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

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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