In any mechanical entity, whether it’s a bicycle or a biplane, the components most likely to fail are those subject to continuous wear and tear. It is the parts that endure the stress of motion, often located where two parts intersect. In the human body, it’s no different. While skin and bone can break from acute impact, the hinges of the human body where bones connect are at risk of little more than normal function and time. As a result, joint replacement is one of the more common types of prosthetic surgeries available in the United States.
Surgeons have been working to replace missing or ailing body parts for millennia. Egyptian mummies have been found with wooden toes, fingers, and limbs attached with leather straps. Joint replacement, or arthroplasty as it is known in the surgical community, was experimented with but not successful until the 19th Century. In 1822, Dr. Anthony White, working out of Liverpool in the United Kingdom, was responsible for the first excision operation that removed the leg portion of a patient’s hip socket. While this preserved mobility, it left the connecting tissue perilously unstable. The first artificial implants and replacements were experimented with only a generation after Dr. White, but septic complications and infection rendered the vast majority of these operations unsuccessful. It wasn’t until 1890 that Dr. Themistocles Gluck completed the first successful joint replacement when he implanted the first artificial knee. In 1891, Dr. Gluck successfully performed a hip replacement. In both cases, the implants were made of ivory and fixed to the bone with nickel plates and screws.
A seminal figure in surgery, largely responsible for the modernization of both the materials and methods used today, is Sir John Charnley. Charnley was an army surgeon during the Second World War, where he served in Cairo. His experiences during the war spurred his interest in prosthetics to improve the mobility and well-being of recovering soldiers. In the early 1960s, Charnley was given control of the surgical center at Wrightington Hospital in Lancashire. One of his major breakthroughs was to disprove the prevailing belief at the time that friction, which greatly inhibited the long-term viability of joint replacement, could only be reduced by fluids lubricating the interface of bones. Charnley showed that it was actually the friction coefficient of the bones themselves that reduced wear. With this knowledge, he sought out an ideal material, eventually settling on High-Molecular-Weight Polyethylene, an early form of plastic. This advancement not only allowed for longer-lasting implants, but it also enabled them to be manufactured mechanically at a lower cost. Charnley was knighted in 1977 for his contributions to medicine.
Today, hip replacement surgery is one of the most commonly performed medical procedures in first-world countries. Joint replacement procedures allow millions of people around the globe to continue mobility into old age. Without the pioneering efforts of men like John Charnley, these advancements would not be possible.