Rob Pittman, CPO/L, President Superior Orthotics and Prosthetics
Posted: Wednesday, February 25, 2009 4:33 pm

The study and development of prosthetic devices and components has experienced rapid development during the past several years, providing great benefits to amputees worldwide.

According to the Web site of the Encyclopedia of Surgery, there are over 350,000 amputees with a prosthetic device in the United States. An average of 135,000 new amputations occur annually with the majority of them resulting from vascular disease, cancer, infection, trauma and birth defects.

Lower extremity amputations, both above and below the knee, make up the majority of all amputations – roughly 97 percent – with the remainder being upper extremity (above and below the elbow) amputations.

Thanks to advances in materials and design and the implementation of electronics in prosthetics, these amputees have access to prosthetic devices and components that promise more complete rehabilitation and outcomes.

Today, amputees are fitted with limbs made of incredibly strong, lightweight materials, including epoxy, modified acrylic resin, carbon fiber, titanium and aircraft aluminum. Materials used next to the residuum for protection and suspension have also been improved.

Prosthetic limbs are generally fitted with soft, flexible liners which roll up over the patient's residual limb forming a secure cushion between the limb and the prosthetic socket. Here, too, recent developments in materials, including the use of silicone and gel, have made the fit more comfortable, more secure and lead to increased patient activities and better outcomes.

Use of these new silicone and urethane materials have led to the development of newer liners and sleeves that offer increased viscous properties that reduce shear and promote residuum health. The development of electronic and mechanical vacuum devices as suspension methods also contributed to liner and sleeve advancements.

Negative pressure suspension is the latest in suspension development. Use of the Harmony System by Otto Bock or the Limb Logic by Ohio Willow Wood gives the greatest level of suspension with the lowest level of pistoning and movement within the socket. An added feature is an improvement in the lymphatic system leading to greater circulation and wound healing capabilities.

In addition to the use of these innovative materials, advances in knee component design and prosthetic feet have revolutionized the field of prosthetics in recent years.

One of the most important developments has been the micro processor knee unit. The C-Leg is a microprocessor-controlled knee prosthesis, developed by the Otto Bock Healthcare company, that enables moderately active amputees to vary walking speeds and travel over changes in terrain. The C-Leg uses hydraulic cylinders to control the flexing of the knee. Sensors send signals to the microprocessor that analyzes these signals, and communicates what resistance the hydraulic cylinders should supply.

The PROPRIO Foot is typically a $30,000 device that uses artificial intelligence, sensors and microprocessors to adjust automatically to the user's gait as well as to surface angles. It is capable of remembering exactly how the amputee walked up a flight of stairs or down a hill, and can be trained to respond accordingly.

Electronics and myoelectric technology have completely changed the design of upper extremity prostheses. Myoelectric components detect small electrical activity in muscle, then amplify the signal and send it to a motor that drives the prosthesis.

Introduced during the summer of 2007, the i-LIMB is a myoelectric hand which uses muscle signals detected by electrodes on the surface of the skin to control the device's movements, which include opening and closing a fist. Its fingers are also individually powered, allowing the user to pinch and hold objects.

Many of the recent developments in materials and design bring with them a large price tag, and patients often find themselves struggling with insurance carriers for coverage of these new, innovative products.

Today's goal is 100 percent patient rehabilitation. With recent government, private and academic research yielding outstanding innovations such as vacuum devices to aid suspension, microprocessor knee units and hands with articulating fingers that can pinch and grip, 100 percent rehabilitation is possible and should be the common goal of patient care and insurance providers. The challenge is educating all parties that these new and exciting breakthroughs, although expensive, make such a tremendous impact and improvement in the patient's life.

Although healthcare reimbursements are declining and many managed care and private carriers are limiting individual benefits, there is no doubt amputees today have many more options when choosing the ideal device for them. The future will undoubtedly see a continued quest for a prosthesis that looks and functions like an original limb.


Rob Pittman is a certified and licensed prosthetist and President of Superior Orthotics and Prosthetics. For additional information on the items mentioned in this article, contact Superior at 615-340-0068 or visit SUPERIORANDP.com.