Review Question - QID 218613

This patient has Charcot-Marie-Tooth (CMT) Disease and a recommendation of lateralizing calcaneal osteotomy would be most appropriate in the setting of a hindfoot-driven cavovarus foot deformity.

Charcot-Marie-Tooth disease is an autosomal dominant disorder where there is a duplication of chromosome 17, which codes for peripheral myelin protein 22 (PMP22). One of the primary orthopedic manifestations is cavovarus foot deformity due to unopposed pull of the peroneus longus which overpowers the peroneus brevis and tibialis anterior muscles. The Coleman block test is used to help determine whether the deformity is forefoot- or hindfoot-driven. If the deformity is forefoot-driven, the first metatarsal will flex when the block is placed under the lateral foot and the hindfoot varus deformity will correct. If the deformity is hindfoot-driven, the varus deformity will not correct with a block under the lateral foot. If the deformity is flexible and forefoot driven, a 1st metatarsal dorsiflexion osteotomy is recommended, whereas if the deformity is hindfoot driven, a lateralizing calcaneal osteotomy and forefoot correction are preferred.

Kaplan et al. reviewed operative management of the cavovarus foot, noting an algorithmic approach must be used based on the muscle imbalances, joint deformities, and contractures present. The goals of surgery are to obtain a stable, plantigrade foot and prevent deformity progression/recurrence. They note that in cases of cavovarus feet with CMT, they typically occur bilaterally with varying degrees of severity and progression.

Louwerens et al. reviewed the operative treatment of foot deformities in CMT patients. They discuss their standard treatment approach based on their classification of the deformity seen. They go on to describe the different procedures utilized to manage these deformities which include but are not limited to osteotomies and tendon transfers based on the location of the deformity.

Incorrect Answers:
Answer 1: A hindfoot cavovarus deformity that corrects with Coleman block testing is an example of forefoot-driven deformity which is best managed with a 1st metatarsal dorsiflexion osteotomy.
Answer 2: A flexible hindfoot valgus deformity with the inability to perform a single leg calf raise would be classified as Stage II posterior tibial tendon insufficiency and best managed with an FDL tendon transfer and medializing calcaneal osteotomy.
Answer 3: A calcaneovalgus deformity is more common in pediatric patients and is managed with stretching and casting.
Answer 5: A rigid hindfoot valgus deformity with forefoot abduction would also be best managed with a triple arthrodesis.