Unravelling bone destruction in total hip replacements with William H. Harris

When orthopaedic surgeon, Dr. William H. Harris discovered massive bone destruction around a total hip replacement that he had implanted, he was startled and dismayed. In fact, he had identified a new condition, “periprosthetic osteolysis”, which came to be the leading factor in failure of total hip replacement (THR) surgery. While THR surgery dramatically reversed severe arthritis of the hip, the same operation simultaneously created a relentless “particle generator” in the body. Ironically, in the effort to do good, doctors were simultaneously doing major harm.

We recently sat down with Dr. Harris, author of Vanishing Bone, to discuss the course of events that led to him identifying the root of the disease and working towards a cure. Today, the disease which affected over a million people has been virtually eliminated — a testament to the success of the solution.

It must be a very rare experience in a physician’s career to be at the forefront of discovering a disease, successfully identifying its cause, and later eliminating it. Can you tell us more about what it was like to be so closely involved with this case?

One of the really compelling and quite unique features revealed in the recapitulation of the conquest of this human disease which had never been previously seen, lies in the time span involved. Remarkably, the initial observation of this disease, the obscure and difficult process of unraveling its nature, and the apparently improbable solution to its elimination by creating a better plastic for the articulation of the artificial human hip joint all took place – in its entirety – during one lifetime. One of the special rewards to me as a clinician-scientist was the opportunity to participate equally in the clinical identification of the disease, as well as contributing unique observations about its basic molecular biology, and then to direct the investigations leading to its solution in the form of the cross-linking of polyethylene.

Some patients even underwent hip transplants to correct the bone destruction that had been caused by the original artificial joint. How did patients react when they learned that they would need to undergo an additional surgery to correct the damage caused and prevent any more bone deterioration linked to the original procedure?

It is peculiar that this disease, whose specific name “periprosthetic osteolysis”, is virtually completely unknown despite involving one million patients around the world. One reason is that the disease existed for many years before it was given a name. More importantly, however, the disease remains “silent” (meaning that it produces no symptoms) until either the prosthesis comes loose or the bone fractures. Because the disease is hard to explain to the patient, surgeons simply avoided using its name and thus avoided explaining the disease, while adopting the expediency of describing the urgency and need of further surgery by telling the patient either “ Your bone has fractured” or “ Your prosthesis has come loose”. Thus it was that few if any patients had a real understanding that their basic problem was the bone destruction surrounding their total hip. Virtually none had any idea that they suffered from “periprosthetic osteolysis”.

In one extreme example of periprosthetic osteolysis, the destruction of the bone was so severe and so extensive in both the thigh bone and the pelvis that we were forced to carry out a “total hip transplant”, not a total hip replacement. This meant that we replaced the entire acetabulum (hip socket) and the upper half of the thigh bone by bone which we obtained from our bone bank from another human individual. That case was the only instance in which that operation was carried out, but it was essential for her.

In a fascinating subsequent development which we had anticipated would take place, we were then forced to carry out a total hip replacement into that total hip transplant, because of deterioration of the transplant over many years. This is the only case anywhere in the world in which this sequence exists. Basically this patient had a total hip replacement into her own bone, followed by a total hip transplant, followed by a total hip replacement into the transplant. This is a salient example of the extreme destruction that periprosthetic osteolysis could produce.

What was the most valuable lesson that you learnt from the experience?

As I reflect on the entire arc of the identification and elimination of this unique disease, the question of what was the most viable thing I have learned from the entire experience calls forth two key observations, not one. In retrospect, neither is a surprise, although both are of maximum importance. The first is simply that crucial element called “persistence”. The urge to cure this disease was driven by the devastation experienced by our patients who are afflicted by it. We had no option but to persist, but the persistence had to last over the total of six decades. Without that persistence success would have never come.

The second factor, equally obvious in retrospect, was the intense application of multiple skills by a huge number of dedicated scientists and physicians over long periods of time in pursuit of the solution. The elimination of a totally unknown disease simply requires the massive application of a multiplicity of talent and skills by large numbers of committed individuals.

What innovations do you predict for the future of hip replacement surgery?

The origination of total hip surgery and its subsequent massive improvement have made it among the most successful of all operations. In fact the standard has been set at an extremely high level, namely 95% success rate after ten years in use. While important continuing attack on the remaining 5% of problems is vital, contemporary focus for innovation has moved to other areas, specifically cost reduction and slowing the progression of the disease. Huge success is being generated in both of these areas and will increase. Equally so, major efforts must now focus on understanding and preventing those circumstances which underlie the causes of hip disease.

Featured image credit: Film x-ray human’s pelvis and arthritis at both hip joint (Gout, Rheumatoid) by Puwadol Jaturawutthichai via Shutterstock.