The annulus fibrosus is the strong wrapping that makes up the outside portion of the intervertebral disc. Its job is to contain and protect the soft material located in the center of the disc. This soft center is called the nucleus pulposus. The nucleus pulposus (and the entire intervertebral disc) provides shock absorption for the spine.
The annulus, as it is called for short, consists of several concentric rings of fibrous cartilage oriented on a diagonal angle. Fibers of each separate layer of the annulus run at a right angle to the fibers in the ring next to it. This scaffolding design increases the strength of the annulus fibrosus as a whole, allowing it to fulfill its purpose as a container for the nucleus pulposus.
One common injury to the annulus is a tear. Tears can be either painful or asymptomatic. Annular tears sometimes lead to bulging or herniated discs, but not always.
Quite often, a tear can be successfully treated without surgery; in other words, physical therapy, exercise, holistic therapies, and medication may be enough to relieve your symptoms.
Most of the time, medical treatments for the intervertebral disc are focused on containing (or clearing away pieces of) the nucleus pulposus.
But more recently, scientists and clinicians have been working on ways to strengthen and/or repair the annulus. According to a March 2009 article by Bron, et. al. published in the European Spine Journal, a new regenerative approach that focuses on the integrity of fibers of the annulus themselves may be necessary in order to prevent re-herniation. The authors that say strengthening and repairing the annulus may actually increase the potential of nucleus pulposus repair. Without repair and strengthening, they continue, normal amount of disc pressure (which is necessary for the disc’s main task of shock absorption) cannot be restored.
This new direction is in its infancy, which means while there’s been testing on animals, treatments that work on people are still a long way out. Meanwhile, here is Bron, et. al.’s list of potential approaches to annulus fibrous strengthening and repair.
The Surgical Approach to Annulus Repair
Suturing, according to Bron, et. al. is designed to contain the nucleus pulposus in a disc replacement surgery. But it doesn't restore lost fibers, nor does it reverse any damage. The researchers say a number of products are already in use during surgery that address some of these issues; just the same, they task future researchers to come up with and perfect even more effective methods.
Annulus Fibrosus Regeneration
Regenerating the fibers of the annulus, by means of tissue engineering, is in some ways, according to Bron, et. al., a better solution than suturing. The problem is, it’s much more difficult for scientists to pull off. The 3 types of techniques that are in the works are: Generating annulus cells, using gene and bio-active factors to influence extracellular matrix productions, and scaffolding.
Ideally, the researchers say, an annulus regeneration strategy will combine techniques that close the tear and regenerate the tissue at the same time. They also say that gene and bio-active strategies cannot be used as standalone treatments, but rather in combination with scaffolding.