Medial Ramus Containment Socket Design For Transfemoral Prosthesis

Introduction

This radically different design for Transfemoral Socket configuration was developed for:

The basic concept of this design is to only contact the ramus medially. It is imperative that the patient's angle of the ramus be duplicated in the cast and the socket. Patient comfort relies on following the angle of the ramus within the socket. Evenly distributed pressure is tolerated quite well.

The containment is as anteriorly on the ramus as possible. This allows for containment to be maintained throughout the gait cycle, as opposed to more posterior containment where the ischium can slip out of the socket at hip flexion. The Ischial containment "ear" is approximately ¾" - 1 ¼" high, and as wide as possible.

The posterior wall is reduced to the gluteal fold level. This improves cosmesis as the buttock is not elevated by the socket. The amputee is allowed to sit on their gluteus muscle group, rather than on a hard socket brim, thereby preventing just imbalance to the pelvis during sitting. The exception to removing material from the socket below the level of the gluteal muscles is for very short residual limbs, then where it is necessary to provide support somewhat higher on the anatomy.

The anterior and medial walls are slightly below Ischial level. There is a significant socket relief for the adductor musculature and almost moderate a Scarpa's modification anteriorly. The anterior lateral contour is critical as the primary medio-lateral stability is derived from a snug fit from between the medial ramus to and the anterior lateral socket wall.

Before the wrap cast is taken some measurements are required. The usual for length of stump and femur, perimeters at two inch increments 0", 1", 2", 4", 6", 8", etc. levels with no tension on the skin. Anatomical A-P measured using methods similar to the like for quadrilateral socket, ischium to Scarpa`s Triangle , with no compression.

Skeletal M-L dimension, the arms of SML measurement device should be parallel to line of progression. Diagonal M-L dimension, in this case the arms of the measurement device should be parallel to angle of ramus.

When casting, approaching the residual limb from the lateral aspect permits easy palpation of the ischial ramus. One hand will be approaching the patient from the posterior, the other hand from the anterior. The index and middle fingers of the posterior hand should follow the contours of the medial aspect of the ischium, just behind the adductor tendon. The ring finger should be on the inferior aspect of the ischium. The thumb compresses posteriorly. The opposite hand, anteriorly, will be controlling the Scarpa's area shape with the thumb. Relief for the adductor musculature will be provided by the web space of the hand.

During the cast modification process, the ramus angle is the reference point, always return to it is position. It is approximately, 30 - 35 degrees in male, higher numbers angles for women. Define the A-P distance from ischial tuberosity to adductor longus tendon, remove plaster anteriorly in Scarpa`s triangle keeping a nice standard anatomical radius; material should be removed from both lateral and anterior lateral to measurements M-L and Diagonal M-L.

The anterior shape of the socket will appear to have a modified quadrilateral socket shape, although it will look internally rotated. Reduce posterior lateral tissue in the Lateral Sulcus. Blend it into lateral wall, as this helps to maintain suction. Reduce the shapes to just to the indentations on lateral femur.

The posterior wall should be a U shape in both the transverse and coronal planes, following the hamstrings and gluteal fold. The trim lines should be ½ - 1" below ischial level, the posterior brim allows the gluteal musculature to escape, remain perpendicular to line of progression. Without pressure on the gluteus maximus, there is improved strength of the hip extensors.

On the adductors apply a BIG relief for the adductor group, the relief should be large enough to provide full function of the adductors during gait.

"Ear" shape-medial containment wall must be flat to prevent locally high pressure points. Create a medial wall that will provide ML support. NOT A SEAT. It needs to be a right angle so the bony ridge of the ramus is relieved. Blend the anterior and posterior aspects of the ramus wall. It should have a comfortable reverse flare or "dome".

The height of the medial containment wall should be between ¾ - 1 ¼ " this will depend on the anatomy of each patient.

During fitting the medial "ear" should be bent out 10 - 15 degrees angle to allow the ramus easier entry into the socket. Check the position of the ramus making certain to keep the ramus angle in line with the ramus and NOT the line of progression.

This socket design has very low trim lines that improves ischial ramal containment and allows the femur to be placed into an over-adducted position to offer the same similar angle of the sound leg.

Do the throchanter test. Compress the hips laterally and socket should move ¼ ", if socket does not move, loosen skeletal M-L , patient will tolerate the socket pressure better.

This socket design has been fitted to more than 80 amputees with a various levels of transfemoral amputations, different kind of activities, ages, sex, types of suspension. Auxiliary suspension belts were not used in any of these amputees.

The Marlo Anatomical Socket (MAS) provides exceptional comfort; there is no virtually uncomfortable pressure felt by the patient, the containment walls do not distribute weight-bearing forces over the ramus and ischium. Range of motion without restrictions, gait, stability, security, and increased proprioception are benefits experienced by those who are wearing the MAS total contact transfemoral socket.

An additional benefit of the MAS design is exceptional cosmesis, the brim results in a discrete socket fit, which is not visible under the patient`s clothing. Not only does this MAS socket design provides an attractive appearance, but also improves range of motion without any restriction, comfort suspension and gait.

Website built by oandp.com