Exam 5: Prosthetics TransFem ReadGuide/Chart; Sockets, Suspensions Flashcards
Transfemoral Prosthetics Reading Guide:
Contrast the knee disarticulation to the typical TF amputation. (6 points about each)
Transfem
- Amputation proximal to the anatomical knee joint
- limb can vary in length
- RL is likely to be a tapered cylinder- helps with donning/doffing
- Tapered cylinder shape is more challenging with prosthetic suspension
- suction suspension may be a good option
- The shorter the RL, the more difficult socket suspension and knee control is.
Disarticulation
- Amputation through the center of the anatomical knee joint
- normal adduction angle for LE is likely preserved
- longer lever arm
- bulbous shape due to retention of femur & its condyles- issue for donning/doffing
- But bulbous shape is good for enhancement of prosthetic suspension
- distal end of femur tolerated end-bearing pressure
Transfemoral Prosthetics Reading Guide:
Features of a transfem (as opposed to a disarticulation) (6)
- Amputation proximal to the anatomical knee joint
- limb can vary in length
- RL is likely to be a tapered cylinder- helps with donning/doffing
- Tapered cylinder shape is more challenging with prosthetic suspension
- suction suspension may be a good option
- The shorter the RL, the more difficult socket suspension and knee control is.
Transfemoral Prosthetics Reading Guide:
Featurs of a disarticulation (in contrast to a transfem) (6)
- Amputation through the center of the anatomical knee joint
- normal adduction angle for LE is likely preserved
- longer lever arm
- bulbous shape due to retention of femur & its condyles- issue for donning/doffing
- But bulbous shape is good for enhancement of prosthetic suspension
- distal end of femur tolerated end-bearing pressure
Transfemoral Prosthetics Reading Guide:
Describe the relative metabolic cost of ambulation and the functional implications for the elderly TF amputee. (5 points)
- The shorter the RL, the more energy required in gait.
- 4 things affecting energy: 1) weight of prosthesis, 2) quality of the socket fit, 3) accuracy of alignment of prosthesis, 4) functional characteristics of prosthetic components
- Increased energy expenditure= more O2 consumed, increased HR/BP, reduction in comfortable self selected walking speed.
- High energy need of short RL means that elderly will be limited community ambulators- may require AD and restricted to flat terrain
- Bilat elderly transfem may opt for a WC for ambulation
Transfemoral Reading Guide
4 things affecting energy:
4 things affecting energy:
- weight of prosthesis,
- quality of the socket fit,
- accuracy of alignment of prosthesis,
- functional characteristics of prosthetic components
Transfemoral Reading Guide
How does increased inergy expenditure affect self-selected walking speed?
Increased energy expenditure= more O2 consumed, increased HR/BP, reduction in comfortable self selected walking speed.
Transfemoral Reading Guide
Describe the functional implications for the elderly TF amputee.
- Short residual limb
- bilateral amputation
- High energy need of short RL means that elderly will be limited community ambulators- may require AD and restricted to flat terrain
- Bilat elderly transfem may opt for a WC for ambulation
Transfemoral Reading Guide
What is a Quadirilateral Socket? (7-9)
- Looks squarish
- Remained the socket of choice until the mid-1980s.
- Has four distinct walls
- Two Primary functions
- provide for weight bearing during the stance phase of gait a
- allow the hip and thigh muscles to function at maximum potential during the stance phase
- A flat posterior shelf, the ischial seat, is the primary weight bearing surface for the ischium and gluteal muscles.
- Anterior wall contours create a posterior directed force at the anatomical Scarpa’s triangle, which is intended to stabilize the ischium on its prosthetic seate
- The socket is narrower in its anterior-posterior dimension than its medial-lateral dimension.
The quadrilateral socket is designed for transfemoral (above knee) amputees. The weight bearing in this socket is primarily on the ischium and the gluteal musculature (buttocks). This combination of bone and muscle rests on the posterior brim (back edge) of the socket which creates a wide seat parallel to the ground. This socket can be held in place on the residual limb with suction, a Silesian or TES belt, or by the use of a soft insert with a suspension locking mechanism. This design aids in ease of sitting and, in comparison to the ischial containment socket, is more successful on long, firm residual limbs. (http://www.plor.net/downloads/resources/prosthetics/transfemoral-amputation-and-knee-disarticulation/Prosthetics.QuadrilateralSocket.pdf)
What is an Ischial Containment Socket? (7-10)
- newer
- Analogous to the TSB transtib socket.
- It is much better than the quadrilateral socket
- Trim line contains the the ischial tuberosity and creates boney lock that provides mediolateral stability and reduces the likelihood of socket rotation.
- When compared to the quad socket, the most obvious difference is the narrow medial-lateral dimension that is highly contoured around the ischial -ramal complex
- Developed out of the ideas of Ivan Long and John Sabolich. Long believed that by aligning the distal femur over the center of the knee and through the center of the foot, the wearer of the prosthesis could bring their residual limb into a normal anatomical position and walk more naturally. Sabolich expanded on Long’s ideas to make the contoured anterior trochanteric-controlled alignment method which maintains an adducted position and controls socket rotation by containing the ischial tuberosity within the contours of the socket.
- Long’s socket design was part of a frontal plane alignment procedure that became known as “ Long’s Line.”
- His ideas were expanded on by John Sabolich to make the contoured anterior trochanteric-controlled alignment method (CAT-CAM) socket.
- Since the CAT-CAM a series of designs have developed that have become known as ischial containment or Ischial-ramal containment sockets (ICS)
- Compared to quad: Narrowed medial-lateral dimension and increased the anteroposterior dimension. The narrow medial-lateral walls better supported the femur to prevent lateral shifting of the socket during stance. The larger anteroposterior dimension allowed better muscle function because there was additional room for muscles to contract.
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Dimensions
- Weight Bearing
- Femur Position
- Gait
- Energy Expenditure
- Comfort
- Medial-Lateral Pelvic Stability
- Dimensions-
- The quadrilateral socket is narrower in its anterior-posterior dimension than its medial-lateral dimension. It is wider in its medial-lateral dimension, which caused an abnormal abduction angle of the femur. (allows the socket to displace laterally during midstance, thus increasing pressure to the perineal tissues and decreasing the efficiency of the glute med muscle).
- The ICS has a narrower mediolateral dimension and larger anteroposterior dimension to support the femur and prevent lateral shifting of the socket during weight bearing. The bigger anteroposterior socket dimension also enhances muscle function by producing more room to accommodate contraction than was possible with the AP dimensions of the quad socket
- Weight-bearing-
- quad socket- a flat posterior shelf, the ischial seat, is the primary WB surface for the ischium and gluteal muscles
- ICS - more like total surface bearing. There is no ischial seat and weight bearing occurs predominantly on the soft tissues of the thigh, gluteal region, and medial aspect of the ischium. (pg 671-672; third edition)
- Femur position-
- Quadrilateral has wider mediolateral walls which abducted the leg more than was ideal and contributed to a wide based gait and a Trendelenburg gait where the individual leaned toward their prosthetic side for compensation.
- ICS is more narrow mediolaterally and allows more anterior posterior room. This means the femur is in a more natural adducted position. The lateral socket wall is contoured in adduction, with additional pressure against the posterior shaft of the femur for added stability and rotational control.
- It is debated that femur position is affected by surgery, not the socket. (however, there were pictures in the book and it seemed generally accepted that the ICS keeps the femur in more natural alignment, as opposed to the abnormally abducted resting position in the quad socket)
- Gait
- The ICS results in a more natural gait because of better femoral alignment and less likelihood of socket rotation. There is less need for compensation for a wide based gait (see medial-lateral pelvic stability)
- Energy expenditure
- ICS is is more efficient because it allows a more natural gait which uses less energy than the quad socket. (see medial-lateral pelvic stability)
- Comfort
- Chart says there is more area for pressure distribution in the ICS compared to the quadrilateral, so the ICS is more comfortable than the quadrilateral
- Other reasons I imagine the ICS socket is more comfortable are as follows: It more closely resembles the shape of a thigh. The brim of the socket captures more of the adductor muscle complex than does the quad socket and prevents pinching in the case of an adductor roll. It reduces socket rotation on the limb, increase the efficiency of gait, and distributes weight more evenly (pg 671, third edition).
- Medial-lateral pelvic stability- (see “Pelvic Stability” pg 669 of third edition)
- The design of a quad socket primarily applies stabilizing forces in the anteroposterior plane so that there is little to keep the femur from drifting laterally within the socket.
- Consequently, the pelvis drops when the intact limb is in swing phase. To compensate, the prosthetic wearer often leans tor lurches laterally towards the prosthetic side. This strategy improves swing clearance but also results in a wide-based, energy taxing gait. Because the femur is held in an abnormally abducted position, circumduction of the prosthesis during swing is likely to occur.
- ICS has a narrower medial-lateral dimension than the Quad socket and is highly contoured to match the unique shape of the user’s residual limb,
- ICS provides better mediolateral stability (which is a common problem for transfem amputees, especially those with short residual limbs, or who have developed flexion, abduction, and external rotation contractures.
- In contrast to the quad socket, the IRC socket attempts to hold the femur in its normal adducted position during stance with an upward and medially directed force along the length of the lateral femur. This strategy enhances prosthetic wearer’s ability to maintain a level pelvis and improves the quality of functional gait.
- The design of a quad socket primarily applies stabilizing forces in the anteroposterior plane so that there is little to keep the femur from drifting laterally within the socket.
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Dimensions
Dimensions-
- The quadrilateral socket is narrower in its anterior-posterior dimension than its medial-lateral dimension. It is wider in its medial-lateral dimension, which caused an abnormal abduction angle of the femur. (allows the socket to displace laterally during midstance, thus increasing pressure to the perineal tissues and decreasing the efficiency of the glute med muscle).
- The ICS has a narrower mediolateral dimension and larger anteroposterior dimension to support the femur and prevent lateral shifting of the socket during weight bearing. The bigger anteroposterior socket dimension also enhances muscle function by producing more room to accommodate contraction than was possible with the AP dimensions of the quad socket
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Weight Bearing
Weight-bearing-
quad socket- a flat posterior shelf, the ischial seat, is the primary WB surface for the ischium and gluteal muscles
ICS - more like total surface bearing. There is no ischial seat and weight bearing occurs predominantly on the soft tissues of the thigh, gluteal region, and medial aspect of the ischium. (pg 671-672; third edition)
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Femur Position
Femur position-
- Quadrilateral has wider mediolateral walls which abducted the leg more than was ideal and contributed to a wide based gait and a Trendelenburg gait where the individual leaned toward their prosthetic side for compensation.
- ICS is more narrow mediolaterally and allows more anterior posterior room. This means the femur is in a more natural adducted position. The lateral socket wall is contoured in adduction, with additional pressure against the posterior shaft of the femur for added stability and rotational control.
- It is debated that femur position is affected by surgery, not the socket. (however, there were pictures in the book and it seemed generally accepted that the ICS keeps the femur in more natural alignment, as opposed to the abnormally abducted resting position in the quad socket)
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Gait
Gait
The ICS results in a more natural gait because of better femoral alignment and less likelihood of socket rotation. There is less need for compensation for a wide based gait (see medial-lateral pelvic stability)
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Energy Expenditure
Energy expenditure
ICS is is more efficient because it allows a more natural gait which uses less energy than the quad socket. (see medial-lateral pelvic stability)
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Comfort
Comfort
- Chart says there is more area for pressure distribution in the ICS compared to the quadrilateral, so the ICS is more comfortable than the quadrilateral
- imagine the ICS socket is more comfortable. It more closely resembles the shape of a thigh. The brim of the socket captures more of the adductor muscle complex than does the quad socket and prevents pinching in the case of an adductor roll. It reduces socket rotation on the limb, increase the efficiency of gait, and distributes weight more evenly (pg 671, third edition).
Transfemoral Reading Guide: Contrast the quadrilateral socket to the ischial containment socket for:
- Medial-Lateral Pelvic Stability
Medial-lateral pelvic stability- (see “Pelvic Stability” pg 669 of third edition)
- The design of a quad socket primarily applies stabilizing forces in the anteroposterior plane so that there is little to keep the femur from drifting laterally within the socket.
- Consequently, the pelvis drops when the intact limb is in swing phase. To compensate, the prosthetic wearer often leans tor lurches laterally towards the prosthetic side. This strategy improves swing clearance but also results in a wide-based, energy taxing gait. Because the femur is held in an abnormally abducted position, circumduction of the prosthesis during swing is likely to occur.
- ICS has a narrower medial-lateral dimension than the Quad socket and is highly contoured to match the unique shape of the user’s residual limb,
- ICS provides better mediolateral stability (which is a common problem for transfem amputees, especially those with short residual limbs, or who have developed flexion, abduction, and external rotation contractures.
- In contrast to the quad socket, the IRC socket attempts to hold the femur in its normal adducted position during stance with an upward and medially directed force along the length of the lateral femur. This strategy enhances prosthetic wearer’s ability to maintain a level pelvis and improves the quality of functional gait.
Transfemoral Reading Guide
Contrast the rigid and flexible socket. (features, advantages, disadvantages)
Rigid socket
- Features
- consists of a resin-laminated or thermoformed plastic socket that is intended to
- have an intimate, total contact fit over the entire surface of the residual limb
- Prosthetic socks are often worn as a soft interface between the socket and residual limb
- Advantages
- Socket is durable, easy to clean, and often less bulky and expensive to produce than flexible sockets
- Disadvantage
- More difficult to adjust the fit of the rigid socket,
- especially for pt. with bony or
- sensitive residual limbs
- More difficult to adjust the fit of the rigid socket,
Flexible Socket
- Features
- A FS is vacuum formed using any number of flexible thermoplastic materials
- Encased in a rigid frame, which provides support during WB and helps to maintain socket shape.
- Advantages
- Accommodates to change in muscle shape during contraction and can be easily modified after initial fabrication to provide relief for bony prominences
- May also be more comfortable to wear, especially in sitting, because there are no hard ridges at the brim to impinge on the groin
- They are especially useful if suction suspension is desired
- Disadvantage
- less durable
- more bulky to wear (requires a socket and a frame)
- more expensive to produce
Transfemoral Reading Guide: rigid socket (contrasted to flexible socket)
- Features (3)
- Advantages (3)
- Disadvantages (1-3)
Rigid socket
- Features
- consists of a resin-laminated or thermoformed plastic socket that is intended to
- have an intimate, total contact fit over the entire surface of the residual limb
- Prosthetic socks are often worn as a soft interface between the socket and residual limb
- Advantages
- Socket is durable,
- easy to clean, and
- often less bulky and expensive to produce than flexible sockets
- Disadvantage
- More difficult to adjust the fit of the rigid socket,
- especially for pt. with bony or
- sensitive residual limbs
- More difficult to adjust the fit of the rigid socket,
Transfemoral Reading Guide: flexible socket (contrasted to rigid socket)
Features (2)
Advantages (3)
Disadvantages (3)
Flexible Socket
- Features
- A FS is vacuum formed using any number of flexible thermoplastic materials
- Encased in a rigid frame, which provides support during WB and helps to maintain socket shape.
- Advantages
- Accommodates to change in muscle shape during contraction and can be easily modified after initial fabrication to provide relief for bony prominences
- May also be more comfortable to wear, especially in sitting, because there are no hard ridges at the brim to impinge on the groin
- They are especially useful if suction suspension is desired
- Disadvantage
- less durable
- more bulky to wear (requires a socket and a frame)
- more expensive to produce
How does the flexible socket fit into the grand scheme of things? (where would we find it used?)
A flexible socket is usually incorporated into one of the more modern socket designs (TSB for transtibial and ICS for transfemoral). It enhances total surface bearing
Describe Pull-in Suction:
- what is it?
- Steps for donning? (3-7)
- Indications (2)
- Advantages (2)
- Disadvantages (3)
Pull-in suction (same as Traditional Pull-in suction)
What is it?
- use negative air pressure, skin to socket contact, and muscle tension to hold the socket onto the limb
- Only creates a negative pressure differential when prosthesis is in swing phase (because of passive expulsion valve)
Steps for Donning
- Can be donned in several ways ways
- donning sock (cotton stockinette or similar material)
- Donning sleeve (parachute nylon or similar material)
- elastic bandage to pull the residual limb into the socket
- add a lubricant to the skin (e.g. powder) to facilitate the residual limb sliding into the socket
- The liquid powder dries quickly, and suction is achieved.
- Once the limb is well seated in the socket, the sock, sleeve, or elastic wrap is pulled through the valve housing at the distal socket, the air and expulsion valve is then screwed back into place
- The air-expulsion valve is then “burped” by pushing or pulling the valve button, to release any trapped air.
Indications:
- Requires mature residual limb
- Requires good stand bal & dexterity to don
Advantages:
- Additional benefits -Wearer often reports enhanced prosthetic control and a better proprioceptive sense of the prosthesis during walking
Disadvantages
- Difficult to maintain suction if edema fluctuates
- Requires mature residual limb
- The high shearing forces associated with donning a suction socket
- may preclude its use for patients with fragile or sensitive skin, painful trigger points, or significant scarring or adhesions.
- must have considerable agility and balance on the part of the wearer
Describe Pull-in Suction:
what is it?
Pull-in suction (same as Traditional Pull-in suction)
What is it?
- use negative air pressure, skin to socket contact, and muscle tension to hold the socket onto the limb
- Only creates a negative pressure differential when prosthesis is in swing phase (because of passive expulsion valve)
Describe Pull-in Suction:
- Steps for donning? (3-7)
Steps for Donning
- Can be donned in several ways ways
- donning sock (cotton stockinette or similar material)
- Donning sleeve (parachute nylon or similar material)
- elastic bandage to pull the residual limb into the socket
- add a lubricant to the skin (e.g. powder) to facilitate the residual limb sliding into the socket
- The liquid powder dries quickly, and suction is achieved.
- Once the limb is well seated in the socket, the sock, sleeve, or elastic wrap is pulled through the valve housing at the distal socket, the air and expulsion valve is then screwed back into place
- The air-expulsion valve is then “burped” by pushing or pulling the valve button, to release any trapped air.
Describe Pull-in Suction:
- Indications (2)
Indications:
- Requires mature residual limb
- Requires good stand bal & dexterity to don
Describe Pull-in Suction:
- Advantages (2)
Advantages:
- Additional benefits -Wearer often reports
- enhanced prosthetic control and a
- better proprioceptive sense of the prosthesis during walking
Describe Pull-in Suction:
- Disadvantages (3)
Disadvantages
- Difficult to maintain suction if edema fluctuates
- Requires mature residual limb
- The high shearing forces associated with donning a suction socket
- may preclude its use for patients with fragile or sensitive skin, painful trigger points, or significant scarring or adhesions.
- must have considerable agility and balance on the part of the wearer
Roll-On suspension liners are incorporated in the following types of suspensions (4)
Included in the following:
- shuttle lock system,
- lanyard system,
- cushion liner with air expulsion valve, and
- A type of liner is also used in elevated vacuum (as a wicked liner)
T/F
Roll-on liners can be worn against the skin