SUNDAY, DAY 7
MEDICAL MILESTONES
As the body ages, our joints suffer and arthritis can develop. Protective cartilage wears away and bones rub together, causing pain and loss of motion—most commonly in the knees and hips.
Doctors theorized for decades that the most effective way to reduce this pain and discomfort might be to simply replace the damaged joint. But finding a safe and effective replacement turned into a major medical challenge.
Early (and unsuccessful) attempts to replace or smooth the surfaces of joints included the use of muscles, fat, pig bladder, gold, magnesium, and zinc. None had the combination of safety and strength needed to replicate a human joint.
One of the doctors working to devise an artificial joint was Boston surgeon Marius Smith-Petersen (1886–1953), whose first design was a molded glass replacement, The glass joint failed to work, but Smith-Petersen continued his research on mold arthroplasty, as he called it, and eventually found better success with plastic and stainless steel.
Efforts to design a working joint replacement received a boost in 1936, when the metallic alloy Vitallium was invented. Part cobalt, part chromium, the alloy was strong enough to walk on and safe enough to insert into the body. The first reported hip replacement with Vitallium took place in 1940 at Johns Hopkins Hospital in Baltimore. New York City doctor Edward Haboush (1904–1973) solved a related problem by devising a way to adhere the artificial joint to the existing human bone. And the English surgeon Sir John Charnley (1911–1982) addressed the issue of pain and function by replacing the hip socket (instead of just the ball) with a Teflon implant in 1958. When Teflon didn’t work, he tried polyethylene, which worked wonderfully. He borrowed a polyethylene adhesive, known as bone cement, from dentists and used it to secure the artificial joint firmly to the bone—resulting in a “total hip replacement.”
At the same time, treatments for knee arthritis were being developed, including a hinged prosthesis and a metal spacer to prevent rubbing between the bones. In New York City in 1972, John Insall (1930–2000) developed the prototype for today’s knee prostheses, with components for all three surfaces of the knee—the femur, tibia, and patella, or kneecap.