Prosthetics & Orthotics Flashcards
For a person with an upper extremity amputation, what is the advantage of choosing a body powered device over a myoelectric device?
(a) Stronger grip force
(b) Better cosmesis
(c) Lighter weight
(d) Less dependence on motor strength
Answer: (c)
Commentary: Main advantages of body powered systems are lower initial costs, lighter weight, easier repairs, and better tension feedback to body. Advantages of myoelectric devices are
cosmesis, less need for motor strength/coordination to operate limb, and stronger grip force.
2013
What prosthesis is most appropriate for a 6-month-old child who has a congenital transhumeral
amputation?
(a) Curve shaped “banana” arm
(b) Myoelectric hand Page 15 of 23
(c) Body powered hook
(d) Friction elbow arm
Answer: (a)
Comment: The banana arm is a passive prosthesis designed to help in reaching and bimanual midline activities in the very young child. A myoelectric hand is most appropriate to initiate about age 1 year; a body-powered hook is appropriate for children age 4-5 years; a friction-elbow arm is appropriate about when a child with a transhumeral amputation starts to walk.
Reference: Gaebler-Spira D, Lipschutz R. Pediatric Limb Deficiencies. In: Alexander MA, Matthews DJ, editors. Pediatric rehabilitation: principles and practice. 4th ed. New York: Demos Medical; 2010. p 342-344, see fig13.9, p343,“banana arm.”
2013
What aspect of gait is improved when a manual locking knee design is chosen for an individual
with a unilateral transfemoral dysvascular amputation?
(a) Overall gait mechanics with decreased energy consumption
(b) Foot clearance in swing phase
(c) Stability in stance phase
(d) Ability to vary the gait cadence
Answer: (c) Page 19 of 23
Commentary: The only advantage of a manual locking knee is its inherent stability. It is typically used for patients with significant weakness or instability, such as very low level household ambulators or patients using prosthetic limb for transfers. Since the knee does not bend during swing phase it compromises gait mechanics. Toe clearance is more difficult and the prosthetic limb is typically designed to be shorter than the intact limb.
Reference: Huang ME, Miller LA, Lipschutz R, Kuiken TA. Rehabilitation and prosthetic
restoration in lower limb amputation. In: Braddom RL, editor. Physical medicine and
rehabilitation. 4th ed. Philadelphia: Elsevier Saunders; 2011. p 305.
2013
What is the benefit of using ankle-foot orthoses (AFOs) for a patient with Duchenne muscular
dystrophy?
(a) Improves the patient’s ambulation Page 20 of 23
(b) Assists the patient with rising from the floor
(c) Prevents contractures when used at rest
(d) Improves wheelchair positioning
Answer: (c)
Commentary: Resting AFOs can help prevent ankle plantar flexion contractures, but are not
required for proper wheelchair positioning. Duchenne muscular dystrophy is an x-linked disease
with progressive muscle weakness/degeneration that is usually diagnosed in early childhood. Loss
of independent ambulation generally occurs in early adolescence, necessitating the transition to a
wheelchair. The progressive weakness leads to compensatory strategies for ambulation such that
AFOs may further impede ambulation or transferring.
Reference: (a) Busby K et al. Diagnosis and management of Duchenne muscular dystrophy, part
2: implementation of multidisciplinary care. Lancet Neurol 2010;9:177-89. (b) McDonald C, Han
J, Carter G. Myopathic disorders. In: Braddom RL, editor. Physical medicine and rehabilitation.
4th ed. Philadelphia: Elsevier-Saunders; 2011. p1126.
2013
What aspect of gait is improved when a manual locking knee design is chosen for an individual with a unilateral transfemoral dysvascular amputation?
(a) Overall gait mechanics with decreased energy consumption
(b) Foot clearance in swing phase
(c) Stability in stance phase
(d) Ability to vary the gait cadence
Answer: (c)
Page 19 of 23
Commentary: The only advantage of a manual locking knee is its inherent stability. It is typically used for patients with significant weakness or instability, such as very low level household ambulators or patients using prosthetic limb for transfers. Since the knee does not bend during swing phase it compromises gait mechanics. Toe clearance is more difficult and the prosthetic limb is typically designed to be shorter than the intact limb.
2013
A 60-year-old woman had a left total hip arthroplasty 4 weeks ago. During her gait evaluation, she is noted to have a left lateral trunk lean during left stance phase. This gait deviation is most likely a result of weakness in which left lower limb muscle?
(a) Gluteus medius
(b) Gluteus maximus
(c) Tensor fascia lata
(d) Vastus lateralis
Answer: (a)
Commentary: Gluteus medius weakness leads to a Trendelenburg gait. This woman’s lateral trunk lean is a compensated Trendelenburg gait. Gluteus medius or hip abductor weakness is common following total hip arthroplasty. In one study, 36 of 76 (47%) patients with total hip arthroplasty had hip abductor weakness. Of those 36 patients, all 36 had weakness in the gluteus medius, 28 had weakness in the gluteus minimus, and 4 had weakness in the tensor fascia latae
2013
What prosthesis is most appropriate for a 6-month-old child who has a congenital transhumeral amputation? (a) Curve shaped “banana” arm (b) Myoelectric hand Page 15 of 23 (c) Body powered hook (d) Friction elbow arm
Answer: (a)
Comment: The banana arm is a passive prosthesis designed to help in reaching and bimanual midline activities in the very young child. A myoelectric hand is most appropriate to initiate about age 1 year; a body-powered hook is appropriate for children age 4-5 years; a friction-elbow arm is appropriate about when a child with a transhumeral amputation starts to walk
2013
A 65-year-old woman with diabetes mellitus has been sent to your clinic for evaluation of
appropriate footwear. She had a diabetic foot ulcer 2 months ago over her first metatarsal head,
which is now healed. Examination reveals distal sensory loss and a mild claw foot deformity.
Which footwear/orthotic recommendation is the most appropriate?
(a) Since the wound is healed, no specialized footwear is needed.
(b) Well-fitting regular tennis shoes or sneakers are the best option.
(c) Off-the-shelf diabetic shoe with a custom molded orthotic based on severity of claw foot
deformity is indicated.
(d) Patellar tendon-bearing ankle-foot orthoses to help unload the metatarsal head should be
used.
Answer (c)
Commentary: The patient is at high risk for future diabetic foot ulcers based on her history of
previous ulcers, claw foot deformity and peripheral neuropathy. Based on this risk profile,
specialized footwear is recommended. Patients with diabetes mellitus (DM) without risk factors
for ulcer could be counseled and educated regarding the use of well fitting tennis shoes and
sneakers. While a custom molded shoe could benefit this patient, they are very expensive and
usually needed for patients with severe foot deformity. At this point a prefabricated diabetic shoe
and custom orthotic would be clinically appropriate and more cost-effective. A patella tendon
bearing ankle-foot-orthosis is not indicated and would not effectively offload the metatarsal
heads. A metatarsal bar or pad placed proximal to the metatarsal head is an effective way to
offload the metatarsal head.
2012
The primary stabilizing effect of the flexible lumbosacral orthosis is its ability to
(a) restrict spinal extension.
(b) prevent atrophy of trunk muscles.
(c) elevate intra-abdominal pressure.
(d) enhance kinesthetic feedback
Answer: C
Commentary:Although they do not effectively restrict motion to a significant degree, flexible
lumbosacral orthoses elevate intra-abdominal pressure, thereby unloading the spine and
supporting structures. This action also provides inhibitory kinesthetic feedback and warmth.
Long-term use of binders and other flexible lumbosacral orthoses may, unfortunately, result in
atrophy of trunk muscles
2009
What is the minimal number of points of contact that an orthosis must have in order to exert
rotational control?
(a) One
(b) Two
(c) Three
(d) Four
Answer: C
Commentary:Rotational control forces or moments across a joint are not effective unless there
are at least 3 points of contact between the device and the limb segment
2009
What is the primary advantage of a body powered upper limb prosthesis compared to a
myoelectric prosthesis?
(a) Greater sensory feedback
(b) Moderate or no harnessing
(c) Less body movement to operate
(d) Enhanced cosmesis
Answer: A
Commentary:The advantages of body powered upper limb prostheses include the following
factors: moderate cost, most durability, highest sensory feedback, and a variety of prehensors
available for various activities. Their disadvantages are that they require the most body
movement to operate, have the most harnessing and require increased energy expenditure to use.
Myoelectric and/or switch controlled upper limb prostheses have the following advantages: they
require moderate to no harnessing, require fewer body movements to operate, have moderate
cosmesis, provide more function in proximal areas and, in some cases, provide a stronger grasp.
Battery powered prostheses are the heaviest and most expensive prostheses. They also require the
most maintenance, provide limited sensory feedback and require extended therapy time.
2009
What advantage does a suspension system that features a gel liner pin have over a sleeve suspension system in a transtibial amputee?
a. Better heat dissipation and reduced sweating
b. Improved cushioning and reduction in shear forces
c. Ease of donning and doffing
d. Ease of liner care and cleaning
b is correct
Because they transmit good control of the prosthesis, offer better cushioning and reduce shear forces on the residual limb, gel liner suspension systems are very popular. They do not provide better heat dissipation, and excessive heat retention and sweating are often major disadvantages. The donning can be difficult, since a gel liner must be positioned correctly on the residual limb to ensure that the pin engages correctly. Lastly, the gel liners require daily cleaning to avoid skin rashes and skin infections.
2014
A 68-year-old woman with well controlled diabetes is asking your opinion on specialized footwear. She has good pedal pulses, intact sensation and no foot deformity. She has no prior history of ulcers. In addition to frequent foot inspections, you recommend
a. custom molded diabetic shoes.
b. well fitting breathable shoes.
c. off-the-shelf diabetic shoes with wide toe box.
d. custom insert with metatarsal pad.
Option b is correct.
Because she has well controlled diabetes (DM), intact pulses, intact sensation and no obvious foot deformity, this patient is at lower risk. Based on her risk profile, specialized footwear is not recommended. Patients with DM without risk factors for ulcer could be counseled and educated regarding the use of well fitting tennis shoes and sneakers. Other interventions listed could be considered, if ulcer risk factors change.
2014
The most appropriate cervical orthosis for an unstable cervical spine fracture is
a. Philadelphia/Miami J orthosis
b. Sternal occipital mandibular immobilizer (SOMI) orthosis
c. Halo orthosis
d. Milwaukee orthosis
Option c is correct.
For an unstable fracture, a Halo orthosis provides the best limitation in range of motion to protect the spinal cord from further injury. A Philadelphia/Miami J orthosis is not appropriate for unstable fractures. A SOMI device is primarily used in cervical sprains or stable fractures with intact ligaments. A Milwaukee brace/orthosis is a cervicothoracolumbosacral orthosis primarily indicated for scoliotic management of high thoracic curves
2014
In a body-powered upper extremity prosthesis, which feature is an advantage of a voluntary opening device over a voluntary closing device?
a. It provides larger prehensile forces.
b. Variable prehensile force is transmitted through the control cable.
c. There is no need for constant pull on the control cable during grasp.
d. It provides indirect sensory feedback.
Option c is correct.
Closing forces in the voluntary opening terminal device rely on springs or rubber bands to provide prehensile force. Typical closing forces range from 5 lbs to 10 lbs. Voluntary closing devices are capable of providing prehensile forces up to 20-25 lbs and provide indirect sensory feedback through the force exerted on the control cable. A disadvantage of the voluntary closing device is the need for a constant pull on the control cable during prolonged grasping.
2014
At mid stance, where is the ground reaction force vector located?
(a) Anterior to ankle, posterior to knee
(b) Anterior to ankle, anterior to knee
(c) Anterior to knee, anterior to hip
(d) Posterior to knee, posterior to hip
Answer: B
Commentary:In mid stance, the ground reaction vector lies anterior to the ankle, anterior to or through the knee axis, and posterior to the hip center. The passive torques created by this vector alignment are ankle dorsiflexion, knee extension and hip extension
2009
The primary advantage of a soft insert fitted into the socket of a transtibial prosthesis is that it is
(a) perspiration resistant.
(b) easy to keep clean.
(c) easily modified.
(d) very durable
Answer: C
Commentary: Soft inserts are fabricated to fit inside the socket. They are recommended for
patients with thin, sensitive, or scarred skin, or peripheral vascular disease (PVD). They are
easily modified. Hard sockets also have their advantages. They are perspiration resistant, less
bulky than sockets fitted with a soft insert, easy to keep clean, and durable. Further, reliefs or
modifications can be located with precision in the hard socket.
2009
Which factor promotes knee stability during the gait cycle of a person with transfemoral
amputation?
(a) Knee component placed anterior to the socket
(b) Hard heel in the prosthetic foot
(c) Polycentric 4-bar linkage prosthetic knee
(d) Anterior position of the shank on the prosthetic foot
Answer: C
Commentary:Flexion moment at the hip, a rigid heel in the solid ankle, cushion heel foot and the
anterior position of the shank all shift the ground reaction force behind the knee joint to produce a
knee flexion moment. The 4-bar linkage with instantaneous center of rotation and the posterior
location of instant center in extension creates knee stability, especially at heel strike.
2009
