Mucoid Degeneration of the Anterior Cruciate Ligament (ACL ) can mimic a tear on MRI. Review of the findings of mucoid degeneration on MRI

Image Above: ACL mucoid degeneration.  Expansion of the ACL but ACL fibres are still seen in normal alignment.

Image Above: Complete tear ( left ) and mucoid degeneration ( right). In mucoid degeneration ACL fibres are still seen in normal alignment and continuity and cysts are present which would not be seen in a tear.

Image Above: ACL mucoid degeneration.  Expansion of the ACL but ACL fibres are still seen in normal alignment. Cyst ( yellow arrow)  present adjacent to the tibial ACL insertion site and bone marrow oedema ( blue arrow)  at the insertion..

Image Above: ACL mucoid degeneration.  ACL not expanded and ACL fibres in normal alignment. Intraosseous cyst and oedema adjacent to the femoral attachement site of the ACL.