Prothstetics

Question 1

Example Gait Faults

Answer 1

Observed Deviations
* bilateral internal hip rotation
* increased knee flexion
* short step length

Potential Impairments
* femoral anteversion
* tibial torsion
* hip weakness
* knee flexion contractures

Mechanical Consequences
* poor leverage for ankle plantar flexion
– reduced gait economy
– decreased gait speed
* incr. retropatellar pressure

Question 2

What are the main causes of amputation?

Answer 2

Vascular disease (54%) + Trauma (45%)

Question 3

The majority of amputations are ___

Answer 3

transtibial (below knee) or transfemoral (above knee)

Question 4

Prosthetic considerations:

Answer 4

Suspension method, socket, limb interface

Question 5

Suspension def

Answer 5

Method of attachment to residual limb

Question 6

Socket def

Answer 6

Encases residual limb and disperses weight

Pressure wounds often seen here.

Question 7

Patient Orthosis Prothesis - What is it?

Answer 7

• Junction between the body tissues and support surface which forces are transmitted
• Seat cushion, prosthetic limb, AFO (Ankle Foot Orthosis)

Question 8

Reaction forces are due to:

Answer 8

• Reaction forces (Newton’s 3rd Law)
  – May be partial - 5x’s BW
  – May be due to the orthosis, prosthesis itself
• Loads on soft tissue may lead to tissue breakdown

Question 9

Osteointegration

Answer 9

Metal placed into the bone. Don’t have to worry about skin problems because it is solid.

Question 10

What do we need to think most about with a prosthetic?

Answer 10

• Pressure and the relationship with Load Transmission and Load Distribution

Question 11

Load Transmission

Answer 11

• Forces traveling through kinetic chain (Try to reduce reaction force)
• Body Weight
• Nature of the activity (walk, run etc.)
• Assistive devices (yes/no)

Ex: Cane for someone with below knee amputee

Question 12

Load Distibution

Answer 12

• Pressure at the interface (Try to reduce pressure)
• Musculature
• Bony geometry of the interface
• Mechanical properties of the tissue and surface

Must consider load distribution early vs late on in injury because throughout time muscle with atrophy.

Putting in foam or something else that forms around the body.

Question 13

Interface Mechanics

Answer 13

Compliant: Put something soft inside that will conform to you.
Rigid: Get entire shape between device and limb to match.

Improper can lead to shear stress or bottoming out (sink so far no material left).

Question 14

Energy Return

Answer 14

• SACH: Solid Ankle Cushioned Heel; Doesn’t move. Minimal energy return.
• High energy retun in flex prothesis. Moment of inertia significantly affected (mass x radius^2). Leg is shorter and mass is reduced. Won’t fatigue as much. At sprinting speed is faster than normal person at top speed but when starting is much harder to get going to get spring to react.

Question 15

Prosthetic device - degrees of freedom

Answer 15

No DOF
1 DOF: DF and PF
2 DOF: DF/PF and Inversion/Eversion

Question 16

Prothetic and Spring

Answer 16

Perfect spring will conserve all energy

Question 17

Prosthetic Hand

Answer 17

• Works based off of EMG

Question 18

Prosthetic

Answer 18

External device that tries to mimic skeletal muscle