Patients who’ve received a STAR Ankle Replacement System should be alert for signs of polyethylene fracture, following a recent warning from Stryker.
The STAR Ankle Replacement System was developed by a prominent surgeon in Sweden, and is the first and only three-piece mobile bearing ankle implant approved for use in the United States.
STAR Ankle Replacements consist of three components:
The total ankle replacement system was initially marketed by Small Bone Innovations, which was acquired by Stryker in 2014.
In a letter to sent to doctors last month, Stryker warned that certain STAR Ankle Replacements were associated with a higher than expected rate of polyethylene fracture.
“This Safety Communication is based on identifying a13.79% polyethylene fracture rate at the eight-year follow-up in the STAR Total Ankle Replacement Post-Approval Study (PAS) for the device, and over 100 polyethylene fractures reported in the FDA (Medical Device Reporting) MDR database, both of which occurred substantially more often than comparable total ankle replacement and with fixed bearing total ankle replacements,” the October 11th letter stated.
The high fracture rate may be due to polyethylene oxidation, either before or after implantation, or implant geometry. Additional contributing factors may also include component malalignment, surgeon learning curve, and reduced insert thickness.
The issue affects STAR Ankle Replacement Systems distributed before August 2014. Because these components had a shelf-life of five years, they could have been implanted as recently as July 2019.
A STAR Ankle Replacement polyethylene fracture could lead to:
Patients who underwent STAR Ankle Replacement surgery in July 2019 or earlier should inform their doctor if they experience.
However, because symptoms of a polyethylene fracture are often subtle and can go unnoticed, doctors are advised closely monitor these patients as well. Those experiencing problems should undergo a detailed examination, including x-rays, to determine if all components are working as designed. However, CAT scans and other specialized imaging studies may be needed to determine if the polyethylene bearing has fractured.