Emerging Insights On Orthotic Prescriptions And Modifications

Our expert panelists discuss current approaches to orthotic management of pediatric flatfoot, whether functional orthoses can have an impact for hallux abducto valgus and when to employ orthotic modifications in rigid and semi-rigid devices.

Q:

Given some of the most recent literature concerning pediatric flatfoot, what is your opinion about using prefabricated or custom orthoses for patients under the age of 10?

A:

As Cherri Choate, DPM, notes, there is ongoing controversy over the approach to flatfoot in this patient population. As the incidence of pediatric obesity rises, she says studies are exploring the incidence of flat feet and other pediatric lower extremity problems in both overweight and obese children. Two different studies found that children with flatter feet have increased plantar pressure and poor performance in physical task completion.1,2

   Dr. Choate says the concern is that these early clinical findings may lead to more severe physical pathology as the children become adults. She notes a paucity of studies showing that orthotics, whether prefabricated or custom, have any negative effect on the growing foot.

   When treating the pre-adolescent patient, Alona Kashanian, DPM, always evaluates the pathology of the flatfoot deformity along with the symptomatic pathology and parental concern. She recommends a prefabricated orthosis for a patient with a calcaneal eversion of less than 5 degrees and mild abduction of the forefoot to rearfoot relationship during stance. If the parents relate infrequent falling, stumbling and fatigue, Dr. Kashanian considers a prefabricated orthosis. In addition, she “highly recommends” custom orthoses for pre-adolescent patients who have calcaneal eversion of 10 degrees or higher, and a moderate to severe forefoot to rearfoot abduction with soft tissue adaptation.

   Dr. Choate prescribes prefabricated orthotics with a deep heel cup and wide plate for children up to the age of 14 to 16 as long as their clinical findings are mild to moderate. Once the child stops growing, she would likely have a custom device fabricated. She says one may also employ custom orthotics when the child’s foot does not fit a prefabricated device, or if he or she is involved in a specific sport that has unique demands for shoe fit or performance.

   Daisy Sundstrom, DPM, uses Kiddythotics (ProLab Orthotics) for quite a few patients up to age 4. She says these devices have several advantages including rigidity and width, a deep heel cup and flat posting for better control. At age 4, when children begin to develop a heel to toe gait, Dr. Sundstrom will use the Kiddythotic or a custom device. She notes that both her daughters have pediatric flatfoot with excessive subtalar joint (STJ) pronation and both have benefited from using Kiddythotics, starting at the age of 2.

   For symptomatic children with a mild to moderate deformity, Dr. Sundstrom first tries using a Kiddythotic or prefabricated device. She checks the fit while the patient is non-weightbearing and then checks the amount of correction at the STJ, metatarsal joints and the medial longitudinal arch with patients standing. If prefab devices do not fit properly or do not obtain enough correction, Dr. Sundstrom prescribes a custom orthotic with more aggressive pronation control for a more severe deformity.

Q:

Do you use functional orthotic devices to treat the functional limitus component of hallux abducto valgus (HAV)? What change do you think the orthoses make to improve the symptoms?

A:

Jenny Sanders, DPM, does use functional foot devices in these patients. She cites a study by Roukis and colleagues, who proposed that reduction in the first metatarsophalangeal joint’s (MPJ) maximum degree of dorsiflexion with dorsiflexion of the first ray is the predominant cause of hallux abducto valgus and hallux rigidus.3 Additional studies have shown that functional orthotics increase first MPJ dorsiflexion by improving the position of the first ray in the sagittal plane.4 Dr. Sanders notes the authors of another study also suggest that in functional hallux limitus (FHL) caused by an abnormal dorsiflexed first ray, one can gradually restore hallux dorsiflexion by using foot orthoses to control the abnormal rearfoot position, which improves the first ray position.5

   Dr. Kashanian feels one can easily treat the functional hallux limitus deformity associated with a hallux abducto valgus with both intrinsic and extrinsic orthotic modifications. For an intrinsic cast modification for the pes plano valgus foot type, Dr. Kashanian uses a minimal cast fill along with a 2 mm Kirby skive and 2 degree inversion technique, which offloads the medial column and prevents excessive pronation.

   Likewise, Dr. Choate uses a reverse Morton’s extension in nearly all patients with functional hallux limitus. Since a dorsiflexed first ray is the primary issue behind functional hallux limitus, she notes a forefoot valgus wedge has been shown to provide the ultimate means of reducing tension in the plantar fascia and “unlocking” the forces leading to first ray dorsiflexion.6 In addition, Dr. Choate tries to recognize any forces, such as an everted calcaneus, that may lead to dorsiflexion of the first ray. She notes that she addresses control in the orthotic prescription with modifications such as medial skive and a deep heel cup.

   For an intrinsic cast modification for the pes cavus foot type, Dr. Kashanian will prescribe minimal cast fill and a deep heel cup, which offloads the forefoot and allows more stability to the midfoot. As far as an extrinsic modification for both foot types, she uses a reverse Morton’s extension to offload the first ray and thus prevent excess jamming of the first MPJ.

   Dr. Sundstrom notes functional foot orthoses bring the subtalar joint to neutral in order to lock the metatarsal joints and stabilize the medial column. As she says, most patients with HAV have some degree of mobility, if not hypermobility, in the first tarsometatarsal joint.

    “With the exception of excessive STJ pronation, this may be the greatest contributing factor to the development of the deformity in the first place,” notes Dr. Sundstrom.

   Due to this flexibility, Dr. Sundstrom notes an orthotic should be able to reposition and stabilize the medial column, and improve the position of the first ray.

Q:

Do you use functional accommodations such as sweet spots and plantar fascial grooves in your rigid or semi-rigid orthotic devices, and what are the indications?

A:

While intrinsic accommodations can be helpful, Dr. Choate rarely uses plantar fascial grooves. She has historically found the placement and depth of plantar fascial grooves challenging. Dr. Choate prefers to use a reverse Morton’s extension in an attempt to decrease tension in the plantar fascia.6

   In contrast, Dr. Sanders routinely uses plantar fascial grooves with both rigid and semi-rigid orthotics. As she notes, since pes cavus feet almost always have a tight plantar fascia, even without a diagnosis of plantar fasciitis, she will incorporate a plantar fascial groove into her orthotics. When it comes to patients who have plantar fasciitis with a tight plantar fascia, Dr. Sanders emphasizes that adding a plantar fascial groove is essential to ensuring a comfortable orthotic device due to the increased plantar fascial thickness.4 Dr. Sanders also uses intrinsic accommodations or depressions in the orthotic plate material to off-weight areas like a prominent navicular.

   Drs. Kashanian and Choate cite the usage of sweet spots. In Dr. Choate’s experience, successful sweet spots are usually deeper and wider than one would initially order on the prescription. Due to the movement of the foot throughout each step, she advises a more “generous” sweet spot to provide more room for errors in placement. Dr. Choate also recommends filling the sweet spot only partially with soft padding and letting the top cover enhance the cushioning for the area in question.

   Dr. Kashanian notes one often prescribes sweet spots to offload symptomatic bony and soft tissue prominence in the plantar aspect of the foot. She says one can treat a symptomatic tight plantar fascia or a painful plantar fibroma with a plantar fascial groove at the appropriate area. In addition, Dr. Kashanian suggests treating a painful rheumatoid cartilaginous nodule with a sweet spot in the orthotic shell. Dr. Kashanian says a sweet spot can also offload a protruding and painful styloid process.

   Dr. Sundstrom does not order such accommodations initially unless there is a severely tight/prominent plantar fascia in a rigid cavus foot or a prominent navicular tuberosity in a rigid flatfoot. Dr. Sundstrom will order accommodations as an adjustment later if the orthotic is not accommodating the deformities/prominences. She utilizes slot apertures on forefoot extensions quite often.

    “I cannot stress enough the importance of balancing the weight distribution under the met heads/forefoot properly,” says Dr. Sundstrom.

   Dr. Choate is an Assistant Professor in the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University.

   Dr. Kashanian is in private practice in Los Angeles. She is a Medical Consultant for ProLab Orthotics in Napa, Calif.

   Dr. Sanders is in private practice in San Francisco. She writes a monthly blog for Podiatry Today. For more information, please visit www.podiatrytoday.com/blogs. Dr. Sanders also blogs at www.drshoe.wordpress.com.

   Dr. Sundstrom is affiliated with the Orthopedics, Podiatry and Sports Medicine Department in the Division of Musculoskeletal Services at the San Francisco Kaiser Permanente Medical Center. She is board certified in foot surgery and in reconstructive rearfoot and ankle surgery.

   Dr. Scherer is a Clinical Professor at the Western University of Health Sciences College of Podiatric Medicine at Pomona, Calif. He is also the CEO of ProLab Orthotics/USA.

References

1. Mickle KJ, Steele JR, Munro BJ. Does excess mass affect plantar pressures in young children? Int J Pediatr Obes 2006; 1(3):183-88.
2. Lin CJ, Lai KA, Kuan TS, Chou YL. Correlating factors and clinical significance of flexible flatfoot in preschool children. J Ped Ortho 2001; 21(3):378-82.
3. Roukis TS, Scherer PR, Anderson CF. Position of the first ray and motion of the first metatarsophalangeal joint. JAPMA 1996; 86(11):538-46.
4. Scherer PR, Sanders J, Eldredge DE, et al. Effect of functional foot orthoses on first metatarsophalangeal joint dorsiflexion in stance and gait. JAPMA 2006; 96(6):474-81.
5. Munuera P, Dominguez G, Polomo I, Lafuente G. Effects of rearfoot-controlling orthotic treatment on dorsiflexion of the hallux in feet with abnormal subtalar pronation. JAPMA 2006; 96(4):283-9.
7. Vohra PK, Kincaid BR, Japour CJ, Sobel E. Ultrasonic evaluation of plantar fascia bands: a retrospective study of 211 symptomatic feet. JAPMA 2002; 92(8):444-9.
6. Kogler, GF, Veer FB, Solomonidis SE, Paul JP. The influence of medial and lateral placement of orthotic wedges on loading of the plantar aponeurosis. J Bone Joint Surg Am 1999; 81(10):1403-13.

   Editor’s note: For further reading, see “Key Insights On Writing Orthotic Prescriptions” in the January 2006 issue of Podiatry Today.