Evaluation of Back Pain – A Pain Generator–Based Clinical Approach
By Daradia: The Pain Clinic, Kolkata (Center for Excellence in Pain Medicine)
Evaluation of Back Pain: Identifying the True Pain Generator
Back pain is not a single disease. It is a symptom arising from multiple anatomical structures known as pain generators.
At Daradia: The Pain Clinic, we emphasize a pain generator–based evaluation rather than generic labels such as “lumbar spondylosis” or “mechanical back pain”.
This approach allows:
- Accurate diagnosis
- Rational use of imaging
- Targeted interventional treatment
- Better patient education
- Improved long-term outcomes
This page explains how to evaluate back pain clinically by identifying the true anatomical source of pain.
Why Pain Generator–Based Evaluation is Superior
Traditional back pain evaluation often relies heavily on MRI findings, which frequently show abnormalities even in asymptomatic individuals.
A pain generator–based approach:
- Correlates symptoms with anatomy
- Reduces over-diagnosis
- Prevents unnecessary procedures
- Improves success of interventional treatments
- Helps differentiate mechanical, inflammatory, neuropathic and sinister pain
Step-by-Step Clinical Evaluation of Back Pain
Step 1 – Pain Localization (Where exactly is the pain?)
Ask the patient to point with one finger:
- Midline lumbar pain
- Paraspinal pain
- Buttock pain
- Groin or anterior thigh pain
- Leg pain (radiating or diffuse)
Clinical importance
| Location | Likely pain generator |
|---|---|
| Midline lumbar | Disc / vertebral body |
| Paraspinal | Facet / muscles |
| Buttock | SI joint |
| Groin | Hip joint |
| Dermatomal leg | Disc prolapse |
| Diffuse leg pain | Stenosis / facet / SI |
Step 2 – Pain Behavior Pattern (When does pain increase or reduce?)
Key discriminators:
- Sitting vs standing
- Walking tolerance
- Flexion vs extension
- Night pain
- Effect of posture
- Cough / strain
- Relief with rest or sitting
These patterns strongly indicate the underlying pain generator.
Step 3 – Screen for Red Flags (Always mandatory)
Urgent evaluation is required if any of the following are present:
- Progressive neurological deficit
- Bowel or bladder dysfunction
- Saddle anesthesia
- Fever, immunosuppression
- History of malignancy
- Unexplained weight loss
- Significant trauma
- Constant night pain
- Age >60 with new onset pain
Major Pain Generators in Low Back Pain
1. Intervertebral Disc as Pain Generator
Disc-related pain occurs in three main forms:
- Internal disc disruption (discogenic pain)
- Disc prolapse (radiculopathy)
- Lumbar canal stenosis
A. Internal Disc Disruption (Discogenic Back Pain)
Pathophysiology
Degeneration and fissuring of the annulus fibrosus activate nociceptors within the disc.
Clinical features
- Predominant low back pain
- Pain worse with sitting
- Increased with bending and lifting
- Reduced with unloading or lying down
- Vague buttock pain may occur
- No neurological deficits
Diagnostic clues
- “I cannot sit for long”
- Pain on rising from sitting
- Mechanical loading sensitivity
B. Disc Prolapse (Lumbar Radiculopathy)
Pathophysiology
Nerve root compression or chemical irritation.
Clinical features
- Leg pain > back pain
- Dermatomal radiation
- Tingling or numbness
- Worse with standing, walking, coughing
- Often relieved by lying down or sitting
Examination findings
- Positive SLR / slump test
- Sensory or motor deficit
- Altered reflexes
C. Lumbar Canal Stenosis
Pathophysiology
Neural ischemia during standing and walking due to canal narrowing.
Clinical features
- Leg pain on walking (neurogenic claudication)
- Relief on sitting or bending forward
- Worse with standing or extension
- May coexist with back pain
Key differentiator
Relief is position-dependent, unlike vascular claudication.
Disc pain patterns summary
| Condition | Dominant symptom | Worse with | Better with |
|---|---|---|---|
| Discogenic pain | Back pain | Sitting | Lying down |
| Disc prolapse | Leg pain | Standing, walking | Rest |
| Canal stenosis | Walking leg pain | Standing | Sitting, flexion |
2. Facet Joint as Pain Generator
Causes
- Degeneration
- Inflammation
- Trauma
Clinical features
- Predominant back pain
- Non-dermatomal leg pain possible
- Worse with extension, rotation, lateral bending
- Relieved with sitting and forward bending
- Pain decreases on walking
- No neurological deficits
Examination
- Pain on extension-rotation loading
- Paraspinal tenderness
- Reduced extension tolerance
3. Sacroiliac (SI) Joint as Pain Generator
Causes
- Degeneration
- Inflammation
- Trauma
- Malignancy
Clinical features
- Localized buttock pain
- Non-dermatomal leg pain
- Pain worse with sitting
- Relief on standing or walking
- No neurological deficit
Examination
- SI provocation test cluster
- Always rule out hip pathology
4. Muscles as Pain Generator (Myofascial Pain)
Causes
- Repetitive strain
- Trauma
- Prolonged spasm
- Postural overload
- Rarely malignancy
Clinical features
- Aching, tightness
- Trigger points
- Worse after prolonged posture
- Improves with movement and heat
- Associated with stress, poor ergonomics
5. Ligaments as Pain Generator
Causes
- Sprain
- Trauma
- Enthesitis
Clinical features
- Focal pain
- Movement-specific aggravation
- Localized tenderness
6. Vertebral Body as Pain Generator
Causes
- Compression fracture
- Malignancy
Clinical features
Fracture
- Sudden pain after minor trauma
- Severe localized tenderness
- Worse with standing
Malignancy
- Constant deep pain
- Night pain
- Progressive course
- Systemic symptoms
7. Bursae as Pain Generator
Causes
- Trauma
- Inflammation
Clinical features
- Focal positional pain
- Local tenderness
- Often lateral hip region
8. Hip Joint – A Common Mimic of Back Pain
Causes
- Osteoarthritis
- Inflammatory arthritis
- Trauma
Clinical features
- Groin pain
- Anterior thigh pain
- Pain on walking, stairs
- Reduced hip internal rotation
Rule:
Always examine the hip in every back pain patient.
Quick Clinical Pattern Recognition Table
| Patient complaint | Most likely source |
|---|---|
| Pain worst on sitting | Discogenic |
| Leg pain dominates | Disc prolapse |
| Leg pain on walking | Canal stenosis |
| Pain on extension | Facet |
| Local buttock pain | SI joint |
| Groin pain | Hip |
| Severe focal tenderness | Fracture |
Clinical Workflow
- Structured pain history
- Pattern recognition
- Focused examination
- Pain generator identification
- Targeted imaging if required
- Individualized treatment plan
Frequently Asked Questions (SEO FAQ section)
What is the most common cause of chronic low back pain?
Disc degeneration and facet joint arthropathy are the most common mechanical causes.
Can MRI alone diagnose back pain?
No. MRI findings must be correlated with clinical pain patterns.
Is SI joint pain common?
Yes. SI joint accounts for 15–25% of chronic low back pain cases.
Why does back pain improve when sitting in stenosis?
Flexion increases spinal canal diameter, reducing neural compression.
Conclusion
Back pain evaluation should not begin with MRI. It should begin with clinical identification of the pain generator.
A structured, pain generator–based approach:
- Improves diagnostic accuracy
- Enhances treatment success
- Reduces unnecessary procedures
- Improves patient satisfaction
