Prosthetic Written Study Guide

Prosthetic Written Study Guide

1. Which of the following circumstances are commonly associated with the gait deviation “vaulting” with the transfemoral user?

a. Excessively tall prosthesis
b. Prosthesis set with too much knee friction (too high extension assist)
c. Weak gluteus maximus (hip extensor)
d. Poor suspension
e. Prosthetic socket that is too loose

2. What is the main function of a constant friction knee unit?

a. Prevents excessive heel rise and terminal impact at a baseline cadence
b. A partially flexed knee unit will hold up user’s body weight
c. Knee unit is able to flex/extend at multiple speeds contingent on cadence
d. Increases stance phase stability

3. During which part of gait does the body reach its tallest peak?

a. Mid-stance
b. Loading response
c. Initial contact
d. Pre-swing
e. Terminal stance

4. A gun shot wound impinged the sciatic nerve at the level of the lesser trochanter, this patient would suffer from muscle weakness at which joint?

a. Talornavicular
b. Calcaneal-cuboid
c. Sacro-illiac junction
d. Ankle
e. Knee
f. Hip
g. Elbow

5. What motion is the primary operator of the terminal device of a shoulder disarticulation prosthesis?

a. Scapular depression
b. Scapular elevation
c. Scapular winging
d. Protraction (abduction)
e. Retraction (adduction)

6. The most appropriate muscle used to operate a myoeletric elbow unit of a shoulder disarticulation amputee is?

a. Pectoralis major and trapezius
b. Infraspinatus
c. Supraspinatus
d. Superior rhomboid and subscapularis
e. Pectoralis major and coracobrachialis

7. The shoulder saddle harness is used to:

a. Prevent excessive pressure along the axilla
b. To enhance the amount of excursion with biscapular abduction
c. Provide and maintain comfort when loading the prosthesis
d. Prevent damage of the brachial plexus
e. All of the above

8. The outside locking joint is utilized for which level of amputation?

a. Long transradial
b. Wrist disarticulation
c. Elbow disarticulation
d. Short transhumeral

9. When fabricating a transhumeral prosthesis, the humeral length is based on which sound side measurement?

a. Coracoid process to medial epicondyle
b. Acromion process to the olecranon
c. Coracoid process to the lateral epicondyle
d. Acromion process to the lateral epicondyle

10. Common attributes of the cross back strap are:

a. Provides greater excursion
b. Prevents the Newington ring from shifting superiorly
c. Increase difficulty of don/doff
d. All of the above

11. What motion is the primary biomechanical force during ambulation for a hip disarticulation patient?

a. Pelvic lordosis
b. Thoracic extension
c. Hip flexion
d. Pelvic rotation

12. Increasing rotational stability of a short AE prosthesis is achieved by extending trim-lines proximally.

a. True
b. False

Answer Key w/ Explanations
Be prepared & Pass your first time!

1. A, B, D, E: Anything that prevents the knee from going into flexion during swing phase will result in vaulting, as the patient will need to clear ground when progressing the prosthetic limb forward. A weak gluteus maximus would primarily affect the stance phase of gait.

2. A: A single axis constant friction knee unit requires the amputee to use his own strength to ensure stance phase stability. However, it allows the user to achieve full knee extension quicker, improving stability. It is often used with a single axis foot so that maximum extension can be achieved quickly.

3. A: During mid stance your body has achieved single leg support placing your body at its highest peak.

4. E: The sciatic nerve is responsible for the proximal posterior muscle groups of the thigh – i.e. the hamstrings. With the loss of the hamstrings, knee flexion will be primarily affected.

5. D: Protraction decrease excursion length opening the terminal device.

6. A: These muscles provide a strong electrical signal, allowing the user to operate the myoelectric terminal device – remember typically antagonistic muscle groups are used for myoelectric control to better provide isolated contractions.

7. E: The shoulder saddle harness helps to distribute pressure along the shoulder girdle reducing pressure being placed onto the brachial plexus and axilla. It also increases the surface area of control, helping to increase excursion.

8. C: allows the user to engage or disengage elbow lock while also providing room for build out.

9. D: Most measurements of the upper extremity are taken with the lateral epicondyle as the reference point.

10. D: The addition of the cross back strap increases difficulty donning due to the extra material/strap, prevents shifting by providing an anchor point for both sides while preventing superior migration along the back. Provides a shorter cable has shorter distance to travel as it has less excursion length.

11. A: Pelvic lordosis is controlled by the muscles of the abdomen and lower back. It is important for these muscles to be tested during the initial evaluation as pelvic lordosis is the primary mechanism to control the knee throughout gait.

12. A: True because the extended trimlines increase purchase along the condyles and decrease ROM.