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General Prosthetic Questions for ABC Written Exam
Terms in this set (120)
Bench Alignment for TT
-1/2" to 1" inset
outward rotation or parallel to the LOP
-37mm posterior (18-65mm range)
-1/4" anterior from ankle bolt to midline
Bench Alignment for TF
- 5* flexion + flexion contracture
- Long's line + 2
-outset foot 1" from ishium + 1
-5* external rotation of the knee
Cuff strap placement
-1cm posterior and 1cm proximal to midline at PTB level
Silesian Belt placement
-1/4" posterior and proximal to G.T. (Lateral)
-1/4" proximal and medial to bisection (Anterior)
Cycle the Elbow in TH prosthesis
- 2lbs force
Operation of TD and Elbow lift (Excursion)
-2 1/2" to lift elbow
-2" for TD
Starting point for EFA
- 1" distal and 1" anterior to elbow center
Hip Bench Alignment
-joint anterior to knee center 25-50mm
-reference line knee center to 37mm posterior to heel
-1/2" anterior and 1" proximal to GT
-Inferior Pubic Ramus
Adduction of the lateral wall of the socket
Re-establishes the normal angulation (6-7*) of the femoral shaft, thereby placing the hip abductor muscles under their normal operation tension
Proper contouring of the lateral wall
-Allows for even distribution of force over the lateral aspect of the residual limb, specifically between the greater trochanter and the lateral distal aspect of the femur
-Relief for the lateral distal end of the femur and for GT
High medial wall
-Proximal medial wall must be high enough to apply counter pressure to maintain good contact between the femur and the lateral wall
Proper mediolateral dimension of the socket at ischial level
-too large an ML will reduce the effectiveness of the lateral and medial walls to stabilize the femur
-Divide the circ of the thigh by pi and subtract 1/4"
Proper anteroposterior dimension of the socket
-too large an AP will tend to permit the IT to be displaced forward, off of the ischial seat.
-correct AP determined by subtracting 1/2" from the anatomically determined distance between the ADDUCTOR longus tendon and the IT
Pressure on Scarpa's Triangle provides
-relieves pressure at initial contact
-comfort for sitting
-relieves the ADDUCTOR longus tendon
-keeps pelvis from rotating
-IT on the seat
-concentrated in the anterior distal tibia and posterior proximal soft tissue
-Socket provides even pressure distribution in the popliteal area and anterior distal relief to prevent excessive pressure
-forces at the proximal medial and distal lateral area force a varum moment at midstance
-Socket must have relief for the distal lateral fibula and lateral stabilizing pressure over the shaft of the fibula and anterior compartment.
-Occurs when the socket moves in a direction opposite to the residual limb's motion.
-Tendency of the socket to rotate on the residual limb
Joint Location for TT J&C designs
-2 1/4" inches superior to the patella tendon protuberance, and slightly posterior to the sagittal midline.
-joints must be square to each other and an equal height from the floor
-line through JCs would be roughly perpendicular to LOP
-slight anterior tilt
-extension stop strap can prolong joint life.
Corset Location and Configuration
- generally 8" long
-Proximal lateral border 1" higher
-Anterior distal edge is proximal to patella
-opening is 1" wide
- When sitting tissue should not be pinched between proximal socket wall and distal corset aspect. 1" clearance needed.
Transradial Amputation Levels
-Very Short: 0-35%
Voluntary Opening TD
-Closed at rest
-Body motion and effort used to open TD
-Max force regulated by the # of rubber bands or springs (1 rubber band = 1lb of pinch force)
-requires 2 1/2 times the pinch force to open the TD
-Open at rest
-Body motion and effort used to close the TD
-Max force regulated by the patient effort and the mechanics of the device
-requires user to overcome the spring/elastic cord
-short to very short limbs
-light to moderate duty
-LL =1 1/2" to 5 1/2"
ROM from 35
-low anterior timelines
-longer limbs, greater than 55%
-good for bilaterals
- mid range limbs
-M-L & A-P compression
-dynamic casting technique
Elbow Flexion Attatchment Adjustment
-more proximal = less required excursion
-more distal = less required force
Proximal Base Plate Retainer
-more posterior and distal = less required excursion
-more proximal and lateral = less required force
-must be 25mm proximal to the cut end of the humerus
Cable Housing and Length
-Cable Length -- extend arm and pronate TD (3mm clearance between hangar and proximal housing)
-Housing Length -- flex elbow, supinate and open TD (3mm clearance between triple swivel and distal housing, 6mm clearance between proximal and distal housings at the elbow joint)
Force Problem -- when flexing the elbow joint, the TD begins to open
-add tension bands
-move EFA distal
-move BPR lateral and proximal
-add spring lift assist
-add second BPR
-check cable efficiency
-check proximal and distal fair lead upon flexion
Transverse Limb Deficiencies
-normal development until the point of deficiency, beyond which the normal anatomy does not exist
Longitudinal Limb Deficiencies
-absence of skeletal anatomy within the long axis of the limb, sometimes includes normal anatomy distal to the affected area
-take off a rubber band
-tighten CAS, as soon as the arm begins to bend
-triple swivel hitting cable housing
-move EFA proximal
-move BPR posterior and distal
-cross back strap, prevents harness migration
-dual ring, expanded cross point, Baha, relieves auxilla pressure, improves line of pull
-long limb = 9-12*
-medium limb = 7-9*
-short limb = 5-7*
Flexion of the socket
-Allows for even stride length
-Puts hip EXTENSOR at a functional advantage
Adduction of the socket
-allows for loading of the lateral distal femur
-puts hip abductors at a functional advantage
-places femur in anatomical alignment
Recommended IC trim lines
-Anterior = 2"
-Lateral = 3.5"
-Posterior = 1"
-Medial = Ischial level
TF Biomechanical Objectives (Frontal Plane)
- Provide ML stability of the pelvis during midstance on the prosthetic side
- Conserve energy by minimizing excessive lateral displacement
TF Biomechanical Objectives (Sagittal Plane)
-Provide AP stability of the prosthetic knee joint between initial contact and terminal stance
-Permit the amputee to take a normal step with the sound side
ML Stability -- Ischial Weight Bearing
-Displaces fulcrum medially, thereby deducting the magnitude of the moment
ML Stability -- Proper foot position
-- Bench, plumb bob from ischial seat will bisect the heel of the shoe
-Quad = 0-65mm outset, IC = 25-37mm outset
-Causes a varus moment at the hip where the pelvis titles toward the unsupported side causing the hip abductors to fire for balance and displacing the femur laterally.
-short limbs will need less inset
ML Stability -- Adduction of the lateral wall
-re-establishes the normal femur angle
-puts abductors on stretch giving them a better mechanical advantage
ML Stability -- Proper contouring of the lateral wall
-allows for even distribution of the force over the lateral aspect of the residual limb
-socket relief must be provided for the lateral distal aspect of the femur and GT
ML Stability -- Provide high medial wall
-high enough to maintain counter pressure the lateral wall providing contact between the femur and the socket
-restrict ML movement
-take pressure from ischium
ML Stability -- proper ML dimension
-too large an ML will lead to a destabilized femur
ML Stability -- Proper AP dimension
-keeps ischium on the seat
Five Prerequisites of Gait
-stability in stance
-clearance in swing
-preposition of the foot in terminal swing
-adequate step length
Three Goals of TT Biomechanics
-Increase weight bearing capacity
-Maintain ML stability at midstance on prosthetic side by providing a varus moment
-encourage knee flexion throughout the stance phase on the prosthetic side
TT Biomechanics - Increased Weight Bearing
-load pressure tolerant areas and relieve pressure sensitive ones
-utilize flexion in the interface
-provide total contact
TT biomechanics - Flexion in the Interface
-increase vertical loading area
-encourage knee flexion moment at initial contact
-decrease or discourage a knee extension moment at terminal stance
TT biomechanics - Total Contact
-increase overall surface area
-minimize distal edema
Center of gravity
In quiet standing the COG is considered to be just anterior to the second sacral vertebrate.
Pressure Tolerant Areas
-Medial Flare of the Proximal Tibia
-Medial shaft of the tibia
-lateral shaft of the tibia
Pressure Intolerant Areas
-lateral flare of the tibia
-anterior tibia tubercle
-crest of the tibia
-head of fibula
-distal end of fibula
Dynamic Forces - AP
-IC to LR
-anterior distal tibia and proximal posterior
-distribute even pressure to popliteal
-anterior distal relief
Dynamic Forces - ML
-Single limb support, force medial to knee joint
-proximal medial and lateral distal
-can be decreased by outsetting the foot, not always desirable
-relief for distal lateral fibula
-lateral stabilizing pressure from the anterior compartment & shaft of the fibula
Femoral Nerve -- L2,3,4
-hip flexion & knee extension
Obturator Nerve -- L2,3,4
-hip abduction, extension and rotation
-adductors (Magnus, longus, brevis)
Superior Gluteal Nerve -- L4,5,S1
-hip abduction, medial rotation
- gluteus medius
-tensor fascia late
Inferior Gluteal Nerve -- L5, S1,2
Sciatic Nerve -- L4,5 S1,2,3
-knee flexion, hip addiction, hip extension
Tibial Nerve -- L4,5 S1,2,3
-planter flexion, inversion, some knee flexion
-flexor halluces longus
-flexor digitorum longus
Common Peroneal Nerve -- L4,5 S1,2,3
-dorsiflexion, inversion, some Everson
-common - short head of bicep fedoras
-Deep - tibialis anterior, EXTENSOR digitorum longus and brevis, EXTENSOR hallicus longus and brevis, Proteus tertius
Superficial -- Proteus longus and brevis
Out of Socket Pressure
Too Deep in Socket pressure
-inferior border of the patella
-anterior distal tibia
-medial aspect of the tibia
Termination of Gait training
-no open areas
-no areas of irritation
-at least 5-8 hours of wear daily
-prosthesis is comfortable
Clues to skin problems
Syme Terminal Toe
Toe (digital disarticulation at metatarsophalangeal joint)
Metatarsal Ray Resection Transmetatarsal
Distarticulation at the midtarsal joint (through the talonavicular and calcaneocuboid joints)
Disarticulation at the midtarsal joint (Calcaneal fragment-tibial arthodesis End Bearing Stump)
Disarticulation at the midtarsal joint (Calcaneal arthrodesis, no heel flap migration, end bearing Stump)
a contrast medium is injected into the femoral artery and the vascular outline is observed roenrgenographically to detect evidence of collateral circulation.
Radioactive Xenon 133
Measuring skin blood flow at the potential amputation site is the determination of the clearance rate of intracutaneously injected Xe.
Directional Doppler Flow detection
A technique for assessing arterial velocity and extermity systolic blood pressure. systolic pressure in excess of 70mm Hg found below the knee is associated with wound healing.
measures the pulsatile change in volume of all of the tissues under the cuff with each heart beat.
Provides a picture of the sympathetic response in the limb by placing the limb in an air or water tight chamber and then measuring the arterial inflow of blow in response to a change in the volume of the chamber
Removal of a part
Surgical technique that builds a tunnel through a muscle of the residual limb to power an artificial limb.
The presence of pathogenic organisms in the blood, which leads to infection.
A thickening, hardening, and narrowing of the walls of the arteries.
A clot or mass of foreign materials that obstructs a vein or artery.
Surgical removal of the lining of an artery.
A clot made of blood and other materials that forms and attaches to the walls of an artery.
Self dissolution of tissue, usually by an enzyme within the body.
A large fluid filled blister.
Lack of blood flow to an area or part.
Congenital absence of one or more limbs.
Longitudinal deficiencies in which part or all of one long bone is missing.
Defective development of tissues.
Proximal focal femoral deficiency.
Multiple congenital abnormalities of the hand and wrist
The congenial joining together of digits.
Complete absence of the hand
Complete abscence of the foot.
Absence of digits
Arms and legs foreshortened like a seal.
Depression and Elevation of Shoulder
40 E & 10 D
Scapular AB & AD
20 AB & 15 AD
Glenohumeral AB & AD
180 AB & 20 AD
Glenohumeral Flex and Ext
180 Flex & 60 Ext
20 Lat & 90 Med
Elbow Flexion and Extension
140 flex & 60 ext
Supination and Pronation
80 sup and 90 pro
Pressures in an TF suction socket
Stance = positive, Swing = negative
Absence of one or more phalanges from all five digits
How much clearance is required in the housing in a split cable system?
12mm or 1/2"
How much rotational force can a elbow turntable resist?
TF alignment for a SACH foot
Heel durometers act as?
A tight fitting shoe can cause what?
Limited heel compression
Range of cuff suspension
tight fit 0
, loose 60
talocrural joint allows PF and DF
Subtalor allows for EV and IN
Metarsophalangeal allows for smooth roll over
CLI Life expectancy
5y = 30%
10y = 50%
Space for UL locking Elbow
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