Aim. Differentiation between bone infarction and bone infection in sickle cell disease has traditionally been difficult, even with modern imaging techniques, and widespread antibiotic use is common. Early differentiation between the two conditions would enable more appropriate targeting of radiological investigations, antibiotics and surgery, and avoid un-necessary antibiotic usage. Method. At our tertiary paediatric sickle cell centre, we have developed a sequencing protocol to be able to accurately differentiate between infection and infarction in sickle cell children using Magnetic Resonance (MR) Imaging. We have undertaken a preliminary retrospective study to analyse clinical and laboratory parameters in these children to see whether earlier differentiation prior to MR imaging is possible. Results. We identified 52 episodes in 27 patients of bony pain in sickle cell children between 2006 and 2012. In 30 episodes in 27 patients, the MR sequences used allowed accurate determination of pathology, diagnosing infarction in 19 episodes in 17 patients, and infection in 8 episodes in 7 patients. The remainder showed no evidence of acute infarction or infection despite pain. As a general trend, admission white cell counts were higher in the infection group, with a temperature on admission also being more likely. There was no significant difference in CRP or platelet count between the infarction and infection groups. Conclusion. From a small retrospective study it may be possible to identify factors making infection as a cause of bone pain in sickle cell disease more likely, enabling better targeting of urgent MR imaging and surgery and preventing un-necessary antibiotic usage. A larger, prospective study is required and is currently underway

The unwell child with an acutely irritable hip poses a diagnostic dilemma. Recent studies indicate that pericapsular myositis may be at least as common as joint infection in the septic child. MRI might therefore be a critical first step to avoid unnecessary hip drainage surgery in the septic child with hip symptoms. We reviewed our own experience with MR imaging in this setting. We searched our PACS system to retrieve MRI scans performed for children with suspected hip sepsis from August 2008 to August 2014 using the following terms: hip, septic arthritis, osteomyelitis, mysositis, abscess, femur, acetabulum. 56 cases fulfilled inclusion criteria that included acute presentation with hip symptoms and 2 or more Kocher criteria for septic arthritis. Recent unsuccessful hip washout was not a contra-indication. 56 patients presented with acute infection around the hip. 47 (84%) had MRI scans before any surgical intervention and 9 (16%) had scans promptly following unsatisfactory hip washout with failure to improve. 20 (36%) were found to have pericapsular myositis. In this group, the infection commonly involved the iliopsoas (4), gluteal (4), piriformis (5) or obturator (7) muscles. 15 (27%) children had proximal femoral or acetabular osteomyelitis and 8 (14%) were diagnosed with septic arthritis. The 13 (23%) remaining scans did not show infection around the hip. This study confirms a high rate of extracapsular foci in septic children presenting with hip irritability. Less than 20% had actual septic arthritis in this series. While drainage of a septic joint should never be delayed in the face of a large joint effusion with debris on US, there is a clear role for MRI scanning in the acute setting when the diagnosis is less certain

Aims

To determine the normal values and usefulness of the C1/4 space available for spinal cord (SAC) ratio and C1 inclination angle, which are new radiological parameters for assessing atlantoaxial instability in children with Down syndrome.

Permanent growth arrest of the longer bone is an option in the treatment of minor leg-length discrepancies. The use of a tension band plating technique to produce a temporary epiphysiodesis is appealing as it avoids the need for accurate timing of the procedure in relation to remaining growth. We performed an animal study to establish if control of growth in a long bone is possible with tension band plating. Animals (pigs) were randomised to temporary epiphysiodesis on either the right or left tibia. Implants were removed after ten weeks. Both tibiae were examined using MRI at baseline, and after ten and 15 weeks. The median interphyseal distance was significantly shorter on the treated tibiae after both ten weeks (p = 0.04) and 15 weeks (p = 0.04). On T₁-weighted images the metaphyseal water content was significantly reduced after ten weeks on the treated side (p = 0.04) but returned to values comparable with the untreated side at 15 weeks (p = 0.14). Return of growth was observed in all animals after removal of implants.

Temporary epiphysiodesis can be obtained using tension band plating. The technique is not yet in common clinical practice but might avoid the need for the accurate timing of epiphysiodesis.

Cite this article: Bone Joint J 2013;95-B:855–60.

The bicompartmental acetabulum is one of the morphological changes which may be seen in children with Legg-Calvé-Perthes’ disease. Three-dimensional CT and MRI were used to analyse the detailed morphology of the acetabulum with special reference to its inner surface, in 16 patients with Perthes’ disease and a bicompartmental acetabulum.

The bicompartmental appearance was seen on the coronal plane image through the acetabular fossa. The lunate surface was seen to grow laterally resulting in an increased mediolateral thickness of the triradiate cartilage. On the horizontal plane images, the acetabular fossa had deepened and had a distinct prominence at its posterior border. The combination of these morphological changes resulted in a bicompartmental appearance on plain radiography. Acetabular bicompartmentalisation appears to be the result of an imbalance of growth between the cartilage-covered lunate surface and the cartilage-devoid acetabular fossa.