Putting Advanced Computer Technology to Work for You

What makes the "The Center Ring" CAD System so good?

• Multiple camera-like lenses are positioned around the Ring to instantly visualize all sides of the residual limb simultaneously. In only 2 seconds the computer has captured the detailed shape and measurements of your limb!!!
• There is no chance for error due to inadvertent movement of the residual limb, prosthetist’s hand, or the equipment such as there is with "Spray Paint Style" CAD systems.
• There is no chance for error caused by interference by nearby metal or electronic equipment such as in "Transducer Dependent" CAD systems.
• "The Center Ring" digitizes and captures the shape of YOUR OWN ACTUAL RESIDUAL LIMB, unlike "Snapshot" style CAD systems which take a snapshot from only the front and one side of your limb, and then match it to the "closest" socket shape in a memory bank of socket shapes.
• With "The Center Ring" the model captured and displayed on screen is a perfect copy of YOUR residual limb, unlike "Closest Match" style CAD systems which create a shape "close to" yours by matching "measurements" to a memory bank of socket shapes.

The term CAD/CAM stands for "Computer Aided Design / Computer Aided Manufacture" and means that we use special computers with advanced software to help us create your artificial limb. First a device scans your residual limb and sends that information to the computer. The computer puts all the measurements and three-dimensional images together to "recreate" your residual limb as a "virtual model" on the monitor screen. Your prosthetist can then tell the computer how to alter this basic model to make it more comfortable and supportive for you to use.

This new information (the modified "virtual model") is sent by the computer to a large carving machine (a kind of complicated lathe) which then carves down a solid block of plastic until it is a solid three dimensional replica of the model created on the computer by your prosthetist. At this point we will use the solid model to make a clear plastic Test Socket. We will attach the Test Socket to a leg for you to walk on in the office during your Fitting. During the Fitting, your prosthetist will make adjustments or changes to the socket to optimize your comfort and support, as well as adjust the rest of the prosthesis to optimize your balance, stability, and ability to walk with the prosthesis.

Prior to the availability of the CAD/CAM system (as well as in some instances today) the prosthetist would have to first obtain the "mold" of your residual limb by wrapping it in Plaster of Paris strips. Then we would have to fill that plaster "mold" with liquid plaster. When the liquid plaster had hardened, we would strip away the original "mold" leaving a solid plaster "model". At this point, the solid plaster model is modified by the practitioner by hand using rasps, knives, a special spatula to apply more plaster, and a sanding screen. A clear plastic Test Socket would be made over this modified model. Both processes result in a Test Socket to be used in a Fitting. The CAD/CAM is a faster method, it is less messy and easier on the patient, and the measurements are very accurate.

Finally, while the solid (real) three dimensional models must be destroyed in the fabrication process, the "virtual model" can be saved in the computer indefinitely.

Compas^TM is a patent pending breakthrough in easy-to-use, sophisticated instrumentation for clinical prosthetists. This unique system of electronic hardware embedded into the prosthesis combines with computer software to harness the power of objective kinetic gait data to ensure optimal outcomes in everyday prosthesis fitting.

Alignment has been recognized as a key element for optimal prosthesis function for many decades. Prosthesis alignment historically, however, has been a learned art rather than a measurable science. Compas^TM enables the prosthetist to use real-time gait analysis data to optimize prosthesis alignment for each individual.

The Compas^TM Gait Analyst software automatically extracts and interprets the relevant information from a series of steps and instantly provides prosthesis-specific gait analysis based on the kinetic measurements. Feedback to the prosthetist is presented in concise and easy to understand language, including straightforward recommendations for adjusting the pyramid screws to optimize sagittal and coronal plane alignment.

Compas^TM hardware and software work together automatically so that clinicians can easily and intuitively harness the power of our computerized alignment interpretation. This system is designed for everyday use by prosthetists without need for supporting engineers or specialized staff. The Smart Pyramid^TM with its embedded sensors is integrated into the prosthesis. The Compas^TM system uses Bluetooth to communicate wirelessly with automatic gait analysis software on a PC or PDA.

A databsae approach was used, resulting in collection of controlled data from perturbations of well-aligned prostheses, to determine statistically how Socket Reaction Forces are related to optimal alignment. An advanced computer model predicts whether and how a prosthesis is misaligned by measuring the Socket Reaction Forces while walking.

The Compas^TM system Smart Pyramid^TM adaptor attaches to any socket using the familiar Euro four-hole pattern or via an integrated tube clamp. To enable gait analysis, the CompasTM Master unit clicks onto the pyramid--providing power, microprocessor control, motion sensing, a laser guide and communications with your PC or PDA. The Compas^TM system continuously measures dynamic forces and balance while the patient is standing or walking, indoors or outside, on any terrain.

Compas^TM is based on direct measurement of the Socket Reaction Forces, using a sophisticated electronic instrument integrated within a Smart Pyramid^TM adaptor attached near the base of the socket. Our extensive research has measured precisely how these forces change with alignment alterations.

Compas^TM shows the prosthetist precisely what is happening biochemically, eliminating the need for time-consuming iterative changes to refine alignment based on assumptions. Amputees see and feel the results throughout the alignment process, and gain confidence from the objective information at the prosthetist's fingertips. Incorporating the Compas^TM Smart Pyramid^TM into the prosthesis saves time during the initial alignment and later through decreased need for adjustment.
To learn more, go to www.orthocareinnovations.com
1-800-672-1710

It is now possible to design custom get liners on-site using the Prosthetic Care Ring CAD System. This is very useful for those clients who have scars, skin grafts, prominent bones, unusual shapes, or deep clefts on their residual limbs. It is also a good tool for persons who have not been successful with other liners. Design Liners can be made with a connection for a Pin-Locking style prosthesis, or can be made as a cushioning liner for other styles.

First, the Ring quickly captures the shapes and contours of the residual limb with extreme accuracy. Next, the computer system makes it possible for the practitioner to sit right there beside you while determining how much gel thickness is needed in each spot, where special reliefs are necessary, and where the gel should be made thin, such as behind the knee or over the kneecap and thigh.

No other methods of customizing liners are so versatile in allowing infinite variations in gel thickness, relief pockets, or filling deep creases.

Not only is the Design Liner system a great way to create a custom molded gel liner, but, once in the computer system, duplicates are easy to obtain. And, later, if your limb size or shape changes, a "new" detailed Design Liner can be created for you just as simply.

Sense of Feeling

Many users of prosthetic arms and legs would like to be able to have "feeling" (sense of touch) in the artificial hand or foot. A number of research projects are looking into this subject. There have been attempts to translate, for instance, pressures along the sole of the foot into spots of vibration against the residual limb, and to try and transmit a sense of temperature from an artificial hand to the skin of the user. So far the results have been disappointing. Most users of lower limb prostheses can already tell when they have their weight on the heel of the foot and when it is on the toe of the foot by means of direct proprioception (feedback from limb position and socket pressures). It has been less than useful to feel a vague battery powered buzz at spots over the shin and calf. The sense of temperature has also not become a practical or useful technology so far. In addition, the systems which have been tried have been plagued with problems such as difficulty of use, inappropriate sensations, abnormal vibrations meant to simulate feelings of "pressure" or "warmth", breakage of the tiny wiring, shorts in the wiring from moisture, and shifting of transmitters away from skin contact as muscles move around. Even so, more work is being done at centers around the world, and we hope that someday prosthetic users will be able to benefit from a built-in sense of feeling.

Electronic Hands

Much research is being done to improve materials and technology in O&P. Some of the most exciting appears in the area of Upper limb prosthetics. Currently, myoelectric control is the best form of neuromuscular control of electronic hands, but is restricted to signaling the hand as a whole to "open" or "close", and determining how fast or how powerful it happens. Research is now looking at ways to utilize EMG Pattern Recognition to allow the user to signal individual finger motions (such as when using a keyboard) which has the potential to greatly expand the functional movements of electronic hands.

Example A: Shape Memory Effect
Shape Memory Effect (SME) is based on the fact that different metallic alloys demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. The key is to develop a way to control the temperature of various parts of the hand in a way that allow it to change quickly and purposefully.

Example B: Residual Kinetic Imaging
Residual Kinetic Imaging uses electric impulses in the arm from "phantom limb" movement. The user’s original motor pathways are used to control robotic hands without relearning how to use their hands. At this time a prototype is being developed to allow individual control of at least three of the robotic fingers by using their original nerve pathways.

Example C: Automatic Grip
The Automatic Grip hand has a small computer in it and uses low level signals generated by the user flexing muscles in the forearm and translating them into action. The hand can follow three basic instructions: open, close, and grip. Sensors inside of the hand decide what grip "shape" to take as well as how hard to squeeze.

Example D: Electromyogram Control (EMG)
EMG’s are the electric potentials measured on the skin surface when muscles contract. Researchers are testing ways to read and harness the EMG signals to control an artificial hand by presuming the user’s intentions.

Researchers are also working on projects to develop smaller and more efficient batteries, materials that better mimic the texture of actual skin, and a means of performing remote adjustments via the Internet.

Direct Attachment

Osseointegration
Osseointegration is the permanent skeletal attachment of a prosthesis, or of a hub to which the prosthesis would attach. It could be used for either arm or leg prostheses. A bolt-like insert is implanted into the bone at the end of the residual limb. The bone grows around the implant for a strong bond. Then the prosthesis can be attached in a way that allows the pressures during use to transmit directly to the skeletal bone instead of to the muscles and soft tissues as happens today.

While there are many benefits to this procedure, there are still many issues to be worked out. First, additional surgeries are required to implant the insert, and later to expose the end of the insert once the bone has healed around it. Second, the healing process is much longer and the time until the patient can walk on a prosthesis is significantly delayed. Finally, the procedure has led to failures when infections developed where the implant extends from the bone end through the skin to the outside, and when the high pressures and leverage on the implant have caused the bone to crack. Because of these limitations, this procedure is not performed in the US. Where it is performed it is considered experimental and only younger unilateral amputees who can't be successfully fitted by conventional means are considered. In addition, they can't have a history of infection, they must have a sound bone, they cannot be smokers, and they cannot have a systemic disease such as diabetes or peripheral vascular disease.

Cineplasty
Cineplasty is actually an old technique from before the First World War that is having a revival in some research projects. In Cineplasty, the surgeon isolates a "loop" of muscle on the chest or arm, and covers it with skin. When healed an arm prosthesis can be operated by contracting the muscle loop to which a prosthetic device is attached by cable. In the past, it was difficult to produce sufficient force to operate conventional body powered arms. With today’s electronic hands, less force is needed, and so more potential exists for success. More research is needed to make this a useful technique.

Suction sockets have long been used to increase the suspension of the prosthetic socket to the limb during swing phase of the gait cycle. Vacuum sockets go one step further by not just sealing the socket so there is no exchange of air, there is an added component that actively evacuates the air from the socket system. This creates negative atmospheric pressure within the socket which increases the “holding power” of the socket to the limb. Not only does this suspend better with virtually no pistoning within the socket, but there are more advantages as well. One of these advantages is the control of volume fluctuation of the limb. No more adding socks to tighten the fit throughout the day! Another advantage is the reports of less perspiration in the socket. This helps keep the skin of the limb dry and comfortable during the day. With virtually no pistoning, no adding of socks during the day, and healthier, dryer skin, you can see why it is a popular choice for amputees of all levels.

Suction sockets have been around for a number of years now and are an alternative to belts and/or straps to hold the prosthesis to the limb during swing phase in the gait cycle. Suction sockets can fit right against the skin or use some type of gel liner that is put on the limb first before entering the socket. The concept of suction suspension is to not let any air into the socket once the limb is in place inside the socket. By either fitting the socket snug against the skin or by the use of a suspension sleeve to seal off the top of the socket, the socket uses atmospheric pressure to suspend the socket to the limb much like lifting fluid out of a glass in a straw by holding your finger over the top of the straw. By not letting any air in the top of the straw the fluid is held inside with suction. This is a very common way to suspend the prosthesis to a residual limb and with the advances made in the types of sleeves used, a logical approach for many amputees today.