The "Partial" Suction Socket
Milton J. Wilder, M.D.
The introduction of the quadrilateral socket with suction suspension completely revolutionized prostheses for above-knee amputees. This method of fitting has become so widely accepted that many clinics and limb manufacturers do not think of varying very much from what has come to be considered the standard above-knee prosthesis.
However, at the Kernan Hospital Amputation Clinic we began to find that results with the standard prosthesis were frequently unsatisfactory. It became imperative that some alternative method of fitting be found. We began to experiment, therefore, with some modifications of the standard limb and found that "partial" suction solved the problem for many amputees.
By "partial" suction we mean a quadrilateral socket which is not dynamically fitted but which allows for the use of a wool stump sock. The anterior wall is not fabricated as high as in the standard limb. This wall can therefore be more readily altered to increase the comfort of the patient. A valve is built into the limb. The patient simply inserts the stump in the socket, pistons it several times, and then inserts the valve. The type of suspension varies with each individual ease--either a silesian belt or pelvic band may be used (Fig. 1 and 2 ). The reasons we see for using "partial" suction in the above-knee prosthesis are:
1. Age. Many older patients have cardiovascular impairment. They find that pulling the stump into a full suction socket demands a great deal of exertion. Some wearers are required to take their limbs off four or five times a day, with a consequent increase in fatigue.
2. Discomfort. The high anterior wall is frequently uncomfortable, particularly for those patients who have to sit for long periods of time.
3. Converting a plug-fit wearer to a quadrilateral socket with full suction. We have found in many instances that this change was unacceptable to the amputee. Primarily the objections related to the high anterior wall, with the socket creating an unpleasant skin sensation. Many patients rejected the attempt to convert them to suction socket wearers and reverted to the plug fit. The use of "partial" suction simplified the conversion.
4. Inconvenience of constant visits to the limb shop. As is well known, the stump undergoes frequent changes in contour and tone. This problem is intensified in those patients whose weight changes frequently. Wearing a stump sock diminishes the need for frequent alterations in the prosthesis. This is a great advantage to the amputee who must travel great distances to visit the prosthetist.
5. Stumps with extensive scarring. Grafted stumps do not tolerate full suction, but in most cases partial suction can be tolerated (Fig. 3 and 4 ). An additional comment is pertinent at this point. Unfortunately, many surgeons do not anticipate the possible need for amputation and use the thigh on the involved limb as a donor site for grafts. When amputation is necessary, these scars produce painful stumps.
6. Stump contour. The management of a poorly shaped stump with redundant tissue is simplified.
7. Economics. Less frequent visits to the limb shop save the patient or the agency expensive alteration costs.
The only disadvantage we have encountered is diminished suction; although in most instances "partial" suction provides adequate suspension, and the limb cannot be pulled off without releasing the valve.
To date we have fitted 33 above-knee amputees with "partial" suction sockets, the oldest being 80 years of age and the youngest, 28. Only two of these fittings have been failures.
We do not mean to imply that the full suction socket prosthesis is not a satisfactory method of fitting. However, for one or more of the reasons cited above, we have frequently varied the prescription to permit the wearing of a sock. The advantages are quite apparent. "Partial" suction has permitted many older patients to wear a limb and to be fairly comfortable for long periods of time.
Milton J. Wilder, M.D. is Chief, of the Amputation Clinic Kernan Hospital, Baltimore, Maryland