L3: Transfemoral Components Flashcards
OBJECTIVES:
- ID various components of transfemoral prosthesis including:
- suspension
- sockets
- knee units
- Adv’s of each
Transfemoral Components:
4:
- Socket→ where RL goes
- Suspension→ holds RL in the socket (usually external)
- Knee unit→ the “new” knee
- Prosthetic foot→ many diff. types
Transfemoral Components: Socket
2 types
- Quadrilateral Socket (Quad)
- Ischial (IC) or Ischial-Ramal (IRC)
- more comfortable
- more common
Transfem Components: Socket
Quadrilateral Socket (Quad)
Explain…
- 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
Transfem Components: Socket
Quadrilateral
Talk about the more narrow dimensions, where are they w/ this socket?
More narrow ANT-POST dimension
TFA→ Quad Socket
ADV’s vs Disadv’s
-
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
Prox. posterior and medial discomfort w/ Quad Socket
Why?
Extra tissue
Lateral thrust and trunk bending w/ Quad Socket
Why?
extra space in Quad socket M/L dimensions
Transfem Components: Socket
Ischial (IC) or Ischial-Ramal (IRC)
- 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
Transfem Ischial Socket maintains normal ________ by distributing pressure thru socket along __________
normal femoral adduction; thru socket along shaft of femur
Transfem Components: Socket
Ischial or Ischial-Ramal
More deets
- 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
Ischial (IC) or Ischial-Ramal (IRC) socket has a more narrow dimension where?
More narrow MED-LAT dimension
TFA: IRC Socket
ADVs vs. Disadvs
-
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
Quad socket: The ischial tube is ______
OUTSIDE
IRC Socket: The ischial tube is ________
INside, contained
IRC vs. Quad Socket
Ischial Tube positioning
see pics
Quad Socket has wider ______ dimensions
Wider M-L
IRC Socket has wider _______ dimensions
Wider A-P
IRC vs. Quad Socket
-
NOTE: IRC socket mushc higher Lateral Wall
- lower medially— comfier
TFA Socket Material:
RIGID
- 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
TFA Socket Material:
FLEXIBLE
- 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
1 reason pts do NOT wear TFA Prosth.
???
Discomfort in sitting
*BUT remember its not MADE for sitting*!!!
TFA Suspension Systems:
- 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
TFA Suspension Systems
Bold and *== Primary
- 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
TFA Suspension systems
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”
TFA Susp Systems
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
TFA Suspension- Pull In Suction
3 components for this system to be effective:
- Neg. air pressure
- Skin to socket contact
- Muscle tension
TFA Susp- Pull In Suction
- Req’s either:
- donning sock→ cotton
- donning sleeve→ nylon
- elastic bandage
-
why?
- to pull RL down into socket
TFA Susp- Pull In Suction
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
Pull In Suction Susp.
ADVs vs. Disadvs
- ADV’s
-
Intimate fit;
- incd control and proprio input for wearing during walking
-
Intimate fit;
- Disadv’s
- Reqs balance/agility
- Fluctuating volume or wt changes
- Incd shear forces precluding those w/ fragile/sensitive skin
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
TFA Susp:
Roll on liners can be used w/ what?
3:
- Shuttle lock- pin
- lanyard
- valve
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
Roll on Susp Liners
Ex.
see pics
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
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
TFA: Prosthetic Knee Units
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!
Prosthetic Knee Units:
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
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!!!
-
Hip Exts
- Pos. knee relative to wt. line (alignment)→ COM
Prosthetic Knee Units: Single-Axis
*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
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
Prosthetic Knee Units:
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
Good option in initial stages of WB
Manual Locking knee
Prosthetic Knee Units:
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!!
More mechanical joint=====
More maintenance!!!
EXCELLENT option for knee disarticulations AND long RLs bc allows lower leg to tuck under thigh when sitting
Polycentric Knee
Prosthetic Knee Units:
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
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
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
Prosthetic Knee Units:
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
Prosthetic Knee Units:
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
Add on components:
Torque absorbers
- Simulate rotation during stance
- Dec shear forces that translate to socket-RL interface
- Indicated for:
- fragile skin
- sports
- uneven terrain
Add on Components:
Transverse Rotational Units
- Allows passive rotation of shin/pylon
- Allows crossing legs
Suspension
Sockets
Knees
Shanks
Feet
see pic
Shank:
Endoskeletal (modular)
Wt absorbed where
wt absorbed by pylon (metal)
Shank:
Exoskeletal (Crustacean)
Wt absorbed where?
Wt absorbed by shell
TFAs- Latest Gen Knees
WATCH VIDEOS
SLIDE 42
Knee w/ MOST STABILITY
Single-Axis, Locked
*Remember—- more mobility=less stability
