OrthoNet

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

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

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

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.