NO180103B - Procedure for direct fitting of dentures - Google Patents

Description

The present invention relates to a method for direct fitting of leg prostheses.

Adapting a prosthesis is today an extensive and labor-intensive process that includes measurement, plaster casting, modulation of a positive plaster model and finally molding a prosthetic sleeve in thermosetting plastic or thermoplastic. Only when this has been done can the prosthesis be tested on the user. During the fitting, the prosthesis is adjusted while the user walks so that optimal pressure load and walking pattern are achieved. When the prosthesis has acceptable function, it must be completed and given its cosmetic design. The user must appear at least three times at the workshop. The first time for measuring, then for testing and finally for fitting the finished prosthesis. Today's method for fitting a leg prosthesis has several disadvantages. It is labor-intensive and divided into production phases with visits by the user at three stages during the production period. This means that there is usually a period of at least three weeks from measurement to delivery of the finished prosthesis. During these weeks, a lot of time is spent on the production of the prosthesis and this is time that could have been used to work directly with other patients. This is a bigger problem the more people who need prosthetic fitting (eg in war-torn areas). A large amount of work per prosthesis also results in an increased production cost. The longer the adaptation process lasts, the longer the user has to wait before the rehabilitation phase with a prosthesis can begin. This is valuable time for a person who is mentally and physically run down after a serious trauma. In addition, each day the rehabilitation phase is shifted will entail increased financial expenses.

US-3,520,002 describes a technique for direct adaptation of leg prostheses where a fast-hardening foam is used to achieve uniform contact between the amputation stump and the sleeve wall. The method is based on the pressure load being distributed evenly over the entire amputation stump. A prerequisite for an acceptable pressure distribution to be achieved is that you find the distribution key between the various areas of the stump. What we are saying is that in some cases some areas must be completely relieved while others can tolerate great pressure. The main point is that the load distribution will be different from person to person. This is not taken into account in US-3,520,002. The pads mentioned (p. 2, 1. 28-29, 1.55-60, p. 3, 1. 136-140) are called "flexible pads C" and are only used to reinforce the foam inside the prosthetic sleeve and not as a means of to influence the shape or volume of the prosthesis sleeve.

FR-2,520,226 describes a "prosthetic sleeve" where the shape of the sleeve can be adjusted by adjusting screws to give greater pressure on parts of the sleeve wall. Basically, the sleeve has a shape that clearly deviates from the shape of the amputation stump it is supposed to enclose. It is not anatomically designed. This means that only a small part of the amputation stump will come into contact with the inside of the sleeve and the pressure distribution will be such that these areas will be exposed to an unacceptable load pattern. That is, a pressure distribution that will cause pressure ulcers.

FR-2,420,335 describes an adaptation technique for femur amputees where, as with today's most used technique, a negative plaster model is used for measuring. This is filled with liquid plaster and the positive plaster model is modeled in the usual way. The finished prosthesis sleeve contains cast-in pockets that can be filled with injected material when the need to adjust the volume of the prosthesis sleeve is present. That is, when the amputation stump has become too small in relation to the prosthetic sleeve. The patent therefore describes an adjustment technique and not an adaptation technique.

FR 2,095,097 describes standard thigh prosthesis sleeves in various sizes, which are characterized by the fact that they provide sufficient space between the sleeve itself and the stump so that plastic can be injected and create an adaptation when casting the stump. The prosthetic sleeve has an opening with a closing mechanism where the foam is poured. This patent therefore describes and explains a principle for filling an excess volume in a prefabricated sleeve for thigh amputees. No account is taken here of where the power transfers will take place in practice.

In order for a thigh stump to be able to assume an unforced position in the sleeve, without the sleeve's angle being regulated, the sleeve must initially have a very large volume (especially in the front part). This makes the sleeve very heavy after filling with foam and also cosmetically unacceptable.

The present invention, on the other hand, describes the adaptation of prostheses which includes the filling of an excess volume as well as the transfer of forces from the prosthesis to the body through the use of relief and load cushions. This enables the necessary individual considerations in a direct adaptation of prostheses to lower leg amputees. Different levels of amputation require the use of very different principles and methods for transferring forces from the prosthesis to the body part. It is important to clarify the differences between a thigh amputation and a leg amputation.

Due to significant soft tissue mass, a thigh amputation is very ill suited to take the vertical load represented by body weight and speed during walking. Because of this, all known classical principles for the transfer of vertical forces from the body to the thigh prosthesis are based on this force transfer not via the upper part of the thigh as described in FR 2.095.097, but via the lower part of the pelvis (seat joint). The thigh amputation thus absorbs little or no vertical force. For stabilization of the prosthesis, on the other hand, it takes up considerable horizontal forces. It is of great importance how these forces are distributed. In FR 2,095,097, these forces will be distributed equally over the entire amputation stump during the curing process. This is in conflict with the fact that the amputation stump consists of the area that definitely can withstand less stress than others.

A leg amputation has a composition of soft tissue, hard tissue (bone) and shape that makes it possible to transfer all forces from the prosthesis to the body through the amputation stump. However, it does not matter where on the stump these forces are transferred. The requirement for fit and for the correct distribution of load and relief areas is very large and requires individual considerations from case to case.

The present invention therefore relates to a method

for direct adaptation of leg prostheses where prefabricated calf shells (1) are used which are selected according to measurements taken of the user's stump (4) and healthy legs, which are adapted directly to the user's stump (4) by removing foam from the inner core (3) so that the user's stump (4) can be placed sufficiently far down into the calf shell (1), a two-component cold-hardening casting compound (11) for example polyurethane-based elastomer with a curing time of 60-180 min., preferably 10-20 min. is filled in the calf shell (1) cavity, the stump (4) with an outer insulating condom (9) is placed in the calf shell (1) and pressed down to the desired position, load is maintained to achieve total contact, then the user takes an optimal position which is held completely until the curing process is over, the stump (4) is pulled out of the prosthesis, the insulating condom is removed and finally the sleeve edges are cleaned and polished, characterized by first covering the pressure-exposed areas of the stump (4) with self-adhesive relief pads (8), after which the insulating condom (9) is pulled off on the stump (4), before this is placed in the calf shell (1), so that the casting compound, when it is filled in the cavity of the calf shell (1), comes into contact with the user's stump (4) and load pads (10) in such a pattern that the load forces from the calf shell (1) towards the amputation stump

(4) is transferred to the areas of the stump (4) that are pressure tolerant and thereby relieve pressure-exposed areas and that finally when optimal pressure distribution against the amputation stump (4) has been achieved, the load pads (10) are permanently glued to areas of hardened casting compound as follows that pressure against the amputation stump is given where this is tolerated by the horse.

During the first adjustment process, the user pulls on 1-10 stump socks (12), preferably 1-3 stump socks (12) on the stump (4), and that the load pads (10) are placed under the outermost stocking.

As indicated above, the casting compound used consists of a plastic material such as, for example, cold-hardening polyurethane-based elastomer.

Other thermosetting plastic systems or silicone-like substances that can harden at body temperature can also be used. The requirement for fixation time, moderate exothermic reaction, adhesion to the calf shell, mechanical strength and costs are decisive.

In the following, the invention will be described in more detail with reference to accompanying drawings where: Fig. 1 shows the right leg with knee strap, calf shell and foot part.

Fig. 2 shows amputation stump with relief cushions.

Fig. 2a, b, c and d respectively show the front (anterior), back (posterior), inside (medial) and outside (lateral). Fig. 3 shows amputation stump with relief cushions and

condom (front).

Fig. 4 shows a prosthetic sleeve with pressure pads and foam. Fig.4a,b,c and d show front (anterior), back (posterior), inside (medial) and outside (lateral), respectively.

The present invention therefore describes an adaptation based on direct technique, i.e. which can make the use of negative and positive plaster models redundant. The adaptation technique can be used for all types of prostheses. With the help of prefabricated components, a special jig/saw stand in which the user stands to achieve the correct position during the process and a unique casting compound, the prosthesis can be adapted directly to the user within about 1 hour. Based on average measurements taken by approx. 70 users, a number of sizes of calf shell are prefabricated in a suitable plastic material (fig 1). These consist of an outer weight-bearing shell 1 and an inner core 2 in a light rigid foam material. Core 2 is removable from ankle level upwards. The upper part 3 of the core 2 is adapted to each individual user by removing sufficient amounts of foam to make room for the amputation stump 4 in the upper part 5 of the calf shell 1. A foot 6 in durable rubber/polyurethane is glued to the lower part of the calf shell. This is selected from an assortment of a number of different foot sizes on the right and left.

Calf shell 1 and foot 6 are selected based on measurements taken of the user's stump 4 and healthy leg. Foam is removed from the inner core 2 so that the user's stump 4 can be placed sufficiently far down into the calf shell 1. The calf shell 1 now has an inner cavity 7 that corresponds to the volume of the calf stump 4 plus sufficient clearance all the way around. The height of the calf shell 1 is adapted to the user's healthy leg.

During the fitting, the amputation stump 4 is examined. Self-adhesive relief pads 8 are attached to the areas that are exposed to pressure (fig 2). A relief pad is placed at the bottom of an insulating condom 9 which is then pulled onto the amputation stump 4 (fig 3). The insulating condom 9 is inserted with a lubricant on the blunt side. A casting compound 11 is mixed well either in a suitable beaker or directly in the cavity of the calf shell. When the cast mass 11 is in the calf shell 1, the user places the amputation stump 4 in the prosthesis and slowly presses down to the desired position. An outer insulating condom 9 is pulled up over the user's knee to prevent spillage of casting compound 11. The user is then instructed to assume an optimal position and this position is held until the curing process is over. The amputation stump 4 is then pulled out of the prosthesis, the edges are cleaned and polished. Then the relief pads 8 and the insulating condom 9 are removed. 1-3 stump socks 12 are pulled on the amputation stump 4 and suitable pressure pads 10 are placed under the outer stump stocking 12 in the desired position (fig 4). The user then places stump 4 with stump socks 12 and cushions 10 in place in the prosthesis. Under load, a knee strap is placed and attached to the calf shell (fig 1). This anchors the prosthesis to the user's stump 4 with a strap and buckle around the thigh above the kneecap. The user can now try on the prosthesis and the foot part is currently only spot-glued. If fine-tuning of the alignment of the prosthesis is desired, the foot part 6 can be shifted in relation to the calf shell 1 before it is point-glued again, as the foot part 6 is somewhat oversized. When optimal alignment has been achieved, the foot part 6 is glued permanently and excess material is removed. When optimal pressure distribution in the prosthetic sleeve has been achieved, the load pads 10 are permanently glued to the inner walls of the prosthetic sleeve to apply pressure to the correct areas of the stump. The prosthesis is now finished and walkable.

An alternative to the above-mentioned adaptation technique is that the cotton stocking is replaced by a rubber/polyurethane stocking. The load pads are sized and glued to the outer surface of the stump stocking in a suitable position. This stump stocking with fitted pressure pads is used as part of the prosthesis. A thin stump stocking, for example in nylon, is pulled over the rubber/polyurethane stump stocking before the stump is placed in the prosthesis.

The advantages of the present method for adapting prostheses are that it will now be unnecessary to go the route of a cast of the user's stump. This means that you also do not have to model a positive model of the user's stump, as well as casting individual sleeves. The user therefore does not have to wait between measurement and final fitting. There will also be very large time savings because it is possible to carry out an adaptation, including adjustments, in about 1 hour. The need for tools and materials is also minimal. Standardization entails a dramatic reduction in production costs. The fitting technique further reduces variations in fitting quality depending on the skill of the professional.

Claims (2)

1. Procedure for direct fitting of leg prostheses where prefabricated leg shells (1) are used which are selected according to measurements taken of the user's stump (4) and healthy legs, which are fitted directly to the user's stump (4) by removing foam from the inner core (3) so that the user's stump (4) can be placed sufficiently far down into the calf shell (1), a two-component cold-hardening casting compound (11) for example polyurethane-based elastomer with a curing time of 60-180 min. , preferably 10-20 min. is filled in the calf shell (1) cavity, the stump (4) with an outer insulating condom (9) is placed in the calf shell (1) and pressed down to the desired position, load is maintained to achieve total contact, then the user takes an optimal position which is held until the curing process is over, the stump (4) is pulled out of the prosthesis, the insulating condom is removed and finally the sleeve edges are cleaned and polished, characterized by first covering the pressure-exposed areas of the stump (4) with self-adhesive relief pads (8), after which the insulating condom (9) is pulled over the stump (4), before this is placed in the calf shell (1), so that the casting mass, when it is filled in the cavity of the calf shell (1), comes into contact with the user's stump (4) and load pads (10) in such a pattern that the load forces from the calf shell (1) towards the amputation stump (4) is transferred to the areas of the stump (4) which are pressure tolerant and which thereby relieve pressure-exposed areas and that eventually optimal pressure distribution towards the amputation stump is reached mp (4) is achieved, the load pads (10) are permanently glued to areas of hardened casting compound so that pressure against the amputation stump is applied where this is best tolerated. 2. Method according to claim 1, characterized in that during the first adaptation process the user pulls 1-10 stubby socks (12), preferably 1-3 stubby socks (12) on the stump (4), and that the load pads (10) are placed under the outermost sock.