Socket Concepts

In the past most sockets were built out of hard laminated plastic materials and were shaped like a bucket with a flat bottom.This is why so many of us old timers (clients and prosthetists) still refer to our sockets as "buckets" The bucket was strapped tightly around the remaining torso and very few of us were able to adjust to being so tightly encased in a hard, bulky, and heavy bucket. For hip-disarticulations, one literally sat with the ischeal tuberosity on the flat section of the bucket. Sitting on a bone right next to a hard base is painful. These types of buckets could never be fitted snugly around the body with comfort and allowed for movement inside the socket such as rocking back and forth, side to side or twisting. This useless motion expends energy, and may cause pain and shearing to the skin and skin breakdown.

Since the late 1980's, several progressive prosthetists investigated the concept of using a contoured socket rather than a bucket. This contoured socket fits closer to the remaining bones, muscles, and soft tissues providing better support, and provides relief where it's needed for comfort. This better attachment, or bony lock onto the remaining pelvic bones increases stability and makes it easier to activate the prostheses. Weight bearing is distributed over a wider area both below and around to the sound side making it more comfortable. Frequently the rigid part of the socket can be cut lower making it lighter weight and allowing for bending at the waist.

HIP-DISARTICULATION
	Old Style Bucket Weight bearing at A, the ischeal tuberosity.
	New Contoured Socket Bone and Muscle Contouring at #1, #2, and #3 provides better bony lock and suspension. This gives more stability and security in the socket.
Diagram courtesy of Tom Guth, C.P.

For hemipelvectomies, we too were encased in plastic and our sockets needed to come up quite high over the ribcage. We literally had to do the weight bearing with our ribs which is very confining, uncomfortable and could cause rib fractures. We had the same problems with movement within the socket plus another movement called pistoning, or moving up and down since there is no bone left beneath us to bear weight. Many types of over the shoulder straps and other contraptions to hold the leg on were tried and usually rejected.

Compression of the soft tissues and contouring the socket spreads the weight bearing over a larger area. The stress is taken away from the ribs and transferred below.

HEMIPELVECTOMY
	Old style, rigid laminated socket. Weight bearing was on the ribs (A) & (B). There is no contouring of soft tissues below (C).
	Instead of weight bearing on the ribs (B & C), the soft tissues are compressed and contoured (D & E)

The following pictures, generously provided by Kevin Carroll CP. illustrate these points using a hip disarticulation skeleton and a clear socket as examples.

Front View

The rigid support for weight bearing is contoured around the bones and muscles and is cut to a minimum. This allows for greater flexibility and less weight.

The remaining pelvis is held in place by a flexible inner liner.

View from Below

Note the contoured, rigid support underneath. The ischeal tuberosity is cupped and held in place by the flexible liner. There is relief over the coccyx and public bones.

View from Above

The pelvis is held snugly in place. Note there is relief over the iliac crest (hips), spine, and pubic rami.