Which bones and joints are commonly affected with osteoarticular TB?
Spine involvement (Pott’s disease) accounts for >50% of cases with the lower thoracic and upper lumbar spine most frequently involved. It usually involves the anterior vertebral border and disc, ultimately progressing to disc narrowing, vertebral collapse, and kyphosis (Gibbus deformity). Although TB may affect only the vertebral body, it usually will cross the disc and involve the adjacent vertebrae. Complications may include paravertebral cold abscess, spread beneath anterior longitudinal ligament causing scalloping of anterior vertebral bodies, psoas abscess, sinus tract formation, and neurologic compromise. Sacroiliac joint involvement accounts for 10% of osteoarticular TB, is usually unilateral when it occurs, and may be misdiagnosed as a spondyloarthropathy.
Peripheral joint involvement typically involves weight-bearing joints, usually the hip, knee, and ankle, and is monoarticular. Subchondral bone involvement may precede cartilage destruction, so that joint space narrowing is often a late finding. Adjacent osteomyelitis is very common. It accounts for approximately 30% of all cases of osteoarticular TB.
Osteomyelitis and dactylitis account for 2% to 3% of all osteoarticular TB. It may only involve the appendicular skeleton; peripheral involvement is dependent on the age of the patient. In adults, metaphyseal regions of the long bones with femur and tibia are most commonly affected. Ribs as well as other bones may be involved. In children, metacarpals and phalanges are more likely to be affected and resemble a dactylitis.
Tenosynovitis and bursitis occur more commonly in NTM infections.