Prosthetics Exam Flashcards
Gait cycle
Heel strike on one side and the following heel strike on the same side
Venous return of the blood to the heart is assisted by the
Action of the skeletal muscles
During normal human locomotion, how many inches does the center of gravity shift from side to side
2 inches
The center of gravity of the adult male is located on the midline of the body at approximately the level of the
2nd sacral vertebra
To minimize lateral bending of the trunk subsequent to unilateral hip abductor weakness, it is best to use:
A cane on the uninvolved side
Surgical attachment of muscle to muscle is known as
Myoplasty
Body’s center of gravity reaches its highest point at
Mid-stance
Pressure is determined by
Force divided by area
During normal human locomotion, b/t heel contact and foot flat, the floor reaction force tends to cause which moments at the hip and knee
Hip flexion
Knee flexion
If the sciatic nerve is severed at the level of the lesser trochanter, muscle function will not be impaired at the
Hip joint
Which muscle is most readily identified by palpation
Sartorius
Muscles which pass posterior to the medial malleolus at the ankle act to
Invert and plantar flex the foot
Which of the following muscles flexes the knee joint
Biceps femoris
Bones which form the acetabulum
Ilium
Pubis
Ischium
Normal hip reaches its maximum extension during
Heel-off
Which of the following muscle inserts on the lesser trochanter
Iliopsoas
In the hip disarticulation Px, the major function of the iliac crest is to
Provide an area for suspension
In a Canadian hip disarticulation socket, which of the following is not affected by A-P placement of the hip joint
Lateral stability during stance phase
With respect to the hip and knee joints at midstance, the floor reaction line for a hip dis. Px may be caused by
Heel wedge that is too hard
The symphysis pubis is
The anterior junction of the pelvic bones
Immediate Post-surgical fitting of the UL amputees offers these advantages
Early maturation of the RL
More rapid rehabilitation
Early return of 2 handed grasping patterns
Advantages of a myoelectric Px system over a cable driven Px
Requires less force and excursion
Provides inherent sensory feedback
Improves the cosmetic result
Pt with loss of the thumb only would probably benefit most from
An opposition post
Mechanical partial hand Px would probably be contraindicated from a transmetacarpal amputation with
The thumb and index finger remaining
The amount of residual supination and pronation retained by a wrist disarticulation Pt while wearing a Px should be at least:
50%
A 23 yo wrist disarticulation amputee intends to return to work as a carpenter. Which terminal device offers the best tool handling capabilities
Dorrance 7 (farmer’s hook)
What would cause decreased pronation and supination in a wrist disarticulation Pt
Proximal trim line is proximal to epicondyles
The motions of supination and pronation of the forearm occur at which of the following joints
Proximal radioulnar
In the medium length BE (below elbow) amputation, which of the following muscles is missing
Pronator quadratus
Which of the following is not part of the BE figure-of-eight harness
Lateral suspension strap
If a BE Px is harnessed with a split cable housing, which Px joints has most likely been utilized
Step-up hinge
A BE Px with flexible hinges should not inhibit flexion at the elbow more than
10 degrees
Primary advantage of a voluntary closing terminal device
Graded prehension
Component which provides the greatest ROM for the bilateral BE amputee
Wrist flexion unit (Sierra type)
Loss of the UL just distal to the supinator muscle will result in what amputation level
Short BE RL
What modifications is made to the figure-of-8 harness for the bilateral BE Pt
The axilla loops are unnecessary
A cross back strap is added
The force applied to open the TD (terminal device) of a BE Px is 7 lbs. How many lbs of force applied at the harness would provide acceptable efficiency
10 lbs
Pt with long bilateral BE amputations who is also blind will have difficult using conventional Px devices. What surgical intervention can be most useful in this situation
Krudenberg’s opperation
When a voluntary opening Px hand is activated, the cable replaces function normally provided by the
Extensor carpi radialis longus and brevis
Prehension patterns provided by a Px hand
Cylindrical
Spherical
Palmar
Main supinator of the forearm
Biceps
Olecranon process is a portion of the
Ulna
An excursion amplifier incorporated in a control system provides increased cable excursion at the expense of
Requiring more force
When the elbow flexion attachment of the AE (above elbow) forearm is moved toward the TD, it will have what mechanical effect
Decrease force required
Increase excursion required
Characteristics of the elbow disarticulation
Provides rotational stability
Preserves a long lever arm
Prevents bony overgrowth
Leaves the epiphyseal plates intact
Above elbow amputation is sometimes performed for a complete brachial plexus injury. For optimum Px function, what other steps would be helpful
Shoulder fusion
The brachioradialis muscle acts primarily to
Flex the elbow joint
The Prosthesis designed for a Pt with a proximal femoral focal deficiency (PFFD) generally utilizes ischial and gluteal WB because the
Hip joint is unstable or non-existent
The main flexor of the hip joint is the
Iliopsoas
During normal heel strike, the forward hip is
Flexed 25 degrees
The biceps femoris produces which of the following hip and knee motions
Hip Extension
Knee Flexion
Which externally powered elbow units is not usually adaptable to a switch control in the harness
Utah
A split-socket for the BE Px Pt is used so that
The amount of forearm flexion is increased
The biceps brachii produces which of the following actions of the elbow and forearm
Elbow flexion
Forearm supination
Characteristics of a Px with step-up elbow joints
Appropriate for very short RL
Weaker flexion power
2:1 excursion ratio
Muscles that plantar flex the foot
Tibialis posterior
Plantaris
Peroneus longus
Gastrocnemius
Which muscles undergoes a lengthening Cx between heel strike and foot flat
Tibialis posterior tibialis anterior
Flexor hallucis longus
Pt loosed what after a transmetatarsal amputation
Push off
Inversion of the foot is accomplished primarily by the
Tibialis anterior and posterior
The talus does not articulate with the
Cuboid
Active plantar flexion of the ankle joint is strongest with the
Knee extended
The chopart level of amputation is performed through the
Mid-tarsal joint
The anterior trimline of the symes Px usually extends to the level of the patellar tendon in order to
Provide a long lever arm to distribute force
To check Px ht, the amputee should
Support their wt equally on both legs
When walking, the normal foot should pass close to the AK Px foot to
Facilitate shift of body wt
Rotation of the foot at heel strike may be caused by
A stiff PF bumper
If the ischial tuberosity is placed too far toward the medial side of the ischial seat, it results in
Crowding of adductor muscles into small area, causing burning sensation
The knee bolt of the Px is usually found to be
In approximately 5 degrees of external rotation
When the adductor longus tightness is observed during initial fitting of the AK socket, you should
Flare and contour anterior-medial corner
When the AK knee amputee must arch his back to maintain the center of gravity of his body in the proper position while pressing back with his stump, it is an indication that the
Stump was fitting into a socket without adequate initial flexion
As the AK amputee places his wt on the Px, the femur presses toward the lateral wall. B/c of this, the lateral socket wall should be
Adducted to stabilize the femur during locomotion
The suction socket Px is aligned so that involuntary alignment stability is minimized and voluntary knee control by stump action is emphasized
In order that a minimum amount of energy is consumed during walking
If a force of 10 lbs is exerted on the 5 foot arm of a lever, what force must be exerted on the 2 foot arm to balance it
25 lbs
Medial whip is cased by
Excessive lateral rotation of knee bolt
In correcting an abducted socket on the adjustable leg, we should
Release the medial tilt screw and tighten the lateral
When pulling the amputee into an AK socket, the most important anatomical landmark is the
Adductor longus tendon
If the ischial seat of the AK socket is made too wide, it will cause
Burning sensation when the wearer is seated b/c of excessive stretching of the skin
gait fault due to incorrect function of Px
Circumduction
How does an excessively stiff PF bumper in the Px foor affect knee stability
Decreases knee stability
At push-off, it is common for an AK amputee with well developed hamstring muscles to force themself off the ischial seat as their stump extends. How can this trouble be avoided
Align the socket in a position of initial flexion
What is the effect of excessively shimming the DF stop to place the shank in a vertical position
Excessive increase in range of PF with increase in knee stability
If the AK amputee complains of pressure on the pubic ramus, the prosthetist should
lower the medial wall 1/8” at a time
Pronounced impact shock at full extension of the Px knee indicates need for
More extension dampening controls
During swing phase, a tendency for the AK Px shin to make a marked inward movement of the knee accompanied by an outward movement of the foot is called
Lateral whip
If the medial-lateral dimension of the AK socket is too large
The ischial tuberosity will move laterally on the seat
What is the result of locating the toe-break too far forward in the Px foot
Gives amputee a feeling of “climbing a hill” causing excessive energy consumption and awkward gait
When hamstring muscle tightness is observed during initial fitting of the AK socket you should
Relieve the lateral border of the Scarpa’s bulge
Pt wt of 200 lbs is assumed to be concentrated at his center of gravity. The effective length of the lever arm b/t his center of gravity and the support point on his socket is 6 inches. The effective length of the lever arm form the support point to the midpoint of his femur is 10 inches. How many inch-pounds of force must be distributed on his femur to prevent mediolateral instability
120
Factors that contribute to vaulting with an AK Px
Px too long
Excessive knee friction
Inadequate suspension
The gluteus medius is most active during
Mid-stance
Characteristic of the constant friction knee
Reduces “heel rise” at normal cadence
The toe of an AK Px rotates externally at heel strike. Which of the following is the major cause of this problem
PR resistance too firm
Selisian Belt Function
Aids in rotational control
Improves suspension
Provides sense of security
How is the medial lateral dimension of the quadrilateral AK socket determined
Divide the thigh circumference at ischial level by 3
In a total contact suction socket, edema is prevented by
Alternating negative and positive distal pressures
Functions of a hip joint and pelvic band
Improves lateral stability
Controls rotation
Controls abduction
Provides suspension
Compared to the AK amputation, the knee disarticulation offers
End bearing
Greater rotational control
More functioning muscles intact
Which adductor muscle is always transected in a knee disarticulation amputation
Gracilis
Swing phase whips are caused by
Knee bolt internally rotated
Rectus channel too shallow
Weak RL musculature
A burning or stretching sensation near the ischial area of an AK Pt, while they sit, most likely caused by
An excessively wide ischial seat
If the amount of adduction must be decreased on the AK plaster mold, how must the posterior shelf (seat) be modified
Add plaster laterally
What would likely cause an AK amputee to walk with an abducted gait
Improperly contoured lateral wall
Which knee provides the least stance phase stability
Constant friction
In an AK quadrilateral socket, what can cause discomfort in the hamstrings
Socket A-P diameter too small
Excessively wide ischial shelf
Insufficient to medial wall angle too large
When a mechanical friction knee is used in an AK Px, it can be expected that excessive heel-rise will occur
A faster than normal cadence
A result of reduced piston action on an AK suction socket it
More toe clearance during swing phase
Ertl procedure
Tibia bridged with the fibula
BK patient feels anterior/distal discomfort in his Px socket. How to address it
-Extend the prosthetic socket (moves pressure more proximal to painful area)
-Add pretibial pads (bridges the painful area so it receives less direct pressure)
BK stated posterior knee or hamstring discomfort
-Lower the posterior medial brim on the Px socket (relieve pressure on hamstring tendon)
-Flex the Px socket (decrease tension on posterior knee joint and hamstring tendon)
-Align Px foot more posterior in relation to the prosthetic socket (more foot posterior to decrease toe lever = decrease extension moment at the knee)
Which levels of amputation may lead to an equinus gait deformity
-Lisfranc and Chopart amputation (loss of DF attachments causes patient to Pf their ankle)
-Transmetatarsal amputation (Transects the peroneus longus tendon which assist the 1st ray
BK wearing PTB style endoskeletal Px with general knee pain and distal end pressure. The Pt doffs their Px and liner and there is redness on the distal tibia and inferior aspect of the patella bone. How to solve it
-Add a gastroc pad to Px socket
-Add a 1 ply Px sock over liner
Myodesis
The suturing and permanent attachment of a muscle to a bone
Symes amputation
-Removal of the malleoli “distal aspect”
-Placement of thick heel pad
-Amputation through the articulation of the ankle
Myoplasty
The suturing or permanent attachment of a muscle to another muscle
2 advantages of myodesis over myoplasty with regards to amputations
-Decreased rate of muscular atrophy
-Decreased rate of antagonistic muscular imbalances
During normal heel strike, the forward hip is how flexed
25 degrees flexion
Which style of muscular tissue management in a HT amputation would be of greatest advantage to a myoelectric Px candidate
Myodesis
TF patient is seen in clinic that exhibits lateral/proximal loss of contact in stance. Upon Px fit exam it is noted that lateral wall is superior to the greater trochanter, the anterior wall contours to the adductor longus tendon, the posterior socket does not encompass the ischial tuberosity, the medial wall is located 65mm inferior to the perineum. What do you attribute the cause of this deviation
The medial wall is located foo far inferior to the perineum
With a Krukenberg procedure what muscles is the driver of the pincher grip
Pronator teres
Median n. (C6, C7), pronate forearm at prox radioulnar joint and flex forearm at elbow
What would be a good quality to look for in a Px foot for a TT amputee who is a K2 designated household ambulator that utilizes his px efficiently during the day but fatigues in the evening and buckles at the knee secondary to quadriceps weakness
-Foot that progresses rapidly into PF during LR
-Heel should have a relatively soft durometer = Quick to foot flat (extension moment at knee and knee stability)
TT Pt is seen presenting with a traditional exoskeletal PTB Px with a SACH foot. Pt states that she feels like the Px is throwing her knee forward as soon as the heel firmly contacts the ground. She has worn the Px comfortably for 2 years until one month ago. What should be the 1st clinical action you should take at this time in the appointment
Check if Pt switched to a shoe with a higher heel height = Will induce flexion moment about the knee
TR patient is inquiring as to which TD would be best for picking up a small coin from a table. Which device would you recommend
5XA (Canted, non-symmetrical = allows better vision)
What are simple options for increase the ease of pre-positioning the Px elbow in flexion, for a TH amputee utilizing a body powered Px who lacks glenohumeral flexion strength and biscapular abduction strength but can operate a elbow lock
-Have the forearm lift tab located distally/anterior (you more the pull angle anterior to bridge the elbow joint whereby decrease the force necessary to move the forearm section)
-Check the level of resistance in the cable housing
What bony landmark is utilized a WB Px in a hip disarticulation
Ischial tuberosity (same as TF)
During dynamic alignment of a PTB Px, excessive knee flexion occurs at the beginning of heel rise. Which adjustment best corrects the problem
Move foot anterior = Decrease socket flexion
(increase toe lever and increase PF extends socket)
Long posterior flap in a BK amputation secondary to ischemia is preferred why
Better blood supply
A tendon that is readily visible or palpable in the popliteal area when the knee is flexed is that of the
Biceps femoris
What is strain
The change in original length of a body divided by its original length
In the transverse plane, as the knee flexes, the tibia ________ with respect to the femur
Internally rotates
“Cookie-crusher” circuit used for pediatric myoelectric Px is analogous in function to a
Voluntary opening TD
Appropriate age to activate a cable driven TD for a child with a congenital TR amputation
15-24 months
Most common cause of LE amputation is
Peripheral vascular disease
Possible cause of the Pt feeling that they are walking uphill
Foot too PF
If forearm lift loop is moved distally away from the elbow, how does it effect force
Decrease force
What might cause the Pt with a TT Px to scuff his toe on the Px side
Foot too PF
Biceps femoris relief should be _____ and _____ than that of the other hamstrings
Higher, smaller
Main extensor of the hip joint
Gluteus maximus
Antero-medial relief in the quadrilateral socket is for the
Adductor longus muscle
In the PTB design, frontal plane socket tilt should be _____ after bench alignment
5 degrees adduction
Childhood disease caused by a bacterial infection, often presents in a client as a bilateral TT and bilateral partial hand amputations
Menigococcemia
In order to check the appropriate length of the distal housing, a hook TD needs to be in a position of
Supination
What type of moment would you expect to see at toe-off if the Px socket were placed excessively posteriorly
Extension
Posterior socket = Longer toe lever = increased extension
*Anterior/Proximal and Posterior/Distal
Anterior deltoid is responsible for _____ when the arm is at your side, and for ______ when the arm is flexed
Gleno-humeral flexion and Horizontal adduction
Thomas test assess
Hip flexor tightness
In the PTB design, at MPT level, bisecting the socket laterally, a plumb line should fall ____ to the center of the pylon
1.25” anterior
Spiking or bony overgrowth usually occurs to the person who has
TT amputation secondary to amniotic band syndrome
Triceps brachii is innervated by the ______ nerve
Radial
Socket is flexed 5 degrees initially in the PTB socket designed to
-Increase the exposure to the appropriate WB surfaces
-Reduce the tendency for the knee to hyperextend during late stance
-Put the quadriceps muscles in initial stretch to increase their ability to contract
Self-suspending socket design that utilizes A-P susupension
Meunster
When using a BK adjustable shank, what would cause the pylon to lean anteriorly during static alignment
Foot heel height too low
A varus moment is desirable in the PTB socket design to
- Duplicate the normal varus moment in gait
- Optimize loading on the medial tibial flare
During static alignment of a TT Px, a socket that is too flexed will cause
- A posteriorly leaning pylon
- Toe to be off the ground
- More WB through the heel
In TT Px, if heel height of the shoe is too low
Pylon will have a posterior lean
Where does the center of the posterior wall trimline on a standard PTB socket design terminate with respect to the MTP
3/8” superior
Most common surgical Tx of a complete longitudinal deficiency of the tibia
Knee disarticulation amputation
