According to a lawsuit filed last June in the U.S. District Court for the Western District of Louisiana, a particular DePuy bone cementknown as SmartSet HV is defective. The DePuy bone cement is used to adhere parts of an artificial knee joint into the femur (upper leg bone) and tibia (the major bone of the lower leg).

Total knee replacements (TKR) surgeries are done at the astonishingly high rate of 600,000 per year in the U.S. alone. This number is expected to increase to 3 million annually by the year 2030.

The Approval of DePuy Bone Cement

As with all domestically-used drug and medical devices and products, the U.S. Food and Drug Administration (FDA) must approve adherence products like DePuy bone cement for the American market.

According to the background section of this SmartSet HV lawsuit, this high-viscosity (HV) component adherent was approved by the FDA in the early part of 2004 through the 510(k) process.

The 510(k) process typically requires 90 days’ notice of intent to market and a similar device that has already been FDA-approved. Companies must simply demonstrate a “substantial equivalence” between their device and an FDA-approved device.

In this particular case, the orthopedic company indicated that SmartSet HV was virtually identical in performance to DePuy 1 Gentamicin and Simplex P with Tobramycin bone cements that were already in commercial circulation.

The linkage of these products, according to the narrative of the lawsuit, was based upon the defendant’s claim that stringent “voluntary performance standards” were held up and product testing was completed. However, the lawsuit contends that little to no testing was in fact completed.

What Does Viscosity Mean?

When it comes to bone cement used in TKR surgery, distinctions are made between attributes of handling and workability. The different cements including DePuy bone cement are divided into low viscosity (LV), medium viscosity (MV), and high viscosity (HV) like the SmartSet HV product.

The complaint acknowledges contributions from the several medical journals that indicate that HV bone cements including the DePuy bone cement known as SmartSet HV are causing components of otherwise well-reviewed knee prosthetics to become loose or even disassociate from the bone. According to one report, a number of orthopedic surgeons have ceased to use high viscosity products for this reason.

Patients that have had high viscosity bone cements used in their TKR surgeries and have experienced loosening, typically suffer a lot of pain and discomfort as well as loss of range of motion. This often culminates in a secondary surgery known as a knee revision.

The second knee revision surgery comes with a host of secondary risks. Some of these include difficulty getting another prosthetic to work due to bone loss and the possibility of leg length discrepancies.

The DePuy Orthopaedics Lawsuit is Case No. 1:18-cv-00791-DDD-JPM in the U.S. District Court for the Western District of Louisiana.