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Ischial Containment Socket in Post-Polio Bracing 

Jennifer Latham Robinson

Infantile Poliomyelitis is a viral infection that affects the anterior horn cells of the spinal cord resulting in flaccid paralysis, but leaving the sensory system intact.  It affects primarily the lower limbs.  The two features, flaccidity and sensation, result in the common pathological picture regardless of the level of involvement.


Generally, the post-polio patient is referred to one of two basic problems, although both, as well as others, are often present in the same patient.  The first is pain which results not just from wear and tear, but also from angular deformity that unduly stresses supporting elements of the involved joint.  These angular deformities are often of a functional nature.  Our goal in treatment is not to restore correct alignment, but to block the extreme of motion and reduce the pain to a tolerable level.  Genu recurvatum is the best example of this principle.  The other category encountered is debility and an ensuing inability to cope as well as before.  The patient will complain of an increase in fatigue, unsteadiness and experiences more falls than before.


The quadrilateral brim is the traditional and generally accepted design for weight bearing KAFO’s in orthotics  and,in the past, prosthetic above knee socket design.  Difficulties in the fitting oforthotic patients with the quadrilateral brim identify a failure to adequately accommodate anatomical structures resulting in unnecessary discomfort of the patient and inconsistent axial unloading.  The current prosthetic above knee socket designs have opened not only significant doors for the amputee, but also for the post-polio patient.


The prosthetic above knee socket design offers a narrow medial lateral design, wide anterior posterior, normal femoral alignment, ischial containment within the socket, good suspension and accommodation of the patient’s own anatomy.  These characteristics of design follow human anatomy to gain skeletal stability through an intimate fitting within the socket.  Thus, comparison of the quadrilateral brim and the ischial containment sockets will illustrate a fundamental difference, that is, the aptient is fitted to the socket in the case of the quadrilateral brim and the socket is fitted to the patient in the case of the ischial containment socket.


The primary advantages of this socket design are as follows:


1.                   A narrower M-L diameter relative to the A-P diameter.

2.                   An ischial containment within the socket.

3.                   Increased control of the femur.

4.                   Increased comfort.

5.                   Increased weight bearing areas.

6.                   Accommodation of the patient’s own anatomy

7.                   Less wear and tear on the patient’s joints.


Initial casting procedures for the ischial containment socket involve a “check socket” procedure, as used in prosthetic fabrication.  This procedure enables the orthotist to delineate any pressure points and modify any areas of concern before fabrication of the final socket.

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