Biomechanics and joint replacement of foot and ankle

Question 1

Biomechanics of ankle joint

Answer 1

Unipolanar hinge joint

Question 2

Why OA ankle is lesser than hip and knee

Answer 2

Highly congruent nature of articulation
Uniform cartilage mantle
Biomechanics make up of cartilage that is more resistant to indentation

Question 3

Technique of percutaneous lengthening

Answer 3

DAMP technique (distal anterior, medial proximal)
Triple cut
Hoke technique

Question 4

Windlass mechanism of plantar fascia

Answer 4

The dorsiflexion of the toes produces the windlass mechanism utilizing the plantar fascia. The “wrapping” of the plantar fascia around the metatarsal heads “pulls” the calcaneus towards the toes. The mid tarsal arches raise up off the ground and the foot transitions from a supple, pronated position to rigid, supinated position. The rigidity of the foot is needed to become a lever that is capable of propelling someone as they walk.

Question 5

ideal position to fuse ankle joint

Answer 5

neutral dorsiflexion
5-10° of external rotation
5° of hindfoot valgus
5 mm of posterior talar translation

Question 6

gastrosoleus weakness and tibialis anterior weakness in gait cycle

Answer 6

Gastrosoleus weakness: Calcaneal gait

Tibialis anterior weakness: high steppage gait