Week 12 - The ankle joint

Question 1

What are the roles of the ankle joint?

Answer 1

• Weight bearing

- Locomotion

Question 2

What are the articulations of the ankle joint?

Answer 2

Between the tibia, fibula and talus

• The tibia and fibula are bound together by strong tibiofibular ligaments, which produces a bracket-shaped socket known as a mortise
• The body of the talus fits snugly into the mortise
• During Dorsiflexion, the anterior part of the talus is held in the mortise, so the joint is more stable (opposite for Plantarflexion)

Question 3

What are the ligaments found in the ankle joint?

Answer 3

Medial:
- Attached to the medial malleolus
- Consists of 4 separate ligaments which fan out from the malleolus and attach to the navicular, talus and calcaneus
- Primary action = to resist over-eversion of the foot
Lateral:
- Originates from the lateral malleolus
- Resists over-inversion of the foot
- Comprised of 3 distinct and separate ligaments: anterior talofibular, posterior talofibular and calcaneofibular

Question 4

What causes Plantarflexion at the ankle joint?

Answer 4

• Gastrocnemius
• Soleus
• Plantaris
• Tibialis anterior
  (- Flexor digitorum longus)
  (- Flexor hallucis longus)

Question 5

Which muscles dorsiflex at the ankle joint?

Answer 5

• Tibialis anterior
• Extensor hallucis longus
• Extensor digitorum longus

Question 6

Where is the subtalar joint?

Answer 6

Between the inferior surface of the talus and the superior surface of the calcaneus

Question 7

How do fractures occur at the ankle joint?

Answer 7

Ankle joint and associated ligaments can be visualised as a ring
- Upper part of ring: articular surfaces of tibia and fibula
- Lower part of ring: subtalar joint
- Sides of ring: medial and lateral ligaments
Can’t break 1 part of the ring without breaking another part

Question 8

Describe ankle sprains

Answer 8

Partial or complete tears in the ligaments of the ankle joint

• Due to excessive inversion of a plantarflexed foot
• Lateral ligament is more likely to be damaged because it is weaker and it resists inversion
• The anterior talofibular ligament is the lateral ligament most at risk of irreversible damage

Question 9

What is a Pott’s fracture?

Answer 9

A bimalleolar (medial and lateral malleoli) or trimalleolar (medial and lateral malleoli and distal tibia) fracture

• Due to excessive eversion
• It occurs by:
• – Forced Eversion pulls on the medial ligaments, producing an avulsion fracture of the medial malleolus
• – The talus moves laterally, breaking off the lateral malleolus
• – The tibia is then forced anteriorly, shearing off the distal and posterior part against the talus

Question 10

What is foot drop?

Answer 10

Damage to the deep fibular or common fibular nerve

• Deep fibular nerve can become entrapped or compressed during its course through the anterior compartment of the leg
• – Causes paralysis of the muscles in the anterior compartment of the leg, so the patient loses the ability to dorsiflex
• Unopposed Plantarflexion
• Makes it difficult for the foot to clear the ground when walking
• Develop an abnormal gait:
• – Waddling (patient leans excessively onto the normal limb
• – Swing out (patient abducts the abnormal limb)
• – High steppage (patient flexes knee and hip excessively on the abnormal limb so as to clear the dropped foot from the floor)

Question 11

What are the main reasons for the deep fibular nerve becoming compressed?

Answer 11

• Excessive use of anterior leg muscles

- Tight-fitting shoes (compress the nerve beneath the flexor retinaculum)

Question 12

What is an antalgic gait?

Answer 12

A gait that reduces pain

• Seen in patients suffering from long standing joint problems
• E.g. Osteoporosis in 1 limb may cause the patient to spend less time on affected limb, reducing pain

Question 13

What is trendelenberg gait?

Answer 13

• Pelvis drops towards the side of the raised limb
• Abductor muscles on the standing limb are greatly weakened/paralysed
• Due to a lesion of the superior gluteal nerve
• Gait:
• – As the pelvic drops on 1 side, the trunk lurched to the opposite side in an effort to maintain a steady pelvic level
• –During the next step, the trunk is whipped back over the pelvis towards the centre, causing the trunk to overcompensate and fall slightly past centre to the opposite side

Question 14

What type of joint is the ankle joint?

Answer 14

Hinge type synovial joint

Question 15

What are the stages of walking?

Answer 15

Stance phase:
- Heel strike
- Support
- Toe off
- Leg lift
Swing phase