Inventor Ernest M. Burgess was an orthopedic professor at the University of Washington. His biographer, Margret Marshall, said “He was just a brilliant man, always thinking, always working because he believed so strongly in what he was doing,” upon his death in 2000.[1] He grew up in Utah and earned a Bachelor’s in Science at the University of Utah, then his doctorate at Colombia University. In World War II, Burgess served as an Army surgeon in the Pacific, where he mainly performed amputations. At this time, he developed his interest in prosthetic devices and making them available and most anatomically correct. During the war, he helped fit 6,000 Vietnamese and wrote, “About two million new land mines are sown annually in combat areas throughout the world… hundreds of thousands of amputees lead hopeless lives of desolation that could be greatly improved by prosthetic limbs.”[2] In 1985, Dr. Burgess opened the Prosthetics Outreach Foundation of Seattle and a similar organization in Vietnam. Also, among his accomplishments were pioneering a new hip-replacement surgery, earning a top Veterans Department honor, the Olin E. Teague Award, and donating time to children’s hospitals for orthopedic surgery.[3]

The Seattle Foot was developed in the 1980’s and patented in 1985 by Ernest M. Burgess, Donald L. Poggi, David E. Moeller, and Drew A. Hittenberger and manufactured by Model & Instrument Works, Incorporated in Seattle.[4] The invention process commenced with Dr. Burgess’s initiative to provide a more effective prosthetic for athletic amputees. Prior to his invention, the patent describes that prosthetic devices have been “primarily designed for walking and, hence, the structure of such conventional prostheses have failed to provide a natural lift and thrust effect for the more active and sports-minded person.”[5] Being a professor at the University of Washington, he began research with Doris Miller and Roger Enoka from the kinesiology department investigating the movements involved with the human gaits with and without prosthetic devices. [6] After the study concluded, Burgess and his research team built a prototype for the Seattle Foot. The prototype featured V- shaped “fiberglass leaf springs in the shape of a cantilever structure with the secured end of the cantilever being joined or fastened to an upper prosthesis.”[7] A rubber bumper was used to cushion compression between the leg and the foot and a cable between the leg and the springs prevented over-extension of the ankle joint. Tests on the original foot yielded positive results; however, it was deemed too heavy for the average amputee, was not efficiently durable, expensive to manufacture, and the high degree of energy-storage made walking slowly difficult.[8]

[1] The Seattle Foot

The Seattle Foot made improvements on the first version for two years and only included Burgess from the original inventors. Burgess recruited engineering consultants from the Boeing Company supported by the Veterans Administration Rehabilitation Research and Development Funds. The patent, applied for in 1985, describes the Seattle Foot as including a “monolithic cantilever keel made of a hardened polymer or polymers and that has an attachment flange at the center of the ankle for fastening to a standard upper prosthesis, a uniformly curved strain energy-storing heel portion that is integrally joined to the rear of the attachment flange and is relatively thickened and arranged to extend in transition first downward and rearward, and to then curve at a radius, selected commensurate with the thickness to maintain a uniform stress, to a downward and forward direction where the keel straightens and extends as a forefoot portion, terminating at a toe end.”[9] The monolithic cantilever beam spring allows initially softer deflection for walking, but becomes progressively firmer as force increases during faster gaits. It is also designed to provide uniform stress over the device in order to dispel wear on the inner parts. The Delrin keel is surrounded by a flexible low-density rubber that is molded into the shape of a realistic foot or a smooth foot. The cover also is designed to cushion during heel-strike (movement of a heel hitting the surface during the human gait) and transfer the force on the horizontal (transverse) plane between the manufactured keel and the other footwear the amputee is wearing at the time. Also, there is an increasing angle between the heel and the toe to minimize stress on the keel and to easily distribute stress along the transverse plane.[10]

The Seattle Foot is specially-engineered with the ability for enough energy-storage that the amputee can be active and run. The invention process took five years over 1980 to 1985 and the product uses the most effective materials for production including Delrin by DuPont and Kevlar Nylon.[11] The Seattle Foot can come in multiple alternate forms to suit the patient’s needs as Dr. Burgess had originally expressed as his main goal.

The patent discusses the importance of “accommodating the needs of a widely varying range of patient requirements.”[12] The foot can have a smooth finish or a covering that is aesthetically similar to a human foot. The amputee can chose to have spaces between the toes or make the end area a solid surface. The Seattle Foot was truly designed with filling amputee’s needs as its main focus.[13]