Is the vacuum sign in the sacro-iliac joint a useful radiological sign of chondrocalcinosis?
To test the contention that intra-articular gas is a radiological finding in chondrocalcinosis (CPPD), the prevalence of the sign was assessed in 44 patients with the disorder and compared to a control group of 272. We conclude that sacro-iliac gas is an inconstant finding occurring no more frequently in those with CPPD than in controls of the same age and sex. Consequently, this radiological finding is of limited clinical value.