Scar Tissue and Pain After Back Surgery

In back surgeries, scar tissue or epidural fibrosis is a collection of fibrous tissue that is formed around the surgically treated spinal nerve root. The fibrous tissue develops as a part of the body’s natural healing process after the surgery and may entrap or adhere to nerve roots and other neural tissues, causing post-surgical pain and dysfunction.

• Scar tissue is common after spine surgery. Research indicates that 24% to 100% of patients develop some degree of scar tissue after back surgery.
• Scar tissue can cause pain and long-term complications. Scar tissue can entrap or compress the nerve root, causing pain, which may sometimes be more severe than the pre-surgical symptoms.
  • Scar tissue is a common cause of failed back surgery syndrome (FBSS), with 20% to 36% of FBSS cases occurring due to pain from this fibrous tissue.
  • The bulk of scar tissue increases progressively with every revision surgery.
  • The presence of scar tissue around a nerve root can increase the risk of dural tears (tearing of the membranes surrounding the spine) in a revision surgery.
  • It is important to note that scar tissue does not always cause post-surgical pain; some patients may have epidural scarring but still have no pain or symptoms.

While the formation of scar tissue cannot be completely avoided, it can be minimized by following specific surgical procedures such as using a barrier between the nerve root and the healing tissues, preserving the fatty tissue around the surgically treated area, and reducing the accumulation of blood around the nerve roots.

When Scar Tissue Begins to Form

Scar tissue begins to form between 6 weeks to 6 months after surgery. By the third month after surgery, scar tissue can be identified on sensitive imaging tests, such as a magnetic resonance imaging (MRI) scan.

By 6 months after surgery, the formation of scar tissue stops, and typically no further changes occur after 12 months.

The severity of scar tissue can range from loose strings of fibrous tissue to dense, continuous fibrous material. Having multiple revision surgeries and back surgeries with spinal instrumentation has a higher likelihood of developing more severe scar tissue.

Scar Tissue and Back Pain

Scar tissue may be the cause of failed back surgery syndrome when a patient who initially feels well after a back surgery begins to experience recurrent pain slowly after 6 weeks post-surgery—the time period that scar tissue takes to form.

Scar tissue may directly or indirectly cause compression, inflammation, swelling, or decreased nutritional supply to the treated nerve roots through the following processes:

1. Scar tissue extends into the bony canal that contains the nerve root, making the nerve root adherent within this canal
2. Scar tissue can adhere to the dura mater—the outer layer of tissue that protects the spinal cord

Symptoms of spinal scar tissue include back pain, which may be accompanied by leg pain and numbness (radiculopathy). Some studies suggest that patients with severe scar tissue are 3.2 times more likely to develop leg pain and radiculopathy symptoms than those with mild scarring.

Pain that starts years after surgery or pain that continues immediately after surgery, is usually not from scar tissue.

Ways to Prevent the Formation of Scar Tissue

The methods to prevent scar tissue formation involve surgical processes and post-surgical interventions. Common methods include^,:

• Modifying surgical techniques to decrease the amount of post-surgical collection of blood (hematoma) by using suction drains
• Using a physical barrier (such as fatty tissue or synthetic materials) between the nervous tissue and the treated area
• Use of certain types of treatments after surgery, such as non-steroidal anti-inflammatory drugs (NSAIDs), and radiation

Surgeons may use a combination of these methods to prevent the formation of scar tissue. The use of fat grafts as a physical barrier is the most commonly adopted method for scar tissue prevention.