At Precision, most BK prosthetics are in two different categories. The popular “pin lock” liner system that has been around since the late 80s, or elevated vacuum sockets which came out about fifteen years later. Although we can still make the old style socket that uses stump socks for the residual limb protection and fit, requests for these are rare.
The pin locking liner system offers better suspension and residual limb protection, especially when used with our “in-house” custom fabricated anatomically correct silicone locking liners. This design is our standard of excellence, and Precision Prosthetics, Inc. of Memphis is one of the few places on this planet that offers this technology. While most prosthetists view this design of “homemade” liner to be too much trouble, we have embraced this concept, since its beginning in 1988, and turned it into a system that only amputees treated at Precision get the benefit from.
First of all and most important is the absence of sweat/perspiration inside the socket against the skin of the residual limb. When properly fitted, this liner offers a dryer environment for the residual limb, all day, no matter the ambient temperature. When the liner is removed at the end of the day, no sweat will pour out on the floor, as seen with prefabricated/off-the-shelf liners.
The second most important feature is better socket stabilization to the residual limb, due to less stretching in the bottom third of the liner, when it must suspend the prosthesis during swing phase of the gait cycle. Our liners do not stretch, which keeps the prosthesis held onto the residual limb more securely.
The inherent stability and toughness of our liners make them the most durable liner an amputee can use. Even though we recommend that a person get new replacement liners within 6 months to a year, we have seen people come in that have been wearing just one liner for a few years!
These liners have been a real plus to our growth and continued success. Most people that have had to leave our care due to insurance reasons cannot wait to get back to get our liners back on.
Vacuum sockets and elevated vacuum sockets represent a very popular alternative to our standard liner system mentioned above. The invention of a vacuum elevating pump system (Carl Casper’s of St. Cloud, Minnesota) offers amputees a socket system with suspension that is second to none. The removal of atmospheric pressure through the introduction of vacuum in a prosthesis, maintains the socket so securely to the amputee’s residual limb, that the prosthesis feels like it’s “part of them” due to the elevated vacuum. The pumps that create the vacuum are of different designs. Initially and still available are the manual style pumps. These work by drawing a small surge of vacuum, which elevates up, through the use of a one way valve. After a few steps, the vacuum inside the socket has elevated to its most functional level and stays that way until extended sitting has occurred.
The electric pump, which is usually incorporated in the endoskeletal structure of the prosthesis, keeps the pre-set elevated vacuum setting continuously, seated or walking, until the pump is turned off. These require daily charging of the internal battery. The advantages of the elevated vacuum socket systems are less piston action/movement of the residual limb inside the socket during prosthesis usage. This is very important when the residual limb has deep/inward shaped scars, especially ones that have adhered to the bone(s) usually caused by extended/slow healing of the residual limb. This type socket design is totally dependent on a good, intact, non-leaking outer suspension sleeve and if the seal is lost, the sleeve needs to be immediately replaced. A back-up sleeve is required. Finally, the most important component of this system is the liner. It is custom made from a cast taken of the amputee’s residual limb. This ensures that the liner will be anatomically correct to exactly match the contours of a badly scarred residual limb, thus eliminating problem causing air pockets inside the liner. The liner is fabricated out of a polyurethane material that is “skin friendly” and has a unique characteristic of being able to “flow” in areas of extra high pressure. This anatomically relieves extra prominent bones or scars on the residual limb.
Most AK/Transfemoral patients get limbs that give them back the opportunity to go down ramps and stairs, as they did, before amputation. Our philosophy is that every prosthetic knee joint that walks out of our front door, should give the amputee a controlled hydraulic stance support that mimics the function of their natural knee, while going down ramps and stairs, foot over foot. Going up the stairs will still be one at a time, leading with the natural leg. A few amputees can walk up foot over foot, but that is rare. The prosthetic knees that provide this natural descent can be, but do not have to be, microprocessor/ computer controlled. We supply “non-electric” knees that offer this ability. The socket design offers a virtually sweat-proof anatomically correct inner socket liner (our specialty) that provides good, secure all day suspension, that remains comfortable until you take it off at bedtime (typical day 6 AM- midnight). The socket liner has features that eliminate unwanted “twisting” of the prosthesis on the residual limb, thus maintaining a good gait, control, and comfort all day. Another commonly used option is the “cross leg” rotator. This feature gives the user the ability to bring the foot up close to make changing a shoe or clothes easier/possible. It also allows getting the prosthetic foot “back out of the way” in certain situations like driving a car or sitting where foot space is limited, like in an event arena, etc. This seems to be one of the greatest options an AK amputee can experience. They love them.
We have many AK/Transfemoral amputees that have returned to riding motorcycles due to their increased comfort and control with their Precision Prosthetics! One of our patients, in particular, that lives in California has two prosthetic legs (from a war injury) and he has ridden a Harley Davidson motorcycle 83,000 miles around the world to prove to amputees that they do not have to give up on life after amputations! Look up “Davebarr1972.com“ to learn about this amazing and inspirational man.
We can make any design AK prosthesis including pull-in suction (skin to socket), waist belt suspension, leather sockets, or any other “favorite” design an amputee may have had good success with in the past.