Ankylosing Spondylitis

Ankylosing spondylitis is a chronic inflammatory disease that primarily affects the joints of the hip, spine, and ribs. It leads to restricted spinal mobility. The manifestations of ankylosing spondylitis vary greatly depending upon the degree of inflammation, the extent of spinal involvement, and systemic involvement. That is why it is one of the most misdiagnosed conditions. The functional impairment and work disability can affect the quality of life to a great extent. Living with the disease also has a considerable cost burden on an individual.

The exact cause of disease or mechanism by which it is caused is not very well known, but genetic predisposition is always there. A specific gene called HLA-B27 is present in most individuals with ankylosing spondylitis. However, HLA-B27 is not specific for the disease as it can be seen in multiple other conditions as well. And some people with ankylosing spondylitis never have this gene, meaning some acquired environmental factors might also come into play for causation.

Males are twice more likely to get affected by ankylosing spondylitis than females. The average age of clinical manifestations is 24-26 years. Clinical symptoms do not appear after 40 years, so it is less likely to develop in older adults. The disease progression in some developing countries can start as early as childhood (before the age of 16) but remains underdiagnosed.

Following clinical signs and symptoms are present in ankylosing spondylitis:

• Back pain and stiffness. Spinal involvement can result in bamboo spine appearance
• Stiffness of hip joints and dull pain in buttocks
• Pain and stiffness in the thoracic region and chest pain. The pain does not settle with rest
• Osteoporosis of the spine
• Loss of spinal mobility or varying degrees
• Extra-articular manifestations of ankylosing spondylitis include anterior uveitis, psoriasis, metabolic bone disease, and inflammatory bowel disease.

Complications of ankylosing spondylitis include:

• Enthesis- which is the erosion of joints and replacement of bone with fibrous tissue
• Spinal stenosis leading to spinal fracture
• Cardiac involvement with aortic insufficiency and conduction defects

The diagnosis of ankylosing spondylitis is based upon clinical features and some radiological findings. Usually, family history, articular and extra-articular manifestations help reach the diagnosis.

• Xray of the sacroiliac joint is routinely performed to look for sacroiliitis that is present in early
• MRI and dynamic MRI of various joints, including spine, hip bone, rib cage, to see articular changes and signs of inflammation. Dynamic MRI can help identify complications due to ankylosing spondylitis, including soft tissue involvement, changes in ligaments, dura matter and microfractures, etc.
• Although no lab tests are specific for ankylosing spondylitis, but anemia of chronic disease can be evident in complete blood count. Inflammatory markers such as CRP and ESR might also be raised in some cases, but their absence does not exclude ankylosing spondylitis.
• Gene typing is done in patients with a family history of ankylosing spondylitis in whom clinical signs have not developed yet. The majority of these patients are positive for the HLA-B27 gene. The procedure is not routinely performed as it is not specific for ankylosing spondylitis and is very costly.

Differential diagnoses of ankylosing spondylitis include:

• Synovitis
• Inflammatory spinal pain
• Congenital spinal deformity
• Diabetic foot ulcers
• Degenerative disc disease
• Kyphosis
• Osteoarthritis
• Reactive arthritis
• Rheumatoid arthritis
• Lumbar spondylosis
• Spinal stenosis
• Psoriatic arthritis 

• Management of ankylosing spondylitis is done through various non-pharmacologic and pharmacologic interventions.
• Amongst non-pharmacologic interventions, the most important lifestyle modification is regular back exercises that help cope with the functional disability as the disease progresses rapidly.
• A Support system for patients in the form of therapy, social groups, and self-help groups, etc., is very important as ankylosing spondylitis can be seriously debilitating.
• Smoking should be avoided as the disease is said o progress more rapidly in smokers.
• Pharmacologic intervention starts with pain management. Pain associated with arthritis is treated with NSAIDs.
• Inflammation is treated with disease-modifying antirheumatic drugs (DMARDs), including sulfasalazine, methotrexate, cyclosporine, etc. However, recent studies have discarded the effectiveness of corticosteroids or DMARDs therapy.
• The most effective drugs against ankylosing spondylitis are anti-TNF drugs. These are given in advanced-stage disease that does not respond to typical DMARD therapy for a long-term course.
• Surgical interventions for ankylosing spondylitis include total hip arthroplasty in patients with refractory pain and disability. Spinal instability can be treated with corrective spinal osteotomy and fusion procedures.
• Extra-articular manifestations of which anterior uveitis is most common are treated with the help of artificial tears, painkillers, and mydriatic drops. It is important to have a multi-disciplinary approach to effectively manage ankylosing spondylitis as the disease involves multiple organs.

Ankylosing spondylitis can be associated with considerable morbidity and mortality. The prognosis of ankylosing spondylitis varies greatly depending upon several factors that include:

• Early diagnosis
• Initiation of medical therapy
• The severity of the disease, particularly at the time of diagnosis
• Quality of medical management as the disease process requires a multi-disciplinary approach for effective management
• Patient compliance with the suggested treatment regimen
• Patients who have disease onset at a young age with poor response to NSAIDs therapy, peripheral joint involvement, and elevated ESR have a poor prognosis

• People with diagnosed ankylosing spondylitis should exercise regularly to strengthen joints and muscles. Exercise helps with improving flexibility at joints and maintaining good posture.
• Smoking should be stopped as it is thought to increase the process of inflammation and hampers breathing. In patients with axial skeleton involvement, it can already be an uncomfortable process as the inflammation of vertebral joints can limit chest wall motion.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 11, 2023. 

References

https://www.niams.nih.gov/health-topics/ankylosing-spondylitis#:~:text=Ankylosing%20spondylitis%20is%20a%20type,the%20spine%20can%20cause%20stiffness.

https://link.springer.com/article/10.1007/s10067-021-05679-7