February 11, 2016
2 min read

Obesity and total joint arthroplasty: Time to examine needs in a different light

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The prevalence of obesity in the general population is increasing. Obesity is estimated to affect approximately one-third of adults in the United States. It is estimated that 6.1 million patients who undergo total joint arthroplasty will be obese by 2040.

It is a known fact that obese patients undergoing total joint arthroplasty (TJA) are at higher risk of all complications in general, particularly infection. An increased risk for wound healing, infection, anemia, acute renal insufficiency, respiratory failure and urinary tract infection have been linked to obesity in patients undergoing TJA. Multiple studies have shown obesity can negatively impact the technical performance of both total hip arthroplasty (THA) and total knee arthroplasty (TKA), as well as influence the implant survivorship.

Implant type

Another issue is the type of implant used in TJA procedures for obese patients. The implants used in obese patients may frequently be “off-label.” Utilization of a drug or medical device outside the scope of indications or population subgroups specifically approved by the FDA is considered off-label use.

Javad Parvizi, MD, FRCS

Javad Parvizi

From 2000 to 2010, there were an estimated 7,769,863 TJA admissions in the United States. Of these, 2,705,697 (34.8%) were categorized as off-label. By 2000, at least 21.8% and 25.1 % of THA and TKA procedures, respectively, were off-label. During this decade, there was an annual increase in the rate of off-label use for each procedure type. In 2010, at least 37.3% and 44.6% of THA and TKA procedures, respectively, were off-label.

Labeling process

Manufacturer-driven device labeling has led most orthopedic implants to be cleared for marketing and sale through the 510(k) process. This process requires the manufacturer submitting a premarket approval application that includes detailed information about the design, manufacturing process, safety and efficacy of the device. However, the 510(k) process requests that device manufacturers only provide proof of substantial equivalence in materials, mechanism of action and purpose in order to confirm a device previously approved for use. While indications of TJA have evolved, the 510(k) implant labeling process has remained largely unchanged.

Is, then, the early failure of TJA seen in obese patients the result of exceeding the mechanical capacity of the implants? After all, implants for TJA that are in use have neither been tested nor cleared for use in obese patients. With the increase in the incidence of obesity and increased need of these patients for TJA, the time has come to examine the needs of these patients in a different light. We need to ensure that higher incidence of complications and failures of TJA in this patient population can be prevented.

Disclosures: Azboy reports no relevant financial disclosures. Parvizi reports he is a consultant to Zimmer Biomet, Ceramtec, Convatec and TissueGene; and has ownership in CD Diagnostics, Hip Innovation Technology, ForMD, Alphaeon and Joint Purification Systems.