Tuberculosis Arthritis: Infection in joints due to TB

What is tuberculosis arthritis?

Tuberculosis arthritis is an infection of the joints caused due to tuberculosis (TB).

Tuberculosis is a chronic, debilitating illness caused by Mycobacterium tuberculosis, which commonly affects the lungs once the microorganism enters the body through droplet infection. In some cases, however, TB occurs outside the lungs, and is known as extra-pulmonary TB. Extra-pulmonary TB in the joints is known as tuberculosis arthritis.

TB arthritis generally affects large joints like the knee, and can lead to serious destruction of the joint and tendon, while also spreading to the surrounding bursa, muscles and soft tissues.

However, TB arthritis must be differentiated from other forms of arthrides. TB arthritis is restricted to a single joint, and the duration of swelling is also longer - with TB being a chronic disease, swelling in TB arthritis is present for six weeks or more. Lastly, a joint affected by TB arthritis is not warm to touch (cold abscess), which is an indicator of most forms of arthritis.

What are the causes of the disorder?

Tuberculosis arthritis is caused by the bacterium, Mycobacterium tuberculosis. While the bacteria mainly affect the lungs, a very small number of people will develop this form of arthritis. The joints most commonly involved are:

• Ankles
• Knees
• Hips
• Spine
• Wrists

Once the bacterium enters the lung, it may spread to a joint through the bloodstream. Initially, the synovial membrane gets inflamed, which is seen as swelling and pain over the affected joint. As the disease progresses, the joint begins to lose function, and becomes susceptible to other bacterial infections like those by Staphylococcus aureus. This secondary infection aggravates the pain and swelling and poses the risk of developing a sepsis.

Risk factors towards developing TB arthritis include:

• A pre-existing arthritis condition like osteoarthritis or rheumatoid arthritis
• Previous trauma of joints
• HIV/AIDS
• Joint damage due to conditions like sickle cell disease
• Malnutrition, poor living conditions

What one needs to know about symptoms or signs?

Symptoms include:

• Joint swelling, tender joints
• Low-grade fever
• Decreased joint mobility
• Muscle atrophy, muscle spasms
• Numbness, weakness or tingling sensation below point of infection (in spine)
• Loss of appetite, weight loss

It is important to note that TB arthritis shows persistent joint swelling over a period of time, and the pain is restricted to a single joint, and does not respond to antibiotics.

What are the screening tests and investigations done to confirm or rule out the disorder?

A physical examination of the affected joint will reveal swelling and irritation. Further diagnosis involves the following:

1. Biopsy- A sample of fluid is taken from the joint and cultured to detect the presence of TB bacilli. Further, the joint tissue will reveal granulomas with Langhans giant cells, with or without the bacilli.
2. Tuberculin skin test
3. Imaging tests- Chest x-ray, joint x-ray, CT scan of the spine and magnetic resonance imaging (MRI) can confirm the diagnosis.

What treatment modalities are available for management of the disorder?

Extra-pulmonary TB is treated with the same set of antibiotics used to treat pulmonary TB. The drugs are taken for a minimum of six months and it is important to take the medicines exactly as directed and to finish the course as prescribed by the doctor.

The treatment cures the infection by fighting against the TB bacteria. A combination of drugs is used: Isoniazid, Rifampicin, Pyrazinamide and Ethambutol. Painkillers help to relieve the symptoms of TB arthritis, along with application of heat or cold to the affected joints.

Surgery is sometimes required to drain spinal abscesses or to stabilise the spine. It is otherwise a rare option for infection at other sites.

What are the known complications in management of the disorder?

TB arthritis can be quite damaging to the tissues. It is important to contain the infection before it spreads to other joints. Possible complications of TB arthritis include:

• Joint destruction
• Nerve compression
• Spinal cord compression
• Collapse of vertebrae, leading to kyphosis

Side effects of tuberculosis medication include:

• Blurred vision
• Jaundice
• Burning pain in feet
• Relapse and aggravation of condition if treatment is discontinued before its completion; germ resistance develops making cure difficult.

What precautions or steps are necessary to stay healthy and happy during the treatment?

The side effects of the medication can be controlled with a balanced, nutritious diet. It also ensures good recovery from the condition.

How can the disorder be prevented from happening or recurring?

Even those who get exposed to an infected person can prevent a full-blown occurrence of TB. Though a skin test for TB (PPD) will turn positive, many people who have been exposed to the bacterium harbor an inactive infection. A preventive therapy can be discussed with the doctor.

However, in cases of active infection, it is important to start treatment at the earliest as it prevents the spread from those with active TB infection to those who are still uninfected. A BCG vaccination is given in countries with a high incidence of the disease, though its effectiveness is disputed.

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