STAR Ankle Component Fracture: Awareness, Not Alarm

OrthoBuzz occasionally receives posts from guest bloggers. In response to a recent “safety communication” from the FDA, the following commentary comes from Ariel Palanca, MD; Adam Bitterman, DO: and Christopher Gross, MD.

During the past decade, total ankle replacement (TAR) has been challenging the gold standard of ankle fusion for treatment of end-stage ankle arthritis. Improvements in TAR component design and refined surgical techniques have led to more predictable and reproducible outcomes.

On March 15, 2021, however, the US Food and Drug Administration (FDA) released a Safety Communication about the Scandinavian Total Ankle Replacement (STAR Ankle), a product line that DJO Surgical acquired from Stryker in November 2020. The FDA’s statement cites a “higher than expected” rate of fracture of the device’s mobile-bearing polyethylene component. The communication goes on to suggest that patients younger than 55 years old and those with an active lifestyle may have a higher risk of component fracture than older, more sedentary patients.

The STAR Ankle received premarket approval from the FDA in 2009, and the FDA is compiling data from 2 post-approval trials of the device. In August 2019, Stryker issued a safety notification regarding the higher-than-expected fracture risk for STAR polyethylene implanted before August 2014. The recent FDA safety notification states there may also be a high risk of fracture for STAR polyethylene components implanted after August 2014, although the agency’s notification acknowledges that “the long-term fracture rate is not known in devices manufactured after the 2014 packaging change.”

The “packaging change” mentioned above refers to the August 2014 changeover when STAR polyethylene started to be packaged in a foil pouch, which virtually eliminates oxidation of the polyethylene and should therefore reduce fracture rates. Additionally, many peer-reviewed journal articles have reported lower STAR-component fracture rates than those found in the post-approval trials at equal or longer follow-ups.

It’s also important to note that the 8-year follow-up FDA study that revealed a 13.8% cumulative polyethylene-fracture rate only included 87 of the 606 STAR patients in the clinical trial. Patients with complications are often more likely to follow up than those with no complications, creating a potential negative bias.

Still, to err on the side of caution, the FDA suggests that surgeons who treat and follow patients with a STAR implant closely monitor them–especially younger, more active patients–for potential component fractures until more post-approval data is analyzed to further clarify any risk.

Ariel Palanca, MD is an orthopaedic foot and ankle surgeon at Arch Health Medical Group in Escondido, California. Adam Bitterman, DO (@DrAdamBitterman) is a foot and ankle specialist, an assistant professor of orthopaedic surgery at Zucker School of Medicine at Hofstra/Northwell, and a member of the JBJS Social Media Advisory Board. Christopher Gross, MD is an orthopaedic surgeon specializing in foot and ankle disorders at the Medical University of South Carolina in Charleston and a member of the JBJS Social Media Advisory Board.

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