Biomechanics Of Transtibial Prosthetics

Question 1

A kinetic analysis in prosthetic involves:

Answer 1

The evaluation of the motion of the prosthesis as well as the forces involved.

Question 2

If the prosthetic foot is positioned too far posterior in relation to the prosthetic socket:

Answer 2

• An excessive knee flexion movement will occur at loading response
• An insufficient knee extension moment will occur at late midstance

Question 3

If the prosthetic foot is too far inset in relation to the socket, the weight line will pass too far medial to the foot resulting in an excessive genu varum movement at midstance.

Answer 3

False

Question 4

Excessive socket adduction results in:

Answer 4

• Excessive medial lean of the pylon at midstance.
• Wide-based gait
• Walking on the medial border of the foot

Question 5

In the human body (standing), the center of gravity is located at approximately 65% of the height (usually slightly anterior to the second sacral vertebrae).

Answer 5

True

Question 6

Where are the pressures in the PTB socket located at loading response?

Answer 6

Posterior-proximal and anterior-distal

Question 7

Which of the following are biomechanically, pressure tolerant areas?

Answer 7

Patellar Tendon

Question 8

At mid-stance, a properly aligned socket prosthesis will increase pressures at the medial flare of the tibial with the corresponding load on the proximal lateral socket.

Answer 8

False

Question 9

Sagittal shear (fore and aft) takes place during which phase of gait?

Answer 9

Throughout stance phase

Question 10

Excessive socket extension:

Answer 10

Places weight too far posterior on the foot

Question 11

Statics is:

Answer 11

The study of bodies in equilibrium. A body is in equilibrium when the sum of all the forces acting upon it is zero.

Question 12

Kinetics is:

Answer 12

The study of the paths of motion of a body and the forces that produce the motion.

Question 13

Dynamics is:

Answer 13

The study of moving bodies and the forces which affect changes in the rate or direction of their motion.

Question 14

Kinematics is:

Answer 14

The study of paths of motion of a material body. The forces causing motion are not considered.

Question 15

Weight line is:

Answer 15

An imaginary line originating at the center of gravity.

Question 16

The floor reaction force is a force vector originating in the surface upon which a person walks. It points upwards and is equal to the magnitude of the forces acting upon the ground as a person walks or stands. It varies in direction and magnitude depending upon the phase of gait. In prosthetics the ground reaction force is significant because its direction and magnitude are related to the torque applied to the residual limb within the socket.

Answer 16

True

Question 17

Newton’s third law:

Answer 17

For every action there is an equal and opposite reaction.

Question 18

Pressure tolerant areas in a PTB socket design include the:

Answer 18

• patellar tendon
• anterior compartment (pretibials)
• posterior compartment (popliteal region)
• medial flare of proximal tibia

Question 19

Coronal initial bench alignment has the socket set in the measured ab/adduction and the foot outset 1/2” relative to the socket midline at PTB.

Answer 19

False