Commonest site of bone and joint tuberculosis?

Ans. a (Spine) (Ref. Harrison's medicine 17th ed., Ch. 158).Skeletal tuberculosis is more common in children. It is due to haematogenous spread from a primary site, usually the lungs. The spine is the most common site of infection and is present in over 50% of children. This is followed by the large joints of the lower extremity like the hip and knee. In skeletal tuberculosis single joint involvement is the most common pattern. The radiographic features of tuberculous arthritis are periarticular osteoporosis and soft-tissue swelling with destruction of the articular cartilage. Joint space narrowing is relatively late. Fibrous ankylosis is more common than bony ankylosis. Reactive new bone formation is minimal or absent. Tuberculous dactylitis involves the short tubular bones of the hands and feet with bony expansion (spina ventosa), increased bone density with periosteal reaction and soft-tissue swelling.SKELETAL TUBERCULOSIS# In bone and joint tuberculosis, pathogenesis is related to reactivation of hematogenous foci or to spread from adjacent paravertebral lymph nodes.# Weight-bearing joints are most commonly affected -- the spine in 40% of cases,- the hips in 13%, and- the knees in 10%# Spinal tuberculosis (Pott's disease or tuberculous spondylitis) often involves two or more adjacent vertebral bodies.# From the anterior superior or inferior angle of the vertebral body, the lesion slowly reaches the adjacent body, later affecting the intervertebral disk.# With advanced disease, collapse of vertebral bodies results in kyphosis (gibbus).# A paravertebral "cold'' abscess may also form.# MRI reveals the characteristic lesion and suggests its etiology.# Pyogenic bacterial osteomyelitis, in particular, involves the disk very early and produces rapid sclerosis.# A catastrophic complication of Pott's disease is paraplegia.# Skeletal tuberculosis responds to chemotherapy, but severe cases may require surgery.Educational points:Vertebral collapse/destruction with maintained or normal Intervertebral disc space is seen in:1. Trauma2. Metastasis3. Osteoporosis