Back pain will affect up to 80% of the people in this country at some point in their lifetime, with 20% to 30% of the population experiencing back pain at any given time.^1-4 The prevalence of BP peaks between the ages of 35 and 60 years.¹ Of the people who develop acute BP, only about 4% develop chronic BP, with about one-third of those permanently disabled due to their pain.¹ People with BP use more health services than people with other disabilities, and BP is the second most common reason patients seek medical care.^1,2 Estimation of annual costs in the U.S., when lost productivity, lost work time, diagnosis, treatments, litigation, and disability are factored in, is up to $100 billion.⁵

Patients with low back pain may have a postural asymmetry. Normal, or good, posture is nonfatiguing, effortless and painless, and requires the least expenditure of energy. With good posture, a person avoids sustained contraction or prolonged shortening of muscles and should have balance from side to side and anterior to posterior. The curve in the cervical region should balance the curve in the lumbar region.

Postural asymmetry may be defined as the malalignment of one segment of the body, whether anteroposteriorly or laterally, that is compensated for by malalignment of another segment or segments. With the malalignment, excessive tension in certain muscle groups may occur that can lead to abnormal stresses on joints, ligaments, and intervertebral discs. Postural asymmetry may produce an excessive amount of tension and tightness in postural (antigravity) muscles, such as hamstrings and back extensors, and less tension and weakness in nonpostural muscles, such as the abdominals and glutei. The asymmetries may vary depending on whether a person is standing, sitting, or lying down.

Postural asymmetry may be related to structural or functional causes. Structural causes include an actual shortening of bone between the mortise of the ankle and femoral head, a small hemipelvis, and idiopathic scoliosis. Functional causes include foot pronation, increased knee flexion, poor footwear, muscle imbalance generated by tightness or weakness, shortening of the fascia about the hip, shortening or relaxation of the ligaments, and flat feet. These structural and functional causes can produce a pelvic obliquity and/or a leg length discrepancy. Poor work habits may also contribute to postural asymmetries. The following discussion will be limited to the diagnosis and treatment of pelvic obliquity, LLD and pes planovalgus, all of which may cause postural asymmetry.

Pelvic Obliquity and Pes Planovalgus

Pelvic obliquity, a tilting of the pelvis (the base of support for the spine), may be a result of asymmetry of the pelvic bones or asymmetry of leg length between the ankle and femoral heads.⁶ Pelvic obliquity or LLD impose strain because the body attempts to compensate for the distortion in posture with a functional scoliosis to maintain balance of the head and shoulders over the feet. The lumbar spine is usually convex toward the short side. The pelvis may also be skewed or rotated. Other compensatory changes include prolonged activation of muscles (glutei, paravertebral, abdominals, or pelvic region muscles) on the long side. A piriformis muscle spasm may compensate by externally rotating and functionally shortening the limb.

Investigators have found that the prevalence of LLD in patients with chronic low back pain is greater than in those without pain.^7,8 In another study that evaluated the amount of pelvic obliquity in patients with and without chronic LBP, there was no significant difference between those two groups.9 Pelvic obliquity and LLD may not cause back pain, but they may aggravate or perpetuate symptoms after a traumatic event.

Typical characteristics of the low back pain associated with pelvic obliquity and LLD have been described by several authors^6,10,11 as gradual in onset, typically beginning in late adolescence or early adulthood, chronic or recurrent, and precipitated by trauma or strain, such as lifting.^6,11 The pain may begin within 20 to 30 minutes of standing and be promptly relieved on sitting.¹⁰ Many other pain complaints involving various body regions have been attributed to pelvic obliquity and LLD, including feet,^6,12-14 knee,¹⁵ hip,^12,16,17 thorax,^6,15 and shoulder⁶ pain. Degenerative joint changes and intervertebral disc disturbances have also been described as associated with pelvic obliquity and/or LLD.^11,12,16-20

The feet are the foundation of an upright posture. One foot whose position is more planovalgus (pronated and flat) than the other may cause a short leg or compensate for a long one. Pes planovalgus may have an intrinsic cause, such as ligament laxity, or extrinsic biomechanical causes, including pelvic obliquity/LLD, spinal scoliosis, rotation of the hip, femur, and/or knee, or valgus or varus deformities of the knee and ankle. These may lead to displacement of the forefoot.

Asymmetric pronation may cause an obliquity of the pelvis in the frontal plane, produce a lateral deviation in the spine, and rotate the vertebral bodies to create a functional lumbar scoliosis and increased lumbar lordosis.¹³ These postural changes are compensatory techniques for maintaining upright and efficient posture. Other postural symptoms may arise if the limb of the pronated foot is more internally rotated. Pathomechanical imbalances between the lower extremity and the pelvis may produce ligamentous, fascial, and muscular tensions, which can contribute to stress and strain in body mechanics.¹³ The sacroiliac joint may also be a site of compensation for leg length asymmetry; internal rotation of the limb due to excess pronation of the foot may lead to sacroiliac joint dysfunction. There is also increased tension in the iliopsoas muscle with internal rotation of the limb.

Diagnosis

The examiner should observe the patient in sitting and standing positions. If the patient has a postural asymmetry, he or she may stand or sit slouched, with shoulders and head forward and one shoulder lower than other and the head or cervical region tilted to compensate for a pelvic obliquity. A scoliosis in the lumbar and/or thoracic spine may be palpated along with differences in heights of the iliac crest.

Assessment of postural asymmetry caused by pelvic obliquity may be done by either of two methods: radiographic measures or anatomical landmarks. There are two commonly accepted radiographic methods of determining the degree of postural asymmetry and thus the amount of lift necessary to correct that discrepancy. The first method, developed by Tilley²¹ and Fann,²² involves determining the amount of pelvic obliquity via sacral base measurements. The second involves measuring femoral head heights. Both of these methods uses a postural x-ray (a pelvic x-ray taken with the patient standing).

In his study, Tilley measured the sacral base instead of femoral head heights since the sacrum “acts like an inverted keystone as mediator of the paired lower extremities and pelvis with the single axial vertebral column,” a statement with which Beal6 and Rothenberg²³ agree. All three studies indicate that the reliability of measurement of pelvic obliquity is between one and three millimeters, similar to those for measuring femoral head height.^7,24-27

A third method, relying solely on tape measurements from anatomical landmarks,^15,24,28-31 appears much less reliable. Palpation methods should be used to provide clues to the clinician as to the presence of an LLD/pelvic obliquity15 but they are inaccurate in determining discrepancies of less than 1 cm.^24,32 From a study that I recently completed of 93 patients with chronic low back pain, the average magnitude of pelvic obliquity was 8 mm (the paper has been submitted for publication).

The examiner should evaluate the foot in both weight-bearing (functional) and nonweight-bearing positions. In a nonweight-bearing position, the examiner should inspect for swelling, masses, and calluses. Calluses develop in response to abnormal weight-bearing and are good indicators of stress and pressure. The examiner should observe the toes. A relatively long second metatarsal with a short first metatarsal (Morton’s foot) may result in increased loading of the second metatarsal head. Hammer- or clawtoes may indicate a collapsed transverse arch. With the patient standing, the foot should be examined for collapse of the arches, especially the transverse (or metatarsal) one. The hindfoot should be examined for varus and valgus deformities that will affect placement of the forefoot. Evaluation should include inspection of the leg for rotational deformities that may affect placement of the forefoot. The foot should be palpated for calluses (which may not be obvious to visual inspection), swelling, and masses.

Treatment

Correction of postural asymmetry caused by pelvic obliquity and/or pes planovalgus should restore biomechanical balance,³³ reduce muscle strain, and reduce or eliminate pain.^29,33

Pelvic tilt. Heel lifts can correct the amount of pelvic obliquity determined from the postural radiographs. In our clinics we usually correct the discrepancy in 1/8-inch increments every 10 to 14 days through the use of cork heel lifts. A lift of as much as 1/2 inch will fit comfortably in most shoes. For correction over 1/2 inch, the amount of lift needs to be added to the outsole of the shoe. We counsel patients that the added lift may increase pain for a few days as the body adjusts to the changes. A follow-up postural radiograph may be done with the lift in place once the goal height has been achieved or if there is a significant increase in symptoms while the lift height is being increased.

Since most patients have asymmetries in muscle flexibility and/or strength that are either compensating for or causing the pelvic obliquity/LLD, they are referred to physical therapy for a flexibility and strengthening home program. Lower extremity flexibility, particularly in the iliopsoas and anterior hip soft tissues, helps prevent back pain by reducing stress on the lumbar spine.³⁴ Trunk extension and flexion strength is thought to protect against back injury by adding support to spinal joints and ligaments and by protecting muscles from excessive strain.³⁵ Other modalities may be used to help correct compensatory changes resulting from the asymmetry. They include trigger point injections, acupressure, manual manipulation, and massage. They facilitate flexibility by different methods and facilitate progress in an exercise program by breaking the pain cycle.^36,37 Because these modalities are passive and are not effective for long-term management, they should not replace an active treatment program.

The patient may also benefit from education about body mechanics. This may include avoiding prolonged neck-forward position by elevating reading materials; avoiding shortening positions at night; physiological positioning at desk or work surface; and correction of kyphotic posture when standing or sitting.

Pes planovalgus. Correcting pronated feet by gradually augmenting orthotic arches may help reduce functional rotational deformities of the hip and knee, as well as correct the position of the foot. For most patients, the medial and lateral longitudinal and metatarsal arches all need to be augmented but to different degrees. Like the heel lifts, the arches should be gradually increased. We usually reevaluate patients with their orthoses about every four weeks and increase the arches gradually until the feet and lower limbs appear to be in a biomechanically correct position when the patient is standing on the orthoses. Because postural changes in the foot can contribute to myofascial trigger points in or to shortening of the intrinsic foot muscles, gradual correction of the arches allows the muscles and ligaments in the patient’s feet to accommodate to the changes by slowly reducing the trigger points and increasing flexibility.³⁸ In my experience, an initial approach that fully corrects the arch is usually ineffective because the patient is unable to tolerate the orthoses and, therefore, does not wear them. Partial correction of the arches that doesn’t increase them does not allow for full postural benefits of the orthoses to be realized.

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