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The quadratus lumborum (QL) muscle is
considered among practitioners who have learned to recognize its
trigger points by examination to be the most frequent muscular cause
of low back pain (LBP), but also one of the most commonly overlooked
(6). Anatomically, the QL is considered a muscle of the posterior
abdominal wall and acts as an extrinsic stabilizer of the trunk,
with attachments inferiorly to the ilolumbar ligament and iliac
crest and superiorly to the twelfth rib and the tops of the
transverse processes of L1-L4 (4). Contracting bilaterally, the QL
extends the lumbar spine (4). Contracting unilaterally, the QL acts
as a lateral flexor of the lumbar region with minimal contribution
to axial rotation (4). In addition, the QL fixes the 12th rib during
movements of the thoracic cage during forced expiration also holds
the twelfth rib inferiorly in inspiration, thereby allowing the
thoracic cage to expand fully (2).
Functionally the QL positions the spine relative to the pelvis, and
aids in maintaining an upright posture while coordinating with the
erector spinae muscle group to create fine lateral movements and
extension (2). Upon standing, the two QLs, in conjunction with the
gluteus medius, position the upper body over the lower body (2), and
the QL assists in the load sharing for spinal stability in the
flexed trunk posture (1). While walking, the QL and gluteus medius
aid in pelvic stabilization as the body weight shifts from one foot
to the other (2); in addition, the QL lifts the iliac crest towards
the thoracic cage as weight shifts to the other foot, which allows
the leg to swing forward without the foot touching the ground, which
is why the QL is often clinically referred to as a “hip hiker” (2,
4).
QL and its relationship to back pain
While there are many possible causes of back pain and discomfort,
including a herniated or degenerated disc, nerve entrapment, muscle
strain, etc., trigger points in the QL are commonly overlooked (6).
Acutely, patients often report a persistent, deep, aching pain at
rest, and can be excruciating in any body position, especially in
the unsupported upright position and in sitting or standing that
increases weight bearing or requires stabilization of the lumbar
spine (6). Travell and Simons suggest that active trigger points in
the QL can refer pain along the iliac crest and sometimes to the
adjacent lower quadrant of the abdomen and into the groin, the
greater trochanter and outer aspect of the upper thigh, the lower
buttock, and strongly to the area of the SI joint (6). An original
study by Iglesias-Gonzalez et al. (2013) found that active trigger
points in the QL, iliocostalis lumborum, and gluteus medius muscles
were the most prevalent in patients with chronic nonspecific LBP
compared to a control group of healthy individuals, and a greater
number of active trigger points was associated with higher intensity
of each participant’s pain episode as well as worse sleep quality
(3).
Over time, weakness in the lower fibers of the erector spinae
muscles can cause the QL muscles to chronically contract
bilaterally, and with impeding muscle fatigue, can result in an
adaptive postural shift placing increased tension on the QL (2).
This chronic contraction of the QL can cause the fascial sheath to
transmit a strain through the rest of the back, even up into the
neck and shoulder regions, and develop muscle spasm which forcefully
contracts when it becomes hyper-excitable. (2).
Another problem with a tight QL is a condition that can develop
during the swing phase in gait, previously mentioned as “hip hiking”
(2). With this condition, a weak gluteus medius and/or minimus can
force the QL and tensor fasciae latae to act as compensatory prime
movers of hip abduction, thus resulting in excessive lateral
compression of the lumbar segments of the spine (2). In a
meta-analysis by Sadler et al. (2017), restriction in lateral
flexion and hamstring ROM, as well as reduced lumbar lordosis were
associated with an increased risk of developing LBP over a 12 month
period (5). Due to the QL having very favorable leverage as a
lateral flexor of the lumbar region (4), it is particularly
interesting that a restriction in lateral trunk flexion might be a
predictor of LBP. There were three studies that assessed lateral
flexion specifically and involved 1,364 total participants (5).
These studies revealed a significant association between reduced
lateral flexion ROM, measured by the distance that participants
could slide their hand down their ipsilateral thigh, and the
development of LBP (OR=0.41, 95% CI 0.24-0.73, p=0.002) with a low
and non-significant amount of heterogeneity present (I2 =15.9%,
p=0.304) (5). Alternatively, this can be expressed as an OR of 2.44
(1/0.41) which means that those participants with limited lateral
flexion ROM have a 144% greater likelihood of developing LBP (5).
Treatment
While LBP can present in a variety of different manners and involve
a several different structures, it is important not to overlook the
role that the QL can play in both acute and chronic LBP cases. Of
course, a comprehensive approach to back pain is always recommended,
but some common strategies to treat an involved QL include assessing
and correcting postural imbalances and compensations such as a
functional lumbar scoliosis or lower limb length inequality,
stretching and strengthening exercises to stabilize the pelvis, and
soft tissue mobilizing techniques including friction massage,
myofascial release, acupressure, and trigger point dry needling to
target restricted connective tissue (2, 6).
Last revised: August 28, 2017
by Nicholas Brzozowski, SPT
References
1) Colloca CJ, & Hinrichs RN.
The biomechanical and clinical significance of the lumbar erector
spinae flexion-relaxation phenomenon: a review of literature.
Journal of Manipulative and Physiological Therapeutics. 2005.
doi:10.1016/j.jmpt.2005.08.005
2) De Permentir P. Quadratus lumborum:
anatomy, physiology and involvement in back pain. Journal of the
Australian Traditional Medicine. 2015;21(4):241-242.
3) Iglesias-Gonzalez JJ, Munoz-Garcia MT,
Rogrigues-de-Souza DP, Alburquerque-Sendin F, &
Fernandez-de-las-Penas C. Myofascial trigger points, pain,
disability, and sleep quality in patients with chronic nonspecific
low back pain. Pain Medicine. 2013; 14:1964-1970.
4) Neumann D. Knee. In: Neumann D.
Kinesiology of the musculoskeletal system: foundations for
rehabilitation. 2nd ed. St. Louis, MO: Mosby; 2010
5) Sadler SG, Spink MJ, Ho A, De Jonge XJ,
& Chuter VH. Restriction in lateral bending range of motion, lumbar
lordosis, and hamstring flexibility predicts the development of low
back pain: a systematic review of prospective cohort studies. BMC
Musculoskeletal Disorders. 2017;18:179.
doi:10.1186/s12891-017-1534-0.
6) Travell JG & Simons DG. In: Myofascial
pain and dysfunction the trigger point manual: the lower
extremities. Vol 2. Philadelphia, PA: Lippincott Williams & Wilkins,
1993.
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