Ankle and Foot Complex Flashcards
Ankle/Foot Complex
Adaptations that optimize its primary role to bear weight
The complementing structures of the ankle/foot complex permit:
Both stability and mobility, depending on current needs
What does the foot need to do in order for pushing off when walking, running, or jumping?
Be stable to provide an adequate base of support and to function as a rigid lever
Why does the foot need to be mobile?
To adapt to uneven terrain, absorb shock as the foot hits the ground, and control forces imposed by the more proximal joints of the lower extremity
How many bones and component joints?
28 Bones; 25 Joints
3 Functional Segments of the Foot
Rearfoot (posterior): Calcaneus and Talus
Midfoot (middle): Cuboid, Navicular, Cuneiforms
Forefoot (anterior): Metatarsals and Phalanges
Motions of the Foot
Dorsiflexion / Plantarflexion
Inversion / Eversion
Abduction / Adduction
Dorsiflexion / Plantarflexion
Sagittal plane around a coronal axis
Inversion / Eversion
Frontal plane around a longitudinal axis
Abduction / Adduction
Transverse plane around a vertical axis
Motion at the Toes
Sagittal plane around a coronal axis
Flex: toes down
Ext: toes up
Pronation / Supination of the Foot
Occur around an axis that lies at an angle to each of the axes for “cardinal” motions
Composite Motions = Combination of the other motions
Non-weightbearing Pronation
DF, EV, ABD
Non-weightbearing Supination
PF, INV, ADD
Valgus
Increase in medial angle between two bones
Calcaneovalgus
An increase in the medial angle between the calcaneus and posterior leg
> 180 deg
Varus
Decrease in the medial angle between two joints
Calcaneovarus
A decrease in the medial angle between the calcaneus and posterior leg
<180 deg
Ankle Joint: Talocrural Joint
Type of Joint
~Synovial Hinge Joint
~1 DOF: DF/PF
~Proximal articular surfaces:
–>Concave mortise:
—–>Distal tibia (tibia plafond)
—–>Malleoli: Medial (tibia), Lateral (fibular)
How many degrees of DF is needed for normal gait?
10 degrees
Ankle Joint:
Talocrural Joint
Ankle mortise is adjustable
~Proximal TFJ
~Distal TFJ
~Interosseous membrane
Ankle
Proximal Tibiofibular Joint
~Plane synovial joint between:
—>Head of fibula and Posterolateral aspect of tibia
~Most common pattern
—>Convex tibial facet
—>Concave fibular facet
Ankle
Distal Tibiofibular Joint
~Syndesmosis between:
—>Concave tibial facet
—->Convex fibular facet
~Separated by fibroadipose tissue
Ankle
Interosseous membrane
~Directly supports both articulations - Prox. and Dist. TFJ
Ankle Mortise adjustability
~Inherently stable
—>Boney congruency
—>Ligamentous support
~Requires mobility for normal function:
—>Primarily due to FIBULA (transmits <10% weightbearing forces)
Ankle Distal Articular Surface
~Body of Talus has 3 facets
1. Lateral/fibular: larger
2. Medial/tibial: smaller
3. Trochlear/superior: Convex and Central groove (slight angle)
~Wider anteriorly: Wedge-shape
Ankle Joint Structure
~Capsule: fairly weak (anteriorly and posteriorly)
~Medial CL
~Lateral CL
~Superior Peroneal Retinaculum
Ankle Medial Collateral Ligament
“Deltoid Ligament”
~Fan-shaped
~Extremely Strong
~Checks eversion and pronation
Lateral Collateral Ligament
~3 Bands
1. Anterior talofibular
2. Posterior talofibular
3. Calcaneofibular
~Weaker
~Checks inversion and supination
Superior Peroneal Retinaculum
~Lies close to parallel to the CFL
~Reinforces CFL
Talocrural Joint
Oblique Joint Axis
~Downward angulation from medial to lateral of 14 degrees from transverse plane
~Rotated 23 degrees from the frontal plane
Talocrural Joint
Shape of Talus
~Wedge-shaped (wider anteriorly)
~Through DF, the talus will “wedge” into the mortise (separates tibia and fibula)
~Supports and enhances stability
Talocrural Joint
Closed-Pack position
Max DF
Talocrural Joint
Open-Pack position
10 deg PF
Talocrural Joint
Arthrokinematics
Open Chain: Convex on Concave
Closed Chain: Concave on Convex
Talocrural Joint
Joint Function
~Overall AMOUNT of motion and PLANES of motion is variable
~Important:
-Observed limitation in DF Post injury and surgery
~Prox. TFJ:
-Concave fibular facet
-Convex tibial joint
~Dist. TFJ:
-Convex fibular head
-Concave tibial facet
Allow fine tuning for normal ROM in all 3 planes
Proximal and Distal Tibiofibular Joints
Subtalar Joint
3 Plane Articulations
~Posterior
~Anterior and Middle
~Tarsal Canal
Subtalar Joint
Posterior
~Largest, receives 75% force transmission
~Concave talar facet
~Convex Calcaneal facet
Subtalar Joint
Anterior and Middle
~Smaller
~Each have a convex talar facet
~Each have a concave calcaneal facet
Subtalar Joint
Tarsal Canal
~Creates 2 separate joint cavities
~Posterior articulation: individual capsule
~Anterior and middle articulations: share capsule with talonavicular joint
~Sinus Tarsi: large end of canal
—>anterior to fibular malleolus
Subtalar Joint
Cervical Ligament
- Strongest
- Lies anterior to sinus tarsi
- Joins neck of talus to neck of calcaneus
Subtalar Joint
Interosseous talocalcaneal ligament
Lies medially in tarsal canal
Runs obliquely from talus to calcaneus
Subtalar Joint Function
Axis of motion:
* 42° inclination up from the
transverse plane
* 16° medially from an AP axis
* Therefore motion crosses all
3 planes
Subtalar Joint Function
2 DoF commonly described:
* Inversion/eversion
* Varus/valgus
* Pronation/supination
* Pronation and supination=component motions of 3 cardinal
planes
Subtalar Joint Arthrokinematics
Posterior: concave talus on convex calcaneus *
Anterior and middle: convex talus on concave calcaneus
Supination Non-Weightbearing
Calcaneal inversion
Calcaneal adduction
Calcaneal plantarflexion
Supination Weightbearing
Calcaneal inversion
Talar abduction
Talar dorsiflexion
Pronation Non-Weightbearing
Calcaneal eversion
Calcaneal abduction
Calcaneal dorsiflexion
Pronation Weightbearing
Calcaneal eversion
Talar adduction
Talar plantarflexion
Foot Posture
Pes Planus (Flatfoot)
Hyper-Pronation
Foot Posture
Pes Cavus (high arch)
Hyper-Supination
Subtalar Joint
Closed Chain Implications
~Subtalar supination
* Tibiofibular lateral rotation
~Subtalar pronation
* Tibiofibular medial rotation
Subtalar Joint
ROM
- Subtalar Neutral
- Controversial
- Normal: 3.5° valgus
- Calcaneal eversion (valgus) 5-10°
- Calcaneal inversion (varus) 20-30°
- Pronation/Supination
- Difficult to measure
Subtalar Joint
Open-Packed position
Inversion/Plantarflexion
Transverse Tarsal Joint
“Transverse Tarsal” or “Chopart” Joint
Formed by: Talonavicular and Calcaneocuboid Joints
Transverse Tarsal Joint
Talonavicular Joint
- “ball” head of talus
- “socket” formed anteriorly by concavity in
navicular, inferiorly by anterior and
middle calcaneal facets - Plantar calcaneonavicular ligament
- “spring ligament”
- Sustentaculum tali to inferior navicular
- Continuous medially with portion of deltoid
ligament and joins bifurcate ligament laterally - Important passive stabilizer to medial
longitudinal arch
Transverse Tarsal Joint
Calcaneocuboid Joint
Anterior calcaneus
* Posterior cuboid
* Reciprocal saddle-shaped
* Reinforced via:
* Joint capsule
* Bifurcate ligament
* Dorsal CCL, short plantar ligament
* Long plantar ligament
* Supports TTJ and lateral longitudinal
arch
Joint Function:
Transverse Tarsal Joint
Motion is described as the talus and
calcaneus MOVING TOGETHER ON the
navicular and cuboid
~Longitudinal axis
~Oblique axis
Transverse Tarsal Joint
Longitudinal axis
- Inclined 15° from the transverse
plane - Inclined 9° medially from sagittal
plane - Triplanar-
supination/pronation - IV/EV moments
predominate
Transverse Tarsal Joint
Oblique axis
- Inclined 52° superiorly from
transverse plane - Inclined 57° from the sagittal plane
- Triplanar-
supination/pronation - DF/PF and ABD/ADD
predominate
Transverse Tarsal Joint
Big Picture
Subtalar joint and Transverse Tarsal joints are mechanically linked
* Transitional link between:
* Rearfoot
* Forefoot
* Purpose:
* Add to the supination/pronation ROM of subtalar joint
* In WBIng or NWBing
* Compensate the forefoot for rearfoot position
Transverse Tarsal Joint
Open-Packed position
Pronation
Transverse Tarsal Joint
Closed-Packed position
Full Supination
Tarsometatarsal Joints
- Plane, synovial Joints
- Between distal row of tarsals and bases of
metatarsals - 1st TMT: own joint capsule
- 2nd -3rd ; 4th -5th : share joint capsules
- Deep Transverse Metatarsal Ligament:
- Prevents excessive splaying of the metatarsal
heads
Joint Function:
Tarsometatarsal Joints
Ray: functional unit
* 1-3: metatarsal + associated cuneiform
* 4-5: metatarsal alone
Joint Function:
Tarsometatarsal Joints Axis of Motion
- First Ray: oblique
- DF is coupled with IV and ADD
- PF is coupled with EV and ABD
- Fifth Ray: oblique
- DF coupled with EV and ABD
- PF coupled with IV and ADD
- Third Ray: close to coronal axis
- DF/PF
Joint Structure: Metatarsophalangeal Joints
- Condyloid, synovial joints
- 2 DOF:
- extension/flexion (DF/PF)
- ABD/ADD
Metatarsophalangeal Joints
Arthrokinematics
Convex: metatarsal head
Concave: base of proximal
phalange
Metatarsophalangeal Joints
1st Metatarsal
2 sesamoid bones
Anatomical pulley for Flexor Hallucis Brevis
Metatarsophalangeal
Joints Supported by:
Plantar plates
Joint capsule
Collateral ligaments
Joint Function:
Metatarsophalangeal
Joints
- Metatarsal Break
- Hinge or “break” point
- Located at the metatarsal heads as they move into
extension - 36-65° overall during gait
- Approx 60-70° at first MTP alone
- Occurs as the heel rises and the metatarsal heads +
toes remain weightbearing - Convex metatarsal heads move on concave
phalanges - Around an oblique axis
Joint Structure: Interphalangeal Joints
Synovial, hinge joints
1 DOF: Ext/Flex
Great toe: 1 IP joint
Toes 2-5: 2 IP joints each
Essentially each phalanx is identical in structure to hand
Plantar Arches
3 Arches
- Medial longitudinal arch
* Largest
* Apex: talus - Lateral longitudinal arch
3.Transverse arch
* Apex at the distal metatarsals: second metatarsal
* Apex at the TMT joints: middle cuneiform
Plantar Arches
Arthrology contributes to first level of stability
* Medial longitudinal arch support:
* Spring ligament, interosseous TC ligament, deltoid ligament, plantar
aponeurosis
* Lateral longitudinal arch support:
* Long and short plantar ligaments
Function: Plantar Arches
~Mobility
* Dampen impact of weightbearing forces
* Dampen rotational motions
* Adapt to surface changes
~Stability
* Allow distribution of weight through the foot for proper weightbearing
* Convert to a rigid lever in gait
Function: Plantar Arches
Plantar Aponeurosis (plantar fascia)
Runs length of the foot
* Metatarsal heads act as pulleys:
* During extension tension is placed on the
plantar aponeurosis
* With progression, heel and MTPs are
drawn closer together
* Longitudinal arch height increases
* Contributes to supination of the foot
(rigid lever for push off)
* Called the: windlass mechanism
Muscular Contributions
To Arches
~Posterior tibialis
* Most consistent function in medial
longitudinal arch support
~Plantar intrinsics
* Active in quiet bilateral stance and in gait
Muscular Contributions
To the Ankle and Foot
- No muscle acts on one joint in isolation
- Position of the muscle relative to the axis dictates
function - Anterior to talocrural:
- DF moments
- Posterior to talocrural
- PF moments
- Medial to subtalar:
- Supination moments
- Lateral to subtalar:
- Pronation moments