ASK DR. BAUGHAN                                             May 14, 1998

ARTIFICIAL JOINT REPLACEMENT

“Could you summarize what is available in artificial hips and knees? . . .”

Total hip replacement is performed over 120,000 times per year in the United States.  The next most common joint replacement is the knee. Over 60% of these operations are performed on patients with osteoarthritis; the rest are done for trauma or other bone diseases.

Who is a candidate for joint replacement?  The two main reasons for performing a joint replacement are disabling pain and limited function of the joint.  Joint replacement is generally considered after all non-surgical treatments have been tried - medications, physical therapy, walking aides, etc.  If people are overusing their joints with too much activity, moderate limitation in activity may be appropriate since the artificial joint may not be able to stand overuse either.  Weight reduction for the same reason is sought to take the strain off the natural joint because results are sometimes not as good with an artificial joint in an obese person.

Who is not eligible for this surgery?  If a person has severe heart or lung disease that makes the surgery very risky, patient and doctor must be cautious.  Since arthritis increases with age and dementia is more common with advancing age, another limitation occurs when the patient because of dementia could not participate in the rehabilitation after surgery and would be unable to remember the precautions necessary to protect the artificial joint.  Joint replacements are vulnerable to infections, so if a person has a chronic source of infection, such as the mouth or skin, this problem should be cleared up before surgery can be performed.

How long can the artificial joints last?  This question is tough to answer because the technology is changing so rapidly.  Ten years ago, the artificial hip joints were usually kept in place with special cements.  Some of them loosened after ten years.  Nowadays, though, many joints are made of a porous material that allows the bone to actually grow into them.  Each new advance takes years to determine how long it will work.  The duration of the joint will also be influenced by how much the person weighs, how active they are, and what other health problems they have, such as osteoporosis or diabetes.

What determines when a doctor recommends or performs such surgery?  If the variables listed above were not complicated enough, some curious patterns emerge if we look at rates of the surgery across the country.  The rate of hip replacements for the same number of people is 50% higher in Boston than it is in New Haven.  Four times the rate of surgeries occur in Utah compared to Wyoming.  Women are usually operated on when their arthritis is more advanced than men.  Blacks are operated on less than half as often as whites.  Not surprisingly, poor people are operated on less often than well-to-do patients.  I could not find any information regarding the rates of joint replacements in patients with HMO insurance compared to other types of insurance.  Like other medical procedures, these findings cause much consternation and controversy over whether too much or too little surgery is being performed.

Undeniably, though, these joint replacements have been some of the most dramatic advances in orthopedics in the past 30 years and have improved the lives of thousands.

APOLOGIES TO DR. FLEMING:  Thanks to the reader who corrected me that Alexander Fleming, not Pasteur, noticed the mold in the petri dish that led to the discovery of penicillin.