Ankylosing spondylitis

Overview

Degeneration of bones, cartilages, and joints occur at the onset of old age and has detrimental effects on the overall health of a person. In most cases, these people suffer from chronic arthritis conditions. According to statistics produced by the Arthritis Foundation, United States, nearly 350 million people suffer from arthritic conditions all over the world. There are about 140 different types of arthritis.

A very common form of arthritis is Ankylosing Spondylitis. It mainly affects adult males, although in some cases it is observed in teens and females as well. Between 0.1-1.8% people are affected by the disease worldwide.The disease undoubtedly has increased the current global burden of degenerative bone diseases.

What is ankylosing spondylitis?

Ankylosing spondylitis (AS) is defined as a degenerative disease of the spine. It is characterized by an inflammation of the soft tissues surrounding the vertebral bones. The disease owes its origin to two Greek root words- “ankylos” which means stiffening of a joint and “spondylo” which means vertebra. This type of spondylitis causes pain and inflammation in the spine or the vertebra. In many cases, the sacroiliac joint, that connects the spine with the pelvis also becomes inflamed. Some of the neighboring joints such as that of the shoulders, ribs, knees, hips and often, the lower extremities are also affected.

The places where the ligaments and the tendons attach to the bones also suffer inflammation. The patients typically experience mild to moderate back pain which is intermittent in nature. In the more advanced stages, a fusion of the affected bones occurs, leading to the loss of flexibility of the bones, stiffening of the rib cage and a subsequent reduction in lung capacity.

Who are likely to get affected?

The onset of the disease begins in the adolescence itself. The symptoms manifest themselves in a full-fledged manner before the age of 30. Nearly 5% of the patients develop the symptoms after the age of 45. In a majority of the cases, men are twice as likely to get the disease compared to women.

What are the main causes of ankylosing spondylitis?

Ankylosing spondylitis is triggered by environmental and genetic factors. Some of the causative factors are listed below-

• Natural disintegration and weakening of body muscles and joints occur with age (above 40) which can lead to joint damage
• Increased pressure on the vertebra due to obesity and overweight conditions
• Injury of the joints due to mechanical blow or rigorous physical activities
• Injured meniscus, tendons or ligaments due to accidental twisting and bending
• Ancestral history of osteoarthritis or spondylitis (due to HLA-DRB1 gene or mutation of collagen II gene)
• Existing joint diseases such as gout, rheumatoid arthritis or septic arthritis
• Lifting of heavy weights on a regular basis due to occupational requirements
• Autoimmune disorders leading to degeneration of the synovial tissues (primary contributor- Protein Tyrosine Phosphatase 22 gene)
• Food materials like artificial fats, processed meat, refined carbohydrates, alcohol that evoke inflammation
• Poor body postures

Genetics of ankylosing spondylitis

The genetics of the disease needs to be discussed separately since it plays a pivotal role in the occurrence of the disease in the future generations. The primary gene that is responsible for the disease is HLA-B27. It is not necessary that people who have this gene are definitely going to have spondylitis. The statistics of the National Institute of Arthritis and Musculoskeletal and skin diseases show that around 1 in 20 people who are the carriers of the HLA-B27 gene have the disease. An interaction between the CD8 T cells and HLA-B is believed to be the contributing factor in these cases. Recent studies have proven the roles of two additional genes- ERAP1 and IL23R in spondylitis.

What are the main signs and symptoms?

Ankylosing spondylitis typically presents with the episodic back pain of varying degrees. The main signs are as follows-

• Stiffness and pain in the joint especially in the morning
• Pain and stiffness in the neck, back, and buttocks
• Pain and inflammation in the tendons and the ligaments, which is felt mainly in the chest, back of the heel or underneath the foot
• Inflammation and swelling of the joints and the soft tissues
• Joint pain during slight movements
• Temporary immobility (permanent immobility may also occur due to ankylosed or fused joints)
• Cracking and crunching sounds during normal joint movements
• Weakness and fatigue of muscles (may lead to muscular dystrophy)
• Pain radiating to neighboring regions (lower extremities)
• Redness around the joint area
• Extreme tenderness and touch sensitivity of joints
• Throbbing pain in the joint and muscles after some activity
• Bone and joint deformities (at an advanced stage)
• Disturbed sleep due to increased joint pain at night
• Difficulty maintaining normal body postures
• Difficulty performing mundane activities such as walking, running, climbing stairs
• Body aches and fever
• Extreme fatigue
• Loss of appetite
• Visible bulges (due to bone spurs)

How to tell if one has ankylosing spondylitis?

Ankylosing spondylitis can be distinguished from other arthritic diseases through a set of diagnostic tests which are given below-

• Blood tests: The patients generally show an elevated level of C-reactive protein (CRP) and ESR. This is not necessarily related to the degree of inflammation since people having very serious inflammation often have normal or close to normal values of CRP and ESR.
• Genetic tests: These are required to test for HLA-B27. Above 90% of the patients diagnosed with AS have been tested positive for HLA-B27.
• BASDAI: The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) gives a measure of the inflammatory burden of the existing diseases.
• Schober’s test: It measures the flexion of the lumbar spine during the preliminary physical examination.

How to treat AS?

The patients are advised to undergo the following set of treatments for AS-

• Non-Steroidal Anti Inflammatory Drugs: Ibuprofen, Aspirin, Naproxen
• Corticosteroids
• Disease-modifying antirheumatic drugs (DMARDs)
• Biological agents: They inhibit the actions of the proteins causing inflammation

The treatment aims to provide symptomatic relief (reduction of pain and stiffness). Efforts are made to prevent or reduce the severity of complications.

The medications that are usually administered are-

Nonsteroidal anti-inflammatory drugs (NSAIDS) such as naproxen and indomethacin. They help in reducing pain, inflammation, and stiffness.Tumor necrosis factor (TNF)blockers are also administered in certain cases. They help in reducing pain, inflammation, stiffness and swollen joints Secukinumab.

The TNF blockers approved by the US FDA (Food and Drug Administration) are Adalimumab, certolizumab pegol, Etanercept, Infliximab, and Golimumab.US FDA has approved IL-17 inhibitors such as Secukinumab for the treatment of ankylosing spondylitis. Physical therapy is advised in order to ease the joint stiffness and improve the mobility. Surgery might be required in some cases with severe joint damage, which requires surgical correction or replacement.

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