Keys To Prescribing Orthoses For Limb Asymmetry And Heel Pain

Author(s): 
Guest Clinical Editor: Joseph D'Amico, DPM

Given the common presentation of limb asymmetry, these panelists describe how leg length discrepancy affects orthotic prescription. They also offer insights on effective orthotic management of patients with heel pain.

Q:

In what percentage of patients do you find differences in lower extremity structure or function, and how does this asymmetry affect your orthotic prescription?

A:

All four panelists have found that most patients have asymmetry in terms of lower extremity structure or function.

   “Virtually all patients I examine have some degree of structural or functional asymmetry,” says Joseph D’Amico, DPM. “In any given year, one would be hard-pressed to find an orthotic prescription that is the same from one foot to another.” However, Dr. D’Amico cautions that not every one of those patients has a limb discrepancy.

   As Justin Wernick, DPM, notes, most patients have a limb length discrepancy. He notes the design of the shell of the device along with the modifications will vary from one foot to the other depending on what one is looking to accomplish. Furthermore, there are circumstances in which only one device is necessary for one foot and the other foot needs a simple shoe modification, according to Dr. Wernick.

   Ronald Valmassy, DPM, always advises his patients that their limbs are typically asymmetrical from one side to the other, generally leading him to prescribe orthotic devices in an asymmetrical fashion.

   “There clearly are instances (in which) a patient may have a forefoot varus deformity on one foot and a forefoot valgus deformity on the other,” he notes.

   In evaluating a limb asymmetry, Stanley Beekman, DPM, first starts with a biomechanical examination, which he has reduced to a few important measurements in adults. He measures dorsiflexion and the anterior superior iliac spine and the posterior superior iliac spine to the ground in neutral and relaxed calcaneal stance positions. From this evaluation, Dr. Beekman can determine if he should treat the asymmetry via heel lifts, orthoses or refer the patient to an osteopathic physician or a chiropractor.

   Some patients will have issues such as a dysfunctional posterior tibial tendon or a tarsal coalition, which may lead to a very obvious asymmetry in foot type and function, according to Dr. Valmassy. However, he feels that even in the more routine cases that present on a day-to-day basis, asymmetry exists quite commonly. For that reason, Dr. Valmassy advises podiatrists to consider orthotic devices as completely independent prescriptions from the right to the left side.

Q:

If an elevation of one extremity is required, how would this affect your orthotic prescription?

A:

For patients with limb length discrepancy, Dr. Wernick uses a heel lift in the shoe first to see if he has the right correction. He generally does not like to put a lift of more than 1/4 inch on an orthotic device itself as higher elevations create shoe fit problems. When adding elevations to the orthoses, Dr. Wernick says it is important to modify the addition by lowering the distal edge so the orthosis does not rock in the shoe.

   In his early years, Dr. D’Amico would ascertain and equalize limb length discrepancies based on clinical and radiographic measurements, and sacral leveling. Today, he relies on dynamic assessment of the phases of gait as well as weight distribution and pressure patterns that he obtains through computer assisted gait analysis. Dr. D’Amico performs this testing two weeks after orthotic dispensing.

   If a lift is required, he usually places it in the shoe under the orthotic. Dr. D’Amico has found that adding a lift to the orthotic itself will cause an increase in lateral rearfoot post wear due to the elevated calcaneal position. As time goes on, this creates an avalanche effect in which the rearfoot becomes laterally unstable. He says it is better to place the device on a platform that is elevated rather than pitch and elevate the device itself. This method also permits easier adjustments in the future, according to Dr. D’Amico.

   “Keep in mind that lifts are not forever and must be periodically re-evaluated to determine their appropriateness,” advises Dr. D’Amico.

Q:

Richard O. Schuster, DPM, once said that when treating biomechanically induced heel pain, the heel seat of the orthotic can never be too deep. In the management of proximal plantar fasciitis and related plantar heel pain, what modifications do you find particularly effective?

A:

In regard to plantar fasciitis and heel cup issues, Dr. Valmassy feels that a deep heel cup clearly is beneficial in treating most foot anomalies, specifically plantar fasciitis. He will be extremely cautious when having the laboratory invert the orthotic device. Dr. Valmassy also may utilize a medial calcaneal skive because, in some instances, the steepness of the skive along with the significant inversion of the rearfoot will actually place some increased pressure at the level of the medial tubercle. This may make it more difficult for the patient to adapt to the orthotic device, according to Dr. Valmassy.

   In cases in which there may be an associated infracalcaneal bursitis, he says a sweet spot or aperture pad with a soft material such as Poron embedded into the orthotic at that level will allow the patient to have a more comfortable heel strike.

   Dr. Beekman will first have the orthoses correct the two external pronatory factors, equinus and asymmetry, with appropriate heel lifts. Then when it comes to medial heel pain, he drops the first metatarsal for functional hallux limitus, narrows the lateral rearfoot post to decrease pronatory torque at heel contact and increases the rearfoot post. If this is not effective, Dr. Beekman will add an extra post to the forefoot and grind under the first metatarsal so there is a small amount of material left (approximately 1/8 inches).

   For central heel pain, Dr. Beekman adds a “U” pad under the calcaneus, subsequently grinds the area directly under the calcaneus and replaces or fills it in with something softer. Then he reinforces the area under the medial and lateral arch. For pain at the plantar posterior heel, Dr. Beekman will lift the posterior portion of the calcaneus and look for trigger points in the leg. Rarely will he find it necessary to make an adjustment for an enlarged medial or lateral condyle of the calcaneus.

   Dr. Wernick emphasizes the importance of differentiating between contact phase heel pain and propulsive phase heel pain. He says patients with contact phase heel plane would do well with a deep heel seat, cushioning materials and beveling the heel of the shoe.

   Patients with propulsive phase heel pain are another story, notes Dr. Wernick. They are being injured when the heel lifts off the ground. He says this is typical of a patient with plantar fasciitis. Since most orthotics do not function after heel lift, Dr. Wernick says it is important to establish control of the foot prior to adding a heel lift. Dr. Wernick adds that the use of a functional orthosis that controls subtalar and midtarsal movement is essential along with modifications that induce plantarflexion of the first ray while increasing dorsiflexion of the hallux. He feels the kinetic wedge design is very helpful for this type of problem. Dr. Wernick also advises physicians to be aggressive in these cases by using several modifications and other modalities such as stretching.

   In regard to the rear portion of the orthotic device, Dr. Valmassy notes a softer rearfoot post material will enhance shock absorption. For proximal plantar fasciitis and related plantar heel pain, he would consider a rearfoot post with 4 degrees of motion to allow an additional amount of movement or motion at the moment of heel contact.

   Dr. D’Amico notes that the majority of biomechanically induced heel pain is precipitated, perpetuated or aggravated by propulsive phase hypermobility with secondary over-stretching of the medial and middle slips of the plantar fascia. Therefore, he calls it imperative not only to control rearfoot alignment and function, but to control the forefoot as well. Dr. D’Amico says this may involve extending forefoot posting to the sulcus to maximize “on forefoot” control. In speedy walkers or during sports participation, he notes appropriate forefoot posting is critical for success in the management of biomechanically induced heel pain.

   Dr. Beekman is a Diplomate of the American Board of Podiatric Surgery. He is also a Fellow of the American Academy of Podiatric Sports Medicine.

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

   Dr. Valmassy is a Past Professor and Past Chairman of the Department of Podiatric Biomechanics at the California College of Podiatric Medicine. He is a staff podiatrist at the Center for Sports Medicine at St. Francis Memorial Hospital in San Francisco.

   Dr. Wernick is a Professor in the Department of Orthopedic Sciences at the New York College Of Podiatric Medicine. He is also a Diplomate of the American Board of Podiatric Orthopedics and the Medical Director of Eneslow Comfort Shoes and Langer, Inc.

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