Presentation
Left shoulder pain after mechanical ground level fall
Patient Data
AP view of the left shoulder shows an acute comminuted fracture of the left proximal humerus involving the surgical neck and greater tuberosity with impaction at the surgical neck. As would be expected, no layering lipohemarthrosis is visible on the AP view with the patient lying supine. On the scapular Y view, there is sharply demarcated lucency superimposing the superior aspect of the shoulder which may in part represent the fat component of lipohemarthrosis, although likely partly artifactual given the extent of the lucency.
CT of the left shoulder in soft tissue and bone windows shows an acute comminuted fracture of the left proximal humerus involving the surgical neck and greater tuberosity with impaction at the surgical neck. There is lipohemarthrosis within the glenohumeral joint, including the axillary pouch and subscapularis recess. Lipohemarthrosis extends into the biceps tendon sheath. Intraosseous hemorrhage is noted at the fracture; no underlying bone lesion is to suggest pathologic fracture. This CT was obtained with the patient lying in a supine position.
Case Discussion
Lipohemarthrosis occurs due to an intra-articular / intra-capsular fracture. It is most commonly seen in the knee, much less frequently reported in the shoulder. In this case, there is no intra-articular fracture through the humeral head, although there is likely an intra-capsular component of the fracture at the surgical neck, allowing fat and blood products to escape from the bone marrow into the joint. Three layers of joint effusion are visible: fat, blood - serum component, and blood - cellular component, increasing in density from anterior to posterior. This has been referred to as the parfait sign.
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