Joint Biomechanics - Ankle and Foot Flashcards
Stable Foot
- Sufficiently support the weight-bearing force from the body.
- Absorb the shock from landing on the ground below.
- Propel the body through space by pushing off the ground.
Generally a factor of dorsiflexion/plantarflexion of the foot at the talocrural joint.
Flexible Foot
- Adapt to the uneven ground surfaces.
Generally a factor of eversion/inversion of the foot at the subtalar joint.
Talocrural Joint
Between trochlear surface of talus (convex) and the distal tibia and fibula (concave).
Synovial hinge joint - Lock and key.
- Mortise: tibia and fibula (lock)
- Tenon: talus (key)
Motion of the Talocrural Joint
Usually combined with subtalar and midtalar joint motion.
- Plantarflexion is usually associated with adduction and inversion.
- Dorsiflexion is usually associated with abduction and eversion
Planes and ROM of the Talocrural Joint
Plantarflexion: Sagittal plane, transversal axis, 50° ROM.
Dorsiflexion: Sagittal plane, transversal axis, 20° ROM (limited due to tension in gastrocnemius).
Talocrural Joint - Position of Talus Regarding Movement
Dorsiflexion: Broader anterior part of trochlear surface of talus is forced between the narrower posterior part of tibiofibular mortise (makes it stiffer, less ROM).
Plantarflexion: Narrower posterior part of the trochlea of the talus moves forward into the broader part of the tibiofibular mortise.
Arthrokinematics of the Talocrural Joint in OKC
Plantarflexion: Convex talus glides on concave mortise (roll and slide in opposite directions), Posterior-anterior slide.
Dorsiflexion: Convex talus glides on concave mortise (roll and slide in opposite directions), Anterior-posterior slide.
Talocrural Joint - Lateral Ligaments
Between the talus and the distal tibiofibular joint. Prevent inversion. Three major ligaments: - Anterior talofibular ligament - Posterior talofibular ligament - Calcaneofibular ligament
Anterior Talofibular Ligament
Origin: Lateral malleolus
Insertion: Lateral side of talus
Posterior Talofibular Ligament
Origin: Lateral malleolus
Insertion: Posterior side of talus
Calcaneofibular Ligament
Origin: Lateral malleolus
Insertion: Calcaneus
Talocrural Joint - Medial Ligaments
Between the talus and the distal tibiofibular joint
Prevents eversion.
Deltoid ligament is a group of 4 ligaments:
- Posterior tibiotalar ligament
- Anterior tibiotalar ligament
- Tibiocalcaneal ligament
- Tibionavicular ligament
Posterior Tibiotalar Ligament
Origin: Medial malleolus
Insertion: Posterior side of talus
Anterior Tibiotalar Ligament
Origin: Medial malleolus
Insertion: Anterior side of talus
Tibiocalcaneal Ligament
Origin: Medial malleolus
Insertion: Calcaneus
Tibionavicular Ligament
Origin: Medial malleolus
Insertion: Navicular
Which ligaments control abduction of the talus?
Tibiocalcaneal ligament
Tibionavicular ligament
Which ligament controls adduction of the talus?
Calcaneofibular ligament
Which ligaments control plantarflexion?
Anterior tibiotalar ligament
Anterior talofibular ligament
Which ligaments control dorsiflexion?
Posterior tibiotalar ligament
Posterior talofibular ligament
Which ligaments control external rotation?
Anterior tibiotalar ligament
Tibionavicular ligament
Which ligament controls internal rotation?
Anterior talofibular ligament
Agonists and Synergists of Plantarflexion
Agonist: Gastrocnemius and soleus.
Synergist: Tibialis posterior, fibularis longus + brevis, flexor digitorum longus and flexor hallucis longus.
Agonists and Synergists of Dorsiflexion
Agonist muscles: Tibialis anterior.
Synergist muscles: Extensor digitorum longus and
extensor hallucis longus.
Subtalar Joint
Composed of three separate talocalcaneal
articulations:
• Posterior facets of the talus and calcaneus
• Anterior facets of the talus and calcaneus
• Medial facets of the talus and calcaneus
Synovial joint
Thin joint capsule surrounding the joint
Planes and ROM of the Subtalar Joint
Eversion: Diagonal plane, oblique axis, 18° ROM (less ROM because of the structures).
Inversion: Diagonal plane, oblique axis, 25-30° ROM.
Arthrokinematics of the Subtalar Joint (OKC) - Inversion
Consider anterior and posterior parts separately.
Inversion: Concave anterior calcaneus glides on the
convex talus and convex posterior calcaneus glides on the concave talus:
- Medial glide (anterior portion)
- Lateral glide (posterior portion)
Arthrokinematics of the Subtalar Joint (OKC) - Eversion
Eversion: Concave anterior calcaneus glides on the
convex talus and convex posterior calcaneus glides on the concave talus:
- Lateral glide (anterior portion)
- Medial glide (posterior portion)
Agonists and Synergists of Eversion
Agonist: Fibularis longus and fibularis brevis
Synergist: extensor digitorum longus
Agonists and Synergists of Inversion
Agonist: tibialis anterior and tibialis
posterior
Synergist: flexor digitorum longus, flexor
hallucis longus and extensor hallucis longus
Ligaments of the Subtalar Joint
• Interosseous (talocalcanean) ligaments: maintains stability, both at rest and during activity.
• Medial talocalcanean ligament:
• Lateral talocalcanean ligament:
Confer a degree of stability to by holding the talus
between the leg and calcaneus.
• Posterior talocalcanean ligament
Which muscles reinforce the ligamentous support of the subtalar joint?
The fibularis muscles laterally and flexor hallucis longus
medially
Talocalcaneonavicular Joint
Synovial joint of the ball and socket variety
• The ball: large continuous facet on the head and lower
surface of the neck of the talus
• The socket: facet for the navicular anteriorly and an
anterolateral facet for the anterior part of the calcaneus
Talocalcaneonavicular Joint - Ligaments
Plantar calcaneonavicular ligaments
Bifurcate ligament
- Major elements contributing to stability of the joint
together with tibialis posterior.
- Resists the tendency of body weight to push the head
of the talus inferiorly.
Dorsal talonavicular ligament
Calcaneocuboid Joint
Between facets on the anterior surface of the calcaneus
and posterior surface of the cuboid.
Calcaneocuboid Joint - Ligaments
Dorsal calcaneocuboid ligament
Bifurcate ligament
Long plantar ligament
Plantar calcaneocuboid ligament
- Major elements contributing to stability
- The calcaneocuboid joint receives the body weight
transmitted on the lateral part of the longitudinal arch of the foot.
Transverse Tarsal Joint
Combination of talonavicular and calcaneocuboid joints.
With subtalar joint, allows pronation and supination movements allowing the foot to be placed firmly on slanting or irregular surface.
Pronation of the Ankle
Eversion + dorsiflexion + abduction
Eversion: Frontal plane, Sagittal axis
Dorsiflexion: Sagittal plane, Frontal axis
Abduction: Transverse plane, Vertical axis
Convex-concave rule does not apply!
Supination of the Ankle
Inversion + plantarflexion + adduction
Inversion: Frontal plane, Sagittal axis
Plantarflexion: Sagittal plane, Frontal axis
Adduction: Transverse plane, Vertical axis
Convex-concave rule does not apply!
Tarsometatarsal Joint
Between the distal row of tarsal bones and metatarsal bones.
Decreased mobility in the 2nd TMT: most stable of the five TMT. Central stable pillar of the foot.
Allows dorsiflexion/plantarflexion, inversion/eversion.
Metatarsophalangeal Joints
Flexion and extension are the primary movements occurring at the MTP.
The concave phalangeal base glides on the
convex head of the metatarsals in the same direction as the movement.
Interphalangeal joints
Flexion and extension are the primary movements occurring.
The proximal and distal concave surface slides
in the same direction as the movement.
Arthrokinematics - Metatarsophalangeal +
Interphalangeal Joint Flexion
Concave phalangeal bones glide on the
convex metatarsal heads, from posterior to anterior.
Arthrokinematics - Metatarsophalangeal +
Interphalangeal Joint Extension
Concave distal phalangeal glides on the convex head of phalanges, from anterior to posterior.
Agonists and Synergists of Interphalangeal Joint Flexion
Agonist: Flexor digitorum longum (toes 2-5)
and flexor hallucis longus (1st toe)
Synergist: Lumbricals, interossei and flexor
digiti minimi brevis.
Agonists and Synergists of Interphalangeal Joint Extension
Agonist: Extensor digitorum longus (toes 2-5) and extensor hallucis longus (1st toe)
Synergist: Lumbricals and extensor digitorum brevis
The Windlass Mechanism
Truss (triangle) formed by calcaneus, midtarsal joint and metatarsals (arch of the foot) and plantar aponeurosis/fascia (forms tie-rod/horizontal line).
- Vertical forces from body weight travel down the tibia (upper angle of triangle) (flatten medial arch).
- Ground reaction forces travel upwards on calcaneus and on metatarsal head (two lower angles of triangle).
What prevents the collapse of the truss (triangle) of the windlass mechanism?
The orientation of the vertical and ground reaction forces would cause a collapse of the truss; however, increased plantar- fascia tension in response to these forces maintains the truss’s integrity.
