Exploring Orthotic Indications For Various Conditions
Q: Does orthosis casting reduce supinatus?
A: Dr. Allen thinks one can reduce a supple forefoot varus deformity and produce a functional medial column. He says clinicians should reduce the forefoot supinatus while casting. If one casts the medial column in varus, he says it will stay in varus. Dr. Allen says the orthotic design must control hindfoot motion, consider equinus and create a stable peroneal pulley to permit plantarflexion of the first ray. He emphasizes balancing the forefoot varus of metatarsals two through five.
Furthermore, one should attempt to reduce any existing supinatus when the rearfoot is neutral since performance and balance are propulsion based about the great toe, according to Dr. Allen. Dr. Williams agrees that orthotic casting can reduce supinatus if one casts properly. He says clinicians can cast out the supinatus by placing the non-weightbearing foot in a slightly pronated subtalar neutral position and then plantarflexing the first metatarsal to light resistance.
Dr. Richie contends that traditional Root suspension casting does not fully reduce forefoot supinatus or acquired forefoot varus. Podiatrists must push the first ray down plantarly to end range of motion in order to achieve a full reduction of forefoot supinatus, according to Dr. Richie. He says this is especially the case when casting a patient with adult-acquired flatfoot deformity. If one does not do so, Dr. Richie warns that “the resultant negative cast will capture an inappropriate amount of forefoot varus, which will ultimately produce an ill-fitting and poor controlling foot orthosis.”
Q: What factors should one consider when designing an orthosis for pes planus?
A: Dr. Richie notes orthotic design for pes planus depends on the etiology and symptomatology of the deformity. For a child with mildly symptomatic flatfoot, he believes a rigid device with a Kirby medial heel skive may be sufficient. For a pediatric patient with equinus, Dr. Richie says adding a heel lift can help relieve symptoms.
For a patient with adult-acquired flatfoot deformity, Dr. Richie says ligamentous disruption “will severely compromise the efficacy of the standard functional foot orthosis.” As he explains, loss of the spring ligament and interosseous talocalcaneal ligament will result in significant transverse plane instability of the foot, severe internal rotation of the tibia and talus, and profound abduction of the forefoot. In such a case, Dr. Richie recommends a deep heel cup, Kirby medial heel skive and a long lateral flange on the footplate. He emphasizes the importance of reducing forefoot supinatus during the casting procedure.
Dr. Allen says one must consider if the pes planus deformity is supple or rigid. For a rigid deformity with underlying arthritis, he says one should design an orthotic to bring the ground up to the foot and prevent motion, which often requires coupling to the leg. Such an orthotic supports the deformity but does not correct it, according to Dr. Allen.
With a supple deformity, one must consider all possible influences upon the foot that encourage abnormal motion, advises Dr. Allen. He notes the difficulty of controlling the suprapedal influences upon the foot. In evaluating the dynamic function of the deformity, Dr. Allen says one must consider the leg, ankle, hindfoot and forefoot as separate units.
Orthotic materials depend on how much motion control the patient needs, according to Dr. Allen. Dr. Williams concurs, saying a 10-year-old may need a Richie Brace just as much as a 70-year-old patient despite the differences in activity levels. Dr. Williams also advocates not restricting the medial column with an orthotic device and suggests using first ray cutouts and various sizes of kinetic wedges.
Dr. Losito is a Professor at the Barry University School of Graduate Medical Sciences. He is the Immediate Past President of the American Academy of Podiatric Sports Medicine and is the Team Podiatrist for the Miami Heat.
Dr. Allen is an Associate Professor in the Department of Orthopedics at the University of Texas Health Science Center at San Antonio. He is a Fellow of the American Academy of Podiatric Sports Medicine and is the Team Podiatrist for the San Antonio Spurs.