Managing Low Back Pain from Annular Tears

The spine comprises of a column of vertebral bones intervening with intervertebral discs. (See diagram on the right) These discs play multiple roles including - shock absorption, allowing spine flexibility and movement, maintain disc height and contributing to spinal stability. In this blog, we discuss about the anatomy of the intervertebral disc, annular tears (a common cause of low back pain in young patients) as well as the treatment of this very painful condition. 

Anatomy of the Intervertebral Disc

The intervertebral disc is situated between the vertebral bodies of the spine, comprising a gel-like inner core called the nucleus pulposus and a robust outer layer known as the annulus fibrosus. The nucleus pulposus contains water-binding proteins and has a high water content, enabling it to absorb shock and withstand compressive forces. In contrast, the annulus fibrosus is composed of tough, concentric layers of collagen fibers, providing strength, elasticity, and protection for the nucleus pulposus.
​
Due to its limited blood supply, injuries to the annulus fibrosus may struggle to heal naturally. The disc is innervated by several nerves, including the sinuvertebral nerves, ventral rami, and grey rami communicantes, facilitating sensory and regulatory functions within the spinal structure.

Above: Lumbar disc consists of central gel-like nucleus pulposis and a tough outer annulus fibrosus.

Annular Tear

An annular tear occurs when there is damage or a rupture the annulus fibrosus. Annular tears are commonly associated with degenerative changes in the spine, traumatic injuries, or repetitive stress over time. These tears can cause back pain by irritation of nerves supplying the annulus fibrosus, Inflammation and Loss of disc function.

Symptoms of an Annular Tear

Annular tears are not always symptomatic. For example, in older adults who are asymptomatic, imaging of the lumbar spine may pick up such tears incidentally. However, in younger and middle-aged adults (particularly after acute trauma), these tears can cause severe localized back pain. The pain tends to worsen with movements that stress the disc, such as bending, twisting, or prolonged sitting.

Diagnosis of an Annular Tear

An annular tear causing low back pain is diagnosed via a combination of clinical evaluation, imaging studies and diagnostic injections. Clinical evaluation is based on history as well as features in your physical examination. The best imaging modality to appreciate an annular tear is a Magnetic Resonance Imaging. 

Not all annular tears are symptomatic. Therefore, the radiological findings of an annular tear does not mean that it is necessarily the cause of the pain. If there is significant doubt regarding the cause of the pain, your doctor may recommend that you undergo a test known as provocation discography. This study involves injection of the affected disc to see if the pain can be replicated. 

Treatment of Low Back Pain from an Annular Tear

The treatment of Annular tears follows the principles of the management of low back pain. While the care of the patient is highly individualized, most patients receive conservative treatment at the start. If the pain is well controlled with conservative treatment, no further action is necessary. Examples of conservative treatments include:

1. Medications
2. Physical therapy
3. Rest and activity modification
4. Preventing of re-injury (eg. limit weight lifting, twisting activites)
5. Weight management

In some patients, the pain persists for weeks to months after conservative treatment. In these patients, more invasive treatments may be warranted. A commonly performed treatment is Annuloplasty. In this procedure, needles are placed in the intervertebral discs and heat is applied across the discs. This procedure helps to denervate the disc and interrupt the barrage of pain signals entering the brain during activity. It can also help to seal up the annular tear in a significant proportion of patients who undergo this procedure.

Annuloplasty is a minimally invasive procedure where special needles are inserted into the discs (see above). These needles can produce heat which help to denervate the discs. This image-guided procedure is performed by a pain specialist in the operating room and under sedation.

If you suspect you have an annular tear, please make an appointment with Dr Christopher Liu who is based at Napier Pain Specialists, Gleneagles Hospital (Singapore).