Only weeks after revelations about DePuy’s defective Attune Knee System, two more prosthetic knee replacements are in the news because of design flaws and resultant device failures. Furthermore, these devices have the same issues. Specifically, the surface of a key component is unable to hold an adhesive bond, resulting in device failure and causing severe pain and loss of mobility. Patients who have received implants invariably require revision surgery.
One of these is the Arthrex iBalance Total Knee Arthroplasty (TKA) system, for which the manufacturer issued an Urgent Medical Device Recall to physicians and hospitals in February 2016. That was followed by a Class 2 Device Recall by the FDA a month later.
Specifically, the problem was caused by a component known as the “tibial tray,” which attaches to the shinbone and supports the upper components of the prosthesis. As was the case with the Attune Knee System, the Arthrex iBalance component had a smooth surface, giving the cement nothing to adhere to (most types of bonding cement require some type of texture in order to work properly). Surgeons performing revision surgeries have reported that they have been able to simply remove the tibial tray manually.
The other device is the Exatech Optetrak knee replacement. First approved by the FDA in 1994, the original tibial tray featured a “finned” design. In addition to the usual situations in which patients suffer from arthritis or other degenerative conditions, the Optetrak was indicated for patients requiring revision surgery following the failure of an earlier knee prosthesis.
The usual finned design provided an inadequate surface for the adhesive, and the result was premature failure. In 2011, the FDA issued a Class 2 recall of the device, after which Exatech quietly introduced a different design. According to a 2012 study published in Science Direct, the keel component of the tibial tray was too small to withstand the stresses involved in bearing the patient’s weight and movements.
Appallingly, both of these devices were “fast tracked” through FDA approval through the 510(k) Premarket Notification process, meaning that they were poorly tested (if at all). The manufacturers needed only to demonstrate that their new products were “substantially similar” to devices previously approved for the market.
Over the past several years, an unacceptably high number of medical devices approved through this process have been injuring thousands of patients. It continues today; currently, the only way to address the problem is to hold such manufacturers accountable in a court of law.