No ambulation potential

Severe cardiac disease 

Poor vision

Poor motivation or compliance

Poor stump - infected, ulceration, poor skin

FFD knee or hip




Young traumatic or neoplastic amputee

Motivated PVD / neuropathy amputee with cardiac reserves




Best to fit prothesis ~ day 14 

- allows most stump shrinkage to occur

- IPOP tends to cause high complication rate especially with PVD


Elements of a Prosthesis


1. Socket

- transmits forces between the stump & the prosthesis in all planes 

- may be proximal, distal or total bearing 


2. Means of Suspension

- suction socket 

- suspension belts 

- neoprene sleeve 

- elastic stocking 

- silicone sleeve 


3. Joint mechanism (knee)


A.  Stance phase control 



- aligns the prosthesis so the ground reaction force passes in front of the knee 

- locks in hyperextension; 2 drums lock at 0-15o

- for elderly 


Mechanical stabilisers 

- braking mechanism activated by the weight bearing load or hydraulics


B.  Swing phase control 

- pneumatic cylinder 

- hydraulic cylinder 

- intelligent prosthesis - computer adjusts rate of swing to cadence (steps/min) 


4. Terminal device / Foot 



- Solid Ankle Cushioned Heel

- wood keel / heel cushion / rubber foot

- use for BKA


B.  Single axis

- some DF/ PF possible

- makes knee stable

- use if knee stiff ie AKA or through knee


C.   Multi - Axis Foot

- hindfoot eversion / inversion + DF / PF

- better for active patient


D.   Dynamic Response

- "Ryan's Superfoot"

- flexible keel allows smoother roll over

- store energy via carbon fibre foot plate

- Aid toe off / more natural gait / save energy

- expensive

- not used in children as turnover too high


BKA Prosthesis




Usually firm PTB design

- can add liner for increased comfort

- definitive socket fitted 1 year (size stabilised by then)

- load patella tendon & medial / lateral flares

- most weight actually borne on medial tibial flare

- extend flares higher if unstable knee




Suprapatellar cuff

- simplest & most common

- dacron & leather

- grips condyles

- advantage is transfers all force to residual leg below knee


Supracondylar mould

- grips above femoral condyles

- young patient or < 5cm residual tibia


Neoprene 5mm liner

- rolled over distal thigh

- frictional fit ± suction

- negative pressures in swing


AKA Prosthesis 





- lack of bony contours

- not truly end bearing

- usually ischial bearing



1. Suction with valve hole

2. Waist or hip belts - if femur too short



- surface tension

- negative pressure

- active muscles

- stable body weight / socket fits




1. Quadrilateral

- traditional socket with narrow AP diameter

- weight bear on ischium / not in socket

- difficult for the femur to sit in adduction


2. CAT - CAM

- narrow medial - lateral diameter

- femur sits in adduction 

- more ovoid

- incorporate ischium into socket via flare

- more comfortable

- better femoral stability in socket


Knee Design Options


1. Single axis

- simple hinge


2.  Polycentric axis 

- 4 bar linkage device

- more natural

- expensive and heavy


3. Friction

- limits knee flexion


A.  Constant

- cheaper

- limited to one walking speed


B.  Variable friction, including with extension

- hydraulic controlled

- resist flexion in extended knee

- easy flexion in flexed knee

- allows different speeds 


4.  Safety knees / Stance control knee

- lock when weight applied 

- good for elderly



- Single Axis Safety Knee


Most expensive & heaviest

- Polycentric Hydraulic Controlled Knee


Through Knee Prosthesis



- endbearing socket



- via femoral condyle flares or strap

- 4 bar linkage knee overcomes previous problems with through knee

- folds away when sitting

- knees at same level