Synovial Facet Cyst
A synovial facet cyst is a fluid-filled sac that develops from the lining of a facet joint in the spine. Typically caused by degenerative wear and instability, these cysts can protrude into the spinal canal or exit zone, compressing adjacent spinal nerves and causing severe radiating pain.
Symptoms
- Radiating pain down the back of the leg (sciatica) or into the buttock.
- Numbness, tingling, or weakness in the affected leg or foot.
- Lower back pain and stiffness near the degenerated joint.
- Pain that worsens when standing or walking and improves when sitting or bending forward (mimicking spinal stenosis).
- Symptoms that may fluctuate depending on the cyst's size and fluid volume.
Clinical anatomical model showing affected spinal structures (no text). Causes and risk factors
- Degenerative osteoarthritis of the facet joints causing breakdown of joint cartilage.
- Spinal instability (such as spondylolisthesis) causing increased friction and joint stress.
- Chronic inflammatory changes in the joint capsule leading to fluid overproduction.
- Age-related wear, most common in patients over 50 years.
How diagnosis is made
- Clinical neurological examination mapping radiating nerve pain.
- MRI of the lumbar spine (the gold standard for visualising the fluid-filled cyst and nerve compression).
- CT scan to assess associated bony changes or cyst calcification.
- X-rays to evaluate spinal stability and alignment.
Typical diagnostic grey-scale imaging scan (MRI/CT). Non-surgical treatment options
- Structured physiotherapy to support lumbar biomechanics.
- Epidural or facet joint corticosteroid injections to reduce inflammation and pain.
- Direct needle aspiration of the cyst fluid under CT guidance (temporary relief, high recurrence rate).
- Oral anti-inflammatory and neuropathic pain medications.
- Activity modification to avoid aggravating positions.
When surgery may be considered
Surgery is considered when a synovial facet cyst causes progressive leg weakness, persistent numbness, or severe radiating pain that does not respond to injections and conservative care. The surgical goal is to remove the cyst and decompress the nerve.
Expected outcomes
Surgical cyst removal provides immediate and dramatic pain relief in over 90% of patients. When joint instability is present, combining decompression with a minimally invasive fusion prevents recurrence and chronic back pain.
Rehabilitation pathways and safe movement restoration. Frequently asked questions
Can a synovial cyst disappear without surgery?
Occasionally, synovial cysts can rupture or spontaneously regress over time, leading to symptom relief. However, if severe nerve compression symptoms persist, surgical removal is recommended.