Free Fragment

Sequestered Disc

Annular tear and irritated spinal nerve root
Annular tear and irritated spinal nerve root.

Free Fragment, Sequestered Disc - What's in a Name?

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.

Diagnosing Sequestered Discs

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.

Free fragments are sometimes reabsorbed by the body on their own. Other times, free fragments and sequestered discs are treated with a back surgery known as discectomy.

An Interesting Study Comparing Conservative Care for Sequestered Discs vs Large, Central Disc Herniations

But a study conducted by Ahn and associates published in the June 2002 issue of the Yonsei Medical Journal entitled, "Comparison of clinical outcomes and natural morphologic changes between sequestered and large central extruded disc herniations," found that conservative care may work well for cases of sequestered disc (as well as for those with large central extruded disc herniations.)

The study compared the changes in the disc size and other characteristics (called morphological changes) in each group to see which type of disc problem responded best to non-surgical treatment. Not only did the researchers review the MRIs of the patients, but they also administered tests and surveys to determine improvements following the treatments.

Seventeen of the 22 people in the study - 11 with sequestered discs and 6 with large, central disc extrusions - had positive outcomes with conservative treatment. 

The researchers reported that for 7 of the patients in the group with sequestrated discs herniated disc material disappeared altogether, and for the other 4,  their MRIs showed a definite decrease in the size of the free fragments.  On the other hand, in the group of patients with the central disc herniations, only 2 showed decreased in herniated disc material size.

The results of this study suggest that if you've been diagnosed with a sequestered disc (or even a large, centrally extruding herniated disc for that matter) and you feel your doctor is trying to rush you into back surgery, convincing her to give you a prescription to physical therapy first may be in your best interest.


Stadnick, M., MD. Free Disc Fragment. MRI Web Clinic. Jan 2004. Accessed: May 2010.

Vaccaro, A. Spine: Core Knowledge in Orthopedics. Elsevier/Mosby. 2005. Philadelphia.

Ahn SH1, Park HW, Byun WM, Ahn MW, Bae JH, Jang SH, Kim YK., Comparison of clinical outcomes and natural morphologic changes between sequestered and large central extruded disc herniations. Yonsei Med J. 2002 Jun;43(3):283-90.

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