Foot & Ankle Flashcards
Stability functions of foot & ankle
1) stabile BOS for the body in weight bearing (without muscular effort or energy expenditure)
2) rigid lever for push off during gait
Mobility functions of foot & ankle
1) dampening of rotations imposed by proximal joints
2) flexible enough to absorb forces from ground
3) conform to terrain
how many bones & joints in foot/ankle
28 bones
25 joints
3 functional segments of foot
hindfoot
midfoot
forefoot
hindfoot
talus
calcaneous
midfoot
navicular
cuboid
cuneiforms (3)
forefoot
metatarsals
phalanges
ankle joint is called
talocrural joint
talocrural joint
- synovial joint
- 1 degree of freedom with oblique axis (goes on an angle)
- proximal concave surface (mortise)
- distal convex surface (talus)
- very congruent joint secondary due to bony mortise & ligamentous support
mortise
concave surface. distal tibia, malleoli of tibia & fibula act as a wrench to allow for plantar and dorsi flexion
why is ankle very congruent
want ROM movement only therefore congruent — unlike the hand we do not need to fully pronate/supinate
anatomy of talocrural joint
head & neck
body
3 facets
oblique axis
lateral malleolus –> body of talus —> distal medial malleolus
- lateral malleolus is more posterior and inferior than medial malleolus
- axis 20-30 deg laterally rotated (transverse plane)
- lower on lateral side by 10 deg (Frontal plane)
the talocrural joint has _______ motion (it moves in ____(number) of planes )
TRIPLANAR; 3 planes
thin capsule of talocrural joint is _____ anteriorly & posteriorly
WEAK
Deltoid ligament (MCL) - ankle
tibia malleolus –> navicular, talus, calcaneous
- very strong
- checks valgus stress (ankles moving close together)
Lateral collateral ligament 3 bands
- anterior talofibular
- posterior talofibular
- calcaneofibular
- weak ligament
- checks varus stress
weakest band of the lateral collateral ligament of ankle
anterior talofibular
- most common sprain location on ankle
- – lots of ROM in this area however bc it is weaker
proximal tibiofibular joint
- synovial
- fibula head
- posterolateral tibia
distal tibiofibular joint
- fibrous union (syndesmosis)
- between distal tibia & fibula
- ligaments for mortise stability
ligamentous structures important for mortise stability
crucial interosseous tibiofibular, anterior/posterior tibiofibular
talocrural kinematics arthrokinematics
convex talus
concave mortise
talocrural kinematics osteokinematics
20 deg dorsiflexion
30 - 55 deg plantarflexion
subtalar/talocalcaneal joint plane articulations (3)
posterior, anterior & middle
posterior talocalcaneal joint articulation
largest joint
concave talus
convex calcaneous
anterior talocalcaneal joint
convex talus
concave calcaneous
middle talocalcaneal joint
convex talus
concave calcaneous
function of subtaler & talocalcaneal joint
- dampen rotation forces imposed by body weight during foot/floor contact
subtalar/talocalcaneal joint arthrokinematics
complex (Screw like motion)
- triplanar motion about oblique axis
- 1 degree of freedom
- supination & pronation
subtalar/talocalcaneal joint ligamentous support
- stable joint
- interosseous talocacaneal ligaments (anterior & posterior bands)
- MCL & LCL of ankle
- posterior and lateral talocalcaneal ligaments
subtalar talocalcaneal supination (non-WB) – calcaneous actions:
adduction (vertical axis) inversion (long axis of foot) plantar flexion (coronal axis)
open chain
turn soles of foot in
subtalar talocalcaneal pronation (non-WB) – calcaneous actions:
abduction (vertical axis)
eversion (long axis of foot)
dorsiflexion (coronal axis)
open chain
soles of foot turn out
subtalar/talocacaneal supination (weight bearing) actions
calcaneous inversion (varus) talus abduction (ER verticle axis) talus dorsiflexion tibial external rotation
closed chain
subtalar/talocalcaneal pronation (weight bearing)
calcaneus eversion (valgus) talus adduction (IR - verticle axis) talus plantarflexion tibial internal rotation
function of subtler/talocalcaneal pronation (weight bearing)
foot = bag of bones (open packed)
weight acceptance during gait
conform to ground
attenuation of GRF
function of subtler/talocalcaneal supination (weight bearing)
foot = lock up foot (closed pack position)
push off during gait
rigid lever
pulls ligaments together – important because pushing off to walk you need a nice firm lever
talocalcaneonavicular joint - key to foot function
= subtalar joint + navicular joint
- talus head (Convex) moves on relatively fixed navicular (concave)
- triplanar motion
- 1 deg of freedom: pronation/supination
navicular socket is deepened by:
talocalcaneonavicular joint
- plantar calcaneonavicular (spring) - inferiorly
- deltoid ligament - medially
- bifurcate/laterally calcaneonavicular ligament -laterally
talus analogous to ball-bearing between
- tibiofibular mortise
- calcaneus
- navicular
transverse tarsal/midtarsal joint
= talonavicular joint + calcaneouboid joint
- divides foot into hind foot & mid foot
- talus/calcaneus moves on relatively fixed cuboid & navicular
talocalcaneonavicular joint
subtalar joint
talonavicular joint
S from side
transverse tarsal/midtarsal joint
talonavicular joint
calcaneocuboid joint
TCN joint dictates motion of _____ joints and ______ joint follows along
transverse tarsal;
calcaneocuboid
TCN is _____ (locked) —-> transverse tarsal is _______ (locked
supinated;
supinated
Functions of transverse tarsal
- transitional link between hind foot and forefoot
- enhance pronation & supination TCN joint
- allows forefoot to remain flat on ground while calcaneus is in varus or valgus (compensation)
TCN pronation —> foot bag of bones –> both hind foot & mid foot are free to _____ to ______ to floor
compensate;
accomodate
Weight acceptance!
TCN supination –> restricts ____________ joint motion –> _________ joint is supinated —> rigid lever to push off from
transverse tarsal;
transverse tarsal;
no floppy foot!!
articulation:
1st TMT = 1st MET + ?
medial cuneiform
2nd TMT = 2nd MET + ?
mortise (cuneiforms)
3rd TMT = 3rd MET + ?
lateral cuneiform
4th & 5th TMT = 4th & 5th MET + ?
cuboid
TMT function
- function is continuation of transverse tarsal joint
- if inadequate motion exists at transverse tarsal joint, TMT will provide additional motion for full compensation
supination twist
- calcaneous pronates
- distal part of foot supinates to walk normal
pronation twist
- calcaneous supinates
- distal part of foot twists to pronate to allow to walk normally
MTP joints deg of freedom
2 DOF
flexion/extension
abduction/adduction
MTP anatomy
1st 2- sesamoid bones = anatomical pulleys for FHB - flexor hallucis brevis
MTP joints which motion is most important
extension is more important than flexion because of GAIT
82 deg/17 deg – 1st MTP
IP joints anat
9
- uniaxial synovial joints
- convex surface of distal aspects of proximal segment
- concave surface of proximal aspect of distal segment
plantar aponeurosis (fascia)
- dense fascia from calcaneus to the proximal phalanx of each toe
- extension of MTP to tighten plantar aponeurosis
- assists in locking up the foot
heel spurs due to
plantar fascitis
plantar fascitis
inflammation of the plantar aponeurosis
longitudinal plantar arches
- based posteriorly at calcaneus and anteriorly at MET heads
- throughout foot but more prominent medially
transverse plantar arches
- viewed at MET heads and anterior tarsals
- middle cuneiform is keystone
- 2nd MET is apex of arch
Plantar arches structure is maintained via
- shape and arrangement of bones
- ligamentous support of joints
plantar arch ligamentous support
stabilize & provide mobility
- spring - plantar calcaneonavicular
- long plantar
- plantar aponeurosis
- short plantar
spring (plantar calcaneonavicular)
medial longitudinal
long plantar
lateral longitudinal
plantar aponeurosis
longitudinal
short plantar (plantar calcneocuboid)
lateral longitudinal
plantar arch function - stability
- distribute weight for proper weight bearing
- conversion of foot to a rigid lever
plantar arch function - mobility
- damening ground reaction forces during weight bearing
- adaptation to ground
- dampening of superimposed rotations from top down
