Download Ankle and Foot

Ankle and Foot
Tibia and fibula held together by interosseous membrane; also serves for muscle
attachment.
Tibia larger and only true weight bearing bone of the leg.
Foot is divided into three parts: hindfoot (talus and calcaneus); midfoot (navicular and
cuboid) and forefoot (three cuneiforms, five metatarsals and all phalanges. Each plays a
specific role during gait. Hindfoot is first to contact ground and "tells" distal parts how to
move to prepare for surfaces. Midfoot provides stability and mobility as movement
moves from hindfoot to forefoot. Forefoot is last in contact with ground.
Ankle and foot perform three main functions:
Shock absorber during gait
Adapting mechanism during gait
Provides stable base of support to move body forward
Motions
PF, DF on sagittal
Inversion and eversion on frontal plane
Adduction and abduction on transverse plane
Adduction and abduction occur in the forefoot and accompany inversion and eversion
Supination is a combination of PF, inversion and adduction
Pronation is a combination of DF, eversion and abduction
Valgus = distal segment positioned away from midline
Varus = distal segment positioned toward midline
Superior tibiofibular joint between head of fibula and posterior lateral proximal tibia.
Uniaxial plane joint with joint capsule reinforced by ligaments. Has minimal gliding
movement.
Interior tibiofibular joint is a syndesmosis (fibrous) between distal tibia and distal fibula.
No joint capsule. Adds to strength of ankle joint based on its strength.
Ankle joint
Talocruraal or talotibial consists of distal tibia sitting on talus surrounded by
medial/lateral malleolus.
Subtalar or talocalcaneal = inferior surface of talus with superior surface of calcaneus.
Gliding.
Anterior talus and calcaneus articulate with posterior surfaces of navicular and cuboid to
make the transverse tarsal joint (midtarsal). Little movement between navicular and
cuboid.
Pronation and supination (between hindfoot and forefoot) occur here.
Functionally the subtalar and transverse tarsal joints cannot be separated so
supination/pronation are actually combined motions.
DF/PF = talocural joint
Inversion/eversion = subtalar and transverse tarsal joints
Ligaments
Ankle has a joint capsule that is thin anteriorly and posteriorly reinforced by collateral
ligaments on sides … actually groups of several ligaments
Medially is triangular deltoid ligament that strengthens the medial side of the ankle, holds
the calcaneus and navicular against the talus, and helps to maintain the medial
longitudinal arch.
Laterally is a group of three ligaments referred to as the lateral ligament. Weaker
anteriorly, fairly strong posteriorly.
Ankle is considered the most frequently injured joint in the body and the lateral ligament
is most frequently injured ligament.
Arches
Foot must absorb great shock, adjust to terrain changes and propel body forward. Bones
of foot arranged in arches to assist. Stand on a triangle with weight bearing borne from
base of calcaneus to heads of first and fifth metatarsals. Between these points have two
arches (medial and lateral longitudinal) at right angles to third (transverse).
Medial longitudinal - medial border of foot. Talus is top of the arch and referred to as the
keystone. This arch depresses during weight bearing and recoils when weight removed.
Lateral longitudinal - normally rests on ground during weight bearing.
Transverse arch - second cuneiform is keystone of this arch
The three arches maintained by shape of bones and relationships, plantar ligaments and
aponerosis and muscles. Ligaments and aponerosis most important features.
Spring ligament (plantar calcaneonavicular) most important because it supports the
medial side of the longitudinal arch
Long plantar ligament is longest and more superficial and spring for primary support of
the lateral longitudinal arch
Short plantar ligament assists long plantar
Longitudinal arch further supported by plantar aponeurosis that acts as a tie rod keeping
the posterior segments from separating from the anterior.
Arches also supported by muscles but total muscular support to the arches has been
estimated to bear only about 15-20% of the total stress to the arches.