Definition: Orthosis is an orthopedic
appliance or apparatus used to support,
align, prevent, or correct deformities or
to improve function of movable parts of
1. To lend stability to a weak joint.
2. Correct or maintain alignment.
3. Correct skeletal deformities, etc.
Principles in designing orthosis
Three point pressure.
Partial weight relieving.
Three point pressure
"The sum of the forces and the bending
moments created is equal to zero.“
A single force is placed at the area of deformity;
two additional counter forces act in the opposing
During "quiet" standing, line of gravity (weight
line) passes through:
◦ posterior to hip joint
◦ anterior to knee joint and
◦ anterior to ankle joint
“Pressure is equal to the total force per unit area. “
The greater the area of a pad of an orthosis, the less
force will be placed on the skin.
P = force
Area of application
Partial weight relieving
“The farther the point of force from the
joint, the greater the moment arm and
the smaller the magnitude of force
required to produce a given torque at
The greater the length of the supporting
orthotic structure, the greater the
moment or torque that can be placed on
the joint or unstable segment.
Lower limb orthosis
Purpose: For supporting lower limbs.
◦ Plastic (recently in demand). e.g. polypropylene,
◦ Metal: aluminum-light weight, stainless steel, etc.
◦ Traditional orthosis were made from metal.
◦ Metals like aluminum-light wt, stainless
◦ Plastic orthosis are formed from a single
piece of thermoplastic.
◦ Plastic components like polypropylene,
Ankle-foot orthosis is a brace, usually
plastic, worn on the lower leg and foot
to support the ankle, hold the foot and
ankle in the correct position, and
correct foot drop.
◦ To control alignment and motion of the
joints of foot and ankle.
◦ For patients affected with muscular
dystrophy, cerebral palsy, etc.
◦ Consists of a shoe attachment, ankle
control, uprights and a proximal leg
◦ Calf bands
◦ Metal uprights
◦ Ankle joint
◦ Shoe attachments
Types of AFO
Dorsiflexion assist AFO:
◦ In case of moderate foot drop.
Plantar flexion assist AFO:
Posterior leaf spring AFO:
Patellar tendon bearing AFO:
◦ In case of severe foot drop.
Knee Ankle Foot Orthosis (KAFO)
A KAFO is a long-leg orthosis that spans
the knee, the ankle, and the foot in an
effort to stabilize the joints and assist
the muscles of the leg.
Material for fabrication: metals, plastics,
fabrics, and leather.
Hip joints and locks
Controls for abduction, adduction and
Controls for hip flexion when locked.
2 position hip locks are also available.
To stabilize the hip joint.
There are two types unilateral pelvic band
and bilateral pelvic band.
It adds weight and increases overall energy
expenditure during ambulation.
A knee orthosis (KO) extends above and below
the knee joint.
Design to control the ligament deficiencies
around the knee.
Provide functional support and rehabilitation
after injury & surgery of the knee.
Free or adjustable knee joint
Thigh and calf cuffs
Types of knee orthosis
Dynamic patellar orthosis:
It consist of an elastic sleeve with patellar cutout.
Its purpose is to prevent the dislocation of
Traditional knee orthosis
It consists of leather thigh, calf cuffs and metal
Pressure pad may be applied to generate medial
or lateral forces.
Swedish knee cage
It used in the management of knee
Two anterior pads and adjustable posterior
pressure pad at the attachment to the upright .
Types of knee joints
Free motion knee joint:
allows unrestricted flexion & extension.
Off-set knee joint:
the hinge is located posterior to the
knee joint stabilize knee during stance.
Hip Knee Ankle Foot Orthosis (HKAFO)
Hip joint and pelvic band attached to the lateral
upright of a KAFO converts it to a HKAFO.
◦ Hip flexion/extension instability
◦ Hip adduction/abduction weakness
◦ Hip internal rotation/external rotation
◦ Sole plate extending to the metatarsal
heads with a crossbar added to the
metatarsal heads area for mediolateral
◦ Ankle joint set at 10° of dorsiflexion
◦ Anterior rigid tibial band (patellar tendon
◦ Offset knee joint with bail lock
◦ Proximal posterior thigh band
Types of HKAFO
Reciprocal Gait Orthosis (RGO)
It is used for upper lumbar paralysis in
which active hip flexion is preserved.
RGO consists of bilateral HKAFO with
offset knee joints, knee drop locks,
posterior plastic AFO, thigh pieces,
custom molded pelvic girdle, hip joints,
and a thoracic extension with Velcro®
straps, in addition to the control
◦ To resist femoral adduction.
◦ Mostly in elderly patients who have had total
hip joint replacement.
◦ Two position lock which permits full extension
and 95 degree of hip flexion and adjustable