L3: Transfemoral Components Flashcards
1
Q
OBJECTIVES:
A
- ID various components of transfemoral prosthesis including:
- suspension
- sockets
- knee units
- Adv’s of each
2
Q
Transfemoral Components:
4:
A
- Socket→ where RL goes
- Suspension→ holds RL in the socket (usually external)
- Knee unit→ the “new” knee
- Prosthetic foot→ many diff. types
3
Q
Transfemoral Components: Socket
2 types
A
- Quadrilateral Socket (Quad)
- Ischial (IC) or Ischial-Ramal (IRC)
- more comfortable
- more common
4
Q
Transfem Components: Socket
Quadrilateral Socket (Quad)
Explain…
A
- Four (quad) distinct walls w/ flat post. shelf and an ischial seat
- Ischial Seat→ Primary WB surface for ischium and glutes
- *Contains ALL thigh musculature
- Ant. wall contours post. @ Scarpa’s Triangle
- stabilizes ischium on its prosthetic seat
- *More narrow ANT-POST dimension vs M/L
5
Q
Transfem Components: Socket
Quadrilateral
Talk about the more narrow dimensions, where are they w/ this socket?
A
More narrow ANT-POST dimension
6
Q
TFA→ Quad Socket
ADV’s vs Disadv’s
A
-
ADV’s
- True UNweighting of distal end→ prevents edema/blood pooling
- LESS $$$
- Easier to fit MOST amputees
-
Disadv’s
-
Prox. Posterior and Medial discomfort
- bc extra tissue here
-
Lateral thrust and trunk bending
- bc extra space M/L dimension
- Usually need pelvic belt
- Pressure on Scarpa’s triangle (aka Femoral Triangle) (remember NAV L→R)
-
Prox. Posterior and Medial discomfort
7
Q
Prox. posterior and medial discomfort w/ Quad Socket
Why?
A
Extra tissue
8
Q
Lateral thrust and trunk bending w/ Quad Socket
Why?
A
extra space in Quad socket M/L dimensions
9
Q
Transfem Components: Socket
Ischial (IC) or Ischial-Ramal (IRC)
A
- Stabilizes socket on RL and controls socket rotation by containing isch tube and pubic ramus
- Maintains normal femoral ADD. by distributing pressure thru socket along shaft of femur
10
Q
Transfem Ischial Socket maintains normal ________ by distributing pressure thru socket along __________
A
normal femoral adduction; thru socket along shaft of femur
11
Q
Transfem Components: Socket
Ischial or Ischial-Ramal
More deets
A
- OPPOSITE SHAPE TO QUAD SOCKET→ more narrow Med-Lat dimension
- *matches anatomical shape of indiv’s RL
- MORE room in the Ant-Post direction→ improves mm function/contractions
- MORE common today vs Quad socket
12
Q
Ischial (IC) or Ischial-Ramal (IRC) socket has a more narrow dimension where?
A
More narrow MED-LAT dimension
13
Q
TFA: IRC Socket
ADVs vs. Disadvs
A
-
ADVs
- more anatomical
- more room for muscle contract.
- Lower medial rim making sitting more comfy
-
Disadv’s
-
poor fit typ for obese pts
- → due to more narrow MED-LAT dimension
-
poor fit typ for obese pts
14
Q
Quad socket: The ischial tube is ______
A
OUTSIDE
15
Q
IRC Socket: The ischial tube is ________
A
INside, contained
16
Q
IRC vs. Quad Socket
Ischial Tube positioning
A
see pics
17
Q
Quad Socket has wider ______ dimensions
A
Wider M-L
18
Q
IRC Socket has wider _______ dimensions
A
Wider A-P
19
Q
IRC vs. Quad Socket
A
-
NOTE: IRC socket mushc higher Lateral Wall
- lower medially— comfier
20
Q
TFA Socket Material:
RIGID
A
- Either resin-laminated OR thermoformed plastic
- Designed for intimate, full interface bw/ socket + limb
- easy to clean
- usually worn w/ prosth. socks
- Uncomf. for those w/ bony or sensitive RL
21
Q
TFA Socket Material:
FLEXIBLE
A
- Thermoplastic mat. encased in a rigid frame specific to indiv. pt. (Comfortflex)
- Accommodates to change in mm shape during contracts→ more comf. w/ prolonged walking
- Softer mat. does NOT impinge on groin
- **Groin pain common early on
- Exc option when used w/ suction susp.
- Post. brim flexible enough to give under wt. of pt to min. pinching during sitting
- More $$$, LESS durable
22
Q
1 reason pts do NOT wear TFA Prosth.
???
A
Discomfort in sitting
*BUT remember its not MADE for sitting*!!!
23
Q
TFA Suspension Systems:
A
- Keeps socket in an optimum align.
-
More diff. for TFAs compared to TTAs
- much more mass w/out bony landmarks to assist in susp.
- Incd distal wt. from knee makes susp more diff
- More inherent rotation @ hip vs knee
- Either single system OR combo of systems can be used
24
Q
TFA Suspension Systems
Bold and *== Primary
A
- Pull-in suction*
-
Roll on suspension liners*
- Shuttle lock
- Lanyard
- Cushion liner w/ air expulsion valve
- the “burping” one
- Silesian belt
- Total elastic suspension belt/TES
- Pelvic belt and hip joint
25
TFA Suspension systems
## Footnote
**PRIMARY**
* Pull in suction
* **neg. pressure built up in socket then capped**
* Roll on susp. liners
* **Shuttle Lock →** pin lock
* **Lanyard system→** loop and velcro
* **Cushion liner w/ air expulsion valve→** “burping one”
26
TFA Susp Systems
## Footnote
**Secondary Susp Systems**
**\*Cannot act alone!!!**
* Silesian belt susp
* Total elastic susp belt/TES→ **velcro**
* Pelvic belt and hip jt
* **always has anatomical “hip joint”** built in----- the metal piece
27
TFA Suspension- **Pull In Suction**
## Footnote
**3 components for this system to be effective:**
1. Neg. air pressure
2. Skin to socket contact
3. Muscle tension
28
TFA Susp- **Pull In Suction**
* Req's either:
* **donning sock→ cotton**
* **donning sleeve→ nylon**
* **elastic bandage**
* **why?**
* to **pull RL down into socket**
29
TFA Susp- **Pull In Suction**
## Footnote
**Once limb in socket…**
* Material used to pull limb in is pulled thru the valve housing at the **distal/medial** aspect of socket
* you've seen this!!!
* Air expulsion valve then screwed back on
* Fit is improved via a **neg. air pressure build up**
30
Pull In Suction Susp.
## Footnote
**ADVs vs. Disadvs**
* ADV's
* **Intimate fit;**
* incd **control** and **proprio input** for wearing during walking
* Disadv's
* Reqs **balance/agility**
* Fluctuating volume or wt changes
* Incd **shear forces** precluding those w/ **fragile/sensitive skin**
31
TFA Susp: **Roll-on Liners**
* Silicone, urethane, elastomer in **varying thick, size, tapers**
* To Don (against skin)→ **liner turned inside out then rolled proximally onto RL**
* **Neg pressure created and adhesive-like bond to skin**
* Can be used w/ shuttle lock (pin), lanyard, valve
32
TFA Susp:
## Footnote
**Roll on liners can be used w/ what?**
**3:**
* Shuttle lock- pin
* lanyard
* valve
33
TFA Susp: **Roll-on Liners**
* **Shuttle lock** or locking liner has a distal cap and pin screw
* Pin engages shuttle lock inside bottom of socket when indiv stands and pushes limb into socket
* **To remove,** release button on medial aspect of socket disengages pin
34
Roll on Susp Liners
Ex.
see pics
35
TFA Suspension: **Silesian Belt**
***Remember this is _Secondary suspension_*****_\*\*\*\*_**
* Attach. to **lateral aspect of socket**, **encircles pelvis, runs a loop or buckle on ANT of socket**
* Usually **secondary suspension** aid to another system (see other cards for **primary)**
* By itself→ **unable to control _rotation of RL_ inside socket**
36
TFA Susp: **TES Belt**
\*Remember this is **Secondary suspension!!!!**
* Same mech. as **Silesian belt**
* goes on **outside of socket**
* More comfy vs. Silesian
* Velcro→ easy don/doff
* Also **Secondary or Aux. suspension**
37
TFA: **Prosthetic Knee Units**
## Footnote
**ALL**
**\*=Cadence responsive→ walk faster/slower**
* Single-axis
* Polycentric (think about the one hard to move w/ fingers------ecc quad)
* Manual locking
* Wt-Activated stance control
* **Hydraulic\***
* **Pneumatic\***
* **Microprocessors\*→ BEST!**
38
Prosthetic Knee Units:
## Footnote
**1.Single Axis**
NO LOCK @ KNEE!
* 1 hinge→ **Flex/Ext**
* Stability in stance achieved by **combo of pos'ing knee relative to wt. line (alignment, COM) and muscular control (Hip Exts)**
* Low maint, lt. weight
39
Single Axis knee prosthetic
Explain further stability in stance achieved by???
* Combo of:
* Pos. knee relative to wt. line (**alignment**)→ COM
* **Wt line _behind knee_==\> Flexion**
* **Wt line _anterior to knee_==\> EXT**
* Muscular control
* **Hip Exts**
* Remember must be controlled w/ joint ABOVE!!!
40
Prosthetic Knee Units: **Single-Axis**
## Footnote
**\*free moving knee**
* NO mech. stability
* **inappr. choice for _short RLs_ OR poor hip and trunk strength**
* Once resistance set→ rate of advance. of shin during swing **remains same regardless of walking speed**
* GOOD choice for those w/ **long RLs** who are able to voluntarily stabilize knee
* **longer moment arm→ closer to “knee” to inc control**
* **Active hip EXT against post. wall of socket**
41
This prosthetic knee is a GOOD choice for those w/ **long RLs and WHY?**
Single-Axis knee
\*Longer moment arm→ closer to “knee” incs control
\*Active hip EXT against posterior wall of socket
42
Prosthetic Knee Units:
## Footnote
**2.Manual Locking**
* Single axis knee w/ **pin-locking mech.**
* Knees locked in EXT providing **max. stability BUT compromises mobility and clearance in swing**
* Manually UNlocked to sit
* **Good option in initial stages of WB**
43
Good option in initial stages of WB
Manual Locking knee
44
Prosthetic Knee Units:
## Footnote
**3. Polycentric**
**\*Ecc. quad feel one**
* 4 bar design simulates **anatomical design more closely**
* Moving center of rot. vs single axis
* Enhances **stance phase stability** for **short RLs** and weaker amps.
* **Excellent option** for **knee disartics.** and longer RLs
* → allows lower leg to tuck under thigh when sitting
* **More mechanical joint=more maintenance!!**
45
More mechanical joint=====
More maintenance!!!
46
EXCELLENT option for **knee disarticulations AND long RLs bc allows lower leg to tuck under thigh when sitting**
Polycentric Knee
47
Prosthetic Knee Units:
## Footnote
**4. Weight Activated Stance Control**
**aka “Safety Knee”**
* **Braking system** activated thru knee during **stance phase**
* “Braking” retards unwanted **knee flex** during **stance**
* Sn can be adjusted to match indiv's lvl of activity and control
48
Prosthetic Knee Units:
**5. Hydraulic**
***Cadence Responsive*****\*\*\***
* **Cadence responsive:** forward progression of prosthetic shin **changes as gait speed changes**
* variable resist. simulates norm. gait
* LESS **swing phase delay**
* Adv'd function **brings incd weight, incd maint. and higher $$**
* LESS responsive in **cold weather**
49
Prosthetic Knee Units:
**6. Pneumatic (think “air”**
***Cadence Responsive*****\*\*\***
* **Cadence responsive** BUT uses **air** instead of fluid
* Compressible air easier to change w/in channels of knee to adj. to indiv needs
* LIGHTER and less $ vs hydraulic
50
Prosthetic Knee Units:
## Footnote
**7. Microprocessor Techno.**
**\*Can mimick _ecc quads_→ STAIRS!**
* 1980s
* Most pop→ C-Leg (Otto Bock)
* 1st computer controlled limb
* Recharge battery→ 25-30hrs capacity
* Knee processor sensor and force sensor gather data @ freq of 50x/sec
51
Prosthetic Knee Units:
## Footnote
**C-Leg or Rheo**
* Real time data sent to hydraulic damper which controls **stance and swing mvmts**
* Greater control on stairs, bike, decline walking (**ecc. quad control\*\*\*\*\*)**
* Customized adjs using PC and specialized software
* **\*NOTE:** NO flexion mechanism→ **cannot flex knee actively**
52
Add on components:
## Footnote
**Torque absorbers**
* Simulate **rotation during stance**
* Dec shear forces that translate to socket-RL interface
* Indicated for:
* fragile skin
* sports
* uneven terrain
53
Add on Components:
**Transverse Rotational Units**
* Allows passive rotation of **shin/pylon**
* Allows **crossing legs**
54
Suspension
Sockets
Knees
Shanks
Feet
see pic
55
Shank:
## Footnote
**Endoskeletal (modular)**
**Wt absorbed where**
wt absorbed by **pylon (metal)**
56
Shank:
## Footnote
**Exoskeletal (Crustacean)**
**Wt absorbed where?**
Wt absorbed by shell
57
TFAs- **Latest Gen Knees**
WATCH VIDEOS
SLIDE 42
58
Knee w/ MOST STABILITY
Single-Axis, Locked
\***Remember---- more mobility=less stability**
