The above magnificent line of iambic hexameter from Robert Burns’ poem “To a Mouse” captures a great deal of the difficulty of modern medicine. This article will detail one relatively straightforward medical misstep (thalidomide) and another somewhat more complicated problem arising out of the yearly implantation of millions of artificial joints. The latter will require a bit of development.
This article’s first infamous example of plans gone awry was the treatment of pregnant women with thalidomide. This was used in the late 1950’s and early 1960’s for number of indications, most notably nausea related to pregnancy. First trimester nausea can be quite debilitating for women and this medication was an attempt to address this. This was widely prescribed in Europe. Sadly, women who took this medication had a significantly increased risk of birth defects in their children especially when taken early in the pregnancy. The birth defect type corresponded to the day of pregnancy when taken since different organs develop at different times during pregnancy. Thanks to vigilance of the United States FDA (especially Frances Kelsey), relatively few American children were affected by this in distinction to children in Europe who suffered in the thousands. The treatment for pregnancy related nausea became more dangerous than the nausea.
The balance of this article will develop a parallel but somewhat more complicated issue. Specifically, we will discuss the costs, risks, benefits, and complexity of artificial joints (prostheses) for the knees and hips.
This is an important subject because each year in the US alone, an estimated 2,000,000 such devices are surgically implanted (according to various sources). As the population ages, the yearly number will likely increase.
In researching this subject, one is struck by how incomplete the information is about the number of procedures per year, the number of different types of hip and knee prostheses (e.g., previously metal on metal prostheses constituted a large volume of the surgeries but that figure is now significantly reduced in favor of metal on polyethylene and other combinations).
Because of lack of centralized records, the price of the procedures is unclear. In 2025, both hip and knee replacements cost approximately $40,000 each with a great deal of variability. Assuming 2,000,000 such surgeries yearly (as above), then the costs are grossly $80 billion/year. These cost estimates exclude patient’s lost income (both during hospitalization and convalescence), lost income to patients’ family members who are caretakers, and the like. The numbers are vast.
The principal indication for surgery is pain compromising the patient’s ability to do daily tasks. If a patient cannot walk even 1 block because of severe knee or hip pain, the patient is likely a candidate for joint replacement/arthroplasty. This has remained a common metric within the orthopedic community.
Interestingly enough, the choice of prosthetic type is still an open question in 2025.
One previously very popular prosthetic type was the metal on metal prosthesis. It is described as having “2 generations” of use in the United States, first in the 1960s-1970s and then later in the 1990s-2012. The metals used were typically cobalt and chromium. Therein was the “rub”. In addition to the “normal” prosthetic failures such as when the prosthesis broke or dislocated, the cobalt-chromium prostheses had the additional potential feature of leaking those 2 metals into the patient’s body. As the ball and the cap burnished, toxic amounts of cobalt and chromium entered the patient. Depending on one’s sources, the United States probably has 1,000,000 patients with metal on metal prostheses each of whom has a significant risk of toxic level of chromium and/or cobalt in the body. The pathological manifestations of this poisoning are many. Heart muscle failure, dementia, neuropathy including blindness, hypothyroidism, and many other life altering (or ending) disease states are possible. To the best of this author’s knowledge, orthopedic surgeons do not follow their patients if the patient has no complaints after completion of the postoperative period. Also, the patient’s primary care physicians do not routinely screen urinary vs. serum levels of cobalt and chromium. Usually, the patient will present with vague complaints which, as time progresses, will become more severe and involve more organ systems. Yet, because this information is often lost once the patient leaves the care of the orthopedist, proper preventative screening cannot be done.
Briefly returning to the discussion of prosthetic type, metal on polyethylene is now a popular combination. The rate of release of chromium and cobalt is greatly reduced in these joints. Additionally, ceramic joints are popular.
If one begins to have excessive plasma levels of cobalt and/or chromium, the preferred treatment is removal of the prosthesis leaving the patient, in some sense, in a worse state than prior to the original surgery.
So the next question is what can be done to improve the safety, efficacy, and cost-effectiveness of hip and knee implantations, past, present, and future? The following are some suggestions.
1-As noted previously in this magazine, all medical records for those in the U.S. medical system should be kept in 1 file so that, in the years following, suboptimal situations like metal on metal prostheses can be better monitored. If the patient changes location and needs a new primary care physician or orthopedist, the type of prostheses which have been implanted should be immediately known.
2-Next, if a patient has a knee or hip prosthesis and the exact type of device is uncertain (i.e., medical records are still not available), then empirically, yearly urinary cobalt and chromium levels should be obtained.
3-Increased studies should be done to understand the core nature of osteoarthritis (we already know that weight loss for patients with an elevated BMI can slow or even arrest progression of osteoarthritis). Other factors must be sought to reduce this $80 billion per year loss. Preserving “original equipment” is always better than insertion of foreign material.
4-Finally, more work should also be done regarding the best choice of prostheses for different patient populations. For example, if a young and very active person needs a hip prosthesis, what would be the optimal type so as to serve the patient’s need but also to avoid early failure requiring replacement? Alternatively, what would be the best type of prostheses for an aged patient who is not so active and has less risk of requiring a second joint replacement? The orthopedic community has patterns of selection related to these and other patient types but has there been any comparative studies of product to product? The manufacturers would not sponsor such a study lest their product not do well under scrutiny. So these types of studies should be done by the NIH or other government agencies to avoid bias.
The final observation is that an average hip or knee prosthesis cost approximately $5000. If there are 2,000,000 prosthetic procedures done every year, the industry may not be entirely forthcoming when the device does not perform as intended. One must walk a difficult tightrope of helping and hurting the patient. That dynamic will never fade.