Exploring The Role Of Orthoses For Flatfoot Conditions And Equinus

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.

   Dr. D’Amico also routinely prescribes peroneal stretching exercises including walking on the lateral border of the affected foot and forcibly attempting to invert the foot while standing. He notes both exercises are more effective if patients perform them in shoes since the sole acts as a lever arm and increases supinatory motion. In the individual with a painful, non-defeatable “spasm,” Dr. D’Amico says a series of intra-articular subtalar joint steroid injections is helpful in restoring motion and reducing pain. He advises accompanying these injections with strapping prior to orthotic dispensing.

   After identifying and categorizing the coalition through a computed tomography (CT) scan, Paul Jordan, DPM, suggests looking for the “trigger” mechanism that initiates the inflammatory response and pain. Dr. Jordan subsequently applies a below knee fiberglass walking cast with the foot in neutral. This often leaves the foot in equinus at the ankle but one can accommodate this with heel lifts, according to Dr. Jordan. He has patients wear the cast for four to six weeks with no activity restrictions. Dr. Jordan says one should change the cast in one to two weeks to further reduce ankle equinus.

   When casting is completed for the equinus, Dr. Jordan fabricates functional custom orthoses. For the long term, he advises continued stretching and orthosis modifications for skeletal growth. In the past 25 years, he notes that less than 1 percent of his patients with peroneal spastic flatfoot have required surgery.

Q:

When do you treat the asymptomatic pediatric flatfoot?

A:

“There is a serious misconception on the part of the public and among a great number of health professionals to equate the problem of ‘flatfoot’ with excessively pronated feet in children,” says Dr. D’Amico. “This is a matter of grave concern since flatness of the arch can be a normal or abnormal finding in foot posture whereas the excessively pronated foot is flattened as a part of a structural malposition.”

   Dr. D’Amico also notes that excessively pronated feet may not immediately produce pedal symptomatology but the associated pathomechanics may aggravate the child’s superstructural pathology. At any age, excessive pronation is abnormal, according to Dr. D’Amico, and if one can visualize the excessive pronation, it is excessive.

   To identify the excessively pronated flexible pediatric flatfoot, Dr. D’Amico suggests checking for medial talar bulge, lateral concavity, medial convexity, marked calcaneal eversion, the “too many toes” sign, an intact windlass mechanism, medial displacement of the center of force and center of gravity, and associated radiographic changes. After identifying an excessively pronated foot, he stresses the importance of ascertaining the underlying etiology for better conservative management of its accompanying pathomechanics.

   Dr. D’Amico says this inherent biomechanical defect of flatfoot is present in “a great majority of children” and is the cause of most lower extremity postural pathology. He cautions that one should not consider excessive pronation of the feet to be a normal finding that children will automatically outgrow.

    “Absence of symptomatology in the pediatric foot is an unreliable indicator of foot function,” according to Dr. D’Amico. “The fact that a child does not complain about his or her feet does not mean they are functioning optimally.”

   Dr. Jordan concurs. Therefore, he suggests asking youngsters about pain in areas like the lower back, hips, knees and ankles. He notes the child’s problem may express itself in compensation as excessive pronation with the pronatory motion being normal compensation for developmental, structural or neuromotor aberration. Dr. Jordan advises managing the degree of compensation permitted in order to treat the primary conditions more effectively.

    “With early and continued orthosis modifications in concert with the child’s growth and maturation, long-term functional disabilities and pain appear not to be inevitable as an adult,” says Dr. Jordan.

   If Dr. Volpe determines that the asymptomatic pediatric flatfoot is “abnormal” for a child of a certain age, he treats the condition. Although he notes a number of ways to define “abnormal” in this context, Dr. Volpe considers the degree of compensation on weightbearing, family history, structural comorbidities leading to pedal compensation and the limitation or modification of activity.

    “I feel very strongly that to wait for a pediatric flatfoot that is abnormal to develop symptoms before treating it is missing a golden opportunity to place a child’s foot in a neutral position, improve function and reduce the likelihood of the child developing symptoms,” says Dr. Volpe. “There is absolutely a preventative medicine aspect to this.”

   Dr. Valmassy often sees asymptomatic pediatric flatfoot via frequent referrals from pediatricians. His initial evaluation includes determining the extent of the pathology from a biomechanical perspective. He has developed a formula wherein if the child initially stands in an everted position of 7 to 8 degrees, then by the age of 7 to 8, the heel will hopefully develop into a perpendicular attitude. Utilizing these numbers, Dr. Valmassy says the child loses approximately 1 degree of calcaneal eversion per year up to age 7 or 8.

   Therefore, if Dr. Valmassy sees a 5-year-old child with a flatfoot and the foot is 5 to 10 degrees everted, he considers the child’s foot to be markedly abnormal. In this case, Dr. Valmassy says the child will most likely not outgrow the condition or develop a normal foot over the next two to three years. For such a child, he will employ a functional foot orthosis to attempt to protect the developing foot and the more proximal structures. For children up to age 3 or 4, he will typically utilize a Kiddythotic (ProLab) and cites very good results with the device.

   Often Dr. Valmassy will add additional forefoot and rearfoot posting to the prefabricated device and customize it for the child. When children develop a heel-toe propulsive gait, he switches to a more standard type of Root or Blake type of functional foot orthoses and typically utilizes a deep heel cup from 18 to 20 mm as well as a flat rearfoot post.

Q:

What are the caveats and what modifications do you employ in prescribing orthoses for the patient with lower extremity equinus?

A:

It is essential for Dr. Valmassy to determine whether the equinus is congenital or if it is secondary to a pronated foot. He says congenital equinus is often compensated by excessive subtalar and midtarsal joint pronation to allow independent forefoot dorsiflexion on the rearfoot. Pronation-related equinus occurs when the foot is pronated from some other cause, which results in a secondary contraction of the posterior muscle group due to the excessive flexibility of the forefoot to rearfoot, according to Dr. Valmassy.

   If the patient has a true congenital equinus, Dr. Valmassy says you need to determine whether you want to achieve some degree of symptomatic relief for the patient prior to initiating surgery or if you want the patient to use an orthotic in lieu of surgery. Most often, he says patients will better tolerate the pronated device. Dr. Valmassy adds that patients often cannot tolerate a neutral device as it causes discomfort and patients can break the orthotic as the pronatory force is much stronger than the orthotic device.

   Dr. Valmassy emphasizes that if one can control a pronated foot in a patient with a congenital equinus, the individual will develop compensation at another level. Therefore, he suggests assessing the patient for potential genu recurvatum at every visit when there is a suspected congenital equinus. If genu recurvatum develops in a patient with equinus during the course of treatment with a functional foot orthosis, Dr. Valmassy advises clinicians to immediately stop the orthotic treatment and consider surgical intervention.

   Dr. Volpe notes that if one does not recognize the equinus influence in the clinical exam and incorporate management of the equinus into the treatment plan, there will be a higher complication rate with orthoses. If the tension remains on the heel cord and there is semi-rigid control under the midtarsal joint, he notes a great likelihood that the patient will pronate into the shell at this joint, which will cause discomfort.

   Dr. Jordan emphasizes the importance of assessing full lower extremity equinus contractures, not just the ankle joint. When there is significant equinus, he says one cannot adequately address excessive midtarsal joint pronation without first correcting the equinus.

   All panelists note the importance of heel lifts. Dr. Volpe will combine heel raises on orthoses to reduce the need for midfoot compensation. If the total equinus is mild to moderate, Dr. Jordan says it is feasible to use heel lifts as temporary accommodation and one should plan on reducing the heel lift height as the child’s equinus influence reduces. Similarly, for patients with a significant equinus in whom surgery is not an appropriate choice, Dr. Valmassy often utilizes a ¼-inch heel lift beneath the orthotic. He says this allows the patient to better tolerate the correction and to put some slack in the posterior muscle group. Both Drs. Volpe and Jordan suggest stretching exercises.

   If one wishes to reduce midtarsal joint compensation, Dr. Jordan suggests using orthoses with a good plantar-lateral inclination angle as well as a sneaker or shoe with a heel for enhanced orthosis control.

    “If the equinus cannot be corrected or accommodated, attempted management of the foot with orthoses will result in pain or unwanted compensation elsewhere,” Dr. Jordan cautions.

   Dr. D’Amico is a Professor and Past Chairman in 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, and a Fellow of the American Academy of Foot and Ankle Pediatrics. Dr. D’Amico is in private practice in New York City.

   Dr. Jordan is in private practice in East Northport, N.Y.

   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. Volpe is a Professor in the Department of Orthopedics and Pediatrics at the New York College of Podiatric Medicine in New York City. He is in private practice in New York City and Farmingdale, N.Y.