MT: Foot and Symes Amputations

Question 1

Normal Foot Functions Heel

Answer 1

• tissues withstand cyclic, high impact forces
• provides sensory feedback

Question 2

Normal Foot Function Subtalar Joint

Answer 2

• Locks/unlocks mid-tarsal joints to change foot from:
• flexible adaptive structure (early stance)
• rigid lever (terminal stance)

Question 3

Normal Foot Functions Midtarsal Joints

Answer 3

• enables forefoot to adapt to the ground through pronation or supination

Question 4

Normal Foot Functions Longitudinal & Transverse Arch

Answer 4

• enables load sharing b/w heel and forefoot
• act as shock absorbers for body

Question 5

Normal Foot Functions Metatarsals

Answer 5

• withstand and spread GRF generated during terminal stance
• maintain ML stability of foot

Question 6

Normal Foot Function Big Toe

Answer 6

• enables normal biomechanical function during terminal stance/swing
• accepts final transfer of body weight
• tightens windlass mechanism with first met
• maximizes lever arm of foot

Question 7

Surgical goals

Answer 7

• primary healing
• preserve length
• soft tissue balance
• prevent revision surgery

Question 8

Post surgical goals

Answer 8

• healing
• ROM
• Pain management
• early ambulation

Question 9

“True” Reality

Answer 9

in order to restore normal gait mechanics, the prosthesis will need to have a rigid ankle contruct and extend proximal to the shoe

Question 10

“false” reality

Answer 10

a silicone or other cosmetic restoration that fits entirley within the shoe and may be visually pleasing but will never allow normal gait mechanics

Question 11

What occurs without a rigid ankle and toe lever

Answer 11

• shortened contralateral step length
• rotation of the residual limb within the prosthesis

Question 12

Toe Amputation

Answer 12

• removal of 1 or more toes
• removing the great toe has larger biomechanical deficit than removing any one of the lesser digits

Question 13

Toe Amputation Characteristics

Answer 13

• reduction in forefoot loading area: increases met head pressures
• loss of propulsion with big toe amputation: decreased ability to transfer body weight during push off

Question 14

Toe amputation aims

Answer 14

• restore normal foot shape
• prevent shoe deformation
• improve toe alignment
• return cosmesis

Question 15

Ray Amputation

Answer 15

removal of one or more toes and a portion of the metatarsal proximal to it

Question 16

Ray Amputation Characteristics

Answer 16

• functional loss depends on position and extent
• 1st ray: inability for fibularis longus to plantarflex the first ray, normal mechanical structure of MLA
• 5th ray: inability for normal locking/unlocking of lateral column

Question 17

Transmetatarsal Amputation

Answer 17

• transection of all metatarsal shafts

Question 18

Transmetatarsal Amputation Characteristics

Answer 18

• complete loss of forefoot loading area
• major muscle imbalance between extrinsic musculature spanning ankle and subtalar joints
• medial foot to become fixed in supination –> compensatory hindfoot valgus so that the medial aspect of the foot

Question 19

TMA High Profile Design

Answer 19

• all resist terminal stance rotation by extending the socket above the ankle and along the anterior shin
• ideal for active community ambulators or athletic individuals

Question 20

Lisfranc Amputations

Answer 20

• disarticualrtion of all metatarsals from the cuboid and cuneiform bones
• tarsal/metatarsal disarticualtion

Question 21

Chopart Amputations

Answer 21

• disarticularion of the talonavicular and calcaneocuboid joints

Question 22

Lisfranc/Chopart Amputation Characteristics

Answer 22

• high risk of equinovarus deformity due to:
• significant loss of foot lever arm
• major muscle imbalance

Question 23

Boyd & Pirogoff Amputation

Answer 23

• through ankle with retention of calcaneus with arthrodesis between the tibia and calcaneus

Question 24

Boyd & Pirogoff Amputation Characteristics

Answer 24

• delayed weightbearing as internal fixation heals
• muscle imbalance
• limited ambulation without prosthesis

Question 25

Symes Amputation

Answer 25

• amputation through ankle with resection of talus and all distal anatomy
• retains calcaneal fat pad and associated neuro