Here at McCarthy + Co Solicitors, we have been contacted on numerous occasions recently regarding DePuy Orthopaedics’s Attune Knee System. The following information is set out to provide guidance to anyone who might currently be experiencing difficulties as a result of this product. Should you have any further questions regarding the following information, please feel free to contact our team on 1800 390 555, or email us at: info@mccarthy.ie.

The knee is a joint consisting of the tibia, the femur, and the patella. The joint is lined with cartilage to protect the bones from rubbing against one another. When significant damage is sustained to the knee joint, whether through degenerative wear and tear, disease or some traumatic injury, total knee replacement (TKR) is a commonly chosen surgical intervention.

DePuy Orthopaedics is a US corporation which is a subsidiary of Jonson & Jonson and which designs and produces orthopaedic prostheses. It gained considerable notoriety in 2010 when it recalled a defective hip product called the ASR triggering thousands of compensation claims worldwide, including several hundred in Ireland.

In 1996 DePuy introduced the DePuy Synthes P.F.C. Sigma knee replacement system. The Attune knee system which was subsequently launched was billed by the company to have built on knowledge learned from the experience of patients who had been implanted with DePuy’s previous knee replacement offerings.

DePuy’s Sigma system was one of the most widely used orthopaedic prostheses used worldwide. Despite the fact that DePuy suggested that the Sigma system had truly impressive success and longevity rates, they nevertheless began to alter the Sigma system design in an endeavour to mimic the total flexion of the natural knee. This development drive led to the launching of DePuy’s Attune knee system.

According to DePuy’s own marketing materials, the Attune system was developed with the intention of improving functional outcomes, to provide more stability, and to simplify implantation of the TKR system.

DePuy claimed that the Attune system featured a gradually reducing femoral radius, an innovative S-curve design of the posteriorly stabilized cam, a tibial base which could be downsized or upsized two sizes versus the insert, novel patella tracking, lighter innovative instruments, and a new polyethene formulation.

According to DePuy, the Attune system was “designed to provide better range of motion and address the unstable feeling some patients experience during everyday activities, such as stair descent and bending.”

Instead of carrying out extensive testing to ensure that the Attune system was safe and fit for purpose, DePuy relied upon a fast-track approval mechanism by invoking the Food and Drug Administration (FDA) “510 (k)” notification process. On this basis FDA clearance for placing the Attune on the market was secured on the basis that it was substantially similar to several prior devices, including DePuy’s Sigma system. Only very limited testing of the Attune was conducted as a consequence. It is interesting to note that DePuy’s failed ASR system made its way onto the market in the same way.

The Attune system includes the Attune Tibial Base, also called the tibial tray, which, as compared to the Sigma system, included a design change to the keel, the surface texture and the finish of the tibial baseplate. The ongoing research being undertaken is suggesting that it is the design and composition of this tibial baseplate that is defective and is causing device failure in implanted patients.

In March 2013 DePuy introduced its Attune system including procedures for implantation to surgeons and consumers.

As time goes on the Attune system is returning significantly higher failure rates than previous DePuy KTR systems due to the debonding of the tibial baseplate. As a result, thousands of knee replacement patients implanted with Attune systems have required or will require expensive and potentially dangerous knee revision surgery to remove and replace the defective Attune system which is currently in situ.

The Attune system fails for the most part due to mechanical loosening which is caused by a failure of the bond between the tibial baseplate at the implant cement interface. The attachment between the artificial knee and the existing bone becomes loose over time and with use, ultimately resulting in device failure.

When mechanical loosening does occur in an artificial knee this will generally cause pain and wearing away of the bone. Once mechanical loosening is diagnosed, the patient may require revision surgery to remove the knee implant and replace it with a new one.

Due to what can be severe bone loss caused by mechanical loosening of the defective device, revision surgeries are typically more complicated than index surgeries and the patient has a greater period of recovery. Risks and complications are higher, including increased pain and limitations in range of motion.

Since 2013 DePuy has been aware of issues with the Attune system through failure reports submitted to and kept in the FDA’s Manufacturer and User Facility Device Experience (MAUDE). Most related reports concern failures caused by Attune system design elements which caused loosening and/or de-bonding at the tibial baseplate cement/implant interface. These MAUDE reports detail a high incidence of aseptic loosening at the tibial baseplate of the Attune system resulting in subsequent revision surgeries.

As a result of the alarming failure rate and the subsequent revisions related to the Attune system, in March 2016, DePuy submitted a further FDA section 510 (k) premarket notice of intent to market the Attune Revised system, which included a new stem, with added length and a keel for additional stability and recessed cement pockets intended to promote cement fixation.

In June 2017 DePuy replaced the original Attune fixed base tibial baseplate with a new tibial baseplate as a result of the original baseplate’s inclination towards failure. However, to date, DePuy has not recalled the defective tibial baseplate.

Despite DePuy’s claims that the Attune system would be easier to implant than earlier generation TKR devices, after being notified of premature tibial baseplate failures, DePuy began alleging substandard surgical technique rather than the Attune system’s defects when worrying failure rates began to emerge.