Adjacent Segment Disease: Everything You Need To Know

The spine is a complex structure designed to be both mobile and stable. Conditions like degenerative disc disease and spinal stenosis may disrupt this balance, potentially contributing to pain, mobility limitations, instability, and dysfunction.

Spinal fusion is sometimes performed to stabilize problem areas in the spine by permanently joining vertebrae. However, this procedure may place added stress on adjacent spinal segments, which could lead to a condition called adjacent segment disease (ASD).

ASD may develop long after spinal fusion surgery as nearby vertebrae experience increased mechanical stress. A 2012 research indicates that ASD occurs in approximately  11-12% of cases within five years after surgery, and in 16-38% of cases within 10 years after the surgery.

Physicians in the licensed Regenexx network offer non-surgical options for managing ASD. Procedures Regenexx lab-processed injectates may be included in a personalized approach designed to support spinal function and help reduce stress on adjacent segments.

What Is Adjacent Segment Disease?

To understand ASD, it’s important first to understand the basic anatomy of the spine. The spine is a complex structure that supports movement, stability, and nerve protection. The accompanying video offers a visual representation of the key spinal components.

The human spine consists of:

• Vertebrae: The spine is made up of 24 movable vertebrae that form a column, extending from the neck (cervical spine) to the lower back (lumbar spine).
• Intervertebral discs: These are gel-filled structures that sit between adjacent vertebrae, helping to absorb shock and provide flexibility.
• Facet joints: Small joints at the back of the vertebrae that help facilitate controlled movement and stabilize the spine.
• Spinal canal: A protective passage that houses the spinal cord, which transmits signals between the brain and body.
• Ligaments and muscles: These tissues hold the vertebrae together and support proper spinal alignment and movement.

The spine’s natural curves—outward in the thoracic region and inward in the cervical and lumbar regions—help distribute body weight and maintain balance.

Age-related degeneration, injuries, and diseases may contribute to spinal instability, pain, and mobility issues. Spinal fusion is sometimes recommended for severe instability or conditions that cause persistent pain or nerve-related symptoms. During the procedure, the intervertebral disc is removed, and the vertebrae are permanently joined with hardware such as screws, rods, or plates.

While spinal fusion may help relieve pain, it can also place additional stress on nearby segments, which may contribute to ASD. ASD may lead to:

• New or worsening back pain
• Reduced flexibility or range of motion
• Degeneration or instability in nearby spinal levels

A 2014 review of 41 PubMed articles reported ASD occurrences of 3% in the cervical spine and between 2% and 14% in the lumbar spine. A 2021 study involving 119 patients found that 33.3% of those who underwent lumbar fusion later showed signs of ASD, with comparable rates between open (31.8%) and minimally invasive (34.9%) procedures.

Other Challenges Faced By Post-Fusion Patients

While spinal fusion may be necessary in select cases of severe instability, it has been associated with certain challenges and risks. Many patients who undergo fusion may experience complications, including:

• The need for revision surgeries. A 2019 study reported that 8–45% of spinal fusion patients underwent additional surgery due to issues such as implant failure, infection, or adjacent segment degeneration.
• Long-term reliance on opioids for pain management. A 2018 study found that nearly 50% of lumbar spinal fusion patients continued using opioids three months post-surgery, with 40% still using them at six months, 30% at one year, and 17% at two years.
• Permanent damage to critical stabilizing muscles. Spinal surgery may affect stabilizing muscles, such as the multifidus muscle, which plays a role in maintaining spinal alignment. A 2023 study linked multifidus changes to the development of ASD.
• High surgical costs with minimal or no long-term improvement. Spinal fusion may contribute to additional stress on adjacent segments, which should be carefully considered when evaluating treatment options.

Identifying Possible Triggers And Causes

ASD may develop as a long-term consideration following spinal surgery, particularly spinal fusion surgery. Research published in 2018 and 2020 suggests that the following factors may contribute to ASD:

• Fusion length: Longer fusion surgeries, such as those involving multiple segments, increase stress on nearby spinal levels, raising the risk of ASD.
• Age and pre-existing degeneration: Longer fusion surgeries, such as those involving multiple segments, may increase stress on nearby spinal levels, which could raise the likelihood of ASD.
• Lifestyle factors: High BMI, smoking, and hypertension may place additional strain on the spine and could contribute to ASD risk, making lifestyle management an important consideration.
• Surgical techniques: Surgical alignment and height adjustments may play a role in postoperative spine stability. 
• Biomechanical stress: Fusion surgery may alter how the spine absorbs stress, which could accelerate wear in adjacent segments. Balance and mobility exercises may be beneficial after surgery.
• Spine and posture issues: Degeneration or alignment factors affecting the spine and pelvis before surgery may influence ASD risk. A 2017 study linked misalignment to an increased rate of complications.

Recognizing The Signs And Symptoms

ASD may develop gradually, and symptoms can sometimes appear years after spinal fusion surgery. These symptoms may be linked to added stress and changes in the spinal segments adjacent to the fusion site. As nearby segments undergo degeneration, they may contribute to nerve irritation, causing a variety of issues.

Common signs and symptoms that may be associated with ASD include:

• Nerve Compression – Changes in discs and joints may lead to inflammation and bony growths, such as bone spurs, which can narrow nerve passageways. Depending on the affected area, this may contribute to sharp, radiating pain in the back or limbs.
• Numbness Or Tingling – Compressed spinal nerves may affect sensory signals, which could result in numbness, tingling, or a prickling sensation, especially in the arms or legs.
• Muscle Weakness – Prolonged nerve compression may impact motor signals, potentially leading to muscle weakness, balance difficulties, and challenges with everyday activities.

How Is Adjacent Segment Disease Diagnosed?

Physicians use several diagnostic tools to help differentiate ASD from other spinal conditions and assess potential changes in adjacent spinal segments. These tools include:

• MRI, X-ray, or CT scans: Imaging plays a crucial role in evaluating spinal health:
  • X-rays may reveal structural changes, such as bone spurs or alignment variations in adjacent segments.
  • MRI scans provide images of soft tissues, including intervertebral discs and nerves, which may help identify disc degeneration or nerve compression.
  • CT scans offer high-resolution views of the bones, potentially detecting arthritis in facet joints or other bony changes, such as fractures.
• Symptom history:A review of the patient’s symptoms helps physicians determine whether reported discomfort may be associated with adjacent segments rather than the fused area. Pain that arises years after fusion surgery and worsens with activity may be explored as a potential indicator of ASD.
• Physical examination: Physicians assess posture, mobility, and areas of discomfort during movement to evaluate possible mechanical stress on adjacent spinal levels.
• Neurological exam: These examinations may include testing reflexes, muscle strength, and sensory responses to help assess nerve function and determine whether changes may be linked to degeneration.

Treatment Options Available For Adjacent Segment Disease

Depending on the severity of symptoms and individual patient needs, options for managing ASD may range from non-invasive therapies to advanced interventional orthobiologic techniques and surgical interventions.

Common approaches to managing ASD include:

• Medication – Medications, including muscle relaxants, may help manage symptoms such as muscle spasms and stiffness that may be associated with ASD.

• Physical Therapy – A structured physical therapy program is often recommended to help strengthen the muscles surrounding the spine, improve flexibility, and support proper posture.

• Decompression Surgery – In cases where conservative measures do not provide sufficient relief, decompression surgery may be considered to help relieve pressure on spinal nerves that may be affected by degenerative changes in ASD.
  
• Artificial Disc Replacement: Artificial disc replacement is a surgical procedure that removes a damaged spinal disc and replaces it with an artificial one to maintain mobility and relieve nerve compression. While it is an alternative to spinal fusion for certain patients, risks may include implant wear, limited long-term data, or potential complications requiring revision surgery.

Manage Adjacent Segment Disease Without Surgery

Physicians in the licensed Regenexx network offer interventional orthobiologic procedures as part of a non-surgical approach to supporting spinal function and mobility.

Regenexx lab-processed injectates, such as platelet-rich plasma (PRP) and bone marrow concentrate (BMC), may be included in personalized care plans based on a physician’s evaluation. These procedures are designed to support the body’s natural repair processes, help manage symptoms, and promote joint function as a less invasive option to surgery.

To determine whether a procedure using Regenexx lab processes may be appropriate for your condition, consult with a physician in the licensed Regenexx network. Exploring these non-surgical options may help support spinal health while reducing reliance on surgical interventions.