Need an Ankylosing Spondylitis Nexus Letter?
REE Medical rheumatology and spine specialists document AS service connection, ROM limitation, and systemic manifestations in nexus letters covering DC 5240 rating criteria.
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Ankylosing spondylitis is a chronic seronegative spondyloarthropathy — an inflammatory autoimmune disease primarily affecting the axial skeleton (spine and sacroiliac joints). The inflammatory process causes new bone formation at the entheses (where tendons and ligaments attach to bone), progressively fusing the vertebrae and sacroiliac joints over time. The classic radiographic end-stage appearance — "bamboo spine" — represents complete spinal fusion from vertebral syndesmophyte bridging.
Key clinical features of AS relevant to VA claims:
VA rates ankylosing spondylitis under DC 5240 in 38 CFR Part 4, using the same range of motion criteria applied to other thoracolumbar spine conditions. The same forward flexion measurement determines the rating level.
However, AS is also distinct in that it can produce complete spinal ankylosis — which carries ratings significantly higher than the maximum achievable through ROM limitation alone. The progression from active inflammation to fusion over years creates a natural rating increase trajectory as the disease advances.
| Forward Flexion (Thoracolumbar) | Rating |
|---|---|
| Greater than 60° | 10% |
| 30° to 60° | 20% |
| Less than 30° | 40% |
| Favorable ankylosis of thoracolumbar spine | 40% |
| Unfavorable ankylosis of thoracolumbar spine | 50% |
| Unfavorable ankylosis of entire spine | 100% |
For veterans in the inflammatory phase of AS (before significant ankylosis), the ROM rating fluctuates with disease activity. During active inflammatory flares, ROM may be severely restricted. The painful motion rule (38 CFR § 4.59) is particularly important for AS because pain is constant and present throughout ROM — VA must account for painful motion even when flexion is borderline at each threshold.
Unlike degenerative spinal conditions, AS has a predictable progression toward increasing spinal fusion. Veterans with early or moderate AS should document their condition comprehensively at each examination and understand that future re-examinations may result in rating increases as ankylosis progresses. Proactively requesting re-evaluation when symptoms worsen significantly can capture the appropriate higher rating sooner.
Sacroiliitis — inflammation of the sacroiliac joints — is the hallmark early finding in AS and is separately recognized in the VA rating schedule under DC 5054 (sacroiliac injury) — but more specifically under the context of AS, sacroiliac inflammation is part of the AS diagnosis. The Schober test and FABER (flexion, abduction, external rotation) test assess SI joint involvement. SI joint findings should be documented as part of the AS examination.
Ankylosing spondylitis is not included on the PACT Act presumptive lists — which primarily cover cancers, respiratory conditions, and certain other diagnoses associated with burn pit and toxic exposure. Veterans cannot claim AS under PACT Act presumptive service connection in 2026.
However, veterans who served in burn pit environments and have AS should not abandon the claim — the pathway is through direct service connection or aggravation, which remains available. Additionally, if research in the future establishes a causal link between specific environmental exposures and AS (AS is immune-mediated and environmental triggers are studied), the presumptive lists may be updated.
Veterans who deployed to Southwest Asia and developed AS during or after service should consult a VA-accredited attorney or VSO about whether any exposure-related arguments can support the nexus, even if presumptive status is not currently available.
Ankylosing spondylitis is a systemic autoimmune disease with well-documented extraspinal manifestations. Each systemic condition caused by AS can be claimed as secondary to the service-connected AS — rated separately and combined with the primary spinal rating. The secondary claim opportunities include:
Uveitis — inflammation of the uveal tract (iris, ciliary body, choroid) — occurs in approximately 25–30% of AS patients at some point in their disease. It presents as eye redness, pain, photophobia, and blurred vision. VA rates uveitis under the vision schedule codes based on visual acuity impairment and frequency of attacks. If your AS has caused documented uveitis, this is a separate, ratable secondary condition.
AS can cause aortic insufficiency (aortic regurgitation from aortic root inflammation), cardiac conduction defects (heart block from fibrosis of the conduction system), and, less commonly, myocarditis. Cardiac involvement is rated under cardiovascular codes based on the severity of the cardiac condition.
Costovertebral joint involvement from AS can restrict chest expansion, reducing lung capacity. In rare cases, AS causes apical fibrosis of the lung parenchyma. Reduced chest expansion is documented on physical exam. If pulmonary function testing shows reduction in forced vital capacity attributable to AS, this may support a separate respiratory rating.
AS is associated with Crohn's disease and ulcerative colitis — inflammatory bowel disease occurs in approximately 5–10% of AS patients. If you have IBD that developed in the context of AS, this may be claimable as secondary to the AS condition.
AS causes arthritis in peripheral joints (hips, shoulders, knees, ankles) in a significant proportion of patients. Hip arthritis from AS is particularly common and may require total hip replacement. Each peripheral joint affected by AS inflammatory arthritis is separately ratable under the appropriate joint DC code (e.g., DC 5250 for hip ankylosis).
Establishing service connection for AS presents unique challenges compared to traumatic or degenerative spinal conditions, because AS is an autoimmune disease with genetic underpinnings (strongly associated with HLA-B27). The VA's tendency is to treat autoimmune conditions as not caused by service. The counter-arguments:
If AS symptoms began during service — inflammatory back pain, sacroiliac pain, morning stiffness that improved with activity, diagnosed by a military physician — direct service connection is established through in-service incurrence. Service treatment records documenting these symptoms and any differential diagnosis or treatment for inflammatory back pain are critical evidence.
Even if AS predated service (e.g., veteran was HLA-B27 positive with sub-threshold symptoms at enlistment), military service can aggravate AS beyond its natural progression. Physical loading, environmental stressors, and physical trauma are documented triggers of AS flares and can accelerate disease progression. A rheumatologist's nexus letter addressing aggravation specifically — that military service activities materially accelerated the AS beyond natural history — supports this pathway.
Certain infections are known triggers for reactive arthritis (previously called Reiter syndrome) — a related spondyloarthropathy that can overlap with AS. If a veteran developed reactive arthritis in service following an enteric or genitourinary infection (common during deployments to regions with poor sanitation), and this evolved into AS, the connection may be more directly traceable to service.
The aggravation pathway requires demonstrating: (1) the condition existed before service at some level, and (2) military service activities worsened the condition beyond natural progression. For AS, the nexus letter must address:
AS with lumbar spinal involvement can compress nerve roots as new bone formation and inflammation affect the foraminal spaces. Secondary lumbar radiculopathy from AS is rated under peripheral nerve codes (DC 8520 for sciatic nerve) as a secondary condition to the AS. See our guide on VA Disability Rating for Lumbar Radiculopathy for complete rating criteria.
Sacroiliac joint involvement in AS — separate from the lumbar spine — can be documented through MRI (active sacroiliitis showing bone marrow edema) or X-ray (chronic changes showing sclerosis, erosion, and eventual fusion). Sacroiliac findings should be documented in every AS examination.
AS Systemic Claims: The Hidden Rating Value
Veterans with AS who only claim the spinal DC 5240 rating are leaving significant compensation on the table. Uveitis, peripheral joint arthritis, cardiac involvement, and radiculopathy can each add separate ratings. REE Medical specialists can document these systemic AS manifestations comprehensively.
Get a Comprehensive AS Nexus Package →claim.vet may receive a referral fee if you use this link. Veterans never pay more.
Editorial Standards: Written by Marcus J. Webb, veterans benefits researcher. Verified against current 38 CFR regulations. Last reviewed: July 2026. Not legal advice — for representation, talk to a VA-accredited attorney.
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