Tuberculous bone infection - Bone and joint infections

Tuberculous bone infection

Definition

Spread of an infection by Mycobacterium tuberculosis to the bone and joints.

Incidence

Patients with tuberculosis have a 5% lifetime risk of developing bone disease.

Age

Usually children or young adults.

Geography

Major illness in developing countries, with increasing incidence in the developed world.

Aetiology

Tuberculous osteomyelitis is usually due to haematogenous spread from a primary focus in the lungs or gastrointestinal tract. HIV has increased the incidence of tuberculosis and tuberculous bone infections.

Pathophysiology

The disease starts in the intra-articular bone. The lumbar and lower thoracic spine is commonly involved (Pott’s disease). A chronic inflammatory reaction occurs leading to caseation and later abscess formation (cold abscess). Abscesses may cause a mass effect on local structures. Weakened vertebrae are prone to collapse.

Clinical features

The onset of symptoms is insidious and often missed. The patient complains of pain and later swelling due to pus collection. Muscle spasm and wasting occur with limitation of movement and rigidity. In spinal tuberculosis, pain may be mild and presentation delayed until there is a visible abscess or vertebral collapse causing pain and deformity.

Investigations

X-ray shows soft tissue swelling and decreased density (rarefaction) of the bone. In early stages the joint space is preserved, but later there is narrowing and irregularity with bone erosion and calcification within adjacent soft tissue.

The ESR is usually raised and the Mantoux test is positive in 90% of immunocompetent patients.

Synovial biopsy for histological examination and culture is often necessary.

Management

Chemotherapy with combination antituberculous agents for 12–18 months. Rest and traction may be useful; if the articular surfaces are damaged, arthrodesis or joint replacement may be required.