Orthopaedic infections in children

• Acute inflammatory reaction with vascular congestion
• Rise in intra-osseous pressure causing intense pain

• At 2-3 days pus forms within the bone and forces its way down the haversian canals to the surface where it forms a sub-periosteal abscess
• The pus can spread from here back into the bone, into an adjacent joint or into the soft tissues (Where there is an intra-articular physis)
• Vertebral infection can spread through the end plate, disc and into the next vertebral body

• At 7 days, rising pressure, vascular stasis, infective thrombosis and periosteal stripping compromise the blood supply to the bone resulting in bone death resulting in a sequestrum

• At 10-14 days this forms from the deep surface of the stripped periosteum forming the involucrum

• With release of the pressure and appropriate antibiotics healing can occur
• There may be permanent deformity

• Unpublished work (quoted in Dee) shows that experimentally bacteria injected intravenously will settle in the metaphyses of bone preferentially

NB - in 10% of cases there is more than one site of infection.

• Pain, malaise, fever
• Limp or not weight bearing

• Failure to thrive, drowsiness, irritable

• The commonest site is the thoracolumbar spine (Batson's venous complex from the pelvis)
• Other bones involved especially in DM, IVDA, immunosuppressed

• Local erythema, swelling and tenderness indicates that the pus has broken through the periosteum