Sonographic evaluation of the posterior cruciate ligament in amputated specimens and normal subjects.

The purpose of this study was to define the sonographic appearance and echogenicity of the normal posterior cruciate ligament. We examined the posterior cruciate ligament of five amputated specimens and five normal subjects using a 10 MHz linear array transducer. One K-wire was inserted into the substance of the posterior cruciate ligament of the amputated knee specimens to verify the location of the ligament on the sonogram. Various angles of insonation were used to examine the echogenicity of the posterior cruciate ligament. The results showed that the in situ posterior cruciate ligament appeared as a hypoechoic band relative to the surrounding tissue on sonograms, but it appeared hyperechoic when it was isolated and immersed in a water bath. The specific spatial orientation of the posterior cruciate ligament and anisotropy phenomenon contributed to the hypoechogenicity of the posterior cruciate ligament in situ on sonogram.