5: Transtibial Flashcards
What type of flap is typically used for transtibial amputation and why?
Long posterior flap because of good vascularization and provides good weight-bearing surface
What is specifically done to the fibula during transtibial amputation surgery?
Is is transected 1-2 cm shorter than the tibia to avoid distal fibula pain
What is a short transtibial amputation?
Less than 20% of the tibia is preserved
What are the results of a short transtibial amputation?
Small moment arm that makes knee extension difficult
What is a standard transtibial amputation?
Between 20-50% of the tibia length is preserved
What is required for a standard transtibial amputation for optimal prosthesis fit?
At least 8 cm of tibia required below the knee joint
What is a long transtibial amputation?
More than 50% of the tibial length is preserved. Not typical due to poor blood supply to the distal leg
What is an Ewing amputation?
During surgery, AMIs are created by linking muscle pairs within the residual limb
What does AMI stand for?
Agonist-antagonist myoneural interface
What is the purpose of an Ewing amputation?
Provide proprioceptive feedback and better control of prosthetic device
What are the 5 pressure sensitive areas for a transtibial amputation?
- Fibular head
- Shin bone
- End of fibula
- End of tibia
- Hamstring tendons
What are the two socket designs for a transtibial prosthesis?
Patellar tendon bearing (PTB) and total surface bearing
What are the four suspension systems for a transtibial prosthesis?
- Thigh corset
- Pin system
- Suction suspension
- Vacuum assisted socket system
Describe the patellar tendon bearing (PTB) socket
Has an indentation over the patellar tendon with specific pressure points. Most basic design
Where is suspension generated with a PTB?
At the medial and lateral areas of the femoral condyles
What type of socket is shown in the image?
Patellar tendon bearing (PTB)
What type of socket is shown in the image?
Total surface bearing
Describe the supracondylar trim lines of a PTB socket
Medial and lateral walls extend above the femoral epicondyles to help with suspension
What are three challenges of the PTB?
- Trim lines limit knee flexion if more active
- Piston
- Cannot tolerate the pressure on their patellar tendon
Describe a total surface bearing socket
Distributed weight bearing over 100% of residual limb surface
How is suspension generated with a total surface bearing socket?
Adhesion between residual limb and the silicon liner
What pt population is indicated for a total surface bearing socket?
All types of residual limbs
What are advantages of a total surface bearing socket?
- Lower trim lines allows pt to be more active
- Reduced pistoning due to total contact
- Increased proprioception
- Suspension is between the socket using locking pins of suction
- More comfortable
What are disadvantages of a total surface bearing socket?
- Volume changes, dialysis
- Short residual limb < 10 cm
- Distal pain
- Increased perspiration
- Soft tissue discomfort
What pt will not prefer a total surface bearing device?
Visual and sensory disturbances or hemiparesis due to difficulties donning and doffing
What is suspension?
Method by which the artificial limb is attached to the body
What is pistoning?
Undesirable motion of the residual limb moving up and down within the socket
Describe the thigh corset suspension system
Heavy, can cause pistoning, difficult to don, not common
Describe the pin system for suspension
Shuttle lock system, helps with pistoning. unrestricted knee flexion
When is a pin system indicated?
TSB socket, scarred or sensitive limb
What are disadvantages of the pin system?
More expensive, not durable, need good hand function
How is a sleeve suspension positioned?
Around the shank and rolled over the thigh
What are advantages of sleeve suspension?
Cosmetic, airtight, showering, unrestricted knee motion
What are disadvantages of sleeve suspension
Not durable, hygiene problems, need good hand function to don and doff
Describe a suction suspension system
One-way valve, pistoning can occur, has to use lines, can apply socks as needed
What are the benefits of a vacuum-assisted socket system?
- Promote fluid exchange
- Reduce moisture build up
- Regulate volume fluctuations
- Increase proprioceptive awareness
- Would healing
What are disadvantages of the vacuum-assisted socket system?
Expensive, heavy, noisy
What is recommendation 1 according to the CPG?
The static and dynamic pressure distribution of the residual limb within the socket are essential considerations in patient comfort, function, and well-being
What is recommendation 2 according to the CPG?
Total surface bearing sockets are indicated to decrease fitting times and enable higher activity levels
What is recommendation 3 according to the CPG?
Compared to traditional foam-based interfaces, visoelastic interface liners are indicated to decrease dependence on walking aids, improve suspension, improve load distribution, decrease pain, increase comfort
What is recommendation 4 according to the CPG?
Vacuum-assisted suspension sockets permits the least amount of pistoning within the socket followed by suction suspension and then pin-lock. The traditional suspension options of supracondylar, cuff, and sleeve suspension provide comparatively compromised suspension
What is recommendation 5 according to the CPG?
VAS sockets are indicated to decrease daily limb volume changes of the limb in the socket while facilitating more favorable pressure distribution during gait
What device is best to prevent pistoning?
VAS - vacuum assisted suspension
