Current Insights On The Use Of Orthotics For Limb Length Discrepancy And Morton’s Syndrome

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Identifying Structural Deficiencies In Pathomechanical Foot And Limb Function That May Contribute To Knee Disorders

Q: What is the role of pathomechanical foot and limb function in knee disorders and how can identification of inherent structural deficiencies prevent these repetitive stress problems from producing degenerative changes later in life?

A: Dr. D’Amico and Dr. Skliar concur that the increased demands of high school sports on young adolescents have resulted in an epidemic of knee injuries.

Dr. Skliar notes several such injuries in decreasing order of frequency: patella and medial knee pain, Achilles tendonitis and calf pain, shin splints and groin pain. Athletes who display greater than 6 degrees of total frontal plane varus compensations make up the largest group of those who seek professional care, points out Dr. Skliar. He says anyone with 10 degrees or higher of total varus should receive biomechanical treatment even if they are asymptomatic.

“Improper athletic shoes for the various sport activities and for different foot types can significantly aggravate or cause excessive stresses to the limbs,” notes Dr. Skliar.

Dr. Skliar suggests providing professional information concerning proper footgear for the individuals involved in a specific sport. He also says there needs to be better recognition of how the foot structure of each athlete can influence how well suited the athlete may be to a specific sport activity. As Dr. Skliar explains, feet with normally low arch structures are usually more stable due to the larger weightbearing surface they present. Those who possess a normally high arch foot are less stable in static conditions but he notes they have a mechanical advantage for speed and jumping activities. Accordingly, Dr. Skliar says a lineman of a football team would fare better with a normal low arch foot while the running back would do better with a high arch foot type.

As Dr. D’Amico says, triplanar compensation associated with any condition producing excessive pronation is not matched to the primarily sagittal plane motion at the knee joint. As a result, he notes the frontal and transverse plane demands are taking place while the foot is planted against an unyielding surface, and the superstructure is moving forward over the supporting extremity. Among other things, he says this increases medial collateral ligament stress and strain as well as the Q angle.

Schuster postulated a mechanism between pedal pronation and the production of knee pain, and recommended treating the underlying pathology via foot orthoses, according to Dr. D’Amico.1 In that article, the author goes on to say, “it is noteworthy that almost every runner we have had the opportunity to treat on a mechanical basis has had a moderate to severe forefoot varus.” Over 20 years later, Dr. D’Amico says Saxena and Haddad went on to confirm this statement in a study of 102 patients with patellofemoral pain syndrome in which they found 91 percent of patients to have had forefoot varus.2

Dr. D’Amico says the research has highly correlated malalignment of the patellofemoral mechanism with excessive pronation.3-5 He adds that an increase in the Q angle has direct correlation of knee pathology especially of mechanical origins.6

“The role of the podiatrist is to identify and neutralize structural deficiencies present in the foot, especially forefoot varus, thereby preventing dysfunction and at the same time reducing the risk of injury,” says Dr. D’Amico.

The “missing link” in all sports at any level is structural evaluation prior to training an athlete, contends Dr. Pack, who treats athletes who have $125 million contracts but have never been evaluated. As he notes, pathomechanical foot and limb function are a major cause of not just knee injuries but many other injuries. For example, Dr. Pack says for an ankle sprain, physicians readily accept the fact that a hard hit in football may be the cause but if the injured individual gets a proper evaluation, a rearfoot varus deformity, equinus of the first metatarsal or other abnormality may often be the underlying etiology.

Dr. Pack says children should have a basic structural screening by a podiatrist. “Doing so would not only greatly decrease injuries but increase sports performance and later decrease arthritic changes,” notes Dr. Pack.

References

1. Schuster RO. Podiatry and the foot of the athlete. J Am Podiatr Assoc. 1972; 62(12):465-8.
2. Saxena A, Haddad J. The effect of foot orthoses on patellofemoral pain syndrome. J Am Podiatr Med Assoc. 2003; 93(4):263-71.
3. James SL, Bates BT, Osternig LR. Injuries to runners. Am J Sports Med. 1978; 6(2):40-50.
4. Jernick S, Heiflitz NM. An investigation into the relationship of foot pronation to patellofemoral pain syndrome. In Rinaldi RR, Sabia ML (eds.) Sports Medicine ‘79. Futura Publishing Company, Mt. Kisco, New York, 1979, pp. 1-31.
5. Eng JJ, Pierrynowki MR. The treatment of patellofemoral pain syndrome. Phys Ther. 1993; 73(2):62-68.
6. Emami MJ, Glaahramani MH, Abdinejad F, Namazi H. The Q angle: an invaluable parameter for the evaluation of anterior knee pain. Arch Iran Med. 2007; 10(1):24-26.

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Author(s): 
Guest Clinical Editor: Joseph C. D’Amico, DPM, DABPO

   Before rendering definitive therapy, Dr. Pack routinely sends limb length discrepancy patients for further consultation including a visit to a physical therapist, chiropractor or kinesiotherapist. He says these clinicians may diagnose things that he would never have considered as possible etiologies for the discrepancy, like tightened muscles in the shoulder region.

   In some cases, it is obvious that correcting a leg length discrepancy has eliminated symptoms. In other cases, Dr. Pack thinks such correction can be preventative.

   Dr. Pack believes any degree of abnormality decreases sports performance, increases the risks of injury and can later cause arthritic changes, adding that optimizing leg length equalization is far more important than physicians often realize. Although he has seen many patients with large differences who appear to be symptom-free, others with small degrees of abnormality have significant symptoms. Ideally, all leg lengths should be as equal as possible, according to Dr. Pack.

Q:

If a discrepancy is significant, how do you address it and what orthotic modifications do you employ?

A:

All panelists emphasize the use of heel lifts. For a significant discrepancy, Dr. Skliar will determine the need for an additional heel lift, with or without an orthotic. He says one should recognize that a heel elevation greater than 1/2 inch cannot usually occur within the shoe itself and adding an elevation to the outside heel would be necessary. If there is excessive pronation on the longer side, he suggests using a corrective pair of orthotics with the heel lift incorporated on the short limb side.

   If a structural deformity is present and/or if one has treated functional leg length abnormalities but the treatment has not maintained corrections, Dr. Pack advises placing small, incremental lifts under the insoles or custom orthotics on the shortened side. He prefers to have the lifts extend at least from the heel to the ball of the foot unless fit is an issue, in which case he will use a heel lift. Dr. Pack says one should use additional corrections until the patient feels overcorrected or that the symptoms are exacerbated. While he incorporated lift corrections into the devices themselves in the past, Dr. Pack no longer does so because functional abnormalities can cause leg lengths to change at any time.

   If a discrepancy is significant, Dr. D’Amico employs the necessary amount of heel elevation to produce functional symmetry as documented on computer assisted gait analysis. Elevations of over 1/2 inch require a tapering to ¼ inch at the metatarsal region and then 1/8 inch distally, according to Dr. D’Amico. If a ½-inch lift cannot remediate a discrepancy, then he would refer the patient for physical therapy evaluation and probable sacroiliac mobilization. The patient would then return to Dr. D’Amico for reassessment of the situation.

Q:

What is your view of the incidence and significance of Morton’s syndrome, especially the short first metatarsal phase, in the production, perpetuation or aggravation of mechanically induced foot disorders? How can one conservatively manage this?

A:

In one of his first published articles, Schuster performed a survey analysis of the incidence of Morton’s syndrome (as evidenced by a short first metatarsal) in a non-patient control group in contrast with a 1,000 patient population, notes Dr. D’Amico.1 In the adult control group, 33 percent had a short first metatarsal in comparison to 79 percent in the adult patient population group. Dr. D’Amico adds that Schuster concluded that the short first metatarsal phase of the Morton theory is “definitely one of the contributing factors in many orthopedic foot disorders.”

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