pain and unimpaired groups were statistically significant for both cross-sectional area and contraction size measures. In the unimpaired group, the contraction size of multifidus was greatest at the L5 segmental level, and then decreased in size at higher lumbar levels. In the chronic low back pain group, the contraction size was the same at L4 and L5 levels and contractions were less at these levels than those at L2 and L3. Three way interactions showed a significant interaction (p<0.05) between vertebral levels, change in thickness and group. Contrasts revealed a significant difference (p<0.05) between upper lumbar levels (L2 and L3) and lower lumbar levels (L4 and L5) across groups. In the unimpaired group, the contraction size of multifidus was greater at lower lumbar levels (L4 and L5) than upper lumbar levels (L2 and L3), while in the low back pain group, the contraction size was less at lower lumbar levels than upper lumbar levels. A similar pattern occurred with multifidus CSA’s. In the unimpaired group, CSA was greatest at L5 and gradually reduced at higher lumbar levels. In the chronic back pain group, CSA’s were the same at L5 and L4 and only slightly greater than L3. Two way interactions showed a highly significant difference (p<0.01) between groups across vertebral levels. There was a significant difference between upper lumbar levels (L2and L3) and lower lumbar levels (L4 and L5). Lower lumbar levels were less in the chronic low back pain group than the unimpaired group, when compared to upper lumbar levels. Estimated marginal means showed that CSA at L5 was significantly less in the chronic low back pain group (confidence interval >95%). Results of the study indicate that chronic low back pain patients have poorer muscle activation and greater muscle wasting of multifidus muscle at the lower lumbar levels compared with higher lumbar levels, than normal subjects. Clinical programmes should aim to restore multifidus muscle activation and size, in patients with chronic low back pain.
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Approximately thirty-four percent of people who experience acute low back pain (LBP) will have recurrent episodes. It remains unclear why some people experience recurrences and others do not, but one possible cause is a loss of normal control of the back muscles. We investigated whether the control of the short and long fibres of the deep back muscles was different in people with recurrent unilateral LBP from healthy participants. Recurrent unilateral LBP patients, who were symptom free during testing, and a group of healthy volunteers, participated. Intramuscular and surface electrodes recorded the electromyographic activity (EMG) of the short and long fibres of the lumbar multifidus and the shoulder muscle, deltoid, during a postural perturbation associated with a rapid arm movement. EMG onsets of the short and long fibres, relative to that of deltoid, were compared between groups, muscles, and sides. In association with a postural perturbation, short fibre EMG onset occurred later in participants with recurrent unilateral LBP than in healthy participants (p=0.022). The short fibres were active earlier than long fibres on both sides in the healthy participants (p<0.001) and on the non-painful side in the LBP group (p=0.045), but not on the previously painful side in the LBP group. Activity of deep back muscles is different in people with a recurrent unilateral LBP, despite the resolution of symptoms. Because deep back muscle activity is critical for normal spinal control, the current results provide the first evidence of a candidate mechanism for recurrent episodes.
Article
Muscular instability is an important risk factor for lumbar spine injury and chronic low-back pain. Although the lumbar multifidus muscle is considered an important paraspinal muscle, its design features are not completely understood. The purpose of the present study was to determine the architectural properties, in vivo sarcomere length operating range, and passive mechanical properties of the human multifidus muscle. We hypothesized that its architecture would be characterized by short fibers and a large physiological cross-sectional area and that it would operate over a relatively wide range of sarcomere lengths but would have very stiff passive material properties. The lumbar spines of eight cadaver specimens were excised en bloc from T12 to the sacrum. Multifidus muscles were isolated from each vertebral level, permitting the architectural measurements of mass, sarcomere length, normalized fiber length, physiological cross-sectional area, and fiber length-to-muscle length ratio. To determine the sarcomere length operating range of the muscle, sarcomere lengths were measured from intraoperative biopsy specimens that were obtained with the spine in the flexed and extended positions. The material properties of single muscle fibers were obtained from passive stress-strain tests of excised biopsy specimens. The average muscle mass (and standard error) was 146 +/- 8.7 g, and the average sarcomere length was 2.27 +/- 0.06 microm, yielding an average normalized fiber length of 5.66 +/- 0.65 cm, an average physiological cross-sectional area of 23.9 +/- 3.0 cm(2), and an average fiber length-to-muscle length ratio of 0.21 +/- 0.03. Intraoperative sarcomere length measurements revealed that the muscle operates from 1.98 +/- 0.15 microm in extension to 2.70 +/- 0.11 microm in flexion. Passive mechanical data suggested that the material properties of the muscle are comparable with those of muscles of the arm or leg. The architectural design (a high cross-sectional area and a low fiber length-to-muscle length ratio) demonstrates that the multifidus muscle is uniquely designed as a stabilizer to produce large forces. Furthermore, multifidus sarcomeres are positioned on the ascending portion of the length-tension curve, allowing the muscle to become stronger as the spine assumes a forward-leaning posture.
Article
Decreases in the size of the multifidus muscle have been consistently documented in people with low back pain. Recently, ultrasound imaging techniques have been used to measure contraction size of the multifidus muscle, via comparison of the thickness of the muscle at rest and on contraction. The aim of this study was to compare both the size (cross-sectional area, CSA) and the ability to voluntarily perform an isometric contraction of the multifidus muscle at four vertebral levels in 34 subjects with and without chronic low back pain (CLBP). Ultrasound imaging was used for assessments, conducted by independent examiners. Results showed a significantly smaller CSA of the multifidus muscle for the subjects in the CLBP group compared with subjects from the healthy group at the L5 vertebral level (F=29.1, p=0.001) and a significantly smaller percent thickness contraction for subjects of the CLBP group at the same vertebral level (F=6.6, p=0.02). This result was not present at other vertebral levels (p>0.05). The results of this study support previous findings that the pattern of multifidus muscle atrophy in CLBP patients is localized rather than generalized but also provided evidence of a corresponding reduced ability to voluntarily contract the atrophied muscle.