ganglion cyst of the anterior cruciate ligament

MRI

characteristics of cysts and “cyst-like” lesions in and around the knee: what the radiologist needs to know. ACL ganglion cysts. Two sequential sagittal fat saturated proton density weighted images in two different patients (upper and lower row) demonstrating a cystic lesion (black arrow) at the upper segment of the ACL with part of the lesion (white arrow) dispersing into the ACL fibres

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Gaillard, F. Anterior cruciate ligament ganglion cyst. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-3582 • CC by-nc-sa 3.0 (modified)

Desai, P. ACL mucoid degeneration and ganglion cyst. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-10041 • CC by-nc-sa 3.0 (modified)

Salam, H. ACL mucoid degeneration. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-12319 • CC by-nc-sa 3.0 (modified)

Schubert, R. Anterior cruciate ligament mucoid degeneration with ganglion cyst. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-14672 • CC by-nc-sa 3.0 (modified)

Abdrabou, A. Anterior cruciate ligament ganglion cyst (intercondylar notch cyst). Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-24903 • CC by-nc-sa 3.0 (modified)

Ibrahim, D. Anterior cruciate ligament ganglion cyst. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-31009 • CC by-nc-sa 3.0 (modified)

Borra, P. Anterior cruciate ligament mucoid degeneration and ganglion cyst. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-69961 • CC by-nc-sa 3.0 (modified)

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Spectrum of

MRI features of ganglion and synovial cysts. Anterior cruciate ligament ganglion cyst incidentally found in a 58-year-old woman during an MRI scan performed in the setting of a knee sprain. Sagittal FS PD-WI shows an enlarged anterior cruciate ligament due to a multiloculated cystic lesion (arrows) embedded within its fibers. ACL, anterior cruciate ligament

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Radiopaedia • CC-by-nc-sa 3.0 • de

Anterior cruciate ligament (ACL) ganglion cysts, commonly referred to simply as ACL cysts, along with ganglion cysts arising from the alar folds that cover the infrapatellar fat pad, make up the vast majority of intra-articular ganglion cysts of the knee.

Epidemiology

Anterior cruciate ligament ganglion cysts are uncommon, with the prevalence reported to be between 0.3-1.3% of knee MRIs, and are usually incidental findings.

Clinical presentation

Knee pain, being the most common presenting complaint, is usually attributable to other pathology.

Pathology

Anterior cruciate ligament ganglion cysts are histologically identical to the ganglion cysts seen elsewhere, most commonly around the wrist. They comprise mucoid material surrounded by a pseudocapsule .

The pathogenesis remains controversial, with two theories being favored:

sequelae of ACL mucoid degeneration
herniation of synovial tissue through a defect in the joint capsule or tendon sheath

Radiographic features

MRI

MRI is the gold standard for diagnosis and has higher sensitivity compared to standard anterior portal approach arthroscopy since an intraligamentous lesion may not be apparent externally (ligament may appear normal arthroscopically) . A posterior approach will allow the arthroscopist to detect changes by probing the ligament and will allow potential aspiration of the cysts.

In one of the largest imaging studies of ACL ganglion cysts, Bergin et al used two out of three criteria for diagnosis :