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Título

Imaging of the Anterior Cruciate Ligament: From Normal Anatomy to Injuries and other Pathological Alterations

Introdução e objetivo(s)

The anterior cruciate ligament (ACL) is one of the most frequently injured ligaments in the knee. The ensuing risk of instability and the early onset of osteoarthritis often necessitate surgical reconstruction. Imaging serves not only to confirm and grade the ACL injury but also to identify concurrent lesions in adjacent structures. This information is pivotal for informed decision-making and optimizing surgical outcomes.

Goals
By the end of this presentation, the reader will be able to:
- Understand the anatomy of the ACL and recognize its normal appearance in imaging exams.
- Identify and grade ACL lesions, distinguishing sprains, partial injuries, and complete tears.
- Recognize the indirect signs of an ACL injury.
- Identify concurrent injuries in adjacent structures, including bones, menisci, and other ligaments.
- Differentiate between acute ACL lesions, chronic scarring, and degenerative changes

Método(s)

We conducted a literature review focusing on the essential knowledge radiologists should possess to accurately interpret imaging results related to ACL injuries. Additionally, we have utilized images from our own database to illustrate these key learning points.

Discussão

The ACL extends from the inner wall of the lateral femoral condyle to the tibial eminences. Composed of two bundles, it displays a characteristic fibrillar morphology on MRI images.
ACL injuries are primarily characterized by edema and a disrupted fibrillar pattern. Direct discontinuity isn't always apparent, making indirect signs, like anterior tibial translation, ligament horizontalization, and the pivot shift lesion, essential for diagnosis.
Concurrent lesions in adjacent structures are frequent, notably bone injuries (Segond fracture, avulsion fractures of the tibial eminences) and meniscal injuries (ramp and Wrisberg lesions).
Lastly, radiologists should distinguish acute ACL injuries from other conditions, including scars from prior injuries and degenerative changes.

Conclusões

The anterior cruciate ligament (ACL) injury holds clinical significance due to its frequency and the subsequent complications that can arise. The accurate interpretation of ACL injuries through imaging is crucial for optimal clinical management and patient outcomes. Radiologists, with a deep understanding of ACL anatomy and associated lesions, provide invaluable insights that guide treatment decisions and surgical planning.

Palavras Chave

anterior cruciate ligament (ACL); indirecto signs; associated meniscal injuries

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