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Bone contusion is a finding substantiated by magnetic resonance imaging (MRI) studies. The entity is recognised as a focal signal abnormality in the subchondral bone marrow, and the appearances are thought to represent microtrabecular fractures, haemorrhage, and oedema of the marrow, without disruption of the adjacent cortices or overlying articular cartilage (fig 1A). Unlike a fracture, bone contusion rarely involves both cancellous and compact cortical bone. These osseous injuries may result from a direct blow to the bone, from compression forces of adjacent bones impacting one another, or from traction forces that occur during an avulsion injury.
Sagittal proton density images showing (A) typical kissing contusion with bone bruise areas of low density signal in the medial femoral condyle and the posterior lip of the medial tibial plateau. (B) Note the menisceal tear.
The terms "bone contusion," "bone bruise," and "bone marrow oedema" have appeared in published reports for at least a decade and seem to be used synonymously. MRI sensitivity for bone contusion is reported to be 91-96% and specificity 86-96%. 1
With respect to the frequency of bone contusion, Binfield and Williams 2 reported a rate of 4% in the immature knee, while Bretlau et al 3 reported a rate of 65% in the acutely injured knee, and Perrin et al 4 a rate of 58% associated with more serious injuries (menisceal tears, ligamentous tears). Bone contusions in both surfaces of the knee (kissing contusion) are rather rare complex injuries of the knee, and their importance has not been well documented. These characteristic lesions, which occur on both the femoral and tibial condyle, are of great importance not only in that they are often a sign of more serious associated injury, but also because they may give rise to prolonged symptoms.
Our aim in this study was to determine the frequency of kissing contusions in acutely injured knees in young athletes, and the type and distribution of these lesions in the overall spectrum of bone contusions following intra-articular and extra-articular injuries.
METHODS
From April 1996 to December 2000, 255 MRI examinations were undertaken in addition to clinical examination in 255 athletes with acute knee injuries (197 men and 58 women), mean age of 24.2 years (range 16 to 32). These athletes were competing...