Anterior cruciate ligament mucoid degeneration: a review of the literature and management guidelines

Purpose Anterior cruciate ligament (ACL) mucoid degeneration is a rare encounter in clinical practice, different, but often confused with ACL mucoid cysts. Its pathophysiology remains unclear. However, recent publications have suggested that it might be underdiagnosed or misdiagnosed, and that the adverse effects of treatment by ACL resection might be underestimated. The object of this work was to summarize this scattered knowledge to improve patient management. Methods The authors carried out an exhaustive and comprehensive review of up-to-date literature. An extensive search of the MEDLINE database was carried out using MESH terms (ganglion cyst, anterior cruciate ligament) and generic search terms (mucoid degeneration, hypertrophy). Results Anterior cruciate ligament mucoid degeneration is determined by interstitial glycosaminoglycan deposits amidst the collagen bundles causing ACL hypertrophy, knee pain, and limited range of motion. It is thought to arise from a primary synovial lesion and is associated with arthritic change or subsequent to acute or repeated trauma. Diagnosis is made on MRI scans and confirmed on histopathological samples. Current treatment involving ACL arthroscopic resection is efficient on pain and range of motion but is not a benign procedure and causes knee laxity. Conclusions Anterior cruciate ligament mucoid degeneration needs to be more broadly known and properly diagnosed so that progress can be made in its management. Further research will be necessary to confirm the current trends in the literature, which suggest being less aggressive with ACL arthroscopic resection when dealing with mucoid degeneration and making more use of conservative measures such as notchplasty. Level of evidence Systematic review, Level IV.