Mechanical Back Pain and Ankylosing Spondylitis: Treatment and Diagnosis
Can You Still Have Ankylosing Spondylitis with Mechanical Pain?
Yes, you can still have ankylosing spondylitis even if your pain appears mechanical, because the two conditions can coexist and distinguishing them clinically is challenging. However, the response to NSAIDs provides a critical diagnostic clue: 75% of AS patients show good or very good response to full-dose NSAIDs within 48 hours, compared to only 15% of patients with pure mechanical back pain 1.
Key Distinguishing Features
Five clinical parameters help identify inflammatory (AS-type) versus mechanical pain:
- Improvement with exercise (suggests inflammatory) 2
- Pain at night that wakes you (suggests inflammatory) 2, 3
- Insidious onset (suggests inflammatory) 2
- Age of onset younger than 40 years (suggests inflammatory) 2
- No improvement with rest (suggests inflammatory) 2
Morning pain on waking strongly suggests inflammatory pain, while pain when lifting, bending, or later in the day suggests mechanical pain 3.
The Diagnostic Challenge
None of these factors strongly discriminate between the two conditions on their own 3. Many patients have overlapping features, and inflammatory markers (ESR, CRP) are not always elevated in AS 4. This is why the NSAID response test becomes diagnostically valuable: if you respond dramatically to full-dose NSAIDs within 48 hours, AS becomes much more likely 1.
Medications for Mechanical Back Pain
First-Line Treatment
NSAIDs are the primary medication for mechanical low back pain, with moderate evidence supporting their short-term effectiveness 5.
- Standard NSAIDs (ibuprofen, naproxen) provide moderate benefit 5
- Meloxicam (a COX-2 selective NSAID) can be used and may have fewer gastric side effects with long-term use 6
- Acetaminophen has little or no evidence of benefit for chronic mechanical low back pain 5
Second-Line Options
When NSAIDs are insufficient, contraindicated, or poorly tolerated:
- Opioids have moderate evidence for short-term use in mechanical low back pain 5
- Topiramate has moderate evidence for short-term treatment 5
- Gabapentin is particularly effective for radicular pain/sciatica with small to moderate short-term benefits 6
- Duloxetine (an antidepressant) has some evidence, though most other antidepressants do not 5
Medications with little or no evidence of benefit include:
If You Actually Have Ankylosing Spondylitis: Treatment Algorithm
Step 1: NSAIDs as Cornerstone Therapy
NSAIDs are the first-line pharmacologic treatment for all AS patients with pain and stiffness, with Level Ib evidence showing improvement in spinal pain, peripheral joint pain, and function 7, 1.
Continuous daily NSAID therapy is strongly preferred over intermittent "on-demand" use for persistently active disease, as continuous treatment may retard radiographic progression over 2 years 7, 1.
For patients with gastrointestinal risk factors (age >65, prior GI bleeding, concurrent corticosteroids):
- Use either a selective COX-2 inhibitor alone OR
- A non-selective NSAID plus a proton pump inhibitor (PPI) 7, 1
- COX-2 inhibitors reduce serious GI events by 82% (RR 0.18) 7
Consider cardiovascular risk when choosing between COX-2 inhibitors and traditional NSAIDs, as both may have cardiovascular toxicity 7, 1, 6.
Step 2: Add Physical Therapy Immediately
Physical therapy and regular exercise should be initiated at diagnosis and continued throughout the disease course as foundational treatment 7. This is non-negotiable and works synergistically with NSAIDs 1.
Step 3: When NSAIDs Fail—Anti-TNF Biologics
Anti-TNF therapy (infliximab, adalimumab, etanercept) should be started when you have persistently high disease activity (BASDAI >4 for >4 weeks) despite adequate NSAID trials (at least 2 NSAIDs for 3 months each at maximal tolerated dose) 1, 7.
Critical point: You do NOT need to fail conventional DMARDs (like methotrexate or sulfasalazine) before starting anti-TNF therapy for axial disease 1, 7. This is a common pitfall that delays effective treatment.
For patients with disease duration <10 years, 72% show at least 50% improvement with anti-TNF therapy 1.
Step 4: What NOT to Use for Axial Disease
Conventional DMARDs (sulfasalazine, methotrexate) have NO evidence of efficacy for axial/spinal AS and should NOT be used for spinal manifestations 1, 7.
- Sulfasalazine may be considered ONLY for peripheral arthritis (not spine) 1, 7
- Systemic corticosteroids have no evidence of benefit for axial disease and should be avoided 1, 7
Step 5: Adjunctive Pain Management
When NSAIDs are insufficient:
- Acetaminophen (paracetamol) or opioids may be added for pain control 1, 7
- Local corticosteroid injections into specific inflamed joints or enthesitis sites can be helpful 1, 7
Common Pitfalls to Avoid
Do not delay anti-TNF therapy by requiring failed DMARD trials in purely axial disease—this wastes time and allows disease progression 1, 7
Do not use systemic corticosteroids for axial symptoms—they lack efficacy and add toxicity 1, 7
Do not employ intermittent NSAIDs in persistently active disease—continuous therapy is superior for symptom control and may slow radiographic progression 7, 1
Do not prescribe methotrexate or sulfasalazine for axial disease—reserve sulfasalazine only for peripheral arthritis 1, 7
Do not assume mechanical pain rules out AS—the dramatic response to NSAIDs within 48 hours is your best clinical clue 1