Congenital Foot Deformity
B. J. Manaster, MD, PhD, FACR
DIFFERENTIAL DIAGNOSIS
Common
Metatarsus Adductus
Pes Planovalgus (Flexible Flatfoot)
Club Foot (Talipes Equinovarus)
Tarsal Coalition
Less Common
Congenital Vertical Talus (Rocker Bottom Foot)
Pes Cavus (Mimic)
Polio (Mimic)
Cerebral Palsy (Mimic)
Rare but Important
Metaphyseal Bar
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Hint: Do not attempt to diagnosis foot deformities without weight-bearing films
Hint: Most congenital foot deformities can be diagnosed by evaluation of 3 relationships
Hindfoot equinus or calcaneus
On lateral radiograph, normal angle between lines bisecting calcaneus and tibia ranges between 60° and 90°
Hindfoot equinus: Tibiocalcaneal angle > 90° (excessive plantarflexion of calcaneus)
Hindfoot calcaneus: Tibiocalcaneal angle < 60° (excessive dorsiflexion of calcaneus); also termed “cavus”
Hindfoot varus or valgus
On lateral radiograph, normal angle between lines bisecting talus and calcaneus ranges between 25° and 55° (termed Kite angle or lateral talocalcaneal angle)
On AP radiograph, normal angle between lines bisecting talus and calcaneus ranges between 15° and 40°
Varus hindfoot: ↓ talocalcaneal angle (bones approach parallel), < 25° on lateral and < 15° on AP
Valgus hindfoot: ↑ talocalcaneal angle (bones diverge): > 55° on lateral and > 40° on AP
Forefoot varus or valgus
On lateral radiograph, metatarsals normally are moderately superimposed, with 5th in plantar-most position; angle of inclination of metatarsals gradually ↑ from 5° for 5th to 20° for 1st
On AP radiograph, metatarsals normally show moderate convergence of bases
Varus forefoot: Inversion and supination; on lateral, ↓ superimposition of metatarsals (ladder-like) with 5th MT in plantar-most position; on AP, ↑ overlap of MT bases
Valgus forefoot: Eversion and pronation; on lateral, ↓ superimposition of metatarsals with 1st MT in plantar-most position; on AP, ↓ convergence of MT bases
Hint: Most congenital foot deformities match type of hindfoot and forefoot deformities
Varus hindfoot with varus forefoot
Valgus hindfoot with valgus forefoot
Hint: If hindfoot and forefoot deformities are unmatched (i.e., varus hindfoot and valgus forefoot or valgus hindfoot and varus forefoot), usually due to spastic foot
Helpful Clues for Common Diagnoses
Metatarsus Adductus
Most common structural foot abnormality of infants
Adduction of metatarsals; normal hindfoot
Rarely imaged, since it is flexible deformity and self-correcting
Pes Planovalgus (Flexible Flatfoot)
Common (4% of population)
Note: It is flexible; non-weight-bearing radiographs are normal
Abnormalities on weight-bearing radiographs
Hindfoot valgus, forefoot valgus, no equinus
Club Foot (Talipes Equinovarus)
Incidence 1:1,000 births
M > F = 2-3:1
Constant structural abnormalities
Hindfoot equinus, hindfoot varus, forefoot varus
Tarsal Coalition
Painful flatfoot: Persistent or intermittent spasm of peroneal muscles
Usually secondary to congenital lack of segmentation of bones of hindfoot
Symptoms begin in late 1st or 2nd decade
Secondary signs
Talar beak: Due to excessive motion at talonavicular joint because of rigid subtalar joint
“Ball and socket” tibiotalar joint: Conversion of this hinge joint to rounded articulation; generally due to unusually extensive subtalar coalition
Calcaneonavicular coalition
Anterior process of calcaneus extends and broadens at union with navicular
Directly visualized on oblique radiograph
Talonavicular coalition
Generally mid subtalar joint (sustentaculum tali) and not directly visualized
Diagnosed by CT or MR where this portion of subtalar joint is directly visualized on radiographs
Rarely will involve posterior &/or anterior subtalar facets
25% bilaterality
Helpful Clues for Less Common Diagnoses
Congenital Vertical Talus (Rocker Bottom Foot)
Rigid flatfoot
Isolated, or part of several syndromes (frequently associated with meningomyelocele)
Constant structural abnormalities
Hindfoot equinus
Hindfoot valgus
Plantarflexed talus, dislocated from navicular
Forefoot valgus
Pes Cavus (Mimic)
Multiple etiologies; none are strictly congenital, hence “mimic” designation
Upper motor neuron lesions (Friedrich ataxia)
Lower motor neuron lesions (poliomyelitis)
Vascular ischemia, Charcot-Marie-Tooth, Chinese bound foot
Polio (Mimic) and Cerebral Palsy (Mimic)
Spastic abnormalities, often with mismatch of hindfoot and forefoot abnormalities (varus-valgus)
Soft tissues show muscle atrophy
Helpful Clues for Rare Diagnoses
