Reference: Mann, R., in Surgery of the Foot and Ankle, 6th ed. Chapter 785
There is much confusion in the literature about pes cavus. The anatomy is very variable and depends partially on the etiology.
Points of Interest
– Pes cavus – a foot with a high arch that fails to flatten with weightbearing.
– The deformity is either hindfoot, forefoot, or a combination of both
– Bony Deformity – well described in the chapter.
– Hindfoot: increased calcaneal pitch >30o, and varus
– Forefoot: plantarflexion of the metatarsals, adduction of the forefoot, and forefoot valgus (due to the plantarflexion of the medial rays more than the lateral)
– MTP: clawing of the toes, with dorsal subluxation of the proximal phalanx
– Soft Tissue Deformity
– Plantar aponeurosis contracture. This is probably a result of the bony deformity, but undoubtedly contributes to it once a significant deformity is established.
– With the hindfoot in a vertical, varus position and the forefoot in equinus, adducted, and valgus position, the overall weightbearing surface for the foot is decreased; the main complaint at first may be metatarsalgia!
– it is produced by a muscle imbalance involving both the intrinsic and extrinsic muscles of the foot; the actual nature of that imbalance is different among disorders.
– eg: Polio – weak posterior calf musculature, normal anterior musculature – unapposed tib ant pulls up on the medial border of the foot, producing a varus hindfoot. Sometimes also have no extrinsics, and the pull of the intrinsics creates a forefoot equinus, and usually hindfoot varus.
– eg: Charcot-Marie-Tooth disease: opposite from polio. The posterior compartment is normal, the anterior compartment is weak. The forefoot is the result of the pull of peroneus longus – forefoot valgus. Also, tib post pulls the calcaneus into a varus position.
– diminished subtalar and forefoot motion results in a decrease in the patient’s ability to absorb the impact of initial ground contact. The cavus foot and decreased plantar surface areas places increased stress on the heel and metatarsal head regions. The hindfoot varus and/or significant forefoot valgus makes the ankle subject to multiple lateral sprains.
– Conservative Treatment: goal is to produce a plantigrade foot, with and even distribution of pressure. Stretching, well-molded, semiflexible orthosis, short leg bracing.
– Surgical Treatment: goal is to produce a plantigrade, stable foot.
– Plantar Fascial release
– First Toe Jones procedure
– First metatarsal osteotomy
– Calcaneal osteotomy – Dwyer (lateral column shortening),
– Triple fusion