talocrural joint Flashcards
what is considered to be the ankle joint
talocrural joint
articulation
b/w the talus and the distal tibia
and
the talus and the fibula
what type of joint is the talocrural joint
hinge joint with one degree of freedom
what does the talocrural joint allow
dorsiflexion and plantar flexion
what is the most congruent joint in the body
talocrural joint
what is the proximal surface of the talocrural joint composed of
the concave surface of the distal tibia and the tibial and fibular malleoli
what will form the almost continuous concave joint surface –> proximal surface
three facets
which malleolus extends further distally
the lateral malleolus
is also more posterior
what shape does the distal tibia and the malleoli resemble
mortise
adjustable and relies on the proximal and distal tibiofibular joints to both permit and control change in the mortise
distal surface of the talocrural joint
formed by the body of the talus
has 3 articular surfaces
3 articular surfaces of the talus –> distal surface
large lateral facet
smaller medial facet
superior/trochlear facet
large lateral facet
lateral malleolus
smaller medial facet
medial malleolus
superior/trochlear facet
articulates w/ distal tibia
what shape is the body of the talus
wedge shaped
wider anteriorly than posteriorly
articular cartilage –> distal surface
continuous across 3 articular facets
very congruent joint
proximal tibiofibular joint
formed by the head of the fibula w/ the posterolateral aspect of the tibia
what kind of joint is the proximal tibiofibular joint
plane synovial joint
proximal tibiofibular joint capsule
reinforced by anterior and posterior ligs
separate from knee joint
amount of motion at proximal tibiofibular joint
small amount of motion
superior/inferior sliding of the fib
fib rotation
distal tibiofibular joint
concave facet of the tibia and the convex facet of the fibula
syndesmosis
distal tibiofibular joint capsule
none
distal tibiofibular joint ligaments
most important is the crural tibiofibular interosseous ligament
injured in a high ankle sprain
fxn of distal tibiofibular joint
limit motion @ tibiofibular joints
maintain a stable mortise
what is normal fxning of the talocrural joint dependent on
tibiofibular mortise
what is the mortise spread apart
it would be unable to grasp and hold the talus
what is the most important part of the mortise
fibula
will bear no more than 10% of our weight
ligaments of talocrural joint
medial collateral ligament (deltoid ligament)
lateral collateral ligament
purpose of ligaments
ankle is dependent on intact ligamentous structure for stability
joint capsule of the ankle is fairly thin and is weak anteriorly and posteriorly
deltoid ligament
superficial and deep fibers
arise from the borders of the tibial malleolus
insert in a continuous line on the navicular anterior and on the talus and calcaneus distally and proximally
is the deltoid ligament weak or strong
very strong ligament
fxns of the deltoid ligament
control medial distraction (valgus) stresses on the ankle joint
help check motion at extreme joint range
lateral collateral ligament
3 separate bands
referred to as separate ligaments
3 bands of the lateral collateral ligament
anterior talofibular
posterior talofibular
calcaneofibular
what ligament is more prone to injury
lateral collateral ligament
weaker
function of lateral collateral ligament
to control lateral distraction (varus) stresses on the ankle joint
help check motion at extreme joint ranges
function of talocrural joint
motions of dorsiflexion and plantarflexion predominate
do not occur purely in the sagittal plane
how do DF/PF occur not in one plane
single motion that crosses 3 planes
triplanar motion
d/t oblique axis of motion and shape of the body of the talus
axis
passes through the fibular malleolus, the body of the talus and through or just below the tibial malleolus
how is the axis oblique
lateral malleolus is more distal than the tibial and lies more posterior
axis is considered to be rotated laterally 20-30 degrees in the transverse plane and inclined 10 degrees down the lateral side
d/y obliquity of the axis
DF –> ABD and eversion
PF –> ADD and inversion
PF/DF
occur in the sagittal plane around a frontal axis
EV/INV
occur in the frontal plane around an A-P axis
ABD/ADD
occur in the transverse plane around a vertical axis
OKC dorsiflexion arthro
convex talus moving on a concave mortise
BM & roll –> anterior
glide –> posterior
OCK PF arthro
convex talus moving on a concave mortise
BM & roll –> posterior
glide –> anterior
CKC arthro
tibia and fib moving on a stationary talus
what will the lateral malleolus do
will move a greater distance on the larger lateral facet of the talus
CKC arthro –> in WB
when the tibia and fibula move over the fixed talus into dorsiflexion
–> movement on the medial side stops while the lateral side continues to move anteriorly
this causes medial rotation of the leg as it passes over the foot in WB dorsiflexion and lateral rotation of the leg in plantarflexion
ROM DF
20 degrees from neutral
neutral
when the foot is @ a right angle to the tibia
dorsiflexion is limited w/
knee extension
passive insufficiency of the gastroc
plantarflexion ROM
30-50 degrees from neutral
