Can Orthoses Help Patients With Low Back Pain?

These expert panelists delve into the relationship between custom orthoses and low back pain, sharing key pearls on examining these patients and how to determine whether orthoses can be beneficial.

Q:

In your clinical experience, have you found a relationship between custom orthotics and the relief of low back pain?

A:

Is there a relationship between biomechanical foot dysfunction and low back pain that orthoses can alleviate? The answer is a “resounding yes” for George Trachtenberg, DPM.

Similarly, in his experience, Joseph D’Amico, DPM, has found that orthotic devices improve or completely ameliorate low back pain in the vast majority of cases for which physicians prescribe them. He notes it is rare that a properly prescribed orthotic device will increase low back pain and cannot recall a single instance in which that has been the case. On occasion, there may be a postural readjustment period, which he says one can reduce by a more gradual introduction to the suggested daily orthotic wearing time.

Since the foot is the foundation for the musculoskeletal system and its only connection to the supporting surface, Dr. D’Amico says defects or deficiencies in the foot will affect the entire skeleton. He says this phenomenon is known as von Baeyer’s Closed Chain of Links, wherein malalignment or irregularity in function or position of one part affects the entire chain.^1,2 The foot therefore is the only unyielding point from which the rest of the body can stabilize, explains Dr. D’Amico.

Kevin Kirby, DPM, notes he routinely has patients who say they are very pleased that, for the first time in years, custom orthoses have resolved their lower back pain. In contrast, he also has patients who have received a referral from a physician for orthoses for their low back pain and have gotten little to no relief.

“Obviously, even though low back pain can be helped by custom foot orthoses, I find, after 31 years of practice, I still cannot accurately predict exactly which patients will get better and which patients will find little relief from custom foot orthoses,” says Dr. Kirby.

In most cases of low back pain “short of falling out of a six-story window, the back of a moving truck or one having a congenital problem,” the pain is based in abnormal sagittal plane gait, points out Dr. Trachtenberg. He emphasizes that the lower extremity is attached to lumbar spinal discs L4-S1 and abnormal movement in the closed kinetic chain has an influence on this region.

One of the primary goals in the management of low back pain is reduction of the lumbosacral angle, which Dr. D’Amico notes is responsible for posterior facet impingement. He notes another goal is to prevent the secondary protective spasm of the low back musculature, which is trying to stabilize the lumbar spine and prevent further derangement. Dr. D’Amico says excessive pronation increases the lumbosacral angle through internal and anterior migration of the tibia, accompanying knee flexion, concomitant hip flexion and anterior tilting of the pelvis. This accentuates the lumbar lordotic curve and subsequently increases the lumbosacral angle, notes Dr. D’Amico.

“One method by which foot orthoses are effective in treating low back pain is through the elimination of abnormal pronation with subsequent lowering of the lumbosacral angle and secondary low back tightness or spasm,” adds Dr. D’Amico.

Dr. D’Amico also considers the excessively supinating patient whose low back pain may be precipitated, perpetuated or aggravated by an inability to absorb shock as well as a failure to adapt to terrain variability. As he notes, the properly prescribed orthotic device can neutralize these shortcomings.

Q:

What are the most frequent considerations when prescribing custom orthotics for patients with low back pain?

A:

Dr. D’Amico cites several factors, such as structural deficiencies, lower extremity ranges of motion, the presence of ligamentous laxity, equinus influences and limb length discrepancy.

No orthotic device can be successful on any level if one does not recognize or address the underlying structural imperfections, according to Dr. D’Amico. Since lower extremity rotations provide propulsive stability, individuals with restricted hip rotations present with obstacles to successful outcomes and he says one should address this through appropriate stretching and/or physical therapy referral.

“This is especially true when there is restricted external hip rotation with the excessively pronated foot and restricted internal rotation in the excessively supinated foot,” says Dr. D’Amico.

If patients have increased low back pain when standing or walking for long periods, Dr. Kirby says it is a good sign that foot orthoses may be helpful for them. In addition, he notes if patients have an overly pronated foot, he will have them stand in a relaxed bipedal position and take note of their low back discomfort. Then while they are still standing upright, Dr. Kirby will have them supinate both feet into subtalar joint neutral position to see if this helps relieve some of their low back pain.

Dr. Kirby notes this “low back pain supination test” works on the theory that excessive internal femoral rotation caused by subtalar joint pronation will cause increased pull of the iliopsoas muscle on the lumbar spine and pelvis, increasing the strain on the lower back. He says the test will allow the podiatrist to better estimate if custom orthotics will help the patient’s low back pain or not.

Equinus influences, especially those affecting the three foot-rocker mechanisms, limit the ability of the superstructure to move freely over the supporting foot, and Dr. D’Amico says this cumulatively increases low back stresses with every step.³ He emphasizes that “the presence of an unidentified limb length discrepancy and its continued pathomechanical compensation will thwart an otherwise successful low back pain orthotic management program.”⁴

Dr. Trachtenberg advises clinicians to determine the podiatric biomechanical dysfunctions that are influencing or causing the low back to be dysfunctional, and prescribing orthoses to address those findings. He emphasizes the importance of looking at leg length differentials as part and parcel of those determinations. As Dr. Trachtenberg notes, the issue would be to eliminate the repetitive motion dysfunctions on the lower back that can be attributed to the abnormal gait.

Q:

What have you found to be most effective when prescribing custom orthotics, specifically for patients who have low back pain?  

A:

As Dr. Kirby notes, many patients with excessively pronated feet have relatively poor standing posture with increased lumbar lordosis. Those patients will also demonstrate increased internal femoral rotation during early stance phase and a lack of external femoral rotation during late stance phase. Dr. Kirby says these compensations put increased strain on the lower back of these patients during gait.

Using a well-designed custom foot orthosis with a medial heel skive, slightly inverted balancing position and well-formed medial longitudinal arch to decrease the pronated position of the foot can relieve some of the patient’s low back pain, according to Dr. Kirby. In addition, he says adding a reverse Morton’s extension to the orthosis to improve foot mechanics during propulsion can also relieve pain.

Emphasizing the importance of the patient assessment, Dr. Trachtenberg advocates a good history and physical, a thorough clinical examination, a biomechanical exam, angle and base biomechanical X-rays, leg length determination, and an appropriate 3D impression of each foot. In his estimation, Dr. Trachtenberg says utilizing slow motion video analysis and in-shoe pressure mapping analysis (such as F-Scan (Tekscan)) is particularly important to ensuring accurate data to interpret to assist in deciding on orthotic corrections.

When the feet move correctly in the sagittal plane and one addresses leg length discrepancy, Dr. Trachtenberg has found that the clinical results with low back pain and dysfunction can be “remarkably good.”

Dr. D’Amico says the prescription of foot orthoses for individuals with low back pain should incorporate rearfoot and, most importantly, forefoot posting in order to prevent midtarsal pronation and excessive calcaneal eversion as the body passes over the supporting foot. He suggests extending the forefoot posting to the sulcus for all sport and fitness activities due to the predominant “on forefoot” position during those activities.

Depending on the range of subtalar and lower extremity motion as well as the presence of equinus influences, Dr. D’Amico says the non-deforming orthotic shell material should possess some degree of flexural “forgiveness.” He says this will allow artificial improvement of limited ranges of motion without sacrificing alignment or control. In addition, Dr. D’Amico says this material will also permit equinus influences to exert a sagittal plane thrust on the device at approximately 50 percent of the midstance phase of gait without producing symptomatology requiring device discontinuation.

Heel raises are useful in restoring functional sagittal plane freedom of motion in appropriate patients, according to Dr. D’Amico. However, Dr. D’Amico cautions that if heel raises are excessive, this will produce a counterproductive effect. He notes elevating the heel beyond what is physiologically appropriate produces knee flexion with secondary hip and pelvic flexion along with a concomitant increase in the lumbosacral angle, similar to what occurs in women who wear higher heel footwear.

Dr. D’Amico suggests one may employ soft tissue supplements either as top or bottom covers in select individuals with severely restricted ranges of motion or low back symptomatology due to an inability to absorb shock at heel contact. However, he cautions that too much supplementation diminishes orthotic control and alignment. Typically, Dr. D’Amico notes a 1/16-inch to a maximum 1/8-inch top or bottom soft tissue supplement is all that is necessary.

Dr. D’Amico is a Professor and Past Chairman in the Division of Orthopedics at the New York College of Podiatric Medicine. He is a Diplomate of the American Board of Podiatric Medicine, and a Fellow of the American Academy of Foot and Ankle Pediatrics. Dr. D’Amico is in private practice in New York City.

Dr. Kirby is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. He is in private practice in Sacramento, Calif.

Dr. Trachtenberg is in private practice in Vestal, N.Y. He specializes in video and computerized gait analysis to evaluate the postural effects of abnormal walking that can lead to disorders affecting the knees, hips, back and other related musculoskeletal dysfunctions. Dr. Trachtenberg is a Fellow of the American College of Foot and Ankle Surgeons, and a Diplomate of the American Board of Podiatric Surgery.

References
1. D’Amico JC. The postural complex. J Am Podiatry Assoc. 1976; 66(8):568-574.
2. Nicholas JA, Marino M. The relationship of injuries of the leg, foot and ankle to proximal thigh strength in athletes. Foot Ankle. 1987; 7(4):218-228.
3. Dananberg HJ, Guilano M. Low back pain and its response to custom foot orthoses. J Am Podiatr Med Assoc. 1999; 89(3):109-117.
4. D’Amico JC. Keys to recognizing and treating limb length discrepancy. Podiatry Today. 2014; 27(5):66-75.

For further reading, see “When Lower Extremity Dysfunction Contributes To Back Pain” in the December 2012 issue of Podiatry Today.