Prescription of above-knee and below-knee prostheses
G. Rubin *
E. Fischer *
M. Dixon *
Abstract
New developments in socket design, materials and fabrication are briefly reviewed. A series of charts is presented which summarize the below-knee and above-knee prescription procedures followed at the Veterans Administration Prosthetics Center.
Introduction
It is the purpose of the authors to present one clinic team's approach to the prescription of above-knee and below-knee prostheses.
Prosthetic prescriptions have varied significantly under relatively similar circumstances from centre to centre, in the experience of the authors. There are many different knee components, prosthetic feet and socket designs available. Modifications of older concepts are continually being added to the armamentarium of the clinic team.
Although the prescription procedures acceptable to the authors appear to have worked well for them and the amputees they serve, they may not be as readily acceptable to others.
If the charted outline of prescription and component selection stimulates discussion and controversy, its purpose will have been accomplished.
Since no two amputees will have the same general physical status, individual stump characteristics, or vocational or occupational problems, a rigid approach is not possible. In some instances, climate, terrain and cultural differences will also affect the prescription. A basic concept, however, with an understanding of such individual restrictions, is presented in this paper.
It is challenging and of continuing importance that new techniques are being tested in various centres throughout the world. Many of these are logical and promising and will undoubtedly, after adequate testing, become firmly established tools of the prosthetist.
Until, however, they have been widely used by a sufficient number of prosthetists other than the developers, and the reports of their experience become available, a final judgement must be held in abeyance.
The newer developments which the authors have recently adopted have prompted them to revise an earlier presentation outlining their clinic team's approach to the selection of components for lower limb prostheses (Rubin and Fischer, 1982).
The format employed in the previous article has been used here with pertinent chart and text modifications to reflect changing attitudes in specific instances. The authors have been very conservative in developing the charts and have preferred to include in the text advances in prosthetics which are still not universally employed rather than in the charts, perse. These include such potentially significant developments as the "Scandinavian Flexible Socket" (Jendrzejczyk, 1985) the "Normal Shape-Normal Alignment" above-knee prosthesis (NSNA) (Long, 1985) and the "Contour Adducted Trochanteric Controlled Alignment Method" (CAT-CAM) (Sabolich, 1985), among others. The authors' experiences with the Scandinavian flexible socket have been quite positive. The amputee's response to the action and cosmesis of the Seattle foot (Burgess et al, 1984), also a recent development, has been generally favourable. There are problems, as with everything new, which will undoubtedly be eliminated by the developers. The very active amputee still experiences too frequent breakage. With the advent of the Seattle foot, other feet incorporating the stored energy concept are continually becoming commercially available. There is, incidentally, some similarity in this concept to the shoe with the addition of a long steel spring and rocker bar that is advisable in orthotics when a solid ankle orthosis is used.
Another foot-ankle that has not yet had broad acceptance is the Mauch hydraulic ankle. This centre was involved in the initial testing of the Mauch ankle, in spite of which it has had limited experience with it. It does have capabilities that other feet do not have, such as adjustability to the terrain when walking up and down-hill. There had been a frequent malfunction problem with this device which limited the frequency of prescription. The authors look forward to gaining experience with the new, lighter, and, presumably sturdier version. It promises to be a very sophisticated ankle.
Xeroradiography(R) (Varnau et al, 1985), has been introduced to prosthetics, but the authors have viewed the routine use of this technique with caution, because the radiation dosage is nine times as high as with routine X-ray exposure and "Syme level as well as long above-knee residual limbs require two pictures merely to complete the image for one projection" (Varnau et al, 1985). If two projections each of an antero-posterior and a lateral view are employed, the basic dosage will be nine times the routine X-ray dosage, quadrupled. A good deal of useful similar information is obtainable with the clear socket method and the occasional use of routine X-ray when specifically indicated (and after consultation with the physician member of the Clinic Team). From the medical point of view excess exposure to radiation should be limited unless no other reasonable alternative exists. Varnau et al (1985) do indicate their concern for the juvenile patient and advise that the "benefits of Xeroradiography(R) must be weighed against the greater radiation dose". It is suggested that this cautionary approach be broadened to include adults as well.
Above-knee amputation socket design is undergoing dramatic evolutionary changes at this time. The reports of Lehneis (1985) Long (1985) and Sabolich (1985) are most significant in this regard. The CAT-CAM of Sabolich and the NSNA of Long have had extensive testing by the originators, and Lehneis, in cooperation with the U.S. Veterans Administration, is at present engaged in investigating the special design indications for the geriatric amputee's socket.
Currently, many other prosthetists are learning and using the CAT-CAM system. Their reports, when available, will make an important contribution to the acceptance of this method.
Similarly, below-knee sockets are being fabricated with flexible plastic at several centres and this concept also appears to have merit. Sidney Fishman and his group at NYU in conjunction with the U.S. Veterans Administration are also involved in exploring the use of a frame and socket configuration for the B/K.
CAD-CAM (Computer Aided Design - Computer Aided Manufacture), a sophisticated approach to the eventual increase in speed of production of prostheses has been under development by several prosthetic centres.
As Murdoch (1985) has indicated the "individual prosthetist will be able to fit more patients in a given time", but his clinical experience and expertise will be required to modify the CAD-CAM product.
The enthusiasm for acronymic description of prosthetic techniques has led to the identification of the "Icelandic Roll-On Suction Socket" as the Ice-Ross system (Kristinsson, 1985a) and the "Icelandic Pull-On Suction Socket" as the Ice-Poss system (Kristinsson, 1985b). Both of these systems employ injection moulded sockets to achieve B/K suction and both are not widely accepted by prosthetists. Because the designs referred to above are still undergoing changes (Sabolich is preparing a new report on a procedure he designates as SCAD-CAM) they have not been included in the basic charts which are part of this paper.
Summary
A series of charts has been presented summarizing the above-knee and below-knee prescription procedures which have been followed at the Veterans Administration Prosthetics Center. There is a very significant evolution in socket design, materials, and fabrication which everyone involved in prosthetics is observing carefully. However, new developments do require extensive trial before becoming universally accepted and these new developments are undergoing such a trial at present. "It would be a truism to point out that some of the devices categorized as research items at the time of this writing will no longer be considered to be such by the time this book (sic) is published. Some will be accepted and others discarded" (Rubin and Wilson, 1981).
References:
- Burgess, E., Hittenberger, D. A., Carpenter, K. L. (1984). The VA Seattle foot In: Veterans Administration Rehabilitation R&D Progress Report, p5.
- Jendrzejczyk, D. J. (1985). Flexible socket systems. Clin. Prosthet. Orthot. 9(4), 27-31.
- Kristinsson, O. (1985a). The Ice-Ross System (abstract) AOPA Almanac 33(10), 50.
- Kristinsson, O. (1985b). The Ice-Poss System (abstract) AOPA Almanac 33(10), 57.
- Long, I., A. (1985). Normal shape-normal alignment (NSNA) above-knee prosthesis. Clin. Prosthet. Orthot. 9(1), 9-14.
- Lehneis, H. R. (1985) Beyond the quadrilateral. Clin, Prosthet. Orthot 9(4), 6-8.
- Murdoch, G. (1985). Editorial Prosthet. Orthot. Int. 9, 1-2.
- Rubin, G., Fischer E. (1982). Selection of components for lower limb amputation prostheses. Bull. Hosp. Joint. Dis. Orthop. Inst. 42, 39-67.
- Rubin, G,, Wilson, A. B. (1981). Research trends in lower limb prosthetics In: American Academy of Orthopedic Surgeons Atlas of Limb Prosthetics St Louis, MO: C.V. Mosby, p 435-439.
- Sabolich, J , (1985). Contoured Adducted Trochanteric - Controlled Alignment Method (CAT-CAM): Introduction and basic principles. Clin. Prosthet. Orthot. 9(4), 15-26.
- Varnau, D., Vinnecour, K. E., Luth, M., Cooney, D. F. (1985). The enhancement of prosthetics through XeroradiographyR. Orthot. Prosthet. 39(1), 14-28.
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