Keywords:
Patterns of Care, Athletic injuries, Education, Plain radiographic studies, MR, Musculoskeletal system, Musculoskeletal soft tissue, Musculoskeletal joint
Authors:
E. Robinson, R. Mandegaran, A. Zavareh; London/UK
DOI:
10.1594/essr2018/P-0007
Background
Mucoid degeneration of the anterior cruciate ligament (ACL) is an uncommon cause of a painful knee of which the exact pathogenesis is unclear.
Some advocate it is simply a consequence of senescent degeneration whilst others suggest it is related to acquired or congenital synovial tissue herniation1 or is a consequence of mild non-specific trauma2-4.
There is no fixed presentation and it often mimics other internal pathologies of the knee with progressive knee pain,
restricted range of movement but without knee instability4,5.
It is predominantly a condition of the middle ages,
affecting patients between 35-55years of age6,7 with an equal gender distribution8.
It is often detected an incidental finding when an MRI is performed to investigate knee pain.
Due to the low prevalence and mimicking features of other,
more common,
knee pathologies an awareness of the mucoid degeneration is required when reporting MRI knee.
The literature has repeatedly shown that mucoid degeneration is an under reported phenomenon and often misdiagnosed as a partial or complete ACL tear3,10.
In this pictorial review we highlight the essential hallmarks of mucoid degeneration on standard MRI sequences to aid the busy musculoskeletal radiologist and how best to distinguish them from partial ACL tears.