Concomitant septic arthritis and osteomyelitis of the hip in young children; a new pathophysiological hypothesis suggested by MRI enhancement pattern

Abstract

BackgroundIn children, septic arthritis (SA) of the hip is either primary or concomitant with acute haematogenous osteomyelitis (AHO). However, seldom, patients with isolated SA at presentation, may later show osteomyelitis in the metaphysis. The aim of this study was to elaborate a physiopathological hypothesis based on the peculiar MRI findings to explain the onset of AHO after SA.MethodsCases of acute infection of the hip admitted between January 2010 and December 2013 were retrospectively reviewed to assess radiographic and MRI features, as well as bacteriological findings. Only children with isolated SA were included in this study, whereas cases of concomitant SA and AHO at presentation were excluded.ResultsTen patients met the inclusion criteria. Six (1–11 months) demonstrated, on the initial MRI, decreased perfusion on gadolinium enhanced fat-suppressed T1-weighted sequence of the femoral epiphysis and developed one month later metaphyseal AHO. Four (5–14 years) did not show decreased perfusion and did not develop AHO on follow-up. The type of germ involved influenced neither the type of enhancement pattern nor the outcome.ConclusionsAge under one year and decreased perfusion of the affected femoral epiphysis increases the risk of secondary AHO. Our study is the first report in human medicine supporting the physiopathological hypothesis described by Alderson et al. in an animal model: primary infection can originally affect the joint, then penetrate the epiphyseal cartilage, and finally spread into the metaphyseal region through transphyseal vessels present only in the first 12/18 months of life.

Role of magnetic resonance imaging in concomitant periarticular infections in septic arthritis of large joints in children: A systematic review

“…Merlini et al recommended performing a contrast-enhanced MR in paediatric hip infection to diagnose osteomyelitis. [ 21 ] Lee et al tried to distinguish between transient synovitis and septic arthritis based on MRI findings. The presence of low signal intensity changes in the bone marrow on fat-suppressed gadolinium-enhanced T1-weighted images and high signal intensity changes on fat-suppressed T2-weighted images indicates septic arthritis.…”

Subacute metacarpal osteomyelitis in a child

“…In spite of the benign nature of this aff ection, other benign and malignant disorders must be considered on diff erential diagnosis, including eosinophilic granuloma, osteoid osteoma, chondroblastoma, tuberculosis, fungal infection, osteosarcoma, Ewing's sarcoma, leukemia and round cell tumors (9-11). Actually, studies of subacute osteomylitis have demonstrated the value of magnetic resonance imaging (MRI) in diagnosing osteomyelitis in children, also pointing to gadolinium-enhanced imaging as the most sensitive one (4,12,13). MRI exploration helps localize the aff ection of the bone and provide an objective view of the lesion extent (10,14).…”

Subacute Metacarpal Osteomyelitis in a Child

“…In spite of the benignity of this affection, other benign and malignant affections must be advocated in the differential diagnosis, including eosinophilic granuloma, osteoid osteoma, chondroblastoma, tuberculosis, fungal infection, osteosarcoma, Ewing's sarcoma, leukaemia and round cell tumours [9][10][11]. Actually, studies of the subacute osteomyelitis showed the important value of MRI in diagnosing osteomyelitis in children also pointing to gadolinium-enhanced imaging as the most sensitive [4,12,13]. MRI exploration helps to localize the affection of the bone and provide an objective control of the lesion extent [10,14].…”