Ankle And Foot Complex Flashcards
FOOT COMPLEX
divided into 3 functional segements
hindfoot - posterior segment composed of talus and calcaneus
midfoot - middle segment composed of cuboid, navicular, and 3 cuneiforms.
forefoot- anterior segment composed of metatarsals and phalanges
ANKLE AND FOOT COMPLEX
25 bones and 25 component joints Proximal and distal tibiofibular joints Ankle joint or talocrural joint talocalcaneal or sutalar joint transverse tarsal joints ( talocuboidal and talonavicular) 5 tarsometarsal joints metatarsophalangel joint 9 interphalangeal joint
ANKLE/ FOOT MOTION
Dorsiflexion/ plantarflexion occurs in sagittal plane around coronal axis
inversion/ eversion occurs in frontal plane around longitudinal or AP axis
abduction/ adduction occurs in transverse plane around vertical axis
FOOT MOTION
pronation and supination occurs in each cardinal axis coupled with DF/PF, INV/EVE, ABD/ADD.
NWB: PRONATION coupled with DF, EVE, ABD, and SUPINATION is coupled with PF, INV, ADD
VALGUS/VARUS FOOT
valgus/calcaneovalgus - toe out/ increase in the medial angle b/w calcaneus and posterior leg
varus/calaneovarus- toe it/ decrease in the medial angle b/w calcaneus and posterior leg.
ANKLE JOINT
ankle is aka as talocrural joint. articulation b/w distal tibia and fibula proximally and body of talus distally. SYNOVIAL HINGE JOINT. joint capsule and associated ligaments have single oblique axis with 1 dof DF/PF
ANKLE JOINT STRUCTURE :
PROXIMAL ARTICULAR SURFACES
concave distal tibia and of tibial/ medial and fibular / lateral malleoli: refers to MORTISE that is adjustable
function of ankle joint is dependent on stability of tibiofibular mortise
mobility role of mortise depends on fibula
PROXIMAL TIBIOFIBULAR JOINT
plane synovial
articulation of head of fibula ( concave facet) with posterlateral tibia( convex facet).
joint capsule with anterior and posterior tibiofibular ligaments and interosseus membrane
motion at this joint is small.
DISTAL TIBIOFIBULAR JOINT:
syndesmosis or fibrous
union of CONCAVE TIBIAL facet and CONVEX FIBULAR facet.
no joint capsule
anterior and posterior tibiofibular ligaments and interosseus membrane .
extremely strong articulations
ANKLE JOINT:
DISTAL ARTICULAR SURFACE :
body of talus is the distal articualtion of ankle joint
body of talus has 3 articular facets:
* large lateral fibular
* small medial tibial
* trochelar superior
body of talus WIDE ANTERIORLY THAN POSTERIORLY
ANKLE JOINT CAPSULE
FAIRLY THIN AND WEAK ANTERIORLY AND POSTERIORLY
LIGAMENTS OF ANKLE JOINT:
anterior and posterior tibiofibular : important for mortise stability
tibiofibular interosseous membrane : supports proximal and distal tibiofibular joints
medial and lateral collateral ligaments: maintain contact and congruence of the mortise and talus, also control medial-lateral joint stability. some portions also support subtalar joint
MEDIAL COLLATERAL LIGAMENT
AKA DELTOID LIGAMENT.
XTREMELY STRONG
eversion or and pronation can injure this ligament
LATERAL COLLATERAL LIGAMENT
3distinct bands:
anterior talofibular: weakest and often injured and stressed with PF, MR, and INV
posterior talofibular: rarely torn in isolation
calcaneofibular ligament: stressed with DF and INV
control INVERSION AND OR SUPINATION of ankle or talus
components are weaker and more susceptible to injury than medial collateral ligament
AXIS OF ANKLE JOINT
in neutral position, axis passes through lateral malleolus and body of talus
angled at 14 degrees
PF- foot moves medially, DF- foot moves laterally
tibial torsion- toe out position in normal standing and 20-40 degrees of ER of tibia
ANKLE JOINT FUNCTION:
normal ROM: DF 20 degrees, PF 50 degrees.
walking 10 degrees DF
loose packed position is PF
with DF wider talus gets wedged in the ankle mortise
DF/PF limited by soft tissue approximation
WB:DF: tibia rotates over talus
ankle joint less stable in PF when narrow posterior is within mortise.
STRUCTURES LIMITING DF/PF:
ACTIVE OR PASSIVE TENSION IN gastrocnemius ( knee extension )and soleus (knee flexed) : primary limitation of DF
TENSION IN Tibialis anterior, EHL, and EDL : primary limitation of PF and protect medial aspect of ankle.
Fibularis longus and brevis protect lateral aspect of ankle.
THE SUBTALAR JOINT:
aka talocalcaneal joint
composite joint
3 separate articulations b/w inferior calcaneal and superior talus
provide triplanar movement
in WB subtalar joint is critical in dampening proximal rotational forces while maintaining contact of the foot with the ground.
SUBTALAR JOINT STRUCTURE:
posterior articulation is the largest and formed by concave talus and convex calcaneus body.
anterior smaller and medial talocalcaneal articulation formed by two convex facets on the inferior body and neck of talus and concave facets on calcaneus.
sulcus is the bony tunnel between these 3 articulations.
bony outcropping on the calcaneus is sustentaculum tali
posterior articulation has its own capsule but medial and anterior articulations share a capsule with talonavicular joint.
SUBTALAR JOINT LIGAMENTS:
calcaneofibular, lateral talocalcaneal, cervical and interosseous ligaments
cervical is the strongest
inferior extensor retinaculum provides stability to subtalar joint.
SUBTALAR JOINT FUNCTION:
motion of talus on the calcaneus is complex twisting or screwlike motion.
triplanar motion of talus around single oblique joint axis producing Pronation/ Supination.
SUBTALAR AXIS
the motion about oblique axis cross all 3 planes.
Pro/sup modeled by single oblique hinge joint
motions are coupled and occur simultaneously as talus twists around subtalar joint
includes equal magnitude of EV/INV and ABD/ADD but less DF/PF.
NWB SUBTALAR JOINT MOTION
Supination is coupled with calcaneal motions of EVERSION , ABDUCTION, PLANTAR FLEXION.
Pronation is coupled with calcaneal motion of INVERSION, ADDUCTION, DORSIFLEXION .
WB SUBTALAR JOINT :
Supination is coupled with CALCANEAL INVERSION, TALAR MOTION OF ABD, DF, AND TIBIOFIBULAR LATERAL ROTATION.
Pronation is coupled with CALCANEAL EVERSION, TALAR MOTION OF ADD, PF AND TIBIOFIBULAR MEDIAL ROTATION.
calcaneus is locked or on the ground but can move INV/EV, but limited DF/PF, ADD/ABD.
EFFECT OF LOWER LEG ROTATION ON THE SUBTALAR JOINT:
Medial rotation of leg in WB is Pronation in the subtalar joint.
Lateral rotation of leg in WB is Supination in the subtalar joint.
RANGE OF SUBTALAR MOTION AND SUBTALAR NEUTRAL
find subtalar neutral
eversion 5-10 degrees
inversion 20-30 degrees
calcaneal valgus is seen in normal weightbearing more in EVERSION
TRANSVERSE TARSAL JOINT
AKA midtarsal or Chopart joint
compound joint
formed by talonavicular and calcaneocuboid joints ( together forms S-shaped joint that divides hindfoot from midfoot and forefoot)
motion consists of motion of talus and calcaneus on fixed naviculocuboid unit.
motion occurs together with subtalar joint.
TRANSVERSE TARSAL JOINT STRUCTURE:
TALONAVICULAR JOINT:
Proximal portion: anterior head of talus and distal portion of concave posterior navicular bone.
Joint Capsule includes anterior and medial facets of subtalar joint
Inferior aspect formed by plantar calcaneonavicular ligament ( spring ligament: supports talus head, one of the main static or passive stabilzers of the medial longitudinal arch)
medially reinforced by deltoid ligament
laterally reinforced by bifurcate ligaments.
concave socket supports convex head of talus.
talonavicular and subtalar joint are functionally linked in WB.
CALCANEOCUBOIDAL JOINT:
Formed proximally by anterior calcaneus and distally by posterior cuboid bone.
complex joint with the combination of concave and convex surfaces
linked with subtalar joint in WB.
Has its own joint capsule.
ligaments reinforcing this joint includes: bifurcate ligament laterally, calcaneocuboidal ligament dorsally, short plantar and long plantar calcaneocuboid ligaments inferiorly.
long plantar is the most important because it spans from calcaneus and cuboid bone to base of 2, 3, 4th metatarsals. also provides support to transverse tarsal joint as well as lateral longitudinal arch.
AXES OF TRANSVERSE TARSAL JOINT:
longitudinal axis is inclined 15 degrees superiorly from transverse plane and inclined 9 degrees medially from sagittal plane.
TRANSVERSE TARSAL JOINT FUNCTION:
linked with subtalar joint mechanically so that any WB subtalar motion causes the talonavicular and calcaneocuboid joint to move simultaneously.
linked between hindfoot and forefoot serving to :
1) add to supination/pronation range of the subtalar joint
2) compensate the forefoot for hindfoot position.
WB HINDFOOT PRONATION & TRANSERVE TARSAL JOINT FUNCTION:
in WB, MR of tibia imposes pronation on the subtalar joint.
WB INDFOOT SUPINATION AND TRANSERVE TARSAL JOINT MOTION:
in WB, LR on the tibia will impose subtalar supination
supination of subtalar joint (locked position) then the transverse tarsal joint is also moved into supination (locked position)-STIFF FOOT.
TARSOMETATARSAL JOINT AND ITS STRUCTURE:
plane synovial formed by distal tarsal bones posteriorly and bases of metatarsals.
1st TMT joint - base of 1st MT and medial cuneiform and has own joint capsule.
2nd TMT joint- base of 2nd MT and middle cuneiform also sides of medial and lateral cuneiform.more posterior than any other TMT joint. Stronger and has restricted motion.
3rd TMT joint- base of 3rd MT and lateral cuneiform and shares capsule with 2nd TMT joint.
4th & 5th TMT joint- base of 4th & 5th MT and distal surfaces of cuboid bone. and shares common joint capsule.
Deep transverse metatarsal ligament provides stability to proximal TMT joint by prventing excess motion and splaying of the metatarsal heads.
AXIS OF TMT JOINT:
each axes is oblique
a ray is defined as functional unit formed by a MT head and its cuneiform.( 1st-3rd ray)
4th and 5th rays formed only by metatarsal alone because MT articulates with cuboid bone.
1st TMT largest ROM. axis of 1st ray is inclined to perform DF-INV-ADD and PF-EVE-ABD.
5th ray more restricted motion DF-EVE-ABD, PF-INV-ADD.
3rd ray coincides with coronal axis, therefore DF-PF.
2nd ay least mobile.
TMT JOINT FUNCTION :
contributes in flattening of the plantar surfaces of the foot.
in WB, TMT functions to augment function of transverse tarsal joint. regulates the position of MT’s and phalanges in relation to WB surfaces.
SUPINATION TWIST :
xtreme pronation at subtalar joint is accompained by ADD & PF of the head of talus, calcaneus eversion,and pronation at transverse tarsal joint because navicular bone is forced down by talus.
and if forefoot is to remain on the ground the TMT joints undergo a counteracting SUPINATION TWIST .
PRONATION TWIST
xtreme supination at the subtalar joint accompanied by talar ABD-DF, calcaneal inversion, and forced supination of the transverse tarsal joint
if the forefoot remain on the ground, TMT joint undergo PRONATION TWIST.
FOREFOOT VARUS:
deformity associated with excessive pronation of the hindfoot.
identified by manually placing NWB calcaneus in subtalar neutral position and determining whether forfoot deviated in the frontal plane from the bisecting line of calcaneus.
PES CAVUS FOOT
SUPINATED
SEEN ON THE MEDIAL SIDE OF THE FOOT
CLAW TOES
PES PLANUS
PRONATED FLAT FOOT EXTERNAL ROTATION IS SEEN. SEEN ON THE LATERAL SIDE OF THE FOOT . AFFECTS KNEE COMPENSATE WITH IR OF FEMUR.
METATARSOPHALENGEAL JOINTS:
5 MTP JOINTS
Condyloid synovial with 2 dof FLEX/EXT(DF/PF), ADD/ABD
Note:
- during last stance phase of walking, toe extension at the MTP joint permits foot to pass over toes.
MTP JOINT STRUCTURE:
formed by convex MT proximally, and concave bases of proximal phalanges distally.
range of MTP extension exceeds MTP flexion
no opposition at 1st MTP joint,instead it moves in the plane of all digits.
2 sesamoid bones at 1st MTP joint that serves at anatomic pulleys for FHB muscle and protect FHL tendon from WB trauma.
MTP joint capsule, plantar plates, collateral ligaments, and deep transverse MT ligament provides stability to these joints.
PLANTAR PLATES
Structurally similar to volar plates.
protect WB surfaces of MTs head with collateral ligaments
contribute to the stability of the MTP joint.
serves as central stabilizing structure with fibrocartilagenous composition.Also withstand compressive loads.
MTP joint Function:
2 dof FLEX/EXT > ABD/ADD also EXT>FLEX serve primarily to allow WB foot to rotate over toes of MTP EXT(aka Metatarsal Break) when rising on toes during walking. Axis is oblique walking has 36-65 degrees of extension limited 1st MTP EXT = Hallucis Rigidus.
MTP joint (side note)
1st toe is normally adducted about 15-19 degrees
increase in normal valgus angulation of 1st MTP joint is known as hallux valgus, and varus angulation of 1st MT at TMT joint is METATARSUS VARUS.
IP joints:
synovial hinge joint
1 dof: FLEX/EXT,
toe- 1 IP joint, lesser toes - 2 IP joints.
toes function to smooth the weight shift to the opposite foot in gait, also help maintain stability by pressing against ground in standing.
PLANTAR ARCHES :
3 arches : medial and lateral longitudinal arch, and transverse arch.
medial arch - the largest arch
not present at birth
STRUCTURES OF ARCHES:
longitudinal arches
- anchored posterior calcaneus and anterior metatarsal heads.
- continuous laterally to medially.
- talus rests on the top of the vault of foot and is considered as “keystone of the arch”
- transverse arch is continuous as well. this arc is reduced at the level of MT heads parallel to WB surface.
- lateral arch is supported by long and short plantar ligaments
FUNCTION OF ARCHES
Serves two contrasting mobility and stability WB functions.
WB mobility function:
-the plantar arches must be flexible enough to allow the foot to dampen the impact of WB forces, to dampen superimposed rotational motions, to adapt to changes in supporting surfaces.
WB stability function:
-the plantar arches must allow distribution of the weight through foot for proper WB, and conversion of the flexible foot to a rigid lever.
PLANTAR APONEUROSIS
DENSE FASCIA covering entire foot.
supports arches of foot
truss and tie rod mechanism example to understand the aponeurosis of in supporting the arch.
TRUSS AND TIE ROD TRIANGLE VS. PLANTAR APONEUROSIS:
talus and calcaneus - posterior strut
tarsals and metatarsals- anterior strut.
plantar aponeurosis- tie rod that holds anterior and posterior struts when body weight is loaded on the triangle.
weighting in the foot will cause compression force on the struts (bones) and tie rod ( aponeurosis) will create tensile forces.
WINDLASS MECHANISM:
as plantar aponeurosis wraps around the MT heads and is tensed with MTP EXT, heel and MTP joint are drwan toward each other as the plantar portion of tie rod is shortened, which in further raises the arch and contributes to supination of the foot.
ELEVATION OF ARCH:
With toe extension occurs as plantar aponeurosis winds through the MT heads and draws the two ends of the aponeurosis toward each other.
Weight distribution :
Bilateral stance - each talus receives 50%of BW.
Unilateral stance- WB talus receives 100% of BW.
Standing- 50% weight received by talus pass through post subtalar articulation to calcaneus. 50% r less weight passes through talonavicular and calcaneocuboid joints yo forefoot.
MUSCLES INVOLVED INT HE ARCHES:
Dynamic support: (Extrinsic muscles ) Tibialis posterior and anterior, fibualris longus , FDL, fibualris tertius
Passive support: (plantar intrinsic muscles ) ABductor hallucis, FHB, FDB, ABDuctor digiti minimi, dorsal interossei.
Muscles of foot and ankle:
muscle activity is critical for dynamic stability
all muscles act over 2 joint muscles.
muscles inserting anterior to the ankle joint axis-DF torque
muscles inserting posterior to the axis- PF torque
muscles inserting medial to subtalar axis cause Supination and lateral to cause Pronation torques.
EXTRINSIC MUSCULATURE:
POSTERIOR COMPARTMENT MUSCLES:
pass posterior to the talocrural joint and therefore PLANTARFLEXORS
includes: Gastrocnemius, soleus, tibialis posterior, FDL, FHL.
Achilles’ tendon large moment arm and referred as a supinator
Triceps surae( gastroc + soleus)=strongest plantarflexors or helps with supination. Any activity of triceps surae on fixed foot will cause ankle PF, subtalar SUP, Elevation of longitudinal arch.
action of FHL causes distal phalanx of the hallux to press against ground, and that of FDL causes 4 lesser toes to grip the ground.
Tibialis posterior - large moment arm for supination
LATERAL COMPARTMENT MUSCLES:
Fibularis longus and brevis primary pronators of subtalr joint.
Fibularis longus runs transversely beneath the foot and inserts into base of 1st MT, and active contraction of this muscle support transverse arch and 1st ray of the root
ANTERIOR COMPARTMENT MUSCLES:
tibialis anterior( DF and Supination) , EHL( weak supinator of foot) , EDL, Fibularis tertius=> pronators of hind-foot and ankle dorsiflexors.
INTRINSIC MUSCULATURE:
Functions:
-stabilizers of toes
-dynamic supporters of transverse and longitudinal arches during gait.
following are intrinsic muscles of foot with their functions:
-EDB extends MTP joints
-ABDuctor hallucis ABD and FLEX MTP of hallux
-FDB FLEX PIP of 4 lesser toes.
-ABD digiti minimi ABD/ FLEX small toe.
-Quadratus plantae adjusts oblique pull of FDL in line with long axis of digits.
- Lumbricals FLEX MTPs, EXT IPs of 4 lesser toes.
-FHB FLEX MTP of toe
- ADD hallucis : oblique head adducts and FLEX MTP of toe, transverse head: ADD MT heads transversely.
-FDM FLEX MTP of small toe
-Plantar interossei ADD MTPs(3-5toes), FLEX MTPs, EXT IPs of 4 lesser toes.
- Dorsal interossei ABD MTPs of 2nd toe (either way), ABD MTPs (3&4toes) , FLEX MTPs, EXT IPsof 4 lesser toes.
