A Closer Look At Orthotics For Pediatric Conditions
- Volume 18 - Issue 4 - April 2005
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For a severely pronated pediatric flatfoot, Dr. Valmassy usually utilizes a Root type of functional foot orthosis that is inverted approximately 10 degrees. He normally uses a 6 mm Kirby or medial heel skive, a 20 mm to 22 mm heel cup and a flat rearfoot post. Dr. Valmassy often uses a medial flange and may incorporate an accommodation at the level of any existing navicular prominence.
In addition, Dr. Valmassy uses a Blake inverted type of functional foot orthosis. With this device, he typically prescribes a 55 degree inverted orthotic with a 6 mm Kirby or medial heel skive, a deep heel cup, a flat post and a medial flange.
When treating both pediatric flatfoot and a severely pronated flatfoot, Dr. Valmassy says the inverting force is essential to correct the child’s foot. He emphasizes that one must explore all factors leading to the pediatric flatfoot, paying specific attention to tight posterior musculature. Dr. Valmassy encourages clinicians to constantly monitor the child’s response to the orthotic. If the device is ineffective in arresting abnormal foot function or symptomatology, Dr. Valmassy says one may need to consider surgical intervention.
Physicians frequently ask Dr. Kashanian how much to skive and/or invert the pediatric flexible flatfoot. As she explains, the pediatric flexible flatfoot demonstrates a calcaneal resting position of 2 to 10 degrees of eversion and the forefoot is abducted to the rearfoot during gait.
“The appropriate prescription for this foot type is a polypropylene device with a deep heel cup and an extra wide arch,” says Dr. Kashanian. “Both of the above dimensions allow more surface area for the orthotic to exert on the hypermobile flatfoot.”
She highly recommends using a minimal plaster cast arch fill, which allows maximum control on the medial column and prevents the midtarsal joint from unlocking and pronating. One would utilize the medial heel skive and inversion of the positive cast together to control the everted calcaneus and pronated subtalar joint, according to Dr. Kashanian. As far as the amount of medial heel skive and positive cast inversion to use, see “Key Orthotic Considerations For Pediatric Flatfoot” above.
When it comes to young children, whether they are infants, adolescents or young teenagers, Dr. Jay feels one should maintain inserts in an approximately 5-degree rearfoot varus posting alone without forefoot posting. He says the talus will go through a valgus ontogeny or, in other words, will rotate inward and down to bring the first ray down in more of a plantarflexed position and eliminate any forefoot varus.
“Placing forefoot varus posts will create an abutment or a brace to prevent the downward ontogeny of the talus and a rigid forefoot varus may result,” says Dr. Jay.
When treating these children, Dr. Jay typically prescribes an inverted heel seat as seen on the Langer Dynamic Innersole System. He also may use a deep-seated heel orthotic with a rearfoot varus post of 5 degrees.
Dr. Volpe advises taking a quality impression in subtalar neutral with a rectus forefoot and dorsiflexion of the hallux to increase the arch. One should limit plaster additions to the positive cast as they tend to reduce arch height. He also suggests using non-compressible shells and incorporating deeper heel seats and flanges when appropriate.
To improve weight transfer through the foot consistent with the tissue stress model, Dr. Volpe recommends adding plaster positive modifications such as medial skives, slight inversion of the cast and calcaneal pitch.
Inverting the cast to treat more severe deformities with higher calcaneal eversions can be effective in increasing arch height and improving weight transfer in the more severely pronated foot, according to Dr. Volpe.
Dr. Feit is a Fellow of the American College of Foot and Ankle Surgeons, and practices privately in San Pedro and Torrance, Calif. He is the Past President of the Los Angeles chapter of the American Diabetes Association.