We can have better understanding of the “significant risk” by reviewing the FDA’s requirement to review all the adverse events. The medical device reporting regulation states that a serious injury is one that is life threatening, results in permanent impairment of a body function or body structure, and makes necessary medical/surgical intervention. Many companies often neglect the latter aspect and focus on if the patient died or was injured. However, MDR requires you to report if there was a medical/surgical intervention to prevent death or serious injury.

http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/ucm2005291.htm