Tuberculosis is a severe infectious disease that usually affects your lungs. When it spreads to your bones, it's known as skeletal tuberculosis.
Tuberculosis is an airborne disease caused by a very infectious bacterium called Mycobacterium tuberculosis. It can travel through the blood to the lymph nodes and bones as well as the spine and joint.
Tuberculosis and Its Types
Tuberculosis is a contagious disease, which means it can spread from one person to another. It's more common in developing countries, but about 7,163 cases were reported in the U.S. in 2020.
Tuberculosis can be deadly. In many developing nations, children get the Bacille Calmette-Guerin or BCG vaccine at birth to prevent tuberculosis.
There are two main types of tuberculosis infections:
- Pulmonary tuberculosis, which mainly involves your lungs. The infection can cause chest pain, trouble breathing, and lung problems.
- Extrapulmonary tuberculosis, when tuberculosis affects areas of the body other than your lungs. This is more often seen in people who have weakened immune systems because of HIV/AIDS.
Extrapulmonary tuberculosis that affects your bones, spine, or joints is called bone or skeletal tuberculosis.
Bone tuberculosis affects your skeletal system, which consists of bones and joints. The most common type is spinal tuberculosis. This happens when the mycobacterium infection spreads into your spinal cord. Spinal tuberculosis is also called Pott’s disease.
This type of tuberculosis is more common in underdeveloped countries. It accounts for 2.2% to 4.7% of the total tuberculosis cases in Europe and the U.S.
Causes of Bone Tuberculosis
Skeletal tuberculosis is also caused by Mycobacterium tuberculosis. Unlike pulmonary tuberculosis, studies have shown that bone or spinal tuberculosis may not spread through the air. The infection can spread through your blood if you come in contact with an infected person’s body fluids or pus.
Skeletal tuberculosis can also be caused by pulmonary tuberculosis. Mycobacteria can easily spread from your lungs to your bones, spine, or joints through blood vessels. This can affect your long bones or spinal vertebrae.
This type of tuberculosis is rare and is typically seen most often in places with widespread AIDS infections. Bone tuberculosis affects people with AIDS because their immune system is weakened by the virus.
Symptoms of Bone Tuberculosis
Often, you may have tuberculosis but not notice symptoms. Bone tuberculosis is very hard to diagnose because symptoms don’t show up until the infection is severe or advanced. They may include:
- Severe back pain
- Inflammation in back or joints
- Trouble moving or walking, especially in children
- Spinal abscess
- Soft tissue swelling
- Neurological disorders
- Tuberculosis-related meningitis
- Muscle weakness
- Paralysis from the waist down (paraplegia) or of all four limbs and sometimes in specific organs (tetraplegia)
- Kyphosis, also known as hunchback
- Bone or spinal deformities
Diagnosis of Bone Tuberculosis
Common methods for diagnosing bone tuberculosis include:
Bacterial culture. If you have bone tuberculosis, you probably have an underlying lung infection. Your doctor may take a blood or sputum sample and test it for Mycobacterium tuberculosis.
Biopsy. Your doctor may order a biopsy, which involves taking part of infected tissue and checking it for infection.
Body fluid test. Your doctor may draw pleural fluid, which surrounds and protects your lungs, to check for infection. Or they may take cerebrospinal fluid from around your spinal cord. For bone or joint tuberculosis, your doctor may draw synovial or joint fluid for testing.
Polymerase chain reaction (PCR) test. The samples that your doctor takes can also be tested using PCR. This test boosts the genetic material of the mycobacterium and helps look for infection from small amounts of fluids.
Immunological tests. Your doctor can use your blood or body fluid sample to check for antibodies against tuberculosis or, in some cases, AIDS.
Treatment of Bone Tuberculosis
Without treatment, bone tuberculosis can be deadly. Treatments to reverse the damage of bone tuberculosis include:
Anti-tuberculosis drugs. Rifampicin, streptomycin, kanamycin, isoniazid, protionamide, cycloserine, and pyrazinamide are the most common anti-tuberculosis drugs. They can penetrate the cerebrospinal fluid and attack the bacteria. It may take 6 to 12 months to cure bone tuberculosis.
Corticosteroids. These medications may be prescribed to prevent complications such as inflammation around your spinal cord or heart.
Surgery. If you have advanced bone tuberculosis, you may need surgery to remove an infected part.