Present status of total hip replacement.

In this discussion of the current status of total hip replacement I shall try to avoid technical details and concentrate on those aspects which will be most interesting to this distinguished body of physicians, which I am deeply honoured in being invited to address. It is impossible to start without some elementary matters and first of all, one might ask 'What is total hip replacement? ' The implants which have been put into the hip joint during the last 40 years have all been partial hip replacements, replacing either the femoral head or, as in the ca§e of the SmithPeterson cup, the acetabulum. Total hip replacement means replacing the socket and the head at the same time. Most of the successful total hip replacements are fixed into the body by means of a quick-setting plastic-acrylic-cement-though some surgeons attempt to avoid using cement. I do not have time to discuss this here though it is one of the most important aspects of total hip replacement; it is obviously futile to use a total hip implant if pain then originates from movement of the implanted elements on the bone. The type of implant in which I am interested uses a small diameter metal head and a plastic socket of high density polyethylene. The small head is essential in the concept ofwhat I call the 'low friction arthroplasty', or the 'low frictional torque arthroplasty', because the resistance to motion is lower with a small than with a large diameter head. The interior of one of these joints after 21 years of service in the body shows a remarkably normal appearance of the tissues; there is no staining by metal particles and the appearances are astonishingly like those of a living joint. After operation the patient gets out of bed usually on the 4th or 5th day, and starts to walk with full weight on the limb on the 7th day, depending of course on his age and agility. Most patients are fit to return home between 2j and 3 weeks after the operation. Young patients have to be positively restrained for 4 to 6 weeks below their capacity for activity. Elderly patients, if they were able to live alone before the operation, will be able to go back to the same circumstances within 4 weeks. No physiotherapy and no attendances at hospital for outpatient treatment are needed after leaving hospital. Physiotherapy is prohibited after the patient leaves hospital lest these patients overdo it. The simple act of walking, or attempting to walk, eventually discarding all walking aids according to the patient's own common sense, is all that is needed in rehabilitation. The first attendance at hospital which is usually made 6 months after the operation is for psychological or social reasons; by that time the patient is almost completely rehabilitated. The optimism which prompts these patients to return home early, or to be glad to go home, is quite different from what we used to see with patients after other types of hip operations; it comes from the fact that they know from their own sensation that the hip is going to be good. This optimism brings a new lease of life and it often works a profound change in their mental attitude, their general appearance at follow-up after surgery being enormously rewarding both for the surgical and nursing teams. There is no special mortality after this operation, if we exclude massive fatal pulmonary embolism (not unique to this operation), which rates at about 0 * 5 to 1 per cent. The post-operative death rate from other causes reflects the risks which the surgeon is prepared to accept in the pre-operative state of the patient, even patients who have been taking cortisone for a long time can be effectively protected by a preoperative and post-operative prophylactic regime. Deep wound infection is a serious post-operative hazard, but is not a hazard to life. Extreme precautions in the operating theatre are revealing themselves to be valuable in reducing this incidence of infection.