Biomechanics of Ankle for DPT students

1. Biomechanics of the Ankle joint
Dr. Abid Ullah PT
Lecturer FIMS
Abbottabad
Email:
dr.abidullahpt@yahoo.com

2. Contents
 Functions of the ankle
 Joint structure of the ankle
 Kinematic of the ankle
 Muscle of the ankle
 Ankle stability
 Mechanism of injury at the ankle

3. Function of the ankle
 To provide stability for weight bearing
 To allow the mobility of foot

4. Joint structure of the ankle
 Joint at the ankle
 Talocural joint (ankle joint): Principle joint at the ankle
complex
 Inferior tibiofibular joint: syndesmosis
 Subtalar joint

5. Talocural joint
 Synonym: ankle joint
 Proximal component: concave ankle mortise
 Concave distal tibia
 Concave distal fibulaa
 Distal component: convex dome of the talus
 Joint types: hing joint
 Motion: convex on cancave
 Ankle dorsiflexion /planter flexion with posterior /anterior
glide of the talus on the ankle mortise
 DOF= I
 Resting position: slight ankle planter flexion (10 degree)
 Close packed position: Full ankle dorsiflesion

6. Inferior tibiofibular joint
 Synonym: distal tibiofibular joint
 Proximal component: convex facet of the distal tibia
 Distal component: convex facet of the distal fibula

7. Kinematic of the ankle
 Ankle dorsiflexion and planter flexion
 Joint involved
 Talocrual joint
 Inferior tibiofibular joint
 Plane of motion: sagittal plane (actually triplane)
 Axis of rotation:
 A frontal axis passing through the center of the latteral
malleolus of the fibular & the lower tip of the medial melleolus
of the tibia
 At an angle of the 13-18 degree laterally from the frontal plane
and angle of 8-10 degree from the transverse plane

8. Cont…

9. Osteokinametic movement
 Range of motion
 0-20 degree for ankle dorsiflexion
 0-55 degree for ankle planterflexion
 Triplanar motion: since the joint axis of the ankle is not just in
the cardinal plane, the motion ocuuring at the ankle joint
present a triplanar motion pattern
 Dorsiflexion range with eversion and adduction
 Planter flexion with inversion and adduction
 Functional range: At least 10 deg of ankle dorsiflexion is
necessary for normal gailt
 Closed kinametic chain motions;
 Deep squating
 Stance phase of thegait cycle

10. Cont...
 Arthrokinematic movement (convex on concave)
 Talocural joint:
 Posterior glide of the talus on the ankle mortise with ankle dorsiflexion
 Anterior glide of the talus on the ankle mortise with ankle flanterflexion
 inferior tibiofibular joint
 Separation of the fibula from the tibia
 Superior glide of the fibula on the tibia e dorsiflexion
 Factors limitting ankle dorsiflexion
 Ankle mortise
 Passive tension of the aclles tendon
 Factor limttingankle planter flexion
 Calcaneous
 Tension of the anteior comparment

11. Muscle of the ankle
 Ankle dorsiflexors
 Tibilus anterior: dorsiflexion +inversion
 Toe extensors
 Peroneus tertius: dorsiflexion +eversion
 Ankle planterflexors
 Triceps surae: Two joint muscle
 Medial head of the gastrocnemic
 Lateral head of the gastrocnemic
 Soleus head of the gastronemic
 Toe flexors or tibilius posterior
 Peroneus longus: planterflexion +eversion

12. Ankle stability
 Factor effecting ankle stability
 Bony configuration: most important
 Shape of down of talus
 Anterior edge > posterior edge
 Medial edge > lateral edge
 Tension of the ligament other connective tissue
 Deltoid ligament (medial collateral ligament): prevent valgus
stress
 Lateral collateral ligament: prevent varcus stress

13. Cont…
 Anterior talofibular ligament: prevent a stress toward
plantarflexion + inversion
 Calcaneofibular ligament: prevent stress toward pure
inversion
 Posterior talofibular ligament
 Anterior inferior tibiofibular (AITF) ligament: hold
two bones together
 Muscular arrangement
 Peroneus longus & brevis
 Tabialis posterior

14. Mechanism of injury at the ankle
 Direct stress
 Ankle sprain
 Avulsion fracture of medial melleolus
 Repeated stresses
 Repeated ankle planterflexion Achilles tendon
tendinitis Achilles tendon rupture
 Repeated eccentric ankle dorsiflexion anterior
compartment syndrome