IDS ::: Orthotics ::: KAFO's

Knee ankle foot orthoses - (KAFO's) are effectively AFO's with a thigh section.

They can incorporate all the designs of mechanism described under the AFO. section. In addition a KAFO. will either have either a rigid extension which includes the thigh (to become a rigid KAFO) or more commonly, have knee joints. The joints will be one of the following categories:

Free – restricted only in that they do not hyperextend. They may be designed to provide some geometrical resistance to flexion in stance by having pivots which are posterior to the load line but are mainly designed to give medio-lateral support.
Locking – designed to lock in full extension and be unlocked to allow knee flexion for sitting. There is a wide variety available, applicable to different requirements. When locked these obviously provide complete stability for the knee joint. They also can reduce/prevent flexion contractures.
Sprung – there are a small number of joints available which have extension assisting springs. These are designed to either enhance gait or reduce flexion contractures.
Stabilised – some recent designs are intended to provide significant resistance to flexion in stance while being free in stance.

KAFO's are routinely used for conditions where there is a severe lack of structural stability or extensor power. In addition they can be used to take axial loading if they are designed to be ischial bearing, where the patients ischial tuberosity is in contact with a specially shaped area of the proximal posterior femoral section. The patients weight is therefore partially transmitted through the structure of the orthosis, by-passing the axial skeleton. This is a very useful feature which is also crucial to trans-femoral prosthetics. It can also create discomfort and should not be incorporated into the design unnescessarily.

Conventional KAFO with locking knee joints and an extension to compensate for a leg length discrepancy.

Otto Bock "Freewalk" KAFO with dynamic knee lock, operated by foot position and ground reaction. It is free in swing and locked in the stance phase of the gait cycle.

Genuvalgam before controlled by a KAFO

Genuvalgam controlled by a KAFO

A lightweight carbon fibre KAFO

Knees destroyed by RA

The same patient using bilateratal rigid KAFO's

A KAFO used as a femoral fracture brace.

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