For millennia, many people lucky enough to survive into their 60s and 70s have developed wear-and-tear arthritis, also known as degenerative joint disease or osteoarthritis. When this type of aging occurs in fingers, the joints became stiff and knobby and perhaps painful, but with ten digits on two hands and neither hand having the duty to bear body weight, people seem to manage.The state of affairs has always been quite different, however, if the disease affects the hips and grinds away the cartilage there. The thigh bone’s ball no longer glides smoothly in the pelvic socket during walking and especially when the owner tries to rise from a chair or climb stairs. Rather, without slippery cartilage covering the ends of the bones and smoothing things over, raw bone rubs against raw bone and causes great pain with every step. Rising off a commode becomes agonizing. A cane, crutches, or a wheel chair has been the mainstay remedies short of surgery, which initially was primitive and only marginally effective.
Even before the discovery of general anesthesia in the 1840’s, surgeons at times merely cut off the end an infected or terribly arthritic thigh bone, possibly relieving pain but certainly rendering the limb short and unstable, at least for humans. Even today in veterinary practice, however, the standard operation for an arthritic canine hip is to remove the ball end of the thigh bone and leave the hip socket empty. Because dogs share weight bearing among four limbs, the limp after this resection surgery is hardly noticeable, and the improved mobility is remarkable.
With the advent of general anesthesia, surgeons could be more methodical with operations and began resurfacing the raw-bone interfaces of arthritic hips. Their ingenuity was boundless, and they were not burdened by any concept of informed consent, a 20th century development. Sure, the doctors followed the Hippocratic teaching of first do no harm, but who was to know how various materials implanted between surfaces of an arthritic joint would fare unless somebody tried it. And try they did, using fat, muscle, celluloid, wax, glass, rubber, and sheets of zinc, magnesium, silver, or gold. Even pig bladder.
Resurfacing posed several, soon-discovered problems. First, the body had to tolerate the artificial material rather than spitting it out, either mechanically, immunologically, or both. Resurfacing also failed to restore adequate motion or comfort. This led investigators to try replacing the entire hip joint rather than merely resurfacing the original one. Shaped like hip joints, first rubber, then ivory, then various metallic components were tried, but replacement added another problem to those of resurfacing. The artificial hip joint’s components needed to be fixed securely to the patient’s pelvic and thigh bones in order to prevent any wobbling or pistoning between the implanted components and the bones. By 1891, surgeons had tried securing ivory implants with metal screws and then with mixtures of plaster of paris, powdered pumice, and resin. All efforts failed.
In the first half of the 20th century, multiple European and American orthopedic innovators experimented with different fixation techniques and with variously configured total hip components made from different metal alloys. It was Englishman John Charnley who brought total hip replacement into practical and wide-spread use.
In the 1930s orthopedics was still considered a minor specialty and did not initially attract the interest of Charnley’s fertile and inventive mind. Among other assignments while in the Royal Army Medical Corps during World War II, Charnley was stationed in Egypt and collaborated with engineers in developing various orthopedic braces and surgical instruments. On return to civilian life, Charnley focused his research on bone grafting, fracture healing, and ultimately on the weighty problem of total hip replacement. Twice his curiosity and inventiveness led him to experiment on himself, first by having a colleague place an experimental bone graft in Charnley’s leg. Infection ensued and required several further operations before healing occurred. Later, Charnley injected wear debris from one of his total hip designs into his own thigh to observe the resultant inflammatory response.
One day in the 1950’s a patient, who had received a hip replacement by another surgeon, commented to Charnley that every time he leaned forward at the dinner table his hip squeaked loudly, which greatly disturbed his wife and prompted her to leave the room. This chance observation set Charnley off on a quest to perfect a low-friction total hip replacement—one that would not squeak.
Charnley machined some of his early components at home on a lathe, which he had purchased using royalties gained from previous inventions. He tried various hard plastics and settled on PTFE (Teflon) for the socket side of the joint. PTFE did not squeak, and Charnley implanted it into 300 patients before its shortcomings became clear. Why that many? The PTFE was suitably durable the first year, less so in the second, and not so in the third, when wear debris became problematic. The body recognized the debris particles produced by hip motion as foreign material and produced a raging inflammatory response. The only recourse was to remove the artificial joint and all the surrounding havoc it had created. Charnley was distraught. He had wasted years and now had to occupy much of his time not making progress but removing the failed implants.
To be continued: A traveling salesman happens by.