|
Year |
2005 |
|---|---|
|
Question Number |
47. |
|
Category |
Foot and Ankle |
Question
An orthosis that would best address the deformities that are characteristic of Charcot-Marie-Tooth disease would post the
1- lateral forefoot and the medial arch.
2- lateral forefoot and the lateral heel.
3- central arch with a negative heel.
4- first metatarsophalangeal and the lateral heel.
5- medial heel only.
Figures
Answer (click for answer)
PREFERRED RESPONSE: 2
The orthopaedic manifestations of CMT include a cavovarus foot, hammer toes with frequent corns/calluses, and peroneal weakness. The neuropathic cavovarus deformity of Charcot-Marie-Tooth disease has been suggested to be caused by a combination of intrinsic and extrinsic weakness, beginning with weakness of the intrinsic foot muscles and the tibialis anterior, with normal strength of the tibialis posterior and peroneus longus. The triceps surae also is weak and may be contracted. The forefoot is pulled into equinus relative to the hindfoot, and the first ray becomes plantarflexed. The long toe extensors attempt to assist the weak tibialis anterior in dorsiflexion but contribute to metatarsal plantar flexion, and the foot is pronated into a valgus position with mild adduction of the metatarsals. Initially the foot is supple and plantigrade with weight-bearing, but as the forefoot becomes more rigidly pronated, the hindfoot assumes a varus position. Treatment consists initially of orthoses management (Miller). The lateral heel should be posted to correct the varus hindfoot, inducing eversion and redistributing loading to a larger area of the foot. A forefoot wedge, beginning just lateral to the first metatarsal recess, extends to the lateral border of the orthosis to accommodate the forefoot valgus.
Reference: RECOMMENDED READINGS: Schwend RM, Drennan JC: Cavus foot deformity in children. J Am Acad Orthop Surg 2003;11:201-211.
Holmes JR, Hansen ST Jr: Foot and ankle manifestations of Charcot-Marie-Tooth disease. Foot Ankle 1993;14:476-486.
Alexander IJ, Johnson KA: Assessment and management of pes cavus in Charcot-Marie-tooth disease. Clin Orthop 1989;246:273-281.