Flatfoot in Adults

Reference: Mann, Roger A, Flatfoot in Adults, in Surgery of the Foot and Ankle, 6th ed, Mann & Coughlin ed., Mosby, 1993

Main Message

Most flatfeet are asymptomatic and require no treatment.
Beware taking on surgical treatment of flatfeet!

Points of Interest

– A spectrum exists.
– Pain may be related to overuse, and the x-ray appearance may be irrelevant.
– In general, it is unusual for an adult with a flexible flatfoot to become symptomatic.
– Can think of it in two ways: Congenital and Acquired

Asymptomatic flexible flatfoot
Symptomatic flexible flatfoot
Tarsal coalition
Accessory navicular
Residua of congenital deformity
– clubfoot, vertical talus
Generalized musculoskeletal dysplasia
– Marfan’s

Posterior tibial tendon dysfunction
Charcot joint – diabetes, peripheral neuropathy
Arthritis – talonavicular, tarsometatarsal, rheumatoid
Post traumatic
Neuromuscular – polio, cerebral palsy, nerve injury

Asymptomatic Flexible Flatfoot
– common; normal variant
– physical exam demonstrates inversion of heel when up on toes, normal subtalar, ankle, and tarsometatarsal motion.
– xrays show a talo-metatarsal angle of 15o (normal is 0o)
– Approach: generally speaking – no treatment

Symptomatic Rigid Flatfoot
– underlying pathology is the Achilles tendon! They get a tight Achilles, which puts them into equinus and stresses the transverse tarsal joint, which eventually gives in and a “rocker bottom” deformity is created.
– full inversion of the hindfoot does not occur when up on toes; probably secondary to joint changes after the midfoot break.
– both dorsiflexion and plantarflexion are decreased, but the underlying problem is in the reduced dorsiflexion
– xrays show an increased talo-metatarsal angle, decreased calcaneal pitch
– Approach: conservative – arch supports and firm heel counters, custom orthotics, UCBL orthosis
– if only absolutely necessary, surgery would include a triple arthrodesis with tendo-achilles lengthening; BEWARE!! The chances of making them worse are high!

Tarsal Coalition
– usually becomes symptomatic in adolescence
– in adults, a history of trauma (mild) is common – probably busts off a synchondrosis
– physical may reveal a normal longitudinal arch! No inversion of the heel is seen on standing.
– xrays may show beaking of the talus, flattening of the arch, and the coalition
– two most common are calcaneonavicular and talocalcaneal
– Approach: in acute injury – cast, 6 weeks, then try orthosis
if no response, surgery
– calcaneonavicular bars should be resected early before secondary degenerative changes occur. The resection is for pain relief, not for flexibility – the subtalar motion will continue to be poor.
– talocalcaneal coalition should be fused

Accessory Navicular
– rarely symptomatic in adults (they have had a flatfoot deformity since a kid)
– often become symptomatic after a minor trauma
– physical reveals the medial prominence (maybe tender) and varying degrees of a sagging longitudinal arch, satisfactory motion at the ankle, subtalar, and transverse tarsal joints
– inversion of the calcaneus does occur when standing on toes
– xrays show the accessory navicular – in adults, it is more likely to be a synchondrosis that was asymptomatic until injured.
– Approach: short leg cast for 4-6 weeks
– if continues to be symptomatic, try Kidner procedure to resect the accessory navicular and plicate the tib post.

Residual Congenital Deformities – Clubfoot, Congenital Vertical Talus
– very difficult
– remember that fusing is tempting, but the forces go elsewhere in the foot/ankle!

Generalized Dysplasia – Marfans, Ehlers-Danlos
– remember that soft tissue procedures will likely not work, because their soft tissues are the problem.
– Approach: try to treat nonoperatively with an orthotic or well-fitted firm shoe. If necessary; triple arthrodesis is their most likely surgical option.

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