Biomechanics Final *Foot and Ankle*

Question 1

What is the Axis of Rotation and Plane of Motion for Plantar Flexion/Dorsiflexion?

Answer 1

Axis of rotation: Medial-Lateral

Plane of motion: Sagittal

Question 2

What is the Axis of Rotation and Plane of Motion for Inversion/Eversion ?

Answer 2

Axis of Rotation: Anterior-Posterior

Plane of Motion: Frontal

Question 3

What is the Axis of Rotation and Plane of Motion for Abduction/Adduction?

Answer 3

Axis of Rotation: Vertical

Plane of Motion: Horizontal

Question 4

What is the Axis of Rotation and Plane of Motion for Supination?

Answer 4

Axis of Rotation: Oblique (varying by joint)

Plane of Motion: Varying elements of Inversion, adduction, and PF

Question 5

What is the Axis of Rotation and Plane of Motion for Pronation?

Answer 5

Axis of Rotation: Oblique (Varying by joint)

Plane of Motion: Varying elements of Eversion, Abduction, and DF

Question 6

What are the characteristics of the Talus bone?
When is joint congruency better? When is the joint most stable

Answer 6

• 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

Question 7

What is the Arthrokinematics of the Tib-Fib joint?

Answer 7

Superior (Proximal) Tib-Fib
- Small Magnitude Translation
- No consensus on direction

Distal Tib-Fib
- Gapping (Distraction)

Question 8

What are the 3 articulations of the Talocrural Joint?

Answer 8

• Tibiofibular
• Talotibial
• Talofibular

Question 9

What are the Osteokinematics and Arthrokinematics of Dorsiflexion? What may limit this motion?

Answer 9

~ 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

Question 10

What are the Osteokinematics and Arthrokinematics of Plantarflexion? What may limit this motion?

Answer 10

~ 20-50° of movement

• The head of talus glides anteriorly and foot moves posteriorly
• May be limited by dorsiflexors and anterior capsule/ligaments

Question 11

What may be other Talocrural (Ankle) joint restrictions? (Other factors resisting dorsiflexion)

Answer 11

• 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

Question 12

When is the Talocrural Joint (ankle) most stable?

Answer 12

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

Question 13

Is the capsule of the ankle strong?

Answer 13

The Capsule is weak and thin, especially anteriorly and posteriorly

Question 14

What are the lateral ligaments (LCL) of the ankle and what do they limit?

Answer 14

• 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

Question 15

What are the medial ligament (MCL) of the ankle and what do they limit?

Answer 15

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

Question 16

Describe subtalar movement in regards of the tibia in closed chain.

Answer 16

Inversion (Supination) requires ER of tibia

Eversion (Pronation) requires IR of tibia

Question 17

What is subtalar neutral?

Answer 17

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

Question 18

What are the recommendations with orthotic and footwear relative to gait?

Answer 18

• 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

Question 19

What are typical consequences of Overpronation?

Answer 19

• The leg will internally rotate and can cause forward pelvic tilt
• Causing foot, knee and back pain

Question 20

In the foot and ankle, what is the difference between open chain and closed chain?

Answer 20

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

Question 21

What is the function of the Mid-tarsal joint?

Answer 21

• 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

Question 22

What is the function of the foot arches?

Answer 22

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)

Question 23

What happens if the arches are too high or low?

Answer 23

If the arches are too high (Pes Cavus) or too low (Pes Planus) they would not function properly?

Question 24

What ligaments support the Arches?

Answer 24

• Spring ligament
• Long/Short Plantar ligament
• Plantar aponeurosis (fascia)

Question 25

Which ankle/foot action has the highest isometric torque?

Answer 25

Plantar flexion

Soleus is one of the strongest muscles of the body

Question 26

Extreme subtalar pronation causes?

Answer 26

Fore-foot supination twist

Question 27

Extreme subtalar supination causes?

Answer 27

Fore-foot pronation twist