Between 1999 and 2008, the number of total knee arthroplasty (TKA) for patients with arthritis went up by 100 percent. As Americans get older and continue to pack on the pounds, it is expected that the annual number of knee replacements will hit 3.5 million within the next decade. Yet one out of five patients who get the surgery say it doesn’t help – and as many as one in three patients who do have knee replacement operations don’t even need it.

That is according to a study published in June of 2014 in the journal Arthritis and Rheumatology. Researchers found that in 60 of the 175 cases examined, “TKA was classified as inappropriate” because their arthritis was not severe enough to warrant the surgery. Furthermore, research appearing in the British Medical Journal in February of 2017 found that TKA had “minimal effects on quality of life” for patients with milder cases of arthritis. Speaking to the press recently, the president of the Society for Patient-Centered Orthopedics admitted, “We do too many knee replacements.”

So – why are so many knee replacements being done?

Given the complexities of the surgery and the recent issues with bone cement used to fix the prostheses in place, this is a serious issue – particularly as a growing number of patients seeking TKA are younger, being in their 50s and 60s. Aside from bone cement failures, knee prostheses do not last forever, having a useful life of approximately 20 years – and even less for obese patients.

Essentially, the younger the patient is, the greater the chances that s/he will literally “outlive” their prosthesis and have to undergo revision surgery. Those second surgeries have a higher rate of complications as well, especially for younger patients. According to a piece published by The Lancet in November 2018, 35 percent of men and 20 percent of women under the age of sixty who undergo TKA wind up needing revision surgery at some point.

A large part of the explanation is revenue. Simply put, knee surgery is an important source of income for hospitals. In a frank interview appearing recently in Kaiser Health News, sports doctor Dr. Nicholas DiNubile acknowledged, “Medical advertising is a big part of the problem. Its purpose is to sell patients on the procedures” – including ones they may not need. DiNubile added that TKA surgeries are “really crucial to the financial health of hospitals and doctors’ practices…the doctor earns a lot more if they do the surgery.”

This phenomenon may also help explain why surgeons would choose to use high viscosity cement (HVC) for TKA, even though it is more prone to failure. HVC is easier to mix and use and has a shorter setting time – a major consideration if the priority is volume (as well as revenue and profits).

K.J. McElrath is a former history and social studies teacher who has long maintained a keen interest in legal and social issues. In addition to writing for The Ring of Fire, he is the author of two published novels: Tamanous Cooley, a darkly comic environmental twist on Dante's Inferno, and The Missionary's Wife, a story of the conflict between human nature and fundamentalist religious dogma. When not engaged in journalistic or literary pursuits, K.J. works as an entertainer and film composer.