Prosthetic Limb Fit and Sock Analysis

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Questions and Answers

What could indicate that a prosthesis is sagging or sitting lower than usual?

Too few socks

Socket is too large (correct)

Excessive pistoning

Improper sock thickness

Which area is NOT considered a pressure-sensitive area of a transfemoral limb?

Ischial tuberosity (correct)

Distal femur

Greater trochanter

Ischial ramis

What is a primary benefit of using a gel liner in prosthetics?

Increased weight

Enhanced rigidity

Decreased sock thickness

Improved comfort (correct)

What happens if there is excessive pressure at the distal end of the limb?

Causes skin breakdown Signup and view all the answers

How can limb shrinkage over time be accommodated in prosthetic fittings?

By adding prosthetic socks Signup and view all the answers

What is a common consequence of having too few prosthetic socks?

Short prosthetic limb sensation Signup and view all the answers

Which of the following describes the pressure-tolerant areas of a transfemoral limb?

Entire distal end of limb Signup and view all the answers

Which thicknesses are typically available for prosthetic socks?

1-ply, 3-ply, 5-ply Signup and view all the answers

Where should socks be added when using a seal-in liner?

Proximal to the seal under the flip down ring Signup and view all the answers

What characterizes the lanyard system in prosthetic assemblies?

The strap is attached to the socket and feeds through an opening Signup and view all the answers

Which suspension system allows for direct skin contact with the socket?

Suction suspension Signup and view all the answers

What is a disadvantage associated with suction suspension systems?

Can cause skin irritation due to direct contact Signup and view all the answers

How does vacuum-assisted suspension (VASS) differ from suction suspension?

It maintains suction through an external vacuum pump Signup and view all the answers

What benefit does vacuum-assisted suspension (VASS) provide over traditional suction systems?

Improved circulation and stability Signup and view all the answers

Which of the following systems provides additional security for the prosthesis during physical activities?

Pelvic belt and hip joint Signup and view all the answers

Which statement is true regarding the need for maintenance in vacuum-assisted suspension systems?

They demand consistent adjustment for effective suction Signup and view all the answers

What is the main weight-bearing area in the quadrilateral socket design?

Ischial tuberosity on a ledge Signup and view all the answers

Which feature is primarily utilized in the sub-ischial brimless socket to minimize movement?

Vacuum suspension system Signup and view all the answers

What is a significant disadvantage of microprocessor knees?

Cost Signup and view all the answers

Which of the following features allows a foot to adapt better to uneven surfaces?

Multi-axis foot Signup and view all the answers

What sensation might a patient report due to having too few socks?

Sensation of dropping into a hole Signup and view all the answers

What is an advantage of the pin shuttle mechanism in prosthetics?

Provides secure suspension Signup and view all the answers

What does the term SACH stand for in the context of prosthetic feet?

Solid Ankle Cushion Heel Signup and view all the answers

Which type of prosthetic foot provides actual range of motion at the ankle?

Multi-axis feet Signup and view all the answers

What discomfort might occur if there are too many socks in the prosthetic socket?

Feeling of a long prosthetic limb Signup and view all the answers

What is a common maintenance issue associated with microprocessor knees?

Requires regular calibration Signup and view all the answers

What is a disadvantage of passive vacuum with a silicone suction suspension sleeve?

Bulky behind the knee Signup and view all the answers

What may describe the sensation caused by improper sock fit in a prosthetic?

"Hammocking" of the residual limb Signup and view all the answers

Which feature is beneficial for knee stability when using prosthetic feet?

Single-axis foot Signup and view all the answers

What audible feature does the pin shuttle mechanism provide?

Audible clicks Signup and view all the answers

What is a drawback related to the weight of microprocessor knees?

They can be heavier compared to traditional knees. Signup and view all the answers

Which prosthetic foot type allows for inversion and eversion?

Multi-axis foot Signup and view all the answers

What is a notable disadvantage of a constant friction knee?

Requires voluntary control to remain stable in stance Signup and view all the answers

What is the primary benefit of using a manual locking knee?

Provides maximum stability during ambulation Signup and view all the answers

Which of the following is an advantage of a polycentric knee?

Improves sitting cosmesis with change in knee center Signup and view all the answers

What describes a candidate suitable for a hydraulic knee?

K3 level with ability for ambulation with variable cadence Signup and view all the answers

What might be a drawback of using a non-liner suspension system?

May cause pressure in the pelvic area Signup and view all the answers

What is a common characteristic of a hydraulic knee?

Changes resistance based on activity level Signup and view all the answers

How does a polycentric knee benefit toe clearance?

Increases toe clearance by accommodating knee motion Signup and view all the answers

Which statement is true regarding manual locking knees?

They lock during gait and can be manually released Signup and view all the answers

Study Notes

Sock Thickness and Fit

Socks are used to adjust the fit of prosthetic limbs, with varying thicknesses for customized adjustments
Too few socks can lead to pressure points, redness, skin breakdowns, and discomfort
Specific areas prone to unwanted pressure with too few socks include the distal end of the limb, distal patella, distal fibula, fibular head, and medial tibial flare
Adding socks can redistribute load, improve comfort, prevent skin damage, and accommodate limb shrinkage
Too many socks can cause a feeling of a long prosthetic limb, discomfort, pressure on the tibial tubercle, and difficulty donning

Gel Liners

Gel liners improve comfort and aid in suspension by dispersing weight-bearing loads
They decrease shear and impact forces, come in multiple thicknesses, and offer different thicknesses for anterior-posterior or proximal-distal adjustment

Pressure Sensitive and Tolerant Areas of a Transfemoral Limb

Pressure sensitive areas on a transfemoral limb include:
- Greater trochanter
- Ischial ramis
- ASIS
- Adductor tendon
- Distal femur
- Inguinal fossa
- Pubic tubercle
- Incision line
Pressure tolerant areas on a transfemoral limb include:
- Ischial tuberosity
- Lateral flare of femur
- Anterior flare of residual limb
- Posterior flare of residual limb
- Entire distal end of limb with total contact socket

Socket Designs

Quadrilateral socket:
- Utilizes opposing forces to keep the ischial tuberosity on a ledge, providing suction suspension
- Offers main weight bearing area and accommodates other suspension methods
Ischial ramus containment socket:
- Focuses weight bearing on the medial aspect of the ischium and the ischial ramus
- Encompasses both the ischial tuberosity and the ramus, with a contour depending on the amputee's musculature, soft tissue, and skeletal structure
Sub-ischial brimless socket:
- Uses a vacuum suspension system and gel liners for constant contact, minimizing movement, maximizing femoral control, and lowering trim lines

Patient Concerns with Insufficient Socks

Short prosthetic limb feeling
Sensation of dropping into a hole
Excessive pistoning
Distal pressure
Pressure on distal patella
Pressure on distal fibula, fibular head, medial tibial flare
Easy donning

Patient Concerns with Excessive Socks

Feeling of a long prosthetic limb
Sensation of hill climbing
"Hammocking" (excess space resembling a hammock causing distal discomfort)
Pressure on tibial tubercle
Difficulty donning

Pin Shuttle Mechanism Advantages

Secure suspension
No sleeve needed
Audible clicks
Allows for sock adjustments with volume changes

Passive Vacuum with Silicone Suction Suspension Sleeve Disadvantages

Liner plus sleeve creates bulk behind the knee, limiting flexion
Donning difficulty with hand weakness or neuropathy

Seal-in Liner Sock Placement

Socks can only be added proximal to the seal, under the flip-down ring

Lanyard and Strap Systems

Lanyard system:
- Strap attached to the bottom of a liner, fed through the socket, and attached to the outside
Fork strap waist belt:
- Removable fork strap and prosthetic belt providing additional security

Transfemoral Suspension Systems Without a Liner

Suction Suspension (Direct or Skin Fit Suction):
- Creates a vacuum seal between the socket and the skin using a one-way valve
- Provides a close fit and allows for better proprioception
- Requires stable limb volume
Vacuum-Assisted Suspension (VASS) Without a Liner:
- Uses an external vacuum pump to enhance the seal
- Provides increased stability, improved circulation, and reduced limb volume fluctuations
- Requires more maintenance and a consistent fit
Pelvic Belt and Hip Joint:
- Uses a waist belt and a hip joint mechanism connected to the socket
- Useful for short or irregular residual limbs or difficulty achieving suction

Constant Friction Knee Disadvantages

Requires voluntary control to remain stable in stance
Single speed ambulation

Manual Locking Knee Advantages

Maximum stability
The knee is locked during gait and the patient releases the lock mechanism to sit down
Decreases hip extension strength for stabilization

Polycentric Knee Advantages

Increase stance stability
Improve sitting cosmesis with the knee center change
Increase toe clearance

Candidates for Hydraulic Knees

K2 and K3 descriptors:
- K2: Ambulation with the ability to traverse low-level environmental barriers (curbs, stairs, uneven surfaces)
- K3: Ambulation with variable cadence, traversing most environmental barriers and may have vocational, therapeutic, or exercise needs beyond simple locomotion

Microprocessor Knee Disadvantages

Cost
Weight
Maintenance
Computerized
Require charging/battery swap every 24-72 hours
Require calibrations
Water-proof
Limited durability under heavy use or loads

SACH Foot

SACH stands for Solid Ankle, Cushion Heel

Single Axis Foot Advantages

Allows for plantarflexion and dorsiflexion when weighted
Assists with knee stability and roll-over
Water-friendly depending on the brand
Allows for inversion and eversion with a multi-axis ankle

Foot/Ankle Features for Uneven Terrain

Hydrolic ankle
Multi-Axis Foot:
- Conforms to uneven surfaces better than a single-axis foot

Type of Foot Providing Actual Range of Motion at the Ankle

Single-Axis Feet:
- Hinge allowing plantarflexion and dorsiflexion
- Limited range of motion in the sagittal plane
- Improves walking stability, especially for individuals with limited knee stability
Multi-Axis Feet:
- Movement in sagittal (up and down), frontal (side to side), and transverse (rotational) planes
- More natural range of motion in multiple directions
- Increases stability on uneven surfaces and provides a natural walking experience
Hydraulic and Microprocessor-Controlled Ankles:
- More advanced options offering customizable responses and adaptability to varying terrain
Each type of foot provides different benefits depending on individual needs and preferences.

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Description

Explore the relationship between sock thickness and the fit of prosthetic limbs in this comprehensive quiz. Learn about how to adjust fit using different sock thicknesses to prevent discomfort and skin breakdowns while improving comfort with gel liners. Understand the critical areas to consider in a transfemoral limb to ensure optimal performance.