Total hip joint replacement

Combining his talents as an orthopaedic surgeon and biomedical engineer, Professor Charnley conducted original laboratory and clinical research in joint lubrication and biomedical characteristics of joint opposition.

The investigations, which took place in the 1950s, led to the development of a revolutionary design of a total hip-joint replacement and the introduction of the use of methyl-methacrylate as a plastic cement to firmly affix the prosthetic components to the bone.

While the pioneering work on joint prosthetics, going back to 1908, cannot be ignored, the present advances were made possible by Professor Charnley's unique concepts. The techniques and concepts which he introduced in 1961 have given patients pain-free hips and restored normal living to tens of thousands of patients throughout the world.

It is estimated that 50,000 Charnley-type hip operations are performed annually and that anywhere from 3 to 5 million persons in the United States alone, with arthritis or other allied conditions, could potentially benefit from this operation.

For his combination of engineering skill and clinical acumen, and for his development of the concept and technique of total hip joint replacement in the treatment of severe arthritis which has opened, throughout the world, new horizons of research, treatment and rehabilitation in painful and crippling joint diseases, this 1974 Albert Lasker Clinical Medical Research Award is given.

John Charnley

Acceptance remarks, 1974 Lasker Awards Ceremony

My involvement in the development of total hip replacement, and the principles applicable to other diseased joints, has had five phases, not all in sequence with some of these existing side-by-side for most of the last twelve years.

The first phase was a return to basic physiological research, in an attempt to discover how Nature obtains its remarkable powers of lubrication in normal joints, and whether this would explain failures of attempts to make artificial joints during the 1950s. This research involved interdisciplinary contacts with lubricating engineers and plastics chemists, and showed that the surgeon's ideas of lubrication in artificial joints were quite fallacious. Surgeons had taken it as self-evident that polished metal surfaces, as for instance the metal ball used to replace the head of a femur, would be slippery when wetted by joint fluids and under the load of the weight of the body, just as they were when examined in the surgeon's hands in the operating room, and without load. The recognition that polished metal surfaces were not lubricated by body fluids when sliding on bare bone, or when sliding metal-on-metal, suggested that high frictional resistance between joint surfaces under heavy load might react on the mechanical fixation of the implants, and result in failure, by loosening of the whole implant in the living bone.

The failure of joint fluids to lubricate metal-on-metal surfaces, or metal-on-bone, led to the second phase, which was the trial of Teflon for the sliding surfaces in an artificial joint because this plastic had extraordinary powers of self-lubrication in the absence of liquids. The outstanding quality of the early results in this period, between 1957 and 1961, showed that the line of approach was sound, but the late results were failures, because inside the hip Teflon showed much poorer resistance to wear than had been predicted from laboratory experiments.

The third phase, which ran parallel with the Teflon experience, was the introduction to orthopaedic surgery of a quick-setting cement with which to bond implants to living bone. It was possible by this means to distribute the heavy load of the patient's body over a much larger area of living bone than was possible using conventional fixations, such as nails or multiple screws. I demonstrated that the strength of fixation to bone, by means of this cement, could be increased by two hundred times over that by conventional methods, which was a factor of safety well outside what was essential. This quick-setting cement had been used successfully for many years in dental surgery, and had been used also to replace defects in the skull. But on all sides there was deep distrust of its safety, and this still persists in some parts of the world.

The fourth phase was the recognition in its surgical application of the extraordinary powers of wear resistance exhibited by high molecular weight polyethylene, a new plastic which had just then become available on the market. This early recognition was rendered possible by having wear-testing apparatus available in the hospital, which I had designed and constructed for the testing of Teflon. A remarkable piece of good fortune was to find that this new plastic, which already had some element of self-lubrication against polished steel in the dry state, exhibited enhanced lubrication with joint fluids.

The fifth phase was the study of the complications which dogged the results of the early efforts at total hip replacement. At first sight these complications seemed almost certainly to be produced by chemical rejection of the cement, because at this time many of these complications appeared to be sterile on bacteriological testing. This possibility seemed likely to ground the whole project, since these complications were occurring in nearly 10 percent of the operations, a rate which would be much too high to consider the technique for general use. Nevertheless, the good results, in the 90 percent of cases without complications, were of such phenomenal quality that it seemed unjustifiable to stop work on the human subject (in whom alone is it possible to study this type of complication) until a definite decision could be made whether these complications were chemical rejection or simply bacterial infection.

The only way was exclusion: whether these complications would be reduced if greater care were taken to exclude organisms of any kind entering the wound during the operation. The only conceivable route of infection, under the already competent aseptic techniques being used during the operation, seemed to be through the medium of the air. Bacteriologists had rejected airborne infection as a cause of the infection of clean wounds in operating rooms, other than as an extremely rare occurrence, in the hundred years following Lister, who used the carbolic spray to destroy bacteria in the air. Despite this, an operating room enclosure was designed and built by means of which it was planned to have the open wound exposed only to filtered air. The immediate effect of relatively crude ventilating techniques reduced the infection rate to less than half its original level, and paved the way for considerable development of more sophisticated methods over the next six years. The bogy of chemical rejection of acrylic cement, as a common complication, was thus satisfactorily settled.

The clean air aspect of theater asepsis in major surgery strangely enough is still one not universally accepted by the medical profession, and not even universally in the special field of artificial implant surgery for which it was designed; time alone will yield the final verdict. Nevertheless, this new look at post-operative wound infection already has revealed two facts basic to bacteriology: first, that the idea of clean operations being auto-inoculated from the bloodstream must be much less common than has always been imagined, and second, that organisms on, or in, the skin can cause infection in the presence of an implanted foreign body, though these may be organisms of a type which have long been regarded as incapable of producing disease in man.

This brief account indicates that there are vast new fields for further investigation, and these may reveal matters of enormous importance in many fields of surgery other than joint replacement.