INTRODUCTION
AFOs provide a force system both above and below the major joint axes of the rearfoot and ankle. Orthoses apply force to stabilize a joint via 3 - point pressure system, which is defined as two forces applied to a body part opposed by a third force applied between the first two. In the majority of AFOs, multiple three - point force systems provide stability to one or more joints in one or more planes throughout the gait cycle.[9]
An ankle-foot orthosis (AFO) is commonly prescribed for weakness or paralysis of ankle dorsiflexion, plantar flexion, inversion, and eversion. AFOs are used to prevent or correct deformities and reduce weight bearing.
LITERATURE REVIEW
ANKLE FOOT ORTHOSIS (AFO)
An ankle foot orthosis (plural = orthoses) is a hard brace which is normally worn externally on the lower leg and foot in order to support the ankle, to hold the foot and ankle firmly in the correct position, to compensate for weakness and to correct the deformities such as foot - drop. This device encompasses the ankle joint and the foot and guides the ankle to be in a normal and neutral position during walking and other daily activities. It is abbreviated as AFO in short and sometimes is also known as a foot - drop brace.
This AFO braces are devices designed for various functions. Besides enhancing the lower leg extremities to be a stable position, they are also worn to increase the function of the ankle and knee, to prevent the continuous deformity of the lower leg, to keep the ankle joint in the proper and functional position, to facilitate the selective motor control, to reduce the level of spasticity and to protect the lower leg extremity from serious injuries in the postoperative phase.
AFO is commonly used in the treatment of disorders that affected the muscle function such as stroke, spinal cord injury, polio and multiple sclerosis. It is also used to control a severe flat foot, an unstable ankle, or a foot / ankle with abnormal or painful motion by providing support to the weak or wasted limbs or by positioning a limb with tight, contracted muscles into a more normal position. Besides, they are also used to immobilize the ankle and lower leg in the presence of arthritis or fracture, and to correct foot drop. Furthermore, these orthoses also aid in controlling the plantarflexion and dorsiflexion at some stages in stance and swing phases during gait analyses. [5] The AFOs can also help in stabilizing the ankle in transverse and frontal planes throughout the gait activities. [5]
Ankle foot orthoses (AFOs) had also shown affirmative results during the experiment regarding the gait of individuals with ankle muscle weakness.[8] Among the improvements observed include normalization in the heel rise phase, heel strike restoration, major progress in the control of plantar flexion following the foot strike phase, better knee stabilization throughout stance phase[6], propulsion amplification during the push - off stage and a severe reduction in the abnormal hip and knee flexion during the swing phase.[7]
TYPES OF ANKLE FOOT ORTHOSIS
There are various types of AFO and hinges available to restore the ability and the normal function of the lower leg. The AFO designs entails the understanding of human biomechanics and the type AFO worn by each patient differs according to their age, the type of lower leg deformity in each cases, selective motor control level and the functional prognosis in infant and youngsters patients. Among the types available currently include:-
PHYSICAL AND MECHANICAL CHARACTERISTICS OF FLEXIBLE - HINGE ANKLE FOOT ORTHOSIS
The subject exhibits a more natural ankle motion during the stance phase of gait, greater symmetry of segmental lower extremity motion, and decreased knee moments during stance while wearing a hinged ankle foot orthosis. [16] The hinged AFO is found to produce more normal dorsiflexion during terminal stance as the tibia transitions forward over the weightbearing foot and increased ankle power generation during preswing in children with spastic diplegic cerebral palsy. [17] Also, it decreases equinus positioning.
MAIN DISEASES WHICH REQUIRES THE AFO GUIDE USAGE
The main disease that requires the assistance of ankle foot orthosis (AFO) guide is Foot Drop.
Foot Drop or Drop Foot (DF) is an expression that illustrates the neuromuscular disorder that influences the capability of the patient to raise and move their foot at the ankle. The 2 widespread complications include falling of foot after heel strike as the patient could hardly control their fool and it causes their foot to hit hard on the ground on each single step. These patients are prone to tripping frequently and instability occurs during normal walking. As an adaption to their disability, these patients tend to use their hip muscles to swing their leg in the outward direction to allow their foot to clear the ground which is known as circumduction or to exaggerate the lifting of their foot above the ground. This action is also known as steppage gait. As a result, the patients tend to drag their toes on the ground bypassing the swing phase.
Among the illnesses that causes Foot Drop to occur are listed as below:-
