Prosthetics Written Boards exam

a BK amputee is seen in your clinic for a follow up appt and states that he feels anterior/distal discomfort in his socket. what could address the problem?

-extend the socket

-add pretibial pads to the prosthetic socket

a BK amputee is seen in your clinic for a follow up appt and states that he has posterior knee or hamstring discomfort. what could address this problem

-lower the posterior medial brim on the socket

-flex the socket

-align the foot more posterior in relation to the prosthetic socket

what level of amputation may lead to an equinus gait deformity

-lisfranc amputation

-chopart amputation

-transmetatarsal amputation

a BK amputee presents in clinic wearing a PTB style endoskeletal socket with general knee pain and distal end pressure. the pt doffs her prosthesis and liner and upon examination you not redness on the distal tibia and inferior aspect of the patella. what could be the most logical clinical action you could take at this point in addressing the problem?

-add a gastroc pad to socket

-add 1 ply sock over liner

-add pretib pads to socket

Suturing muscle to bone

myodesis

Suturing muscle to muscle

myoplasty

what are two advantages of a myodesis over myoplasty with regards to amputations?

-decreased rate of muscular atrophy due to providing an anchor for the muscle to pull against

-decrease rate of antagonistic muscular imbalances

which style of muscular tissue management in a TH amputation would be of greatest advantage to a myoelectric prosthesis candidate?

myodesis

with a krukenburg procedure what muscle is the driver of the pincer grip?

pronator teres

what would be a good quality to look for in a prosthetic foot for a TT amputee who is a K2 designated household ambulator that utilizes his prosthesis efficiently during the day but fatigues in the evening and buckles at the knee secondary to quad weakness?

foot that progresses rapidly into PF` during LR

a TR patient is seen in your clinic and is inquiring as to which terminal device would be best for picking up a small coin from a table. Which device would you recommend?

A. 555

B. #7

C. 5XA

D. mechanical prosthetic hand

C. 5XA

what are simple options for increasing the ease of pre-positioning the prosthetic elbow in flexion, for a TH amputee utilizing a body powered prosthesis who lacks glenohumeral flexion strength and biscapular abduction strength but can operate an elbow lock?

-have a forearm lift tab located distally/anterior

-check the level of resistance in the cable housing

what bondy landmark is utilized for a weight bearing prosthesis in a hip disarticulation?

ischial tuberosity

what is an option for pre-positioning the elbow in flexion for a TH amputee utilizing a triple control body powered prosthesis who lacks glenohumeral flexion strength and biscapular abduction strength but can operate an elbow lock?

change triple control to dual control, switch split housing to single housing, utilize ballistic motion for forearm

why is choosing a SACH foor with a firm heel durometer not advised for a TT patient with poor prosthetic side knee stability

it will decrease stability

TT sockets that are excessively extended cause excessive pressure in what areas?

anterior-proximal

posterior-distal

Outsetting the prosthetic foot on a TT prosthesis increases pressure where?

medial-distal

lateral-proximal

what structures are removed with a forequarter amputation?

arm, clavicle and scapula

in a transmetatarsal amputation you would expect to see what gait deviation?

absent push off

DF the prosthetic foor is synonymous with doing what?

flexing the socket

why is it necessary to utilize a berkeley alignable componentry prior to final fabrication of an exoskeletal prosthesis?

this will allow for you to align the prosthesis properly because exoskeletal prostheses cannot be realigned

what group of muscles would you expect to be the weakest in above knee amputees and why?

hip adductors

-they are transected more than other muscles

when flexing an AK socket to accommodate a flexion contracture what concurrent alignment adjustment should also be made?

move the prosthetic knee posterior

what is a main cosmetic concern with a knee disarticulation?

knee extends too far out when sitting or kneeling

what are some of the benefits of a knee distarticulation over an above knee amputation with prosthetic fit?

-socket rotational control

-natural weight bearing surface

-muscular balance equalized with abductors and adductors

-larger surface area for prosthetic socket

why are polycentric knees are considered inherently stable?

they have a theoretical knee center which is located posterior and superior

what are the boundaries of scarpa's triangle?

Inguinal ligament, sartorius and adductor longus

what are the benefits of prosthetic knees?

-they relatively shorten in swing phase

-they provide increased cosmesis when sitting due to linkages folding tighter than other knees

-they are inherently stable

A TH amputee is seen in clinic utilizing a body powered prosthesis with a Hosmer mechanical elbow and complains that he can operate it throughout its full range of motion but it requires too much effort. How could you remedy this?

install a spring lift assist

what is a simple option for pre-positioning the prosthetic elbow in flexion, for a TH amputee utilizing a body powered prosthesis who lack glenohumeral flexion strength and biscapular abduction strength but can operate an elbow lock

move the proximal base plate and retainer on the humeral section anterior

-you move the pull angle anterior to the elbow bridge decreasing effort required to move the forearm

a TF amputee is seen in clinic, upon doffing the suction socket you notice red, wart like formation and cracked skin distally. what is the name of this and cause?

-verrucous hyperplasia

-incomplete seating of the residual limb in the socket

a TH patient is seen in clinic. The patient is utilizing a body powered prosthesis and is wondering which terminal device would be best suited for holding a broom?

555

what is used for suspension in a hip disarticulation prosthesis?

iliac crest

what joints produce pronation and supination?

distal radioulnar joint and proximal radioulnar joint

upon fitting a TF amputee in an IC socket, you notice the ischial tuberosity is not located on the seat but further in the socket. What could you do to remedy this?

-add a sock

add a pad to scarpa's triangle

what is the coronal alignment for a SACH foot in a TT prosthesis?

0-12mm inset

A TT patient is seen in clinic. He has been successfully been using a TT prosthesis for 10 years but has a grade 1 osteochondral defect to his medial femoral that is painful during weight bearing. What alignment change could you incorporate to assist in the patient discomfort?

outset the foot 3 mm to create a genuvalgum moment at the knee assisting in opening the medial knee compartment

Many prosthetic knees require the toe to be loaded and unweighted in order to transition from stance into swing. Why would recommending two knees that function in this way to a bilateral TF amputee be contraindicated?

the patient would be unable to sit

what is the primary supinator of the forearm?

biceps brachii

in regards to TT prosthetics, excessive adduction of the prosthetic pylon would cause what at midstance

genu varum

what muscle is transected in a knee disarticulation?

adductor longus

why would forefoot adductus be a common deformity in a trans-metatarsal amputee?

the peroneus longus is transected causing weakness of the pronators allowing for supinators to override the foot and ankle comprex resulting in equino varus

a prosthetic knee that utilizes fluid resistance to modify TF swing

hydraulic single axis knee

what type of knee is most adversely affected by cold weather?

hydraulic knees

in TF prosthetic alignment, the relationship between the posterior socket shelf and the lateral wall is referred to as what?

adduction angle

where will the pressure of the socket increase at if you inset the foot?

lateral-distal

medial-proximal

what is the maximum amount of knee flexion contracture that could be fit with a traditional TT PTB socket

25 degrees

when evaluating the mechanics of a prosthetic foot, it could be said that the resistance of the prosthetic keel is acting like which muscular groupd and what type of muscular contraction?

ankle PF and essentric contraction

when aligning the prosthetic socket posterior in relation to the foo, forces present in the socket will increase where?

anterior-proximal

posterior-distal

when deciding to add a cross back strap to a figure of 8 harness, which material would be best to fabricate the cross back strap out of?

inelastic strapping

why are flexible elbow hinges recommended for longer TR amputees?

allow patient to maintain natural pronation/supination

when recommending prostheses for a bilateral TR amputee, what style socket would not be appropriate and why?

munster self suspending sockets because they require a pull sock

why is it necessary to preflex the elbow in a TH prosthesis

to decrease force necessary to lift forearm

what measurement is found by measuring the ischial level circumference divided by 3 and subtracting 6mm in a TF quad style socket?

ML measurement

what is the minimum acceptable cable/cable housing efficiency

70%

what is the appropriate location for a hip joint in a TF socket?

12mm anterior and 25 mm superior to the greater trochanter

what is the location of the lateral stabilization bar in a TT prosthesis?

between the fibular head and cut end of the fibula

what is the purpose of a silesian belt?

reduce socket rotation and assist in suspension

in TT prostheses, during initial contact, the knee is fully extended/hyperextension moment occurs. what are the possible causes and how do you fix them?

-faulty suspension does not maintain knee flexion of 5-10 degrees --> correct suspesion

-insufficient knee preflexion --> increase flexion of socet

-foot to anterior --> slide foot posteriorly

in TT prostheses, during initial contact, the knee is flexed more than 10 degrees. what are the possible causes and how do you fix them?

-faulty suspension maintains knee in greater than 10 degrees flexion --> correct suspension system

-flexion contracture --> accomodate contracture, stretch out through alignment, refer to PT

in TT prostheses, during initial contact, there is an unequal stride length. what are the possible causes and how do you fix them?

-faulty suspension --> correct suspension system

-poor gait pattern --> train patient

in TT prostheses, at midstance, the pylon leans medially. what are the possible causes and how do you fix them?

-too much adduction in the socket --> reduce adduction/abduct socket

-foot too outset --> inset foot

in TT prostheses, at midstance, the pylon leans laterally. what are the possible causes and how do you fix them?

-not enough adduction in socket --> adduct socket

-foot to inset --> outset foot

in TT prostheses, at midstance, there is no varus moment. what are the possible causes and how do you fix them?

foot outset --> inset foot

in TT prostheses, at midstance, there is an excessive varus moment. what are the possible causes and how do you fix them?

-foot too inset --> outset the foot

-socket ML too wide --> reduce ML

in TT prostheses, at midstance, there is a narrow base of support/there are less than 2 inches between feet. what are the possible causes and how do you fix them?

-foot to inset --> outset foot

in TT prostheses, at midstance, there is a wide base of support/there are more than 4 inches between feet. what are the possible causes and how do you fix them?

-foot to outset --> inset the foot

in TT prostheses, at midstance, there is lateral trunk bending to the prosthetic side what are the possible causes and how do you fix them?

-prosthesis too short --> correct length

-residual limb pain causing patient to lean laterally to reduce torque --> evaluate socket fit or inset foot

-prosthesis too long --> correct length

-foot to outset --> inset foot

in TT prostheses, during preswing,there is drop off where the patient appears to fall to quickly to the sound side. what are the possible causes and how do you fix them?

-foot to posterior --> move foot anteriorly

-foot too DF --> PF foot

-socket too flexed --> extend socket

in TT prostheses, during preswing, the socket appears to drop away from the residual limb. what are the possible causes and how do you fix them?

-socket too loose --> tighten suspension/add socks

what are causes of lateral trunk bending in TF prosthetics?

-prosthesis too short causing pt to feel as through they are stepping into a hold causing excessive pelvic dip

-pain proximal or distal --> ramus pressure to great causing patient to move away from socket or cut end of the femur swings laterally causing patient to pull away from distal lateral end of socket

-weak hip abductors --> patient cannot stabilize femur causing the pt to try an gain stability by leaning over prosthesis outsetting the foot

-short residual limb

what causes abducted gait in TF prosthetics

-prosthesis too long --> patient tries to keep hips level by abducting the prosthesis

-high medial wall --> patient feels ramus pressure most likely due to wide AP and tries to hold away from ramus

-improperly shaped lateral wall --> femur is not being stabilized

what causes circumducted gait in TF prosthetics?

-prosthesis too long --> patient unable to clear foot

-alignment stability too great --> too difficult for pt to bend knee at toe off

-friction at knee too great --> to difficult for pt to bend knee at toe off (could be extension aid to strong or flexion resistance to tight)

-foot excessively PF causing knee to be too stable

what is the cause of lateral rotation of the foot at heel strike in TF prosthetics?

-PF bumper or heel wedge too stiff --> stiff heel allows no compression at heel strike

-posterior medial wall angle too tight --> socket rotates when glutes fire

-insufficient flaring for gluteal musculature at posterior brim --> socket rotates as glutes fire

what causes a medial whip in TF prosthetics?

-externally rotated knee bolt

-socket too tight

what causes a lateral whip in TF prosthetics?

-excessive internal rotation of knee bolt

-socket too tight

what causes vaulting in TF prosthetics?

-prosthesis too long

-socket suspension poor

-knee friction too loose causing excessive heel rise

-poor gait habit

what causes excessive lordosis in TF prosthetics?

-insufficient preflexion of socket

-hip flexion contracture

-improperly shaped posterior wall --> posterior wall does not support femur allowing it to migrate posteriorly losing flexion advantage

what causes knee instability of the prosthetic knee in TF prosthetics

-PF bumper or heel too stiff --> knee flexion moment at heel strike

-knee joint to anterior

-heel height not accommodated --> higher heel height of shoe will move knee center forward producing a knee flexion moment

what causes drop off in TF prosthetics?

-DF bumper too soft --> foot DF too rapidly losing anterior support of foot causing knee to drop forward rapidly

-socket too anterior

-foot too posterior

-keel of foot too soft or short

what causes foot slap in TF prosthetics?

-PF bumper too soft

-patient drives foot into ground

what causes uneven heel rise in TF prosthetics

-knee joint has insufficient friction --> knee flexion resistance too loose

-inadequate extension aid --> allows heel to rise excessively

what causes terminal impact in TF prosthetics?

-amputee forcibly extends prosthesis to assure full extension

-knee extension aid too strong --> extension aid pulls lower leg forward to forcefully

-insufficient knee friction --> no resistance to extension

what causes a long prosthetic step in TF prosthetics?

-initial flexion insufficient

-hip flexion contracture not accommodated

what causes uneven timing in TF prosthetics?

-improperly fitting socket --> socket to tight causing the patient to want to spend less time on the prosthesis

-extenstion aid too weak or friction too loose --> causes excessive heel rise and prolonged swing through

-knee alignment unstable --> patient fears falling and avoids standing on prosthesis

what causes uneven arm swing in TF prosthetics?

-socket causes discomfort

-poor suspension --> pt attempting to hold prosthesis

a TF amputee presents with knee instability while standing and you see knee buckling with weight shift. what could be the cause?

knee to anterior

a TT amputee experience a mild knee extension moment at the knee in stance phase. What could be the cause?

heel too soft

a TF amputee complains of knee instability during gait, what could you possibly adjust to regain stability?

extend the prosthetic socket

a TT amputee experiences external rotation of the heel at heel strike. what could be a cause of this?

prosthetic heel too firm

what is the appropriate alignment for a SACH foot in TT prosthetics?

lateral view

-socket 37mm anterior to ankle bolt

-socket flexion 5-7 degrees

anterior view

-foot inset 0-12mm

-socket adducted to match valgum angle (~5 degrees)

what is the appropriate alignment for a TF prosthesis?

lateral

-knee 6-10mm posterior to socket

-vertical pylon

anterior

-socket adducted 6-7 degrees

-foot below the knee to slightly outset

what are the prosthetic knees types in order from least stable to most stable?

-outside hinges

-single axis knee

-weight activated friction control

-polycentric

-manual locking

what are the mechanical knees when listed from mechanical stability to volitional control

-manual locking knee

-polycentric knee

-weight activated stance control

-single axis hydraulic

-single axis hydraulic

-single axis friction

-single axis no dampening

what is the degree of stance flexion at heel strike?

15 to 20 degrees

what style sockets should a bilateral TF amputee have?

narrow ML with low medial trimlines

what is an amelia birth defect?

full limb missing

what is an incomplete hemimelia birth defect?

missing midshaft of bony segment (ie mid of shank/forearm)

what is a complete hemimelia birth defect?

missing full bony segment (ie tibia and fibula/ulnar and radius missing)

what is a pre or post axial radial hemimelia birth defect?

missing radius down (includes ulnar side of hand)