![]() ![]() development of pressure gradient across the joint cavity). 9 As described earlier, in normal ageing the decrease in signal intensity on T 2. Signal loss on T 2 is an early indicator of intervertebral disc degeneration on MRI. As a result of a sudden contraction of the surrounding muscles, there is a distraction of the joint, resulting in an increase in joint volume creating a negative pressure (i.e. Other signs, including sclerosis of the vertebral endplates, osteophytes, vacuum phenomenon and calcification, are more reliable, though they indicate late degenerative changes. Possible mechanisms for gas entry include development of negative pressure within the joint cavity. The presence of gas in a joint can occur in almost any joint, such as the sternoclavicular joint, where it may outline the intra-articular disc (see case 2). 2 On MR images, the vacuum generally has low signal intensity with all sequences, and it appears as a signal intensity void on gradient-echo images because of magnetic susceptibility effect. This cleft represents a collection of gas (air) within the vertebral body. Thus, we consider that it is necessary to confirm Kümmell’s disease with bone necrosis under biopsy. This is a joint-specific example of the vacuum phenomenon. The intravertebral vacuum cleft sign is more easily seen on CT scans, on which it has a heterogeneous distribution and an irregular shape, than on radiographs. vacuum cleft sign (2) which can be seen on advanced imaging. Therefore, intravertebral clefts are not characteristic sign of Kümmell’s disease, but they are highly suspicious sign of the disease. The vacuum cleft sign: An uncommon radiological sign. ![]() Awareness of this potential pitfall and an understanding of the characteristic appearance and location of this collection of intra-articular gas may help prevent misdiagnosis of intra-articular loose bodies or chondrocalcinosis. trauma after surgery (6) no complication after surgery, including leakage of. This can cause circular or linear areas of low signal intensity on GRE MR images of the shoulder obtained with external rotation of the arm and represents small foci of intra-articular gas. It is a very common occurrence, particularly in external rotation. However, the presence of gas does not categorically imply merely degenerative disc disease, as other processes can lead to discs containing gas. Pathology This commonly occurs in association with intervertebral disc degenerative disease. 8 Further studies with the advent of MRI, demon. Clinical presentation This phenomenon is asymptomatic. 5 This was confirmed with a later study documenting cleft sign sensitivity and specificity of 85 and 99, respectively. Vacuum phenomenon in the shoulder refers to the presence of intra-articular gas in the shoulder joint. The intravertebral vacuum cleft was first described related to avascular necrosis with histological specimens from biopsy suggesting a reparative process following bone ischemia. ![]()
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