Method of providing prosthetic sockets and temporary prosthetic socket

A method of providing prosthetic sockets (30) for a patient's residual limb (21). While the residual limb (21) is swollen with post-trauma edema (22-25), a resin-impregnated temporary shell forming sock (52) is placed onto the edema-swollen residual limb (21). The resin is activated to cause it to harden into a temporary prosthetic shell (30), but prior to hardening of the resin, the sock (52) is conformed to the patient's edema-swollen limb (21). After swelling of the residual limb (21) has substantially dissipated, a permanent prosthetic socket conforming to the patient's unswollen residual limb (22b-25c) is formed and the temporary prosthetic socket (30) is replaced with the permanent prosthetic socket. A temporary prosthetic socket (30) is also disclosed in which a resin-hardened temporary sock (52) is bonded to a socket liner (49) over a prosthetic attachment assembly (48) in a configuration substantially conforming to the patient's residual limb (21) when in an edema-swollen (22-25) condition.

TECHNICAL FIELD 
The present invention relates to methods and apparatus for the formation of 
prosthetic devices, and more particularly, relates to the formation of 
prosthetic sockets which are used to support and connect prosthetic 
devices to the residual limbs of patients. 
BACKGROUND ART 
Prosthetic devices which are used to replace missing limbs are typically 
mounted by a socket to the residual limb or amputation stump of a patient. 
The sockets are most preferably custom made to conform to the 
configuration of the residual limb so as to be capable of supporting 
weight, in the case of a leg, or loading forces, in the case of an arm. 
It has been found that it is highly desirable for patients to begin use of 
prosthetic devices as soon as possible after the required or accidental 
amputation of a limb. If a patient can be fitted with a prosthetic device 
soon after limb amputation, the prognosis for long term, effective use of 
the prosthetic is much higher. Additionally, the adverse psychological 
impact of an amputation can most effectively be minimized by rapid 
adaptation of the patient to a prosthetic in order to reinforce the 
patient's realization that he or she will be able to be self-sufficient. 
While it is generally accepted that it is desirable to have patients begin 
using prosthetic devices soon after a limb amputation, there are serious 
practical difficulties in implementing such a procedure. Immediately after 
limb amputation, whether such amputation was a result of a planned 
surgical protocol or traumatic accidental occurrence, the residual limb or 
amputation stump will experience considerable post-operative or 
post-trauma edema or swelling. Such edema, of course, is also accompanied 
with considerable pain and discomfort. Even after the pain and discomfort 
subside to acceptable levels, the edema will continue for two to three 
months until the body gradually absorbs the fluids from the residual limb. 
Since limb prosthetic devices are most typically mounted to a patient by a 
socket which is customized to the configuration of the patient's residual 
limb, formation of a prosthetic socket within a few weeks of limb 
amputation results in a socket which conforms to the configuration of the 
swollen or edema-affected residual limb. 
One approach to forming prosthetic sockets, for example, is to form a 
plaster of Paris or other cast of the residual limb. The cast is removed 
from the limb and used in the laboratory as a negative. A positive plaster 
of Paris cast can be made from the negative and then a residual limb 
prosthetic socket built in the laboratory over the positive. Typical of 
prior art using this general approach are the systems described in U.S. 
Pat. Nos. 1,351,789; 1,907,511; 4,307,056; 4,473,421; 5,376,127; 
5,376,129; 5,376,132; 5,405,405; and 5,503,543. These patents describe 
techniques of using a negative cast made from the residual limb as a basis 
for creating a customized prosthetic socket. Common to these various 
systems is the labor-intensive reality of making negatives, positives and 
thereafter forming a prosthetic socket on the positive. Accordingly, 
prosthetic sockets formed using such conventional techniques have been 
relatively expensive. 
More recently, prosthetic systems have been devised which eliminate the 
need for formation of a negative of the residual limb. Rather than taking 
the negative to a laboratory, forming a positive and thereafter forming 
the socket, these techniques employ casting the socket in place directly 
on the patient's residual limb. Prior art showing this type of system 
includes U.S. Pat. Nos. 4,193,395; 4,923,474; 5,258,036; and 5,387,245. 
One cast-in-place system is now commercially available in the United States 
under the ICEX trademark through Ossur USA, Inc. of Carpeteria, Calif. The 
Ossur USA system is described in detail in a manual entitled "IceCast 
Compact Technical Manual." Even such in-situ or cast-in-place systems, 
however, are very expensive. 
The materials in the Ossur USA ICEX system, for example, will cost over 
$600, primarily because a carbon fiber sock is used to make a permanent (3 
to 5 years) prosthetic socket. 
The major problem which has occurred in prior art prosthetic socket casting 
procedures has been that, if the procedure is performed early, the 
resulting socket will reflect the edema or swelling in the residual limb. 
As the patient's body absorbs the edema, however, the swelling will 
subside, resulting in a poor fit between the prosthetic socket and the 
residual limb. Patients attempt to accommodate this edema absorption by 
adding additional socks over their residual limb before placing the limb 
in the prosthetic socket. The additional socks are used to fill the space 
left in the socket as a result of limb shrinking due to edema absorption. 
Since the edema will not generally be uniform and socks are uniform, the 
use of this technique is only partially satisfactory. 
Two other approaches are taken to accommodate residual limb shrinkage. The 
first is to simply recast the socket, that is, to form a second prosthetic 
socket after the edema has dissipated, for example in two to three months. 
The second is to wait two to three months before forming the prosthetic 
socket. Both of these approaches have substantial disadvantages. The first 
is costly, while the second is undesirable in terms of the likelihood of 
the patient's successful adaptation to the prosthetic and psychological 
problems attendant to waiting. 
Accordingly, it is an object of the present invention to provide a method 
for forming prosthetic sockets for patients' residual limbs which can be 
used during the post-operative or post-trauma period in which the 
patient's residual limb is swollen with edema. 
Another object of the present invention is to provide a method and a 
temporary prosthetic socket which provides better conformance to the 
patient's residual limb. 
Still a further object of the present invention is to provide a method and 
apparatus for forming prosthetic sockets which is relatively low in cost, 
minimizes pain and discomfort to the patient, and can be used with 
patients which have very substantial residual limb swelling. 
The present invention has other objects and features of advantage which 
will become apparent from, or are set forth in more detail in, the 
accompanying drawings and the following Best Mode of Carrying Out the 
Invention. 
DISCLOSURE OF INVENTION 
The method of providing prosthetic sockets for a patient's residual limb of 
the present invention is comprised, briefly, of the steps of: while the 
residual limb is swollen with post-trauma edema, placing a resin 
impregnated, temporary shell-forming sock onto the edema-swollen residual 
limb; activating the resin in the sock to cause the resin and sock to 
harden into a temporary prosthetic socket; prior to hardening of the 
resin, conforming the socket to the patient's edema-swollen residual limb, 
preferably without applying sufficient pressure to the sock to 
substantially alter the configuration of the edema-swollen residual limb; 
after swelling in the residual limb has substantially dissipated, forming 
a permanent prosthetic socket to the patient's unswollen residual limb; 
and replacing the temporary prosthetic socket with the permanent 
prosthetic socket. In the preferred method a second temporary prosthetic 
socket is formed after edema swelling has reduced significantly from the 
level at which the first temporary prosthetic socket was formed. 
In another aspect, a temporary prosthetic socket is provided which is 
comprised, briefly, of a socket liner formed to mount over a portion of 
the patient's residual limb; a prosthetic attachment assembly; and a 
resin-hardened fabric sock mounted over and bonded to the liner and 
secured to the prosthetic attachment assembly. The socket liner and 
resin-hardened sock substantially conform in configuration to the 
patient's residual limb when in an edema-swollen but unconstrained 
condition, and most preferably a lofted glass yarn sock with elastomeric 
fibers is employed.

BEST MODE OF CARRYING OUT THE INVENTION 
The problems associated with making prosthetic sockets for residual limbs 
during the post-trauma period in which the limb experiences substantial 
swelling and edema, can be understood by reference to FIGS. 1A through 1D. 
In FIG. 1A a residual limb or amputation stump, generally designated 21, 
is shown, which in this case is a leg that has been amputated below the 
knee. It will be understood that the present method and apparatus are 
equally applicable to above-knee amputations and amputation to arms. In 
FIG. 1A residual limb 21 is shown soon after amputation, and includes 
edema-swollen areas 22, 23, 24 and 25. Notwithstanding the presence of 
such edema, it is highly desirable, as above set forth, to be able to have 
the patient begin walking with a prosthetic device. This requires that a 
residual limb's prosthetic socket be formed for attachment of a pylon and 
prosthetic foot assembly. 
The prosthetic socket which is cast based upon residual limb 21, however, 
will conform to the residual limb including edema-swollen areas 22-25. 
Such a socket would be entirely suitable for use while the edema is still 
present in the residual limb, but as edema dissipates or is absorbed, the 
socket will no longer properly fit and support residual limb 21. 
As can be seen from FIG. 1B residual limb 21 has experienced some 
shrinking. Thus, edema-swollen area 22 has reduced to area 22a, while the 
edema at 23 has dissipated to that shown at area 23a. The edema at area 24 
has been absorbed to the volume shown at 24a, but the edema at area 25 
remains substantially unchanged. Thus, in areas with edema, the absorption 
is not uniform and all areas of residual stump 21 do not include edema. 
In FIG. 1C further edema absorption is shown at areas 22b, 23b and 25b. The 
final, unswollen configuration of residual limb 21 is shown in solid lines 
in FIG. 1D. Thus, areas 22c, 23c, 24c and 25c define the amputation stump 
in its final configuration. As will be seen from FIG. 1D the difference in 
configuration of residual limb 21 can be significant, although as 
schematically shown in FIG. 1B, 1C and 1D, the changes have been made 
somewhat larger in scale for purposes of illustration. 
As will be appreciated, therefore, a prosthetic socket made for residual 
limb 21 in the condition of edema shown in FIG. 1A will not fit well for 
residual limb 21 as shown in FIG. 1D Depending upon the nature of the 
trauma and reason for amputation, the change from the immediate 
post-trauma event of FIG. 1A to the final unswollen residual limb 
condition of FIG. 1D can range from two to four months, and possibly 
longer. During this time, however, it is highly desirable for the patient 
to be using a limb prosthetic device. The method of the present invention 
enables the patient to have the advantages of a prosthetic device early 
after limb amputation. 
In the method of the present invention, at least one, and often a 
plurality, of temporary prosthetic sockets are formed using relatively 
low-cost materials which are suitable for temporary use as a prosthetic 
socket. Moreover, the socket preferably is formed on the edema-swollen 
residual limb without applying sufficient pressure to the socket-forming 
materials so as to significantly alter the configuration of the 
edema-swollen residual limb. The resulting socket is then used for a 
relatively short period of time, for example, one month, and another 
prosthetic socket is made of the residual limb under a condition of 
reduced edema. 
Referring to FIG. 2, therefore, a low-cost temporary prosthetic socket is 
shown as it is being made over the residual limb of FIG. 1B, including 
edema-swollen areas 22a, 23a, 24a and 25. After some period of time in 
which some edema has been absorbed, a prosthetic socket (not shown) made 
over the limb of FIG. 1A is discarded and a new casting is made of the 
residual limb, for example, when it is the condition as shown in FIG. 1B 
and FIG. 2. This temporary prosthetic socket, generally designated 30, can 
then be discarded and the process repeated after another period of time 
for the limb of FIG. 1C. Finally, the last temporary prosthetic socket is 
discarded and a final permanent prosthetic socket is formed of the limb of 
FIG. 1D, in its unswollen condition. 
As will be appreciated, for some patients, only one temporary prosthetic 
socket needs to be formed before a final prosthetic socket is made from 
the unswollen limb of FIG. 1D. In other patients, two or even three 
temporary prosthetic sockets are made over the residual limb as the 
swelling of the limb recedes over time. Because none of the temporary 
sockets will be used for more than a month or two, the socket forming 
materials can be relatively low-cost and do not need to have the same 
structural strength and durability as would be required for a permanent 
prosthetic socket. Obviously, even "permanent" prosthetic sockets may have 
to be replaced after some period of time, for example, 3 to 5 years. 
In the method of the present invention, it is preferred that the temporary 
prosthetic sockets be formed by casting the socket in place on the patient 
using a resin-impregnated sock that can set up or harden in a relatively 
short period of time, for example, 10 to 20 minutes. While broadly known 
in such prior art systems as the Ossur USA, Inc. system, in the method of 
the present invention, a temporary low-cost casting sock is employed. In 
the Ossur USA, Inc. system, a carbon fiber casting sock is used to form 
the socket on the residual stump because the socket is intended to be 
permanent or very long lasting. 
In the method of the present invention, the casting sock which may be used 
does not have to last long. Thus, a lofted glass yarn sock with 
elastomeric fibers can be employed instead of a carbon fiber sock. This 
lofted glass yarn material is described in more detail in our U.S. Pat. 
No. 5,228,164, which is incorporated herein by reference, except that the 
socket forming sock of the present invention employs double the yarn 
density and thickness and is a ribbed knit, tuck stitched sock having a 
width of 5 inches. A corresponding increase in resin must be used relative 
to the sock of U.S. Pat. No. 5,228,164 in light of the greater sock yarn 
weight. This sock material and water activatable resin is commercially 
available through Minnesota Mining and Manufacturing of St. Paul Minn. The 
casting sock material of our patent had previously been used in preparing 
lasts for custom footwear, but in the present method and apparatus, it 
provides a low-cost system for the formation of a temporary prosthetic 
socket. 
The prosthetic socket casting material of the present invention costs about 
$125, as opposed to the $600 cost for carbon fiber materials of the Ossur 
USA, Inc. system. The resultant socket is not as sturdy or durable as the 
prosthetic socket constructed using the Ossur USA system, but it is 
entirely satisfactory for use as a temporary prosthetic socket having a 
life on the order of one or two months. 
While the present temporary prosthetic sockets can be formed by other 
techniques, casting them in place on the residual limb is advantageous in 
terms of conformance and in terms of keeping the cost low. The present 
method for casting the prosthetic socket in place will be briefly 
described, and it is based upon the process which is used by Ossur USA, 
Inc. in forming a permanent prosthetic socket, with three important 
changes. The first change is that the resin-impregnated sock material is a 
relatively low-cost lofted glass yarn with elastomeric fibers. The second 
change is that no special pylon attachment device needs to be secured to 
the casting sock, as is done with the Ossur carbon fiber sock. The third 
important difference is that conformance of the yarn to the residual limb 
need not be accomplished using a bladder and pump system. 
The first step in casting a prosthetic socket in place on a residual limb 
is to mount a silicone liner 41 on the limb. Liner 41 includes a connector 
assembly or threaded plastic socket 42 at the closed end thereof, which is 
well known in the art and is used in the Ossur USA, Inc. ICEX system. The 
technician can then place padding over bony prominences, such as pads 43 
and patella pad 44. Patella pad 44 is used to provide a channel permitting 
removal of the socket from the residual limb over the patella after 
hardening of the socket. The pads 43 and 44 can be held in place by a 
plastic wrap layer 46 so that the padding will not be permanently bound to 
the resulting socket. 
A spacer disk 47 can be mounted over a post 51 threaded into attachment 
disk 42 provided on the silicone liner closed end. Next, a knit fabric 
liner 49 is rolled onto the residual limb and over the various pads, 
plastic wrap and spacer 47. Liner 49 has an opening in the end to allow 
passage of threaded post 51 therethrough. In the Ossur system, post 51 
also is used to attach a bladder and pump, but they are not used in the 
present system. Pin 51 merely aligns and secures spacer 47 to the 
attachment disk 42 and the attachment assembly for the prosthetic pylon on 
the end of the silicone liner. 
Next, an attachment coupling assembly 48 is mounted on post 51 over liner 
49. The attachment device 48 typically will have a plurality of threaded 
bores which can receive fasteners that can be used to couple a prosthetic 
connector for the prosthetic pylon to the end of the resulting prosthetic 
socket. During casting, the threaded bores have screws in them so as to 
prevent the entry of resin into the bores during the casting procedure. 
Finally, an elastic resin-impregnated lofted glass yarn knit sock 52 is 
soaked in water to commence activation of the water-activated resin. Once 
sock 52 is thoroughly soaked, it is rolled onto the residual limb over 
attachment coupling assembly 48. Sock 52 also has an opening to receive 
threaded pin 51, and additional water can be sprayed on sock 52 after it 
is unrolled onto limb 21 to insure activation. Silicone liner 41, knit 
fabric sock 49 and resin-impregnated fabric sock 52 preferably are all at 
least slightly resilient. Thus, they tend to conform to the configuration 
of residual limb 21, including edema-swollen areas 22a, 23a, 24a and 25. 
However, instead of using a bladder and pump to apply 70 to 100 
millimeters of mercury pressure, as is done in the Ossur USA system, in 
the present method, the prosthetic technician merely manually smooths and 
eases the sock over the residual limb and its swollen areas. Thereafter, 
plastic wrap can be used to cover the sock and a resilient strip of 
material, such as a resilient bandage (ACE Bandage, for example) can be 
wrapped around the sock to urge the sock fibers together and to conform 
the sock to the residual limb, including the edema-swollen areas, without 
altering or changing the limb configuration in a manner which would 
produce pressure concentrations once the prosthetic is hardened. In 
formation of permanent prosthetic sockets, higher bladder-induce pressures 
insure that the carbon fibers are urged into closer proximity for greater 
strength and durability, but in a temporary prosthesis, that is not 
required, but can be used if desired. 
About 10 to 20 minutes is required for a water-activated resin to harden 
sufficiently to enable a prosthetic socket or shell to be formed. Once 
hardened, the resilient wraps and plastic can be removed from the outside 
of the socket, post 51 can be removed, and the prosthetic shell can be 
pulled off of silicone liner 41. The resin-hardened sock material 52 at 
the area of post 51 can be ground down to expose the attachment assembly 
48, and the temporary fasteners in assembly 48 can be removed so that the 
prosthetic pylon can be attached to the socket by attachment assembly 48. 
The resin in the casting sock 52 will have bound to the socket liner 
material 49 and will mechanically trap the pylon attachment device 48 in 
the end of the socket. As can be seen from FIG. 2, attachment member 48 
also can have ridges in the sides thereof to assist in locking with 
hardened sock 52. Once the shell has been removed, the silicone liner 41 
can also be removed from residual stump 21. 
The result is a cast, temporary prosthetic socket which substantially 
conforms in configuration to the patient's residual limb when in an 
edema-swollen condition. As will be seen from FIG. 2, such a socket will 
conform to the edema-swollen areas 22a, 23a, 24a and 25, and will be 
usable until the swelling has dissipated or been absorbed. The eventual 
residual limb configuration is shown at phantom lines 22c through 25c, and 
when swelling has substantially disappeared, a permanent prosthetic socket 
can be formed on this final configuration of the residual limb using, for 
example, the process and apparatus of the Ossur USA, Inc. system. 
The method and apparatus of the present invention allow patients to begin 
using prosthetic devices well before edema in their residual limb has been 
absorbed. The result is more effective use of their prosthetic device, as 
well as greater patient confidence and mental well-being.