Ankle Flashcards
type of joint
hinge
uniaxial, triplanar
ankle joint has how many degrees of freedom
1
what are the osseous structures of the ankle joint
Lateral surface of the medial malleolus
Medial surface of the lateral malleolus
Tibial plafond
Trochlear surface of the talus
what are the 3 articulations of the ankle joint?
Talotibial
Talofibular
Tibiofibular
ankel joint is located — from sagittal plane
82
ankle joint is located — from transverse plane
8
ankle joint is located — from the frontal plane
20-30
clinically, how can the ankle joint axis be located
by finding the distal tips of the malleoli
clinically, where does the ankle joint pass through
passes laterally, posterior and plantar to medial, anterior and dorsal
what type of motion does the ankle joint provide
pronation
supination
why does the instantaneous axis of rotation move very little
b/c the articular surfaces are greater than 90% congruent. As a result, the ankle joint comes very close to having true hinge-like motion
small amount of anterior and posterior rotation of the fibula during dorsiflexion and plantarflexion due to
large fibular facet
small tibial facet
clinically, how can the ankle joint axis be located
by finding the distal tips of the malleoli
what type of motion does the ankle joint provide
pronation
supination
primary motion of the ankle joint occurs in what plane
sagittal
ankle joint stability is due to what
- stable joint due to the tight fit of the talus into the ankle mortise
- interosseous membrane and interosseous ligaments prevent separation of tibia and fibula
what position is the ankle joint more stable in (dorsiflexed or plantarflexed)
dorsiflexed position
talus is wider anteriorly (tighter fit)
what are 3 sagittal plane restraints provided by muscles?
Dorsiflexion is limited by the Achilles tendon
Plantarflexion is limited by the anterior leg muscles
If these muscle restraints are not intact, the limitation may be bony and arthritic changes are likely to develop
the trochlear surface of the talus has a —fibular facet and a —tibial facet
larger
smaller
small amount of anterior and posterior rotation of the fibula during dorsiflexion and plantarflexion due to
large fibular facet
small tibial facet
b/c of the large weight-bearing surface of the talus, the load:area (stress ratio) is —-
less
in static stance w/o muscle effort, each ankle bears —of the body weight
1/2
fibula bears —weight according to some textbooks
1/6
during gait, maximum load occurs at
heel lift (beginning of propulsive phase or near the beginning of terminal stance)
at heel lift, the ankle bears — body weight
5X
the greatest amount of dorsiflexion required during gait occurs when
at or near heel lift
this dorsiflexion occurs passively as the momentum carries the tibia over the foot
what is the normal ankle joint ROM
10 degrees dorsiflexion w/ knee extended
greater than 10 degrees dorsiflexion with knee flexed
plantarflexion should be >20 degrees
ankle joint ROM is measured while the subtalar joint is in —- position
neutral
if the subtalar joint is allowed to pronate what will happened to the ankle joint ROM
will be an increase in dorsiflexion as a result of dorsiflexion at the midtarsal joint axis
during gait, maximum load occurs at
heel lift (beginning of propulsive phase or near the beginning of terminal stance)
at heel lift, the ankle bears — body weight
5X
the greatest amount of dorsiflexion required during gait occurs when
at or near heel lift
this dorsiflexion occurs passively as the momentum carries the tibia over the foot
ankle joint ROM is measured while the subtalar joint is in —- position
neutral
if the subtalar joint is allowed to pronate what will happened to the ankle joint ROM
will be an increase in dorsiflexion as a result of dorsiflexion at the midtarsal joint axis
inversion and eversion are resisted by
ligaments
stable bony architecture
are lateral and medial ankle ligaments weaker
lateral ankle ligaments
are the first to go with an inversion injury of > 10 degrees
what factors resist ankle joint dorsiflexion?
- the position of the knee - the gastrocnemius crosses both the knee and the ankle joints. If it is tight, knee extension will increase its tension and may limit ankle joint dorsiflexion. When the knee is flexed, the tension on the gastroc is released and dorsiflexion may improve
- osseous structures
- tight intrinsic muscles of the foot or tight plantar fascia
provide an example of osseous structures of the ankle joint that may limit motion
an exostosis at the dorsal aspect of the talus or the anterior aspect of the distal tibia so that bony impingements results when the ankle joint is dorsiflexed
trochlear surface of the talus is —shaped
wedged shaped
aka truncated cone (a cone with both ends cut off), with the base directed laterally
