Biomechanics of the ankle & foot complex Flashcards
Conflicting functions of the ankle-foot
Stability -Provides stable BOS -Acts as a Rigid Lever Mobility -Dampens LE rotations -Adapt to varied surfaces -Flexible to absorb shock
Forefoot
Metatarsals and phalanges
- Adapts to terrain
- Heavily influenced by hindfoot
Midfoot
Navicular Cuboid 3 Cuneiforms -Transmits hindfoot motion to forefoot -Promotes stability -Heavily influenced by hindfoot
Hindfoot
Talus
Calcaneus
-Converts LE transverse plane motion into sagittal, frontal, and horizontal plane motion
Pronation (Composite)
Dorsiflexion
Eversion
Abduction
Supination (Composite)
Plantarflexion
Inversion
Adduction
Distal Tibiofibular Syndesmosis
Stabilizes mortise with crural interosseous tibiofibular ligament.
Ligament pulls fibula towards tibia
Distal Talocrural Joint structure Transverse Plane
Talus body width greater anterior than posterior
Lateral surface area greater than medial surface area
Talocrural Dorsiflexion
20-30 degrees
Talocrural Plantarflexion
30-50 degrees
Talocrural Medial Rotation
7 degrees
Talocrural Lateral Rotation
10 degrees
Talocrural Inversion
5 degrees
Talocrural Eversion
5 degrees
Talocrural Gait requirements
10 degrees dorsiflexion
20 degrees plantarflexion
Talocrural Ascending stairs requirements
20-25 degrees DF
10-15 degrees PF
Talocrural Running Requirements
25 degrees DF
25 degrees PF
Gait talocrural compression force
4.5 times body weight
Talocrural OKC DF Arthrokinematics
- Convex talus moving on concave mortise
- Anterior talar roll and posterior slide
- More posterior talar excursion laterally=Abduction of talus
Talocrural CKC DF Arthrokinematics
Concave mortise on convex talus
Anterior roll and anterior slide
More anterior excursion laterally=Adduction of mortise on talus
Superior glide of Fibula as larger part of talus enteres motise
Frontal plan ankle axis
8-10 degrees from horizontal