Treating Piriformis Syndrome
By Mark Charrette, DC
Evaluating your patient’s gait can provide valuable information, especially
in cases of slow response or other special situations. Many of the chronic or
recurring cases of pelvic, hip or low back complaints are directly associated
with gait imbalances. Take time to watch your patients walk around.
When patients don’t respond to chiropractic care as expected, there is often
an underlying collapse in the postural platform formed by the feet. A 1999
study found that “there are small, but important, intersegmental movements
of the spine during gait.”1 Abnormal motion initiated by excessive or
restricted joint interactions of the feet and lower extremities will eventually
interfere with the normal intersegmental motions and lead to pain syndromes.
Locating the Origins of Pain
Specifically, I would like to discuss the common clinical findings of
excessive foot flare, externally rotated femur, and piriformis muscle
contracture. This triad of findings is often found in the patient with
generalized hip and sacroiliac pain and dysfunction that may even include
classic findings of sciatic nerve irritation. The same patient may enjoy
temporary relief from symptoms following pelvic adjustments and/or the
combination of stretching and massage. However, all too often, the underlying
cause of the dysfunction is altered foot biomechanics, especially the
hyperpronated foot.
When patients turn to chiropractic care for pain relief, few, if any, expect
an area of their anatomy distant from the perceived pain to be at fault.
However, in seven of 10 patients with back pain, postural fatigue
and spinal strain cause their discomfort.2 The ultimate cause of
pain may originate in any tissue or joint involved in the kinetic structure.
This is the exact scenario that, with time, produces the symptoms we are
discussing.
As you observe your patient walking, take note of unilateral toeing out. Toe
out is an adaptive muscular response to the biomechanics of hyperpronation (loss
of medial longitudinal arch integrity) during stance phase, which accentuates
walking with foot flare, which should normally be in the range of 10 to 20
degrees. Associated with excessive pronation and foot flare is marked wear along
the lateral border of the heel. Excessive lateral heel wear is a good indicator
of the chronicity and extent of the deformation. Excessive lateral heel wear
also indicates the need to properly support the medial longitudinal arch.
The strength and function of the three natural arches of the foot depend upon
the proper alignment of bones and the support of the ligamentous tissues –
plantar fascia and bone-to-bone ligaments. The most common structural
misalignment of the lower extremity is excessive pronation, affecting the medial
arch primarily. Whenever there is compromise of the arch structures or the
supporting soft tissues, the postural foundation is adversely affected.
In addition to the normal degrees of foot pronation during the stance phase
of the gait cycle, there is a series of coupled motions that results in medial
rotation of the entire lower limb and pelvis. With hyperpronation, this torquing
is accentuated. The increased rotational forces are transmitted into the pelvis
and hip region. One of the primary antagonists to this excessive medial rotation
is the piriformis muscle.
Piriformis Syndrome
The piriformis has its origin on the second through fourth anterior segments
of the sacrum and on the sacrotuberous ligament. The muscle travels anterior and
inferior through the greater sciatic foramen as it passes superior and posterior
to the femoral head. The muscle inserts on the greater trochanter, allowing the
muscle to laterally rotate the thigh and assist in the tracking of the femoral
head within the acetabulum.3
The following have been proposed as possible mechanisms by which irritation
of the piriformis muscle leads to apparent or actual sciatic neuritis. First, in
many cases, branches forming the sciatic nerve first pass through the belly of
the piriformis muscle. Spasm and hypertrophy can physically irritate the
nerve.4 Second, when irritated, the piriformis can release inflammation
byproducts that have been shown to be chemical irritants.5
With the patient prone, efforts to place the thigh into internal rotation
will be limited both by the contracture of the muscle and by reproduction of the
patient’s symptoms. Externally rotating the femur accentuates the subluxated
position of the femur and should result in shortening of the reactive leg during
functional leg checks.
Treatment involves contacting the posterior aspect of the greater trochanter
and adjusting with an anterior and slightly inferior line of drive. However, the
long-term solution is to remove the underlying irritation by the use of
custom-made, stabilizing orthotics to support the three arches in each foot and
absorb the shock of the foot striking the ground – both of which help to
facilitate neuromuscular control for coordinated gait with each step.
Our discussion of hyperpronation leading to a piriformis syndrome is only one
example of the possible consequences of poorly supported arches. Remember that
excessive motion in the feet will irritate the weak links farther up the kinetic
chain. A custom-made orthotic will help your patient’s feet adapt to their
environment, regardless of the circumstances.
Support and Shock Reduction: The Role of Orthotics
Not only does the orthotic support the arches of the foot, but it also
reduces the transmission of shock into the spine. Pathological shock occurs when
normal walking on hard surfaces exacerbates irritated structures. Force
generated at heel strike can reach five to seven times body weight, with the
musculoskeletal system itself absorbing a significant percentage of the total
(under normal conditions).6 Specially designed orthotics contain
unique viscoelastic materials to absorb a considerable amount of shock at the
heel.
Chiropractic adjustments of the spine improve proprioceptive input by
normalizing joint alignment and muscle tonus. Furthermore, because the feet
contain approximately one-quarter of all the body’s joints and, therefore, a
concentration of proprioceptive fibers, it becomes logical to conclude that
support of the postural foundation using custom-made orthotics will enhance the
balance of our patients who need it most. In fact, this was the basis for research
involving custom-made orthotics published in the Journal of Manipulative
and Physiological Therapeutics.7
Obviously, not every patient is a candidate for orthotic therapy; but nearly
all patients over the age of 40 can benefit from using orthotics.8 By
this time, the effects of walking and standing on hard surfaces, ligament laxity
(age-related or postpartum) and repetitive microtraumas have often contributed
to significant plastic deformation in the feet. Prescribing custom-made,
stabilizing orthotics provides highly dynamic and adaptive responses for an
increased level of mobility and stability. If you are watching your patients
come and go from your office, you’ll know when they need it.
References
- Sychewska M, Oberg T, Karlsson D. Segmental
movements of the spine during treadmill walking with normal speed. Clin
Biomech, 1999;14:384-388. - Brunarski DJ. Chiropractic biomechanical evaluations; validity in myofascial low
back pain. J Manip Physiol Ther,1982;5(4):155-161. - Moore KL. Clinically Oriented Anatomy. Baltimore: Williams &
Wilkins, 1982:346. - Cox JM. Low Back Pain: Mechanism, Diagnosis and Treatment, 5th
Edition. Baltimore: Williams & Wilkins, 1990. - Steiner C, et al. Piriformis syndrome: pathogenesis, diagnosis, and treatment.
J Am Osteopath Assoc, 1987;87:318. - Voloshin AS, Burger CP. Interaction of Orthotic Devices and Heel
Generated Force Waves. 9th International Congress on Applied Mechanics,
Canada, 1983. - Stude DE, Brink DK. Effects of nine holes of simulated golf and orthotic
intervention on balance and proprioception in experienced golfers. J
Manip Physiol Ther, 1997;20:590-601. - Schafer RC. Chiropractic Management of Sports and Recreational
Injuries. Baltimore: Williams & Wilkins, 1982:517.
