According to an FDA news release, there is a higher-than-expected risk of the polyethylene (plastic) component of the device breaking as early as three to four years after implantation of the STAR (Scandinavian Total Ankle Replacement), which can lead to surgery to repair or replace it.
The FDA’s analysis of post-approval studies and adverse event reports observed that the risk applies to all STAR ankle devices, regardless of manufacture or distribution date.
However, the FDA noted that the implant remains appropriate for certain patient populations, such as older patients with lower activity levels. Those with more active lifestyles, osteoarthritis or those aged younger than 55 years may have a higher risk of the plastic component breaking.
The FDA said that patients considering a STAR ankle implant should discuss all treatment options for painful arthritic ankle joints with healthcare providers.
Those who have a STAR ankle implant should speak to a healthcare provider if they encounter new worsening pain, inability to bear weight, new grinding or another noise or instability in the ankle implant. A healthcare provider may need to obtain X-rays to evaluate the issue and in some instances, they will use CT scans.
Based on the study, the plastic component fractured at a cumulative rate of 13.8% (12/87) at eight-year post-implantation, with all fractures requiring additional surgery. Fractures were observed as early as three to four years after implantation. Stryker acknowledged previous concerns over the fracture rate, but communications over the matter excluded devices manufactured after Aug. 1, 2014, when changes were made to the inner-pouch foil packaging, limiting the material degradation of the plastic component. Those changes followed a company warning over issues with plastic fractures in the implants in 2019.
Since 2009, at least 1,841 adverse events reports have been received for the STAR ankle. The FDA concluded that 300 of the reports cited fractured plastic components and included devices manufactured after that Aug. 1, 2014 cut-off.
Stryker provided the FDA data on 244 removed STAR ankle implants that showed 72 plastic component fractures. Most fractures showed material oxidation degradation after three to four years of implantation. The FDA stressed that this particular sample size was small.
The FDA said it is still working with Stryker to understand better the factors contributing to the issue. The two entities will work together to ensure patients and providers are aware of the potential risk of component fracture.