Quick answer. Psoriatic arthritis and ankylosing spondylitis (now often called axial spondyloarthritis) belong to a family of inflammatory rheumatic diseases called spondyloarthritis, which affect the spine, joints and entheses (where tendons and ligaments attach to bone). A key feature is inflammatory back pain, low back and buttock pain that is worse with rest and at night, improves with exercise, and comes with prolonged morning stiffness, often starting in people in their late teens to forties. These conditions are linked to skin psoriasis, nail changes, sausage-like swollen digits and eye inflammation. The genetic marker HLA-B27 is associated but not required for diagnosis. Anyone with chronic inflammatory back pain or arthritis alongside psoriasis should see a rheumatologist. This is general information, not medical advice.
Spondyloarthritis is a group of related inflammatory diseases that includes ankylosing spondylitis (increasingly referred to as axial spondyloarthritis) and psoriatic arthritis. Unlike mechanical back pain from strain or wear-and-tear, these conditions are driven by immune-mediated inflammation of the spine, joints and entheses, and they often begin in younger adults. They are also notable for their links to the skin, nails and eyes. Recognising inflammatory back pain early matters, because timely treatment can relieve symptoms and help preserve spinal movement. This guide explains the symptoms, the skin and eye connections, how these conditions are diagnosed, and the main treatment options, with reference to Singapore clinical sources.
At a glance
| Feature | Inflammatory back pain | Mechanical back pain |
|---|---|---|
| Typical age of onset | Often under 40 | Any age |
| Effect of rest | Worse with rest and at night | Usually better with rest |
| Effect of exercise | Improves with movement | Often worse with activity |
| Morning stiffness | Prolonged, over 30 minutes | Brief or none |
| Onset | Gradual, over weeks to months | Often sudden, after strain |
| Associated signs | Psoriasis, eye redness, sausage digits | Usually none |
What is spondyloarthritis?
Spondyloarthritis is an inflammatory rheumatic disease affecting the spine, joints and entheses, the sites where ligaments and tendons attach to bone. It is an umbrella term that includes ankylosing spondylitis, psoriatic arthritis, enteropathic arthritis (linked to inflammatory bowel disease), reactive arthritis and undifferentiated spondyloarthritis. These conditions share features such as inflammation of the sacroiliac joints and spine, enthesitis, and a tendency to affect younger people. Because they overlap, a rheumatologist assesses the full picture, including joints, skin, nails, eyes and bowel symptoms, to make a diagnosis.
Ankylosing spondylitis (axial spondyloarthritis)
Ankylosing spondylitis, recently renamed axial spondyloarthritis, mainly affects the spine and the sacroiliac joints, causing both inflammation and, over time, new bone formation that can reduce spinal flexibility. It typically begins in the late teens to forties and is more common in men. The hallmark is inflammatory back pain: low back and buttock discomfort that is worse at night and after inactivity, accompanied by morning stiffness, and which eases with exercise. As the disease progresses, any part of the spine may be involved, and chest expansion can become limited. Hip and heel pain from enthesitis can also occur.
Psoriatic arthritis and the skin connection
Psoriatic arthritis is a chronic inflammatory arthritis that affects people who have, or who develop, the skin condition psoriasis; arthritis develops in roughly 5 to 10 percent of people with psoriasis. It can cause joint pain, stiffness and swelling, and is part of the spondyloarthritis family, so it can also involve the spine. Characteristic features include nail changes such as pitting and separation, and dactylitis, where a whole finger or toe swells up like a sausage. The skin and joint disease do not always run in parallel, so joint symptoms can appear before, with or after the rash.
Skin, eye and nail links you should not ignore
Spondyloarthritis is a whole-body condition, and clues often appear outside the joints. Psoriasis on the skin and nail pitting point towards psoriatic arthritis. Eye inflammation, particularly acute anterior uveitis, can cause a painful, red, light-sensitive eye and may be the first sign of underlying spondyloarthritis; it needs prompt eye assessment. Sausage-like swelling of fingers or toes and inflammation at the heel are further pointers. Bowel symptoms can indicate associated inflammatory bowel disease. Mentioning these features to your doctor helps connect the dots toward the right diagnosis.
How are these conditions diagnosed?
Diagnosis combines the clinical history of inflammatory back pain or arthritis with examination and tests. Blood tests may include a full blood count and inflammatory markers such as ESR and CRP. The genetic marker HLA-B27 is associated with spondyloarthritis, but it is important to understand that most people who carry HLA-B27 never develop the disease, so it supports rather than confirms a diagnosis. Imaging of the spine and pelvis, including X-rays and often MRI, helps detect inflammation of the sacroiliac joints and spine. The rheumatologist interprets all of these together.
How are psoriatic arthritis and ankylosing spondylitis treated?
First-line treatment for spinal symptoms is usually non-steroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation and pain, combined with a regular exercise and physiotherapy programme to maintain posture and flexibility. For psoriatic arthritis with peripheral joint involvement, conventional DMARDs such as methotrexate may be used. When disease remains active, biologic therapies, including TNF inhibitors and other targeted agents such as IL-17 inhibitors, can be effective for both skin and joints. Treatment is individualised by the rheumatologist, often in coordination with dermatology for the skin and ophthalmology if the eyes are involved. This is general information only and not a prescription.
How to prepare for your rheumatology appointment
A clear history helps the rheumatologist recognise spondyloarthritis, because the diagnosis rests heavily on the pattern of your symptoms. Before your visit, note when your back or joint pain began, whether it is worse at night or after rest, how long morning stiffness lasts, and whether movement eases it. Mention any psoriasis or scaly patches (even on the scalp, behind the ears or around the navel), nail changes, episodes of a painful red eye, swelling of a whole finger or toe, heel pain, or bowel symptoms such as persistent diarrhoea. Bring a list of your current medications, any previous X-ray or MRI reports, and a record of which painkillers or anti-inflammatories have helped.
Self-management and daily life
Medication works best alongside steady physical activity. Many people with axial spondyloarthritis benefit from a regular programme of stretching, posture exercises and mobility work, often guided by a physiotherapist, to help maintain spinal movement and chest expansion. Low-impact aerobic exercise such as swimming or brisk walking, attention to good sitting and sleeping posture, not smoking, and keeping to a healthy weight all support better long-term outcomes. Pace flares sensibly: rest a little more when inflammation is high, but try not to stop moving altogether, as prolonged inactivity tends to worsen stiffness.
Common questions
Does a positive HLA-B27 test mean I will get the disease?
No. HLA-B27 is associated with spondyloarthritis, but most people who carry it never develop the condition. It supports the overall picture rather than confirming a diagnosis on its own.
Can psoriatic arthritis appear before the skin rash?
Yes. Joint symptoms can come before, with or after psoriasis, and the skin and joint disease do not always follow the same course, so tell your doctor about any joint pain even if your skin is settled.
Related guides
- Best Rheumatology Clinics in Singapore — our editorial shortlist
- rheumatology clinics directory
- Rheumatoid arthritis
- Lupus / SLE
- When to see a rheumatologist
Sources
Part of our Autoimmune & rheumatology guides · Browse all health topics