structural foot deformities

what is the subtalar joint

articulation between the inferior talus and superior calcaneus

how many facets does the subtalar joint have

3

what is the primary function of the subtalar joint

to dampen the rotational forces from body weight while maintaining foot contact with the ground

what are the articulating surfaces of the superior calcaneus

anterior and middle facets

posterior facet

calcaneal sulcus

which facet of the calcaneus is the largest

posterior

what facet has its own capsule

posterior

which joint do the anterior and middle facets share a capsule with

talonavicular

what are the different talocalcaneal ligaments

medial, posterior, and lateral ligaments

what is the role of the talocalcaneal ligaments

reinforcement of the posterior articulation

the talocalcaneal ligaments are secondary stabilizers to what joint

talocrural joint

is the tarsal canal and its ligaments intra or extracapsular

extracapsular

in non weightbearing which bone moves on what during pronation and supination

calcaneus on talus movement

what are the movements involved in pronation during nonweightbearing

dorsiflexion, abduction, and eversion of the calcaneus on talus

what are the movements involved in supination during nonweightbearing

plantarflexion, adduction, and inversion of the calcaneus on talus

what bone moves on what during pronation and supination while WEIGHTBEARING

talus on calcaneus

what are the movements involved in pronation during weightbearing

the talus plantarflexes and adducts on the calcaneus and the calcaneus everts

what are the movements involved in supination during weightbearing

the talus dorsiflexes and abducts on the calcaneus, the calcaneus inverts

what effect does STJ motion have on the LE during pronation while WB

LE medially rotates

knee flexes

medial arch flattens

what effect does STJ motion have on the LE during supination while WB

LE laterally rotates

knee extends

medial arch elevates

what is typical ROM of the subtalar joint

inversion: 20 deg

eversion: 10 deg

what is the ratio of inversion to eversion ROM

2:1

what is the position of the calcaneus in rearfoot varus

calcaneal inversion

RF varus =

calcaneal varus + tibfib varum

what is the possible cause of FF varus

head of talus doesn’t completely rotate → navicular and cuneiform are in cephalad position → elevated medial side of the foot

what are the 2 types of forefoot valgus

all MTH are everted or plantarflexed first ray with 2-5 MTH in appropriate plane

what is the possible cause of FF valgus

excessive rotation of talar head w

what plane does forefoot equinus occur in

sagittal

what is forefoot equinus

MTH lie below tubercles of calcaneus → PF forefoot when compared to RF

what are the primary sites for compensatory motion

STJ and/or MTJ

how can compensation be made at the STJ or MTJ joints

amount, speed and/or timing of STJ/MTJ motion

what happens if there is an increase in excursion of ROM in order to compensate

stresses the limits of joint excursion → stress on non-contractile tissues

excessive strain on muscles that decelerate (post tib)

what happens if there is a decrease in excursion ROM in order to compensate

decreased dissipation of GRF → increase forces on articular surfaces

what results if there is an increase in speed of motion to compensate

excessive strain on the musculotendinous unit (esp if it primarily performs eccentric contractions)

what is the position of the foot when it is a rigid lever for push off

supination

what is the typical compensation for RF varus

the calcaneus everts and STJ/MTJ pronate in order to bring the medial calcaneal tubercle to the ground

what type of compensation occurs @ STJ/MTJ for RF varus

increased amount of compensation

increased speed of compensation

what is the result of compensation made for RF varus

distal FF symptoms

secondary proximal symptoms

what happens if there is no compensation made at the STJ with calcaneal varus

callous formation under 5th MTJ

decreased to absent shock absorption a rigid foot

what kind of compensation is made for FF varus

the calcaneus everts and STJ/MTJ pronate as MSt begins to bring the medial FF to the ground

what type of compensation is made at the STJ for FF varus

excessive pronation at the wrong time w

what happens if there is no compensation at the STJ

uncompensated FF varus with callous formation along the lateral border of the foot and 5th MTH

decreased to absent shock absorption - a rigid foot

what type of compensation is made at the STJ for FF valgus

STJ/MTJ supinates normal pronation is prevented

minimal to absent pronation with an earlier return to supination

what are the distal effects of compensation at the STJ joint for FF valgus

lacks ability to accommodate to terrain

susceptible to inversion sprains

plantarflexed 1st ray is commonly noted

what are the secondary proximal effects that occur due to compensations made for FF valgus

decreased shock absorption distally → compensations proximally

increased varus stress on knee

what is the typical compensation made for FF equinus

MTJ pronation in mid to late stance

what is the result of compensation made for FF equinus

MTJ compensation in midstance produces clinical S/S that resemble those of a compensated FF varus