Adjacent Segment Disease
Breakdown of the spine level next to a previous fusion
Quick Facts
- Type: Degenerative spine condition
- Affects: Segment next to a spinal fusion
- Cause: Extra stress after fusion plus aging
- Symptoms: New back, neck, or nerve pain
Overview
Adjacent segment disease is degeneration or breakdown of the spinal level immediately above or below a previous spinal fusion. When two or more vertebrae are fused together, that section of the spine no longer moves. The neighboring segments may then take on extra movement and stress, which over time can accelerate wear and tear there.
It is a recognized cause of new symptoms after spine surgery and is closely related to the natural age-related changes that occur in everyone's spine. Distinguishing the effect of the fusion from normal aging can be difficult, since the adjacent level might have degenerated anyway. Adjacent segment disease ranges from changes seen only on scans, with no symptoms, to significant new pain or nerve problems that require treatment.
Symptoms
Symptoms usually develop months or years after the original fusion and resemble those of other degenerative spine conditions at the affected level.
- New or recurring back or neck pain, often near a previous fusion
- Stiffness and reduced movement
- Pain, numbness, tingling, or weakness spreading into an arm or leg if a nerve is compressed
- Pain that worsens with activity or certain positions
- In the neck, symptoms may include arm pain or hand clumsiness; in the lower back, leg pain or difficulty walking
Causes
The condition arises from a combination of mechanical and age-related factors:
- Increased stress after fusion: the segments next to a fused area may move and load more, accelerating wear on discs and joints.
- Natural aging: discs dry out and thin, joints develop arthritis, and bone spurs form, processes that affect everyone over time.
- Pre-existing degeneration: the adjacent level may already have been wearing before surgery.
- Spinal alignment: changes in the overall balance of the spine after fusion can add stress.
Because aging affects the whole spine, it is often hard to know how much of the change is due to the fusion itself.
Risk Factors
- Previous spinal fusion, especially of multiple levels
- Older age
- Pre-existing degeneration at the neighboring level
- Poor spinal alignment
- Smoking
- Obesity and high physical demands on the spine
- Osteoporosis
Diagnosis
Diagnosis combines the pattern of new symptoms with imaging of the spine.
- History and examination: identifying new pain or nerve symptoms and where they point, with tests of strength, sensation, and reflexes.
- X-rays: to assess alignment, disc height, and the previous fusion, sometimes in different positions.
- MRI: to view discs, nerves, and the spinal canal at the adjacent level.
- CT scan: for detailed bone images and to assess the fusion.
Findings are always interpreted alongside symptoms, since degeneration on a scan does not always cause pain.
Treatment
As with other degenerative spine problems, most people are managed without surgery, and surgery is considered only for significant, persistent symptoms or nerve compression.
- Physiotherapy and exercise: to strengthen supporting muscles, improve posture, and maintain mobility.
- Pain relief: simple painkillers and anti-inflammatory medicines.
- Activity modification: adjusting activities that aggravate the pain.
- Injections: such as epidural or nerve root injections for targeted relief of nerve pain.
- Surgery: may involve decompressing a pinched nerve or extending the fusion to the affected level, reserved for cases that do not respond to other care.
Prevention
It is not always possible to prevent adjacent segment disease, but several measures support spine health and may reduce risk or severity:
- Keep the back and core muscles strong with regular exercise
- Maintain good posture and use safe lifting techniques
- Maintain a healthy weight
- Do not smoke
- Treat osteoporosis to keep bone strong
- Attend follow-up and report new symptoms early
When to See a Doctor
See your doctor or surgeon if you develop new or worsening back or neck pain, or new nerve symptoms, after a previous spinal fusion, so the cause can be assessed. Seek urgent or emergency care if you experience:
- New or worsening weakness or numbness in an arm or leg
- Problems with balance, walking, or hand coordination
- Loss of bladder or bowel control
- Numbness around the groin or buttocks
Frequently Asked Questions
What is adjacent segment disease?
It is degeneration of the spinal level next to a previous fusion. Because the fused section no longer moves, the neighboring segment can take on extra stress and wear out faster, sometimes causing new pain or nerve symptoms months or years after surgery.
Is adjacent segment disease caused by the fusion or just aging?
It is often a mix of both. Fusion places extra stress on the neighboring level, but the whole spine also ages naturally, and that segment might have degenerated anyway. It can be difficult to separate the two, which is why findings are interpreted alongside symptoms.
Does adjacent segment disease always need more surgery?
No. Most people are managed without surgery using physiotherapy, exercise, pain relief, and sometimes injections. Surgery, such as decompressing a nerve or extending the fusion, is considered only for significant or persistent symptoms or nerve compression.
How soon after fusion can adjacent segment disease develop?
It usually develops gradually over several years, though the timing varies. Some people never develop symptoms, while others notice new pain or nerve symptoms at the neighboring level over time. Regular follow-up helps detect changes early.
When is leg or arm pain after fusion an emergency?
Seek emergency care for new or worsening weakness or numbness in a limb, loss of bladder or bowel control, numbness around the groin, or problems with walking or coordination. These can indicate serious nerve or spinal cord compression.
References
- American Association of Neurological Surgeons (AANS).
- North American Spine Society (NASS).
- Mayo Clinic. Spinal fusion and degenerative spine disease.
- MedlinePlus, U.S. National Library of Medicine.