What are the purposes of a partial foot prosthesis?
To restore foot function (toe break in the shoe) and to simulate the shape of the missing foot segment.
What is a transmetatarsal prosthesis?
Plastic socket attached to semi-rigid shoe insert with toe filler (to restore foot length)
What is a Chopart prosthesis?
Plastic socket attached to semi-rigid shoe insert insert with toe filler but add plastic calf shell strapped around leg to keep foot in shoe during swing phase.
What is a Syme's prosthesis?
Socket, with or without medial opening, that encompasses most of leg and prosthetic foot.
When comparing the Syme's versus Transtibial what is important to remember?
Symes = removal of all tarsal bones and malleoli.
Transtibial = amputation through the tibia & fibula.
Symes = WB through distal end of residual limb; contour provides suspension.
Transtibial = WB is not through distal end; needs extra suspension.
What is a non-articulated foot?
Solid Ankle Cushion Heel (SACH) vs SAFE, energy storing feet: springlite - C-walk. Most common to have non-articulated.
What is an articulated foot?
Single-axis foot with A-P bumpers or Multiple axis foot and propriofoot.
When fitting a geriatric with a prosthetic what is important to remember about Nonarticulated and SACH feet?
Nonarticulated = no seperate ankle joint, which provides stability.
SACH = durable, lightweight and less expensive (also not used barely at all anymore)
Describe the typical transtibial socket.
Triangular socket - Anterior tibial tuberosity, Medial - semimembranosus and semitendinosis, Lateral - Biceps Femoris.
What are the reliefs of the transtibial socket?
Concavities - inside socket; channels over pressure sensitive areas to relieve pressure on the lateral/medial tendons.
What are the build-ups of the transtibial socket?
Convexities inside socket; bulges over pressure tolerant areas.
Mid-shaft - patellar tendon bearing
What are the different types of receptacles for sockets of the residual limb?
Transtibial - Patellar tendon bearing (PTB) socket, Total surface bearing (TSB), Supracondylar Patellar Tendon (PTS), and Supracondylar - Suprapatellar (SC-SP).
Symes - Long residual limb with good contouring inside socket for distal end WB & suspension.
What two types of sockets are there?
Lined and unlined.
What are the pros and cons of Lined sockets?
+ cushions limb, easy to alter socket, provides sensory input.
- heat insulator (dissipates heat) Macerated skin.
What is needed for an unlined socket?
A distal pad to protect end of limb. Sock to wear over limb that comes in contact with the socket.
What is the purpose of a foot-ankle assembly?
Absorbs shock at heelstrike and allows toe break action in late stance.
What two types of Shanks are there?
Exoskeleton and Endoskeleton.
Describe an Exoskeleton.
Rigid exterior shaped to contour leg. Polyester laminate, tinted color. More like a lobster.
Exoskeleton = exterior
Describe an Endoskeleton.
Rigid Pylon covered by foam rubber. More cosmetic, expensive and less durable. It's more life like.
Endoskeleton = pylon
What are the modes of suspension for transtibial prosthesis?
Cuffs, Brims and Others like thigh corset, silicon sheath w/ distal pin and vacuum assisted socket.
Describe cuffs for suspension of transtibial prosthesis.
Supracondylar - goes above condyles
Fork strap & waist belt - encircles waist
What types of knee axis systems are there?
Single axis hinge and polycentric linkage.
SAH - has 1 pivot - less expensive & more commonly used.
PL - has 2 pivot points to increase knee stability, more expensive
What is a C-leg?
Microprocessor - controlled hydraulic units use electronic sensors that detect rate & range of leg movement. 50+ times/second. Provides almost instant friction adjustment to changes in gait pattern.
What kind of extension aids are there for the knee?
External and Internal. They assist knee extension during swing phase.
External - elastic webbing on anterior knee (that pulls knee up when sitting)
Internal - elastic strap or coiled spring within the knee unit, that keeps knee flexed when sitting.
What are knee stabilizers?
Knee action can be controlled by hip action and TKA line. Manual lock or friction brake.
Describe Transfemoral sockets.
Quadilateral - low walls: Post (Glutes) & Med (adductors)
High walls: Anterior (quads) & Lateral (vastus lateralis/TFL)
Concave relief in corners
Convex in anterior walls: Scarpa's bulge
What is an Ischial containment socket?
Contoured adducted trochanter-controlled alignment method. Posterior wall covers ischial tuberosity to increase socket stability. Narrow mediolateral width.
What are modes of suspension for Transfemoral prosthesis?
Total suction - 1 way air release valve (low pressure inside) may add suspension sleeve.
Partial suction - socket has valve , pt. wears socks, may add pelvic band or Siliesian bandage.
No suction - socket has a hole, but no valve. Requires hip joint and pelvic band.
What's important to remember about Stump Socks?
Can't exceed 15 ply thickness. Converts shape into plug fit.
Fabric - cotton, wool, lycra or nylon.
What is it called when the tibia and fibula are gone, but the knee is intact?
Knee disarticulation. Sockets - WB on ipsilateral ischial tuberosity and both iliac crests. Knee units - thin plate to keep knee length more in line with sound side.
What is it called when the entire femur is gone but the pelvis is intact?
Hip disarticulation. Sockets - WB on ipsilateral ischial tuberosities and around iliac crests. Hip unit axis is anterior to weight line to increase hip stability. Knee unit axis is posterior to WB Line.
To increase hip extension force you need to?
Have an anterior placement of hip jt. axis, so LOG falls behind hip jt. axis.
To increase knee extension force you need to?
Have a posterior placement of knee jt. axic so LOG falls anterior to knee jt. axis.
What factors are good to consider prior to formulating prosthetic prescription?
Patient - anticipated activity level, overall strength, balance, $ resources, access to clinic.
Limb - length, skin/scar condition, amount of soft tissue, MMT, AROM, PROM.
*The best shape of a residual limb is cylindrical.
What kinds of prosthetic training is there?
Donning/Doffing, Stairs, curbs & inclines, gait training, transfers, balance and coordination.
If a prosthesis is too long what kind of gait patterns might you see?
Excessive PF of foot and/or too much knee friction.
If a prosthesis is too short what kind of gait patterns might you see?
Improper fabrication and/or too high medial wall (pinch)
Lateral trunk bending
With knee instability from excessive DF in foot and/or stiff heel cushion -> delayed PF roll over - what gait pattern deviation might you see?
Forward trunk flexion
Excessive knee flexion
In the Transverse plane malalignment from excessive rotation of the knee, excessive toe out and/or inadequate suspension what gait pattern deviations might you see?
Rotation of forefoot at heel strike
Medial (or lateral) whip