Tram-track appearance of the posterior cruciate ligament (PCL): correlations with mucoid degeneration, ligamentous stability, and differentiation from PCL tears.

ABSTRACT

OBJECTIVE: The purpose of our study was to describe the MRI findings in the posterior cruciate ligament (PCL) analogous to mucoid degeneration in the anterior cruciate ligament (ACL); to correlate MRI findings in the PCL with ligamentous stability; to differentiate the PCL tram-track appearance from the appearance of PCL tears; and to emphasize the coexistence of PCL and ACL mucoid degeneration, cruciate ganglia, and meniscal cysts. CONCLUSION: The tram-track PCL appearance commonly coexists with ACL mucoid degeneration; ganglia; and, less frequently, meniscal cysts. Both PCL tears and MRI findings suggestive of PCL mucoid degeneration show ligament thickening and increased PCL signal intensity. Tram-track PCLs are usually asymptomatic and typically have no ligamentous instability.