Bone bruises (also known as bone contusion, trabecular microfracture) are an osseous injury that results from compression of bone structures.
Bone bruises represent trabecular microfractures with hemorrhage and without a discrete fracture line or contour abnormality . They typically appear within 48 hours of injury and can persist for up to six months .
Most bone contusions are a result of a direct blow to the bone, traction from avulsion trauma, or load to a subchondral surface . Depending on where bone contusion is seen, the underlying trauma mechanism can be identified.
They can progress to osteochondritis dissecans .
Plain radiography will not demonstrate cancellous features but can show regions of impaction, for example, a Hill-Sachs lesion .
MRI is the modality of choice when investigating bone marrow. Bone (marrow) contusion is typically focal and ill-defined with the following signal characteristics :
- T1: focal hypointense area of bone marrow
- T2 fat-saturated: focal hyperintense area of bone marrow