Introduction:
Ankylosing spondylitis is a chronic inflammatory autoimmune disorder of the spine characterized by pain and stiffness with a variable course. It mainly affects the joints of the spine and sacroiliac joints in the pelvis. As the severity increases, the joints start to fuse resulting in a rigid spine.
What Is the Pathophysiology of Ankylosing Spondylitis?
Antigen-antibody reaction triggers the inflammatory process. Inflammation takes place at bone-ligament and bone-tendon junctions. Synovitis of synovial joints of the body, such as sacroiliac joint, hip joint, facet joint, etc., also occurs. The joint becomes swollen, and the movements of joints are limited. Destruction of articular cartilage occurs over time, followed by subchondral bone formation.
The costovertebral joints are frequently affected by chest expansion limitations. Inflammation of bone-ligament junctions affects the sacroiliac ligaments, intervertebral joints, symphysis pubis, and manubrium sterni. The inflammatory reaction is characterized by cellular infiltration, granulation tissue formation, and erosion of the adjacent bones. Granulation tissue is replaced by fibrous tissue, which gets ossified over time, leading to ankylosis of the joint.
The ossification of the longitudinal ligament results in syndesmophytes between two adjacent vertebral body bridges that limit movement, and as a result, the spine becomes stiff like bamboo. And so we call it the bamboo spine.
What Are the Types of Spondyloarthritis?
Spondyloarthritis encompasses two categories:
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Axial spondyloarthritis primarily affects the spine. Ankylosing spondylitis, identifiable on X-rays, falls under this category. Non-radiographic axial spondyloarthritis lacks X-ray evidence.
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Peripheral spondyloarthritis predominantly affects limb, heel, finger, and toe joints.
Individuals may exhibit characteristics of both categories.
What Are the Clinical Manifestations of Ankylosing Spondylitis?
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Insidious onset of intermittent low back pain and morning stiffness occurs. In the beginning, there will not be any pain at rest. The pain will be present only with movements and activities. Pain radiates down the buttock. Gradually, when the disease progresses, one may experience continuous pain at rest or on movement, and the stiffness will be increased.
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Involvement of the synovial joints is characterized by swelling, pain, and limitation of movements. Inflammation of the bone ligament or bone-tendon joint (enthesopathy) is characterized by localized pain, tenderness, and swelling.
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It usually involves the insertion of the Achilles tendon at the ankle joint. In about 10 % of cases, the disease starts from the peripheral joints, usually the hip joint.
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Asymmetrical polyarthritis may develop. As the disease progresses, it involves the lumbar spine, the lordosis (concavity of lumbar spine) gets obliterated, and then kyphosis (convexity of the spine) may develop.
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It may be associated with head-forward posture and hip joint flexion deformity. The joint movement limitations may further give rise to disability.
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Chest expansion will be limited with the involvement of the costovertebral joints.
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Peripheral joints such as the shoulder, hip, and knee may be involved with effusion, loss of mobility, and movements. Pain and tenderness are also present.
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Progressive spinal deformity gives rise to typical kyphotic posture and subluxation of the atlanto occipital or atlantoaxial joint.
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Apart from the fusing of the bones, ankylosing spondylitis leads to eye inflammation, compression fractures, heart problems, inability to breathe deeply, etc.
Extra Musculoskeletal Manifestations:
It includes,
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Ocular inflammation in above one-third of the patients.
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Carditis.
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Pulmonary fibrosis.
What Are the Risk Factors of Ankylosing Spondylitis?
Symptoms typically manifest during late adolescence or early adulthood. While the majority of individuals with ankylosing spondylitis carry the HLA-B27 gene, it's worth noting that many carriers of this gene never develop the condition.
How Are Ankylosing Spondylitis Diagnosed?
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X-ray - The cardinal sign in the early stage is the erosion of the sacroiliac joint, and later periarticular sclerosis usually develops on the iliac side of the joint. The sclerosis will be present in the x-ray.
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ESR - Erythrocyte sedimentation rate increases during the active stage.
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Presence of HLA-B27 in 90 % of cases.
How Are Ankylosing Spondylitis Managed?
1. In the absence of a specific cause, the disease is managed by anti-inflammatory and analgesics. Nonsteroidal anti-inflammatory drugs (NSAIDs) like Naproxen and Indomethacin are the medicines most commonly given by doctors to treat ankylosing spondylitis. It helps to relieve the pain, inflammation, and stiffness. However, these medications may cause gastrointestinal bleeding. When these medicines are not helpful, the doctor will suggest a biologic medication, like an interleukin-17 (IL-17) inhibitor or a tumor necrosis factor (TNF) blocker.
Tumor necrosis factor blockers will target a cell protein that causes inflammation. Interleukin-17 acts as the body's defense against infection and inflammation. Tumor necrosis factor blockers help reduce stiffness, pain, tenderness, and swollen joints. These blockers are administered by injecting the medicine under the skin, or an intravenous (IV) line is preferred. The tumor necrosis factor blockers approved by the FDA (Food and Drug Administration) to treat ankylosing spondylitis are,
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Adalimumab.
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Certolizumab pegol.
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Infliximab.
Interleukin-17 inhibitors approved by the FDA (Food and Drug Administration) to treat ankylosing spondylitis are,
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Secukinumab.
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Ixekizumab.
The tumor necrosis factor blockers and interleukin-17 inhibitors can reactivate untreated tuberculosis and improve the infection. When we are not supposed to take tumor necrosis factor blockers or interleukins-17 inhibitors because of some other health conditions, the doctor recommends the Janus kinase inhibitor Tofacitinib. This is an approved drug for psoriatic arthritis and rheumatoid arthritis, and research is still going on for ankylosing spondylitis.
2. Physiotherapy is very important in maintaining the joint’s range of motion, prevention of deformity, and prevention of muscle wasting.
3. Radiotherapy can also be done to improve the patient's well-being and functional activities.
4. There is a variable mode of onset and course of the disease. The patient must be educated properly regarding the onset, course of the disease, and prognosis.
5. Surgery - Most people with ankylosing spondylitis do not require surgery. However, the doctor might recommend surgery when there is joint damage or severe pain or if the hip joint is damaged and needs to be replaced.
6. Postural awareness plays a vital role in preventing disability. Typically, there is a gradual onset followed by remission and then relapse. In some cases, the disease runs a chronic course without remission or relapse.
7. Stay healthy and fit with regular exercise and say goodbye to drugs.
What Are the Complications of Ankylosing Spondylitis?
Severe ankylosing spondylitis prompts new bone formation, leading to spinal fusion and rib cage stiffness, limiting lung function. Complications may include eye inflammation, compression fractures, and heart issues, necessitating prompt medical attention.
Conclusion
Coping with any form of arthritis can be challenging. Ankylosing spondylitis, specifically, presents a literal pain in the back. The discomfort, stiffness, and related symptoms can significantly impact daily energy levels. However, the positive aspect is that AS is controllable.