Why Does My Leg Still Hurt After Disc Surgery?
If pain persists after surgery, there may have been a different cause from the beginning. Research shows that approximately 27% of patients with persistent post-surgery pain actually had cutaneous nerve entrapment as the cause.
Why Pain Persists After Spinal Surgery
When leg pain continues after disc surgery or spinal decompression, it’s called ‘Failed Back Surgery Syndrome (FBSS)’. This usually occurs for the following reasons.
1. The Disc Was Not the Cause From the Beginning
Although MRI showed disc herniation, the actual pain may have been caused by nerve compression elsewhere. Research showing that many people with disc herniation have no pain supports this.
2. Cutaneous Nerve Entrapment Was Also Present
Separate from the disc problem, there may have been cutaneous nerve entrapment where peripheral nerves are compressed by muscles or ligaments in the buttocks, pelvis, or thighs.
3. New Problems Developed After Surgery
Adhesions or scar tissue from the surgical process may compress surrounding nerves, or posture changes after surgery may increase burden on other areas.
Important Fact
30-40% of normal people show disc herniation on MRI but have no symptoms. What appears on MRI cannot be definitively concluded as the cause of pain.
What Is Cutaneous Nerve Entrapment?
Cutaneous nerve entrapment is when nerves from the lumbar spine are compressed by muscles, ligaments, or bones not at the spine but elsewhere (buttocks, pelvis, thighs, etc.).
Why Is Diagnosis Difficult?
- It doesn’t show on MRI. A spinal MRI only images the spine, so peripheral nerve compression cannot be identified.
- The symptoms look alike. It causes leg pain that radiates just like a disc problem, which is why it is sometimes called pseudo-sciatica.
- It is easy to overlook. Many doctors assume lower-limb pain means a disc and don’t consider other possibilities.
How Are Disc and Cutaneous Nerve Entrapment Different?
| Criteria | Disc (Nerve Root Compression) | Cutaneous Nerve Entrapment |
|---|---|---|
| Pain Location | Entire dermatome (broad and vague) | Specific nerve territory (narrow and clear) |
| Muscle Weakness | Present (ankle, knee, etc.) | Absent (pure sensory nerve) |
| Reflex Test | Decreased or absent | Normal |
| Aggravating Factors | Coughing, sneezing, sitting | Specific postures, local compression |
| Tender Points | Lower back centered | Buttocks, pelvis, inguinal region, etc. |
| MRI Findings | Disc herniation confirmed | Normal (periphery not visible) |
Common Cutaneous Nerve Entrapment Sites
Representative cutaneous nerve entrapment sites that cause leg pain.
Upper Buttock (Superior Cluneal Nerve)
This causes upper buttock pain that radiates down the back of the thigh, much like sciatica. The tender point sits on the iliac crest, the top of the pelvic bone lateral to the spine, and can usually be pinpointed with a single finger. Symptoms tend to worsen with back extension, prolonged standing, and walking.
Lateral Thigh (Lateral Femoral Cutaneous Nerve)
This brings burning pain, numbness, and reduced sensation over the outer thigh. The tender point lies at the lateral inguinal region, near the groin. It tends to worsen with tight pants or a belt, prolonged standing, obesity, and pregnancy.
Medial Knee (Saphenous Nerve)
This produces pain running from the inner knee down to the inner ankle. The tender point sits on the inner thigh, about 10cm above the knee, and it tends to worsen when climbing stairs or with repetitive leg movements.
Lateral Calf (Peroneal Nerve)
This makes it hard to lift the ankle upward, known as foot drop, along with numbness on the outer calf. The tender point is at the outer knee, around the fibular head. If ankle inversion strength stays normal, the cause is cutaneous nerve entrapment rather than a disc problem, which would also weaken it.
How Is It Diagnosed?
1. Thorough Physical Examination
Press specific points along the nerve pathway to see if the familiar pain is precisely reproduced. If there’s a tender point identifiable with one finger, cutaneous nerve entrapment is likely.
2. Strength and Reflex Testing
Check ankle dorsiflexion, knee extension strength, knee reflex, etc. If all are normal, it’s likely cutaneous nerve entrapment as pure sensory nerve.
3. Muscle Response Testing
If testing the suspected area’s muscles causes tingling elsewhere, it signals that muscle is compressing the nerve.
4. Diagnostic Nerve Block
Confirm the suspected area with ultrasound and inject a small amount of anesthetic. If pain immediately decreases by over 70%, that location is confirmed as the cause.
Resolution With Circulation Therapy Without Surgery
Cutaneous nerve entrapment does not require surgery. Release adhesions and tension around the nerve and remove compressive factors.
Stage 1: We bring the swelling down
Circulation HD gently releases muscle and fascial adhesions around the nerve, creating space for free nerve movement.
Stage 2: We wake the muscles up
Circulation PT awakens weakened pelvic and lumbar muscles to restore support so nerves aren’t compressed.
Stage 3: We make the movement stick
Correct posture and movement patterns to prevent nerve re-compression in daily activities.
Diagnostic Nerve Block + Treatment
Ultrasound-guided nerve block confirms the cause and provides simultaneous therapeutic effect. Combined with Circulation Therapy, it is even more effective.
Signs That Point to Cutaneous Nerve Entrapment
- Pain persists over 6 months after disc surgery
- MRI shows normal disc but leg hurts
- Pain area can be precisely pointed to with one finger
- Pressing specific area causes radiating tingling to leg
- Ankle and knee strength and reflexes are normal but sensation is abnormal
- Moving lower back doesn’t significantly change pain
- Coughing or sneezing doesn’t worsen pain
Related Questions
References
- Daniell JR, Osti OL. Failed back surgery syndrome: a review article. Asian Spine J. 2018;12(2):372-379.
- Chan CW, Peng P. Failed back surgery syndrome. Pain Med. 2011;12(4):577-606. PMID 22337598
- Thomson S. Failed back surgery syndrome — definition, epidemiology and demographics. Br J Pain. 2013;7(1):56-59.
- Rigoard P, et al. Multicolumn spinal cord stimulation for refractory failed back surgery syndrome. Pain. 2019;160(7):1560-1571.
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