Double posterior cruciate ligament sign

The double posterior cruciate ligament sign (double PCL sign) is a radiological finding seen on magnetic resonance imaging of the knee, specifically in the context of a bucket-handle tear of the medial meniscus. It refers to the appearance of a duplicated posterior cruciate ligament, where the displaced fragment of the torn medial meniscus lies parallel and inferior to the PCL, mimicking a second ligament. ^[1] The double PCL sign has high specificity for meniscal tears when noted on MRI. ^{[2] [3]}

Pathophysiology

A bucket-handle tear is a specific type of longitudinal meniscal tear in which a fragment of the torn meniscus displaces toward the intercondylar notch of the knee. The displaced fragment often remains attached at its anterior and posterior horns but flips centrally into the notch. ^[4] This displacement causes the torn meniscal fragment to align closely and parallel to the PCL, resulting in the appearance of a "double PCL" on sagittal MRI sequences.

Imaging characteristics

The double PCL sign is best observed on sagittal T2-weighted or proton density-weighted MRI images. ^[5] Key features include: ^[6]

• Duplicated PCL Appearance: The native PCL appears as a curvilinear low-signal intensity structure in its typical anatomical location.The displaced meniscal fragment appears as a second parallel low-signal structure inferior to the PCL.
• Meniscal tear: Evidence of a longitudinal tear, often in the medial meniscus.
• Joint effusion: Joint effusion may be present, often associated with acute injury.
• Bone contusions: Sometimes seen in traumatic injuries causing bucket-handle tears.

References

1. Venkatanarasimha, Nanda; Kamath, A.; Mukherjee, K.; Kamath, S. (1 August 2009). "Potential pitfalls of a double PCL sign" . Skeletal Radiology. 38 (8): 735–739. doi:10.1007/s00256-009-0654-5. ISSN   1432-2161. PMID   19234702 . Retrieved 27 December 2024.
2. Hadidi, O; Ellanti, P; Lincoln, M; Hogan, N (10 October 2017). "Double PCL sign on sagittal MRI of the knee". BMJ Case Reports. 2017. doi:10.1136/bcr-2017-222914. PMC   5652627 . PMID   29021146.
3. "The Radiology Assistant : Meniscus special cases". radiologyassistant.nl. Retrieved 27 December 2024.
4. Editor, Data Trace (22 July 2020). "Bucket Handle Meniscus Tear". Wheeless' Textbook of Orthopaedics. Retrieved 27 December 2024.{{cite web}}: |last1= has generic name (help)
5. Vaishya, R; Vijay, V; Vaish, A; Agarwal, AK; Ghonge, NP (November 2017). "Double Posterior Cruciate Ligament Sign on Magnetic Resonance Imaging: Imaging Variants, Mimics, and Clinical Implications". Journal of Orthopaedic Case Reports. 7 (6): 76–79. doi:10.13107/jocr.2250-0685.958 (inactive 1 July 2025). PMC   5868891 . PMID   29600217.
6. Camacho, Marc A. (November 2004). "The Double Posterior Cruciate Ligament Sign" . Radiology. 233 (2): 503–504. doi:10.1148/radiol.2332020945. ISSN   0033-8419. PMID   15516620 . Retrieved 27 December 2024.