The lower limit of ultrasonography detection in traumatic joint lipohemarthrosis

Abstract

Objective To determine the lower limit of fat layer thickness the ultrasonography can detect in traumatic joint lipohemarthrosis and its clinic application. Methods In the experimental group, 20 samples, composed of fresh blood and pig marrow, were fully agitated and examined by ultrasonography after standing for 10 minutes. In the clinical group, 40 knees with lipohemarthrosis were examined by ultrasonography, X-ray, CT and MR before operation from January 2007 to December 2007. Results In the experimental group, the fat layer thickness ranged from none to 14 mm. The former showed spot medium echo,floating on the top of serum, not clearly. The fat layer thickness beyond 0. 5 mm (fat mass 0.07 mL) was shown clearly, with medium echo. In the clinical group, ultrasonography showed lipohemarthrosis clearly in all the 40 knees. The fat layer ranged from 0. 6 mm to 12. 0 mm. The fat layer was less than 3.0 mm in 6 knees.The ultrasonography results were parallel to those of CT and MRI. The fracture line was shown in 12 knees.Six cases of occult fracture were diagnosed by lipohemarthrosis. X-ray showed lipohemarthrosis in 33 knees and fracture line in 34 knees. Both CT and MRI showed lipohemarthrosis and fracture line. Conclusion Since ultrasonography is very sensitive to the fat layer of joint lipohemarthrosis, with the detection lower limit of 0. 5 mm, it is one of the best imaging methods to detect the joint lipohemarthrosis. Key words: Knee joint; Ultrasonography; Wounds and injuries; Lipohemarthrosis