POAT Unit 1: General Princ. of Orthotics and Prosthetics

Question 1

What are the 3 Fundamental Principles and Concepts in Orthotics and Prosthetic Rehabilitation for Physical Therapists?

Answer 1

• Pressure tolerance
• Alignment of Joint Axis
• Moments and Force Transmission

Question 2

What are the Biomechanical Principles Underlying All Orthotic and Prosthetic Designs?

Answer 2

Question 3

What is an Orthosis?

Answer 3

“An externally applied device applied to a part of the
body to correct deformity, improve function, or
relieve symptoms of a disease.”

• A device which supports or assists the musculoneuro-skeletal system

Ortho = Straight

Question 4

What are the Purposes for Orthotic Prescription?

Answer 4

Question 5

What are the 3 Orthotic Design Purposes?

Answer 5

• Control Movement
• Assist Movement
• Combinations of both

Question 6

What are 4 Steps PT take when prescribing Orthoses to patients?

Answer 6

Question 7

What are Temporary Orthoses?

Answer 7

Question 8

What are Temporary Orthoses?

Answer 8

Question 9

What are Fixed Deformities?

Answer 9

These cannot be passibely corrected

Question 10

What are Dynamic Deformities?

Answer 10

Result from over- activity of muscle tendon groups but when at rest are passively correctable.
- Can also develop in adjacent joints in response to coupling effects of deformities above or below

Question 11

What is the Management of Direct Orthotic Management?

Answer 11

It alters joint movements, alternates shear forces, or all-terrain axial forces

• Orthotics work through the application of external forces

Question 12

What are the Corrective Control Systems Utilized by LE Orthoses (Modifying Joint Moments)?

Answer 12

• GRF Control System(s)

AND/OR

• 3-point (pressure) control System(s)

Question 13

Biomechanics 101

Force systems with orthoses generally act, in effect, in what lever system?

Answer 13

First Class Lever System

Question 14

What happens if a 1st class lever has Force Equilibrium?

Answer 14

If there is Equilibrium: Forces(t) must sum to zero

Question 15

In this picture, what is this AFO trying to control?

Answer 15

Knee Flexion; buckling

Question 16

In an Orthotic design, each plane and direction of motion under orthotic control must have at least how many 3-point loading systems?

Answer 16

At least ONE 3-point loading system

• 4, 5, 6 point systems can be utilized to control other rotations and/or translations

Question 17

What are the Mechanical Goal(s) of Orthotic Interventions?

Answer 17

To apply forces of specific magnitiude at specific point(s) on a limb/trunk segment to achieve desired control

Question 18

With the orthotic design, an orthosis must utilize a minimum of how many points of control?

Answer 18

A minimum of 3 points of control

These represent systems which are in static equilibrium, meaning there are no unbalanced forces acting on these

Question 19

If you have a patient with severe genu recuvatum during static standing, where would you apply the 3-points of force to control the unwanted hyperextension?

Answer 19

2 forces anteriorly and 1 force posteriorly

• We must consider each of the 2 anterior forces as one that creates torques around the knee joint. With the counterforce in place, the thigh creates a rotational force in a counterclockwise direction while the anterior shank force creates a clockwise rotational force around the knee joint
• The force of the thigh decreases as the point of application is moved from close to the opposing force as the knee axis to a position more proximal on the anterior femur and more distal on the tibia.

Question 20

General Considerations: Levers and Contact Areas

This orthosis is used to control knee flexion, what is the effect on skin pressures of using short levers and small contact areas?

Answer 20

Increased local skin pressures

Question 21

General Considerations: Levers and Contact Areas

This orthosis is used to control knee flexion, what is the effect on skin pressures of using short levers and large contact areas?

Answer 21

Less increased local skin pressures

Question 22

General Considerations: Levers and Contact Areas

This orthosis is used to control knee flexion, what is the effect on skin pressures of using long levers and small contact areas?

Answer 22

Less increased local skin pressures

Question 23

General Considerations: Levers and Contact Areas

This orthosis is used to control knee flexion, what is the effect on skin pressures of using long levers and large contact areas?

Answer 23

Smaller (lowest) local skin pressures

Question 24

For effective and comfortable utilizations of an orthosis, orthotic forces should..?

Answer 24

• be distributed over large surface areas to minimize local skin and ST pressures

and

• be applied using larger moment arms possible/practical

ST = Soft Tissue

Question 25

For effective and comfortable utilizations of an orthosis, the sum of primary and coounterforces of each control system shoudl equal what?

Answer 25

Zero

Question 26

Answer 26

2) Lateral Femoral condyle; Medial Proximal Femur; Medial Proximal Tibia

Question 27

How can the orthotic design of this picture reduce medial joint compartment loading?

Answer 27

- They reduce the various angulation across the knee - They decrease the adduction moment created by the ground reaction force vector

Question 28

How can we change shearing forces across a knee joint using an ACL brace for example?

Answer 28

*ACL bracing is typically utilized following surgery to protect the lig. from tensile overloading* - There is a force pushing the shank (tibia) forward and its not moving, then there must be an opposing force in the opposite direction. Without an opposing force, the shank moves in an anterior direction - Using a 4-point control system, the forces prevent unwanted translatation, instead of appluing forces to control segment rotation

Question 29

What is One Key Consideration with orthoses emloyment on mechanical joints and their design?

Answer 29

Allow rotation between one limb segment and another

Question 30

What happens when the mechanical axis does not match the anatomical axis during osteokinematic motions?

Answer 30

They can create: - deformation of joint reactive forces - increase friction/shear skin irritation - increase in psitioning within the orthotic device

Question 31

What are common materials in orthotics?

Answer 31

Question 32

What is Shore Durometer?

Answer 32

A measurement of a material's hardness (ability to resist permanent indentation)

Question 33

What are some considerations PTs should keep in mind?

Answer 33

Question 34

With the UE/LE/Trunk, what are static othoses?

Answer 34

Orthotic devices with no moveable joint incorporated into the design - Blocks motion(s) - Alter local pressure

Question 35

With the UE/LE/Trunk, what are dynamic othoses?

Answer 35

Orthotic devices with moveable joints - Blocking/control of selected motions - Supporting/substituting for weak ms - Increase motion via traction