Trans-Fem Prosthetics Flashcards
What does axial load through amputated side rely on?
- body weight distribution through remaining anatomy
What does coronal plane stability rely on
- socket fit and alignment
What does swing phase control of the prosthetic knee rely on?
hip ROM/musculature
what does stance phase control of the prosthetic knee rely on?
hip ROM/musculature and manipulation of body weight
3 Types of TF socket Designs
- Quadrilateral
- Ischial Containment
- Sub0Ischial
Quadrilateral (Quad) Socket
- Ischial weight bearing
- Rectangular shape, tight AP
- Scarpa’s triangle
- Accommodates functioning muscles
- Total contact
What is the issue with a quad socket?
lack of proximal/medial stabilizing force
Ischial Containment
- boney weight bearing
- femur stabilization
- controls transverse forces, triangular
- has coronal stability unlike quad
- Ischial weight-bearing + containment on medial side
- Total Contact
What muscles does ischial containment accommodate
hamstrings
adductor longus
advantages of ischial containment
- enhanced stability
- improved confort
- less soft tissue distortion/injury
disadvantages of ischial containment
- a lot of variance in design
- may be challenging to fit well
- possible ROM restriction
Sub-ischial brim
- hydrostatic loading (controls varus moment through suction or vacuum)
- improved hip ROM
- sitting comfort
- not having ischial containment has a lot of advantages (scissor legs/touching toes)
What should you consider with TF suspension
- additional weight
- transverse forces
Lanyard
- use for someone with balance issues
- works well for sock ply- good for someone who is changing volume
Suction - skin fit
- put bare residual limb into socket
- at bottom, open the valve and pull nylon bag through to create hydrostatic load
- good for very short residual limb
suction - seal in liner
- most TF will have this liner
- a lot more soft tissue so seal can just absorb into it
- a lot of athletes
- more proximal seal
vacuum
- seal in liner with vacuum
- liner and suspension sleeve with vacuum
- seal between outside of liner and inside of socket
TES Belt
- total elastic suspension
- mostly auxiliary
- good for peds/congenital limb anomalies
Silesian belt
- non elastic
- rotation control
- may be stand alone
- made out of seat belt material
- prevents unwanted transverse deviations in the socket
Hip joint and pelvic band
- coronal stability
- rotation control
- Someone who has laxity at the hip
- Previous use
- Very short/almost hip disarticulation level
- Very rigid hip joint
- Involves side is contoured leather
- Prevents dropping away laterally/Trendelenburg type
Suspenders
- non elastic
- correction tension to allow flex/ext
what purpose does a knee serve
- Enable sitting
- Swing phase clearance
- Efficiency
- Safety with resistance
- Accommodate to various postures
how to achieve stability
- Voluntary control
- Alignment
- Knee design- mechanics
- Resistance/friction
To what extent can the patient contribute to stability?
- hip strength (extensors)
- residual limb length (lever arm)
- balance, body weight manipulation
TKA Line
- line from troch to ankle
- identifies knee inherent stability from an alignment perspective
3 knee alignments
- Trigger alignment: directly through the knee
- Overly stable: slightly ant - sitting on end (ext) stop - “safe” alignment
- Post (unsafe): nothing to rest on - going to bend the way it want to
Prosthetic knee- friction
to primarily control knee during swing phase
- flexion: limit heel rise
- extension: prevent terminal impact
two types of friction
mechanical
fluid
Mechanical Friction
- K1/K2
- Constant force
- 1 speed ambulators
- Several designs
- Light weight
- Low maintenance
** medicare only covers friction knees for K1/K2 (will not pay for fluid knee for K2)
Fluid Friction
- K3/K4
- Hydraulic or pneumatic
- Supports variable cadence
- Controlled in a variety of ways * More expensive
- Adds weight
- ramps up resistance to the force you are putting on it
Extension assist
- Limits heel rise to make the knee ext faster (knee responds quicker)
- Helps achieve full knee extension
- Safety for new users
- Adjustable
- Add a terminal impact, they should feel when it is fully extended to know when it is safe
single axis knee
- less moving parts and simple
- lower fabrication cost
- less stable at heel strike
- one axis to absorb forces applied
polycentric knee
- inherent stability at heel strike
- easy to initiate swing phase
- often heavier
- increased maintenance
- instantaneous knee center
- indicated for long residual limbs
- K2 is mechanical friction
- K3/4 if fluid friction
manual lock knee
- K1 or K2
- optional lever release on socket
single axis knee
constant friction (k2) or fluid control (K3)
multiaxial knee
- additional stability through geometry
- slide/glide articulation at knee
microprocessor knee
- sensors to predict action
- stumble recovery
- real time knee adjustments
- allows for step over step
TF Biomechanics - Coronal Plane Goals
- ML stability of the pelvis @ midstance
- Conserve energy by minimizing lateral displacement of CoG
TF Biomechanics - Sagittal Plane Goals
- Provide AP stability of the knee joint during stance,
smooth advancement. - Step length symmetry.
Coronal Plane - ML stability of the pelvis during midstance
- Slight varus moment of the socket
- Minimal socket gapping due to boney lock or other means of stabilization
- No trunk compensations
coronal plane - varus moment factors
- Prosthetic alignment
- Limb length, soft tissue structure
- Socket fit
More coronal plane stuff
- Foot should start beneath the
ischium, should produce a varus moment at the hip - Pelvis drops to unsupported side
- Hip abductors fire
- Femur ABducts
Coronal Plane Socket Design
- Adduction angle: Femoral/pelvic angle is assessed
- Lateral wall: Maintains femoral angle
- Medial wall height: Counterforce, boney lock
- ML dimension
- Hip joint and waist belt: If unable to ABduct
Alignment in coronal plane
- Inset foot = increased varus moment
- Outset foot =decreased varus moment
Sagital Plane priority
- AP stability of the knee joint during stance
- alignment
- voluntary control
- knee selection
- foot selection
softer feet
the softer the feet the easier it is to control the hip
sagittal plane alignment
- TKA reference line maintains GRF ANTERIOR to the knee joint
sagittal plane - component selection
- knee
- foot (single axis foot, heel stiffness)
sagittal plane - step length symmetry
- Often a prosthetic socket is pre-flexed
- 3-5 degrees beyond Thomas test measure
Step length Requirements
- 3 deg lordosis
- 5 deg femoral ext
- 7 deg knee flexion (stance flexion)
- = 15 degrees
more step length stuff
- Knee must be fully extended to stand on prosthesis.
- 3-10 deg lordosis
- 5-12 deg femoral ext
- 1st step with sound leg
- Accommodation vs therapeutic alignment.
Prosthetic cause of gait deviations
- Identify alignment or design aspects of the prosthesis
that can cause or contribute to the deviation. - Determine what adjustments or modifications to the
prosthesis can be made to correct the deviation
amputee cause of gait deviations
- Identify habits, activities or conditions that the patient
is doing that can cause or contribute to the deviation.
therapy goals
- Determine what therapy or gait training intervention
can be provided to assist the patient to correct or
address the deviation.
medial whip - prosthetic cause
- External rotation of the knee
- Tight socket
- Incorrect foot rotation
medial whip - amputee cause
- Gait habit
- Socket not put on properly
- External rotation of hip at toe off/hip flexion
medial whip - therapy goals
- Encourage proper donning
- Strengthen internal hip rotators and hip extensors
- Modify activity that may increase external rotation
lateral whip - prosthetic cause
- Internal rotation of the knee
- Loose socket
lateral whip - amputee cause
- Gait habit
- Socket not put on properly
- Internal rotation of hip at toe off/hip flexion
- Tight adductors, int. rotators, flexors
lateral whip - therapy goals
- Encourage proper donning
- Strengthen external hip rotators
- Stretch hip flexors and adductors
- Modify activities that increase internal rotation of hip
Abducted Gait - Prosthetic Cause
- Prosthesis too long
- Medial wall too high
- Insufficient femoral stability in socket
abducted gait - amputee cause
- Abduction contracture
- Pt insecure and wants wide base
abducted gait - therapy goals
- Stretch abductors
- Strengthen core, residual limb and sound leg
- increase proprioception
Circumducted Gait - Prosthetic Cause
- Long prosthesis
- Excessive knee friction/stability
Circumducted Gait - Amputee Cause
- Lack of confidence in flexing knee
- Abduction contracture
- Weak hip flexors
- Habit, using entire hip and pelvis to initiate gait
Circumducted Gait - Therapy Goals
- Stretch abductors
- Strengthen hip flexors
- Gait training
Vaulting - Prosthetic Cause
- Long prosthesis (or heavy)
- Poor suspension
- Excessive plantar flexion of foot
- Excessive knee resistance or stability
- Inadequate knee extension assist
Vaulting - Amputee Cause
- Gait habit, fear of catching toe
- Weak or improper initiation of hip flexors on residual limb
Vaulting - Therapy Goals
- Strengthen hip flexors
- Work on timing and symmetrical pelvic rotation
- ADL training
Heel Rise - Prosthetic Cause
- Inadequate extension aid
- Insufficient knee friction
Heel Rise - Amputee Cause
- Excessive use of hip flexors to initiate swing phase, overpowering knee unit
Heel Rise - Therapy Goals
- Work on coordination and encourage symmetrical motion of the femurs
- Work on timing of flexor firing
Knee Instability - Prosthetic Cause
- Excessive dorsiflexion
- Knee aligned in unstable position…TKA
- poor socket flexion or foot alignment
- Incorrect knee settings
Knee Instability - Amputee Cause
- Weak hip extensors
- Hip flexion contracture
Knee Instability - Therapy Goals
- Strengthen hip extensors
- Stretch hip flexors
Uneven Timing - Prosthetic Cause
- Socket Pain
- Weak extension aid
- Unstable knee*
- Leg length discrepancy
- Poor suspension
Uneven timing - amputee cause
- Patient insecurity*
- Weak hip muscles
- Poor balance
Uneven Timing - Therapy Goals
- Strengthen hip flexors and extensors
- Improve balance and proprioception during ADL
Lateral Trunk Bend - Prosthetic Cause
- Foot too far outset
- High medial wall
- Aligned in abduction
Lateral Trunk Bend - Amputee Cause
- Inadequate balance
- Short residual limb (or weak GM)
- Habit
Lateral Trunk Bend - Therapy Goals
- Improve balance
- Strengthen core
- Activity modification and
retraining during ADL
Toe Drag - Prosthetic Cause
- Long prosthesis
- Excessive plantar flexion
- Excessive knee friction
Toe Drag - Amputee Cause
- Weak hip extensors
- Weak hip abductors on sound side
- Poor posture
- Poor gait habits
Toe Drag - Therapy Goals
- Strengthen hip extensors and hip abductors
- Encourage pelvic motion to initiate enough knee flexion for swing phase
Wide Gait - Prosthetic Cause
- Prosthesis too long*
- Medial wall too high*
- Insufficient femoral stability
Wide Gait - Amputee Cause
- Abduction contracture
- Poor gait habit, patient insecure and desires wide
base in belief it will increase stability
Wide Gait - Therapy Goals
- Stretch abductors
- Strengthen core, residual limb and sound leg
Internal Foot Rotation - Prosthetic Cause
- Internal knee rotation
- Internal foot rotation
- Excessive quad pressure
Internal Foot Rotation - Amputee Cause
- Improperly donning socket
- Flexed at the hip during gait, typically with walker or
crutches, looking down at ground
Internal Foot Rotation - Therapy Goals
- Work on donning correctly
- More upright position during ambulation
External Foot Rotation - Prosthetic Cause
- External knee rotation
- External foot rotation
- Socket design
- Tight adductor channel in socket
External Foot Rotation - Amputee Cause
- improperly donning socket
external foot rotation - therapy goals
work on donning correctly
Skilled therapy should be a combination of :
- Strengthening
- ADL analysis, modification and retraining
- Proprioception activities
- Balance activities
- Donning and doffing for consistent alignment
- Decrease fear/increase confidence resulting
from lack of sensory input in prosthesis
I dont feel like we need to know osseointegration but idk maybe im wrong
