Most Common Types of Hip Knee Ankle Foot Orthotic

Hip Knee Ankle Foot Orthotics (HKFO)

Hip Knee Ankle Foot Orthotics is bilateral knee ankle foot orthotics joined with hip joints. The orthotic hip joints can be placed between the legs or connected laterally to a pelvic or lumbar band or a lumbosacral corset. Orthoses which include extensive trunk bracing sometimes referred to as nose -hip-knee-ankle-foot-orthotics.

By joining two knee ankle foot orthotics together, hip-knee-ankle-foot-orthotics substitute for paralysis of the hip abductor muscles and provide mediolateral stability during stance. In addition, they prevent the pelvis from tilting downwards on the unweighted swing leg. Assists this foot clearance during swing and reduces the need for the upper limbs to lift the swing leg.

However, the torques tending to tilt the pelvis downwards during swing are significant, especially in heavy patients to resist these torques, hip-knee-ankle-foot orthotics needs real lateral rigidity. If the orthotics are insufficiently rigid, swing leg clearance involved.

The three most common types of hip-knee-ankle-foot orthotic are the hip guidance orthotics, the reciprocating gait orthotics, and the medical-linkage orthotics. Various types of hip and knee joints can used in all three orthoses. A summary of each given below

Hip Guidance Orthotics

The hip guidance orthotics, also called the ParaWalker, was first introduced for children with spina bifida in the 1970s.

It consists of two knee ankle foot orthotics attached to a rigid body brace with laterally placed hip joints.

The hip joints are low friction and restrict flexion and extension, although they can be released to enable sitting. During the leg flexes like a pendulum, and swing phase of gait.

That is; hip flexion is achieved solely by the effects of gravity on the unweighted leg. Gravity will only act to flex the hip when the leg extended with the mass of the leg behind the hip joint.


Reciprocating Gait Orthotics

The reciprocating gait orthotics joints two knee ankle foot orthotics to a trunk corset with a laterally placed joints. An essential feature of the reciprocating gait orthosis is the coupling together of the hip joints, preventing, bilateral hip flexion instance. The hip mechanism designed so hip extension on one leg could assist hip flexion on the other foot when stepping. However, the effectiveness of this mechanism may be overstated. The hip joints can be unlocked to flex simultaneously, and it's essential for sitting.

Early versions of reciprocating gait orthotics coupled the two hip joints together with cables. The cables were attached under high tension so that forces from extension in one leg transmitted to flexion of the other. In more recent years, a pivot bar has replaced the cables. The pivot bar is positioned centrally and at the back of the corset in the lumber region. Reciprocating gait orthotics incorporating pivot blocks are called eccentric reciprocating gait orthotics. A variation is the advanced reciprocating gait orthotics.

Medical Linkage Orthotics

The medical linkage Orthotics, also known as the Walkabout orthosis, has a hinge-like joint positioned between the legs. The joints limit hip flexion and extension but do not mechanically assist either. Instead, gravity flexes the hip and moves the unweighted leg forward. Hip extension is achieved by leaning the trunk backwards and extending the lumbar spine. Consequently, even slight loss of passive hip extension can be a problem, increasing patient's reliance on their upper limbs to hold the trunk upright. The medical-linkage orthotics is aesthetically more appealing than other types of hip-knee-ankle-foot orthotics but it provides a slower and more energy consuming gait.

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