Biomechanics Final *Foot and Ankle* Flashcards
What is the Axis of Rotation and Plane of Motion for Plantar Flexion/Dorsiflexion?
Axis of rotation: Medial-Lateral
Plane of motion: Sagittal
What is the Axis of Rotation and Plane of Motion for Inversion/Eversion ?
Axis of Rotation: Anterior-Posterior
Plane of Motion: Frontal
What is the Axis of Rotation and Plane of Motion for Abduction/Adduction?
Axis of Rotation: Vertical
Plane of Motion: Horizontal
What is the Axis of Rotation and Plane of Motion for Supination?
Axis of Rotation: Oblique (varying by joint)
Plane of Motion: Varying elements of Inversion, adduction, and PF
What is the Axis of Rotation and Plane of Motion for Pronation?
Axis of Rotation: Oblique (Varying by joint)
Plane of Motion: Varying elements of Eversion, Abduction, and DF
What are the characteristics of the Talus bone?
When is joint congruency better? When is the joint most stable
- The body is wider anteriorly than posteriorly
- The talus/Tibia congruency is better in dorsiflexion than plantarflexion
- Joint stability is better when the joint is dorsiflexed
Tib-Fib is often mobilized to allow for more dorsiflexion ROM
What is the Arthrokinematics of the Tib-Fib joint?
Superior (Proximal) Tib-Fib
- Small Magnitude Translation
- No consensus on direction
Distal Tib-Fib
- Gapping (Distraction)
What are the 3 articulations of the Talocrural Joint?
- Tibiofibular
- Talotibial
- Talofibular
What are the Osteokinematics and Arthrokinematics of Dorsiflexion? What may limit this motion?
~ 10-20° of movement
- The head of talus glides posteriorly and foot moves anteriorly
- May be limited by Tricep Surae (Gastroc., Soleus, Plantaris) with the knee extended and by soleus/posterior capsule ligaments with knee in flexion
What are the Osteokinematics and Arthrokinematics of Plantarflexion? What may limit this motion?
~ 20-50° of movement
- The head of talus glides anteriorly and foot moves posteriorly
- May be limited by dorsiflexors and anterior capsule/ligaments
What may be other Talocrural (Ankle) joint restrictions? (Other factors resisting dorsiflexion)
- An osseus structure of the ankle joint may limit motion
- Tight intrinsic muscles of the foot or tight plantar fascia may limit the amount of ankle dorsiflexion available
When is the Talocrural Joint (ankle) most stable?
When in dorsiflexion because of the tight fit of the talus in the ankle mortis. (The talus is wider into mortis in dorsiflexion)
- Interosseus membrane and ligaments help increase stability by preventing separation of the tibia and fibula
Is the capsule of the ankle strong?
The Capsule is weak and thin, especially anteriorly and posteriorly
What are the lateral ligaments (LCL) of the ankle and what do they limit?
- Anterior Talofibular Ligament (most commonly injured)
–Limits anterior translation
–Also Inversion, adduction, Plantarflexion - Calcaneofibular ligament (second most commonly injured)
–Limits Inversion, dorsiflexion - Posterior Talofibular Ligament
–Limits posterior translation
–Also Abduction, inversion, dorsiflexion
What are the medial ligament (MCL) of the ankle and what do they limit?
Deltoid Ligaments
- Tibiotalar fibers
–Eversion, dorsiflexion with associated posterior slide of talus - Tibionavicular fibers
(Talocrural Jt.) –Eversion, abduction, plantarflexion with associated plantarflexion
(Talonavicular Jt.). –Eversion, abduction - Tibiocalcaneal Fibers
–Eversion
Describe subtalar movement in regards of the tibia in closed chain.
Inversion (Supination) requires ER of tibia
Eversion (Pronation) requires IR of tibia
What is subtalar neutral?
The point where the subtalar joint is neither pronated or supinated, the neutral position is 0°
- In this position the joint is typically 1/3 the distance from full eversion and 2/3 the distance from full inversion
What are the recommendations with orthotic and footwear relative to gait?
- There should be enough pronation (eversion) for shock absorption
–During the load response phase
–Heel contact to foot flat
~ 0 - 10° of the gait cycle - There should be enough supination (inversion) for rigidity during push-off
–Just before heel off
–End of midstance
~ 40 - 60° of the gait cycle
What are typical consequences of Overpronation?
- The leg will internally rotate and can cause forward pelvic tilt
- Causing foot, knee and back pain
In the foot and ankle, what is the difference between open chain and closed chain?
In open chain, the fore-foot always moves in the same direction as the foot
In closed chain, the fore-foot may move in the opposite direction to the foot
What is the function of the Mid-tarsal joint?
- Allows the fore-foot to demonstrate greater inversion/eversion ROM relative to the shank than the subtalar
- Compensate for hindfoot positioning in Closed chain to maintain the entire foot in contact with the ground
What is the function of the foot arches?
Allows the foot to act as rigid or elastic
- During the first half of stance:
(Dampens and/or stores impact forces) - Second half of stance
(Transmits push-off forces)
What happens if the arches are too high or low?
If the arches are too high (Pes Cavus) or too low (Pes Planus) they would not function properly?
What ligaments support the Arches?
- Spring ligament
- Long/Short Plantar ligament
- Plantar aponeurosis (fascia)
Which ankle/foot action has the highest isometric torque?
Plantar flexion
Soleus is one of the strongest muscles of the body
Extreme subtalar pronation causes?
Fore-foot supination twist
Extreme subtalar supination causes?
Fore-foot pronation twist
