Diagnostic implications of a cold hip on isotope bone scanning in the paediatric patient

Abstract

Background: Diagnosing a child with hip pain or limping is challenging. Isotope bone scanning is often utilised to diagnose or exclude  septic arthritis where diagnostic difficulty is encountered.

Objectives: The aim of this study was to determine the diagnostic implications  of a cold hip on bone scan, as well as the overall accuracy of bone scans in the setting of septic arthritis of the hip.

Methods: A  retrospective review of all patients who underwent bone scans for suspected septic arthritis of the hip, over a 10-year period, was  performed. All patients that demonstrated a cold hip were included. Demographic and clinical data were extracted from medical records.  Patients with septic arthritis and a cold hip were compared to those who had different diagnoses to determine indications for surgical  intervention. Sensitivity and specificity data analyses of all patients that underwent a bone scan to diagnose or exclude hip septic arthritis  were performed.

Results: We included 59 patients of whom 29 demonstrated a cold hip on bone scan. Septic arthritis was  present in 17 (58%) of patients who had a cold hip. There was a significant difference in clinical and haematological variables between  patients with septic arthritis and those with other diagnoses. The sensitivity and specificity of a cold hip on bone scan for the diagnosis of  septic arthritis were 81% and 68% respectively. The positive predictive value was 59% and the negative predictive value 87%. The overall  sensitivity and specificity of bone scan to diagnose hip septic arthritis was 95% and 66% respectively.

Conclusion: A cold hip on bone scan  is diagnostic of septic arthritis of the hip in the presence of typical clinical and haematological features of infection. The strength of  this investigation lies in its high sensitivity and negative predictive value and its ability to exclude the diagnosis of septic arthritis.