ankle and foot pt 3 Flashcards
what is the job of the tarsometatarsal joint?
attempts to maintain forefoot contact with supporting surface especially when transverse tarsal motion is inadequate
what is the motion that occurs at the tarsometatarsal joint?
considered triplanar joint but not supination pronation but rather supination twist and pronation twist (bc not much abd/add)
how are the axes in the tarsometatarsal joint?
independent oblique axes for each ray
what are the coupled motions for the 1st and 2nd ray axis?
inversion with DF
eversion with PF
what are the coupled motions for the 4th and 5th ray axis?
eversion with DF
inversion with PF
what motion occurs at each ray when the foot is inverted?
1 and 2 DF
4 and 5 PF
what motion occurs at each ray when the foot is everted?
1 and 2 PF
4 and 5 DF
what motions occur if transverse tarsal supination is inadequate to offset hindfoot pronation?
medial foot will compress into the ground
lateral side will tend to lift off ground
1st and 2nd ray will DF and invert
4th and 5th ray will PF and invert in attempt to contact the ground
the entire foot inverts or supination twists
if in CKC 5th ray will PF and IV which is?
supination twist
if in CKC 5th ray will DF and IV which is?
pronation twist
what does too much varus NWB lead to?
supination twist
describe which motion is occurring at the TMT joint?
calcaneus eversion
talar adduction and PF
talonavicular PF
TMT DF and IV (1st and 2nd ray)
TMT PF and IV (4th and 5th ray)
supination twist
describe which motion is occurring at the TMT joint?
calcaneus inversion
talar abduction and DF
talonavicular DF
TMT PF and EV (1st and 2nd ray)
TMT DF and EV (4th and 5th ray)
pronation twist
when does pronation and supination twist of the TMT joints occur?
when the TTJ function is inadequate:
unable to counter rotate or is insufficient to fully compensate for hindfoot position
when do plantar arches evolve?
during childhood (5 years old) with WB progression
what are the plantar arches?
the structural vault of the foot. twisted osteoligamentous plate with anterior margin horizontal and posterior margin vertical
what is the design purpose of the plantar arches?
design allows absorption and distribution of BW forces
what do plantar arches tend to do?
flatten with WB
describe the transverse plantar arch?
osteoligamentous twist imposes both a longitudinal and transverse arch
what does the transverse arch do from TMT to MTP?
decreases in curvature
where does the longitudinal plantar arch run?
continuous from calcaneus to MT heads
what ligaments provide arch stability?
spring, long plantar , plantar aponeurosis, short plantar
where does plantar apononeurosis (fascia) originate from and insert?
originates from medial calcaneus and inserts into plantar pads of MTPs
what does the plantar apononeurosis do?
stabilizes arch as a “tie-rod” would
explain the tie-rod analogy
“struts” of the truss are subject to compression load (talus and calcaneus would be posterior strut and tarsals and metatarsals would be anterior strut)
“tie-rod” is subject to tension load (plantar apononeurosis would be tie rod)
what is the windlass mechanism?
the ability to convert rotary (torque) motion into linear motion
when the planar pads move distally during toe PF what happens to the plantar fascia?
it is pulled forward and around the “windlass” of the MT heads which results in supination and reduces the distance between the MT heads and calcaneus so the arch heigh increases
what could happen to someone that has a high arch or pes cavis?
will cause soft tissue that has gone on slack for the short term will adaptively shorten for the long term
what could happen to someone that has a low arch or pes planis?
further pulls on fascia and adaptively lengthen tissue and creates reactive inflammatory process that leads to plantar fasciitis
what is an ideal normal ankle foot alignment?
calcaneal bisector and lower leg midline aligned. perpendicular relationship between MT heads and calcaneal bisector
how much body weight is distributed through the talus in bilateral stance?
50%
after the weight is distributed to the talus then where does it go?
50% is passed through the transverse tarsal joint to the forefoot, 50% is passed through the talocrural joint to the rear foot
where is ground reaction force at heel strike?
just lateral to calcaneal centerline
where does force shift to conclude stance?
medially to 1st MT head
what is foot pressure?
intensity of load contact area
where does tibialis posterior insert?
1st ray at the medial cuneiform
what does the tibialis posterior do?
will PF and Add 1st ray. important for stabilization at push off
what is a distal biomechanical consequence of compensatory pronation?
adduction and plantarflexion of the talus then navicular and medial cuneiform depression leads to tension overload to tibialis posterior
where does fibularis longus insert?
into the 1st ray (1st MT base and medial cuneiform)
what does the fibularis longus do?
abd and PF 1st ray, important for stabilization at push off
what is the cuboid pulley?
displaces the fibularis longus tendon inferiorly to improve PF moment
what is the point of the cuboid pulley?
reduces fibularis longus mechanical advantage to PF and abd first ray
what is distal biomechanical consequence of compensatory pronation?
alteration of cuboid pulley reduces fibularis asvantage to PF and abd first ray which results in dorsiflexed first ray and 2nd MT head overload
what is occurring in rearfoot varus when uncompensated?
calcaneal inversion position. medial plantar condyle will be off the ground, excessive weight bearing of the lateral foot, 5th metatarsal head callus, failure of STJ to pronate reduces shock absorbing qualities of foot
what is occurring in rearfoot varus when compensated?
calcaneal eversion from STJ pronation
what is occurring in forefoot varus when uncompensated?
forefoot inverted position. medial forefoot will be off the ground, excessive WB 5th ray, 5th metatarsal head callus
what is occurring in forefoot varus when compensated?
medial MT depression from STJ pronation
what is occurring in rigid forefoot valgus when uncompensated?
everted position of forefoot. lateral forefoot will be off ground, excessive WB 1st ray, 1st metatarsal head callus
what is occurring in rigid forefoot valgus when compensated?
lateral MT heads to floor by STJ supination, failure of STJ to pronate reduces shock absorbing qualities of foot and poor surface adaption. inversion sprain risk
