ULPx - Transhumeral + Elbow Disartic

transhumeral vs transradial

soft tissue to bone ratio

rotation

suspension

number of controls

do transhumeral have a high rejection rate

yes

factors that influence transhumeral acceptance rate

level of amputation

functional expectations

comfort level

cosmetic expectations

assess to peer + professional support

must achieve functional goals w/in pts comfort tolerance

transhumeral surgical stabilization

usually biceps + triceps undergo myodesis → maintain bony control

myoplasty → provide counterbalanced muscles + distal padding, muscles tend to migrate medially, + be aware when searching for myosites on mature limbs

transhumeral postop care

same as transradial

30 day rule

edema control → healing

desensitization

pain mgmt → rigid dressing can be used as endo px to begin training, early use helps incorporate inot body image + learn kinesthetic awareness, + care team should establish immediate, short term, + long term goals

PT for ROM/MMT

psychology

therapy for training → stage use of componentry

mods to socket as limb changes → stabilization of residual limb shape (definitive px)

factors that influence fit

length of humerus → determine lever arm + functional load it can support, bone lengthening is an option

thickness + condition of subcutaneous skin

shape of limb

condition of musculoskeletal substructure → is distal end of cut bone beveled (beveled = bad)

load tolerance of pt

ROM of glenohumeral + sternoclavicular joints

what are the prosthetic options for transhumeral

none

passive non-prehensile px

body powered px

externally powered px

hybrid px

what are the pros + cons of a passive transhumeral px?

pros → good cosmesis, useful for supporting/stabilizing objects

cons → decreased function (non-prehensile), high cost

what are the pros + cons of a body powered transhumeral px?

pros → feedback, proprioception, good function + durability (robust), can use in all environments, good for heavy duty/manual labor

cons → decreased cosmesis esp w/hook, harness discomfort/nerve issues

what are the excursion requirements for a body powered transhumeral px?

terminal device → 50mm

elbow → 50mm

total → 100mm w/fair lead cable

elbow lock → 12mm, typically shoulder depression or abduction

how does the dual control fair lead cable work?

elbow flexion + terminal device → sequential

elbow lock → dedicated

how does the triple control cable work?

dedicated terminal device cable, elbow lock, + elbow flexion

what are the pros + cons of an externally powered transhumeral px?

pros → less harnessing, less excursion required, options for increased function w/hand grips

cons → increased cost, some consideration for hostile environments, suspension, maintenance, charging

what are the pros + cons of a hybrid transhumeral px?

pros → decreased excursion compared to body powered, can decrease complexity for multiple components

cons → similar to body powered + externally powered alone, decreased cosmesis esp w/hook, harness discomfort/nerve issues, increased cost, some consideration for hostile environments, suspension, maintenance, charging

what does socket design influence?

good fit increases excursion

proximal trimlines can change based on length + rotational issues

shape of wings help to support the socket

proximal trimlines for a short limb

include acromion + acromioclavicular joint

medial to deltopectoral groove ~25mm

medial to lateral border of scapula ~25mm

proximal trimlines for a mid length limb

up to acromion

include deltopectoral groove

include lateral border of scapula

proximal trimlines for a long limb

exclude acromion

deltopectoral groove

lateral border of scapula

what are the A/P socket loading forces?

compression btwn infrascapular spine + superior pec tendon

what are the lateral socket loading forces?

length of humeral shaft

10mm proximal to distal end

what are the wide M/L proximal socket loading forces?

leads to proximal lateral gapping = pad proximal medial to reduce proximal lateral gapping + distal lateral pressure

what does carrying angle impact?

the way the pt holds the limb in coronal plane

consider alignment of elbow unit

how does alignment of elbow below residual limb influence hanging moments on residual limb

push in socket design

historic

common for elbow disartic

easy to fab

looser fit

often have bell clapping fit

if too tight → hammocking, mushrooming

pull in socket design

popular w/shorter limbs

socket circumference smaller than residual limb

common w/myoelectric

typically lower trimlines bc of better grasp on limb for control

donning more challenging

typically need dexterous contralateral limb to assist in donning

contraindicated for bilateral pt

suspension for transhumeral px

harness

suction → skin fit, roll on liner

roll on locking liner → pin + lock, lanyard

anatomical contouring

combination

figure 8 dual control differences from single control

elastic suspensor + elbow lock strap instead of inverted Y

need 12mm excursion to activate elbow lock

lateral support strap addition → suspension, reduces lateral tipping

transhumeral elbow components

outside locking

flail arm hinges

internal locking

friction

ergo arm

endoskeletal

active lift (external power)

when is an outside locking elbow used

elbow disarticulations w/no room for elbow unit

7 locking positions

5 heavy duty

what is a flail arm hinge?

locking + spring loaded → locking medial side, spring lateral side

brachial plexus injury → flail arm hinges contain oversized clock spring mechanism to partially counterbalance wt of forearm

may be used singly or in pairs → depending on degree of counterbalance desired

may be combined w/single free joint or single locking joint as necessary

what is an internal locking elbow

11 positions (10 pediatric)

can use lift assist (xtra component)

12mm to lock/unlock

amputations thru humerus approx 5cm/2” prox to elbow joint provide adequate space to accom inside locking elbow mechanisms

inside locking units permit amputee to lock elbow in any 11 positions of flexion

inside locking units incorporate friction held turntable

turntable permits manual prepositioning of px forearm as substitute for external + internal rotation of humerus

how are the elbow units flexed

forearm lift table assembly → elbow flexion attachment, positioning affects force + excursion

forearm lift assist → medial side, increases lift/spring loaded, excursion benefit (tab placement), installs into Hosmer locking turntable elbows

ergo arm

infinite number of locking positions

slip stop function

unlocks even under load

7mm excursion needed

models may be body powered or hybrid

friction elbow

manual positioning

adjustable friction

passive px

friction elbows req passive positioning of forearm but are very lightwt + simple to operate

appropriate for cosmetic restorations, pediatrics, congenital anomalies, + instances when brachial plexus injuries or other factors preclude active elbow function

endoskeletal elbow

elbow lock

button release

lever release

externally powered hybrid elbows

ottobock → axon arm ergo, ergo arm x2, dynamic arm

steeper → espire classic plus, espire hybrid

fillauer → utah hybrid arm, motion arm

these elbows have a lock + are prewired to go from signal sites to wrist/terminal device → manual/electric lock depending on elbow

externally powered power lift elbows

mobius bionics → luke arm

steeper → espire pro

fillauer → utah arm 3+, motion E2 elbow

dynamic lift

heavier than other elbows

offer free swing mode

difficulties w/transhumeral px

intimate sockets/harness

more excursion needed for full body powered

decreased lever arm

motions needed for operation

excursion needed for terminal device, elbow, + total

elbow disartic pros over transhumeral

maximal lever arm

minimal soft tissue disruption

load tolerant distal end

potential supracondylar suspension

elbow disartic cons over transhumeral

build ht

outside hinges → bulk, cosmesis

when is elbow disartic often used

in pediatrics

surgeons may restrict growth of ipsilateral arm to reduce discrepancy between arms

no incidence of bony overgrowth

pt may have resection (osteotomy) of humerus to move condyles proximally

other surgical variation → angulation osteotomy of distal humerus to provide better suspension

elbow disartic socket designs

removable medial door

stovepipe liner

spiral mod

inflatable bladder

clamshell

open design

where will the pt experience forces on the limb in the socket with the elbow flexed to 90?

anterior distal

posterior proximal

where will the pt experience forces on the limb in the socket with the shoulder abducted, esp if a short transhumeral?

distal lateral

proximal medial

where will the pt experience forces on the limb in the socket with a body powered transhumeral px w/dual control cable and base plates on lateral side of socket?

the px will rotate

how much force is on a pts limb if they are transhumeral, their shoulder is at 0 degrees, elbow is straight, and they are holding weight?

low force

where does the northwestern ring need to be placed on a figure 9 harness?

inferior to C7 and midline or slightly contralateral

how do you determine the cable housing length for a transhumeral pt?

1/4” gap at TD + elbow when elbow fully flexed

3/4” proximal end

determine with hook open + supinated

proximal cable housing btwn retainer + forearm lift tab needs enough gap btwn housings to allow full forearm flexion

amount of cable housing proximal to base plate we don’t want it so short it cuts into socket with excursion but not so long it rubs against pt shirt/skin

how do you determine the cable length for a transhumeral pt?

determine with hook closed + pronated, elbow extended

1/4” gap on either end from housing

what pt presentation is the muenster socket used for?

short + very short below elbow amputees

what is a benefit of split socket w/step up hinges?

provide full ROM of elbow flexion to amputees w/very short below elbow residual limbs

what are 3 drawbacks of split socket w/step up hinges?

decrease lifting power available to amputee

increase bulk of px at the elbow + proximal forearm

historically have lacked durability

what is the expected forearm flexion angle for a muenster socket at the end of its extension range?

35 degrees

what is the expected forearm flexion angle for a muenster socket at the end of its flexion range?

105 degrees

what is the expected flexion range for a pt in a traditional transradial socket?

135 degrees

what is the minimum residual limb length needed for a muenster socket?

1.5”

what is the maximum residual limb length (%) that can be fit with a muenster socket w/o considerable modifications?

55%

what 2 modifications are often used to fit longer muenster sockets?

socket is made looser

posterior trimlines are reduced to just above olecranon

why is it difficult for bilateral pts to wear 2 muenster sockets?

difficulty donning w/o assistance + limitation imposed by restricted elbow flexion esp on dominant side

what is the 0 point when measuring the length of a residual limb for a muenster socket?

olecranon

what is the distal point of the length measurement on a muenster?

distal redundant tissue

what is the elbow flexion angle of pt for casting a muenster?

90 degrees

what is hand positioning + direction of force for anterior hand in a muenster?

index + middle fingers are placed on either side of biceps tendon + along anterior surface of residual limb

moderate pressure is extended simultaneously into cubital fold + downward onto anterior surface of residual limb

avoid concentration of pressure distally

what is the hand position for the clinician’s posterior palm of hand in a muenster?

grooved so the thenar + hypothenar eminences form a channel

digits 2-4 → cupped + positioned on distal posterior surface of humerus just above epicondyles, apply gentle downward pressure w/pads of fingers, avoid pressure on olecranon

digits 1 + 5 → curled to make contact w/medial + lateral epicondyles respectively, these digits do not exert pressure

how much pressure is applied to the olecranon while casting a muenster?

none

what are the trimlines of a muenster?

posterior → line connecting 2 points from M/L trimline above condyles

M/L → 1” superior to medial + lateral condyles

anterior → 1/2” above midcubital space

what is the preferred type of plaster for a muenster cast?

elastic plaster bandage

how high should the plaster be wrapped wrt trimlines when casting a muenster?

2 circular turns above elbow joint over the olecranon + cubital fold

what is done to the proximal edge of the elastic plaster after it has hardened when casting a muenster?

reinforced w/several turns of nonelastic plaster bandage to minimize distortion

how do you test the comfort + ROM of a muenster cast?

having the amputee exert force against resistance in elbow flexion, extension, + rotation

what are the 3 reasons for limited flexion range in a muenster socket?

insufficient relief for the olecranon

too small of a channel for the biceps tendon

or too high of an anterior wall

what is the reason for limited extension range in a muenster socket?

too high of a posterior trimline

what length of limb is a northwestern socket designed for?

all lengths of below elbow amputations

what is the most important measurement that is taken snug at the apex of the condyles for a northwestern socket?

M/L distance at apex of condyles

what is the flexion angle of the elbow when the length measurement is taken for a northwestern socket?

90 degrees

what are the 2 end points that are used to measure the length measurement for a northwestern socket?

posterior edge of the olecranon to the end of the longest cut bone

what is the elbow flexion angle that is used during casting for a northwestern socket?

45 degrees

how far should the plaster extend proximal to the olecranon + humeral condyles for a northwestern socket?

no less than 1” superior to olecranon process + humeral condyles

what is the clinician hand position (premods) during casting for a northwestern socket?

none

avoid distorting the cast

what is the path/channel in the socket for the condyles to enter the socket for a northwestern socket?

anterior-proximal corner of socket trimline

what is the width of the condyle channel in a northwestern socket?

1/8” smaller than M/L at condyles

how can the condyles fit through an opening smaller than the bony dimension in a northwestern socket?

slight expansion of the socket + flexibility of resin in the definitive socket

if the limb is longer than 5”, what percent of length should be the distance to the distal most anterior trimline in a northwestern socket?

45%

what should the width (PML of anterior trimline wrt humeral condyles) be in a northwestern socket?

3/8” smaller than M/L at condyles

what is the minimum height of the posterior trimline in a northwestern socket?

at least 1/2” cupped over olecranon

how much relief should be built over humeral condyles in socket for a northwestern socket?

at least 1/8” thick

how much relief should be built over the olecranon in the socket for a northwestern?

at least 1/8” thick

what angle should the elbow be placed in to practice hand position and to take the cast in for a TRAC socket?

90 degrees

proximal medial + lateral compression is applied where and where wrt epicondyles for a TRAC socket?

anterior + slightly inferior to epicondyles using thumb + index finger

directed toward olecranon

if using the posterior hand position for the impression in a TRAC, the thumb webspace can be used to compress what portion of the mold?

superior to olecranon to ensure appropriate contouring of supraolecranon region

how can the stockinette be secured to pt for a TRAC cast?

figure 8 harness

what position should the elbow be in when marking landmarks for a TRAC?

90 degrees

what is the location of the anterior trimline for a TRAC socket?

following the cubital fold

what is the M/L width dimension of the anterior trimline for a TRAC?

parallel to medial border of ulna + lateral border of radius

what is the posterior trimline for a TRAC?

approx 12-18mm proximal to superior aspect of olecranon

how wide is the posterior trimline for a TRAC?

width similar to width of olecranon

where is the apex height of the medial + lateral trimlines in a TRAC?

40-50mm proximal to superior aspect of epicondyles

how high should plaster be wrapped wrt the anterior trimline of a TRAC?

1cm proximal to cubital forld + previously delineated anterior trimline

how high should plaster be wrapped wrt the posterior trimline in a TRAC?

not exceeding the posterior trimline

how high should the plaster extend wrt medial + lateral trimlines in a TRAC?

enough to secure the medial + lateral splints just past the margins of the trimlines

the second hand should be positioned with which 2 fingers providing compression + where for a TRAC cast?

compress borders of biceps tendon w/a force directed to the olecranon using index + middle finger