Exploring The Role Of Orthoses For Flatfoot Conditions And Equinus

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

Q:

What is your approach and what has been your success with the conservative management of peroneal spastic flatfoot secondary to tarsal coalition?

A:

Noting that peroneal spastic flatfoot/tarsal coalition can be very difficult to treat with orthoses, Russell Volpe, DPM, may use a peroneal block to break the spasm and then fabricate a neutral cast. After fabricating the orthoses around this neutral cast, he says the child may have difficulty tolerating it if the foot goes back into peroneal spasm. In such cases, he makes his orthosis from a pronated cast, which patients can likely tolerate better.

   In this scenario, Dr. Volpe tries to limit what little motion there is in that type of foot. Doing so will often lead to a reduction in symptoms associated with even slight movement of the subtalar joint, according to Dr. Volpe.

   Similarly, with the initial presentation, Ronald Valmassy, DPM, will attempt to break the spasm with a sinus tarsi injection of a local anesthetic. Then he will often place the patient into a cast to again break the peroneal spasm. At that point, he proceeds with the use of a functional foot orthosis, which often will be a maximally pronated device with a deep heel cup and flat rearfoot post.

   After a period of time, Dr. Valmassy may attempt to control the foot in a standard fashion, addressing either the forefoot varus or forefoot valgus deformity rather than using a pronated cast. However, he finds that the results are extremely variable and these patients often seem to progress more comfortably with surgical excision of the coalition. He finds that a calcaneal navicular coalition typically responds best to surgical excision followed by the use of functional foot orthoses.

    “Tolerating the device, or more specifically the control from the device, is always a challenge with peroneal spastic flatfoot and tarsal coalition,” says Dr. Volpe. “In some cases, these patients just cannot tolerate orthoses and a surgical solution will have to be considered sooner rather than later.”

   After deciding to proceed with the use of prescription foot orthoses, Joseph D’Amico, DPM, suggests taking a neutral to supinated plaster impression of the foot. As the foot and ankle improve, he says one should take additional impressions that reflect current changes in range of motion, alignment and function. When treating patients for whom it is not initially possible to position the foot in neutral, Dr. D’Amico notes his assistant will stabilize the leg while he forcibly supinates the foot into an improved position.

   Dr. D’Amico says the orthotic shell material has to be sufficiently rigid in order to hold the foot and ankle in the desired position, and resist further contractural forces but patients must also be able to tolerate the device. He uses materials including graphite composites, Rigidur, subortholene and high density polyethylene. His shell modifications include a markedly deepened heel seat, medial and lateral flanges, reduced undercuts, aggressive posting, heel elevations and a Kirby skive. In severe cases, Dr. D’Amico also uses the Blake cast modification. The resultant device should resemble what he calls a “functional” UCBL.

   As Dr. D’Amico notes, the presence of equinus influences the secondary, adaptive contracture of the Achilles tendon due to the prolonged, maximally everted position of the calcaneus, which one must identify and address. He says this may involve a night splint to prevent further plantarflexion contracture or serial plaster or fiberglass walking casts to realign the foot and ankle not only in the sagittal plane, but in the transverse and frontal planes as well. For less severe contractures, one may use conventional stretching of the Achilles tendon.

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