Socket Fit - TF

What should you always recommend to patients when getting a new prosthesis?

Get new shoes! Great for alignment

What do I need to ensure patient remains safe?

ALL fittings must take place inside of the parallel bars! Walker used if not bars are present

Gait belt is lower voluntary control/requires transfer assist

No walking unless the distal socket and attachment plate are wrapped with fiber glass!

Fitting sequence

1. Proper orientation

2. Socket comfort

3. Overall prosthesis height/length

4. Ischial containment and trimline check

5. Suspension check

6. Stance symmetry - width and AP placement

7. Knee/foot stability - weight distribution

8. Dynamic alignment

Donning and orientation

Ensure socket is oriented to anatomy

Assist patient with donning if necessary

Orientation to anatomy

IT containment strut angle matches ramal angle

Adductor longus tendon at anterior-medial corner

Donning sock

Should have some resistance as it’s pulled down the limb. Unloading, pull as loading

Seal-in liner donning

Should take two or three cycles of loading and unloading

Palpate the ischium

Move anteriorly along the ramus - ramus exiting without impingement, appropriate flare to medial brim, adductor roll?

Find adductor tendon

Medial brim trimline assessment

Place one hand on the proximal lateral brim, other on the ipsilateral iliac crest

Pull socket toward you gently but firmly

Lateral displacement test

Push on proximal lateral socket and contralateral iliac crest

Medial displacement test

How much displacement are you looking for in the medial and lateral displacement tests?

<1/2”

What should you look for when assessing skin fit?

Look for even blanching (lighter shade)

Areas of darker shade indicate gapping

No areas of excessive pressure/blanching

Areas of darker shade indicate what in a skin fit?

Gapping

Burning sensation during seated assessment

Posterior brim is too wide

Distal gapping

First assess ischium location - tells us if we need to increase volume of the socket

Check to see if socket is too tight or too long

If there is distal gapping and the socket is too tight, what do you do?

Loosen fit to place ischium in correct location

If there is distal gapping and the socket is too long, what do you do?

Distal padding

What does the skin look like and what does the patient feel if it is a loose fitting socket?

Patient feels short and has perinium pain - add pads or socks

Skin proximal-medial/distal-lateral pressures or redness. Initially skin is pink but darker once socket is doffed

What does the skin look like and what does the patient feel if the socket is tight fitting?

Patient will feel tall with minimal ischial containment, having low pressure/pain

Skin will have distal redness due to no contact

What coloring of skin do we want?

Even marble pink color of skin

Weight shifting initially

Have patient step forward and back in the parallel bars to simulate heel strike and toe off

Dynamic alignment goals of gait

1. Smooth transition from IC to LR

2. Knee stability throughout stance

3. Minimal trunk compensation

4. Symmetric step lengths and timing

5. Symmetric knee motion during swing

High socket pressures in the sagittal plane during early stance - why?

Proximal anterior, distal posterior

Trying to pull knee into extension

High socket pressures in the coronal plane during midstance - why?

Proximal medial, distal lateral

Femur is trying to abduct for good lateral rotation - connection to lateral gapping/ischial containment

When a person is wearing a TF prosthesis, where does the socket normally apply pressure on the limb during midstance in the coronal plane?

Proximal medial, distal lateral

A person wearing a TF prosthesis will normally experience greater pressure at the anterior proximal and distal posterior socket during which phase of gait?

Early stance

What role does the gluteus medius play during gait in a TF prosthesis?

It abducts the femur against the lateral wall of the socket to lift the pelvis

Which of these factors are considered part of the voluntary control?

A. Muscle strength

B. Component type

C. All of these

D. Alignment

Muscle strength

Which factor or factors effect suspension choice for a TF prosthesis?

A. All of these are correct

B. Patient preference

C. Effect on energy consumption

D. Limb length

All of these

Trim line at the inguinal crease

Anterior brim

Loads medial aspect of the ischium - relieves the ramus and adductor longus

Medial brim

Prevents ramus from sliding downward into the socket

M/L dimensions

Provides reliefs over the greater trochanter and counter pressure to keep ischium in place

Lateral wall

Accommodate muscular groups of the thigh and wide pressure distribution

A/P dimension