A knee-ankle-foot orthosis (KAFO) is an externally applied orthopedic appliance which encompasses the foot, ankle, lower leg, knee and thigh.
The KAFO provides the features of an AFO but in addition provides protection, correction and support of the knee joint.
Some KAFOs are still made from metal and leather but most designs now use thermoplastics with metal only being used for the hinges at the knee.
The lightweight plastic designs offer more support, are more cosmetically acceptable and can fit into various shoe designs.
While the metal braces are more adjustable, they tend to be heavier, bulkier and require special attachments for fitting to shoes.
A heavier shoe is also generally required when using the metal brace.
Very lightweight carbon fibre designs also exist but are not economical, lack adjustability and are rarely more suitable than thermoplastic designs.
KAFOs are commonly used to treat symptoms due to spina bifida, cerebral palsy, paraplegia, polio, trauma or muscular dystrophy.
KAFOs with a knee lock are generally used to keep the knee from bending when there is a loss of or weakness of the muscles(quadriceps) that straighten the knee.
When there is adequate strength and only support of the ligaments is needed as in sports injury, the lock and foot section are not needed.
Such a device is called a knee brace or orthosis.
KAFOs and knee braces come in various designs and the appropriateness of each design is determined by the type of deformity and functional levels of the individual.