A free fragment (also known as a sequestered disc) is a piece of a spinal disc that breaks away from the main disc structure and escapes through a tear in the annulus. The free fragment often travels out the side of the disc and then up or down. Once outside the disc, the fragment may cause pain, pins and needles, weakness, numbness or other symptoms (called radiculopathy) if it presses on a nerve root.
A free fragment can be hard to diagnose. An MRI may be taken to help the doctor see the fragments.
There are two types of MRIs - T1 weighted and T2 weighted. The T1 weighted allows the doctor to discern between the free fragment and the adjacent fat inside the epidural space. For this reason, the T1 weighted MRI is key for diagnosing a sequestered disc.
Stadnick, M., MD. Free Disc Fragment. MRI Web Clinic. Jan 2004. Accessed: May 2010. http://www.radsource.us/clinic/0401.
Vaccaro, A. Spine: Core Knowledge in Orthopedics. Elsevier/Mosby. 2005. Philadelphia.