Determining The Best Orthotic Fit For Patients
- Volume 24 - Issue 12 - December 2011
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Dr. Kirby uses the same negative casting method for making custom foot orthoses that he learned from his biomechanics professors at the California College of Podiatric Medicine both as a student and as a biomechanical fellow. This entails the supine neutral position suspension casting technique with plaster splints. As he elaborates, his casting technique involves loading the lateral column at the fourth and fifth digital sulcus in a dorsiflexion direction while placing the subtalar joint in the neutral position.
Over the last 27 years, Dr. Kirby has used numerous modifications of this classic casting technique depending on the patient’s specific pathology, foot structure and his or her predominant weightbearing activity. His common modifications include plantarflexing the medial column to increase arch height, dorsiflexing the medial column to decrease arch height and/or casting with the subtalar joint pronated from neutral.
What are your criteria for choosing the type of material for orthotic fabrication?
The two main types of orthosis shell materials that Dr. Kirby uses for custom foot orthoses are polypropylene and high-density polyethylene foam such as Plastazote #3. In 27 years of fabricating more than 15,000 pairs of orthoses for his patients, he has found polypropylene to be “by far the most durable and fatigue/breakage resistant orthosis material available.” His patients will routinely return to his office with polypropylene orthoses that are over 10 to 15 years old and show little sign of wear or flattening.
Dr. Kirby says one can use Plastazote #3 orthoses to treat distance runners who weigh less than 180 lbs., as well as pediatric and adult soccer players. As he notes, other uses for Plastazote #3 include treating chronic plantar heel pain for patients who walk and stand on hard surfaces all day. Patients should replace Plastazote #3 orthoses every four to five years due to the gradual compression set that occurs with this lightweight orthosis material, according to Dr. Kirby.
Dr. Levine bases his material selection on the type of shoes the patient wears, the foot structure, the range of motion and the goal of treatment. There are some patients who might do well with a semi-rigid material for everyday use but if these patients run, he suggests a softer, more supportive device might be necessary.
Likewise, Dr. Romansky bases the orthotic material on the patient needs and using common sense, noting that one would not put a 400-lb. patient in graphite because the device would break. He also factors in if he will heat or mold the material. For example, Dr. Romansky says graphite can only stand so much heat before it breaks.
Furthermore, Dr. Romansky suggests using multiple labs as not all labs are created equally. As he notes, not every lab offers the same material, some labs are more specialized than others and some labs cost more.
“Podiatrists need to hybridize or customize because they have a lot of options now,” says Dr. Romansky.
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. Levine is a Fellow of the American Academy of Podiatric Sports Medicine. He is in private practice and is the director and owner of the Frederick, Md.-based Walkright and Physician’s Footwear, a fully accredited pedorthic facility.
Dr. Romansky is a Fellow of the American College of Foot and Ankle Surgeons. He is in private practice at Healthmark Foot and Ankle Associates in Media and Phoenixville, Pa.