ARRS 2022 Abstracts

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E2067. Spectrum of Meniscal Injuries: A Pictorial Review
Authors
  1. Luqman Wali; Medway Maritime Hospital
  2. Ali Shah; Kent and Canterbury Hospital
  3. Tanzeel Hussain; Basildon And Thurrock University Hospital
  4. Mohammad Hussain; Princess Royal University Hospital
Background
The menisci are multifunctional, fibrocartilaginous, semi-lunar structures located between the medial and lateral tibiofemoral compartments of the knee. The menisci are critical in the biomechanical function and stability of the knee. Meniscal injuries are common and can lead to early development of secondary osteoarthritis; hence, accurate diagnosis in a timely manner is critical to avoid long-term sequalae and allow for appropriate management. MRI of the knee allows for non-invasive assessment of the menisci and related structures. Accurate identification and description of meniscal injuries is critical in communicating the degree of internal derangement to the orthopaedic surgeon, facilitating appropriate treatment.

Educational Goals / Teaching Points
This educational exhibit aims to give an illustrated overview of meniscal tears. An explanation of essential meniscal anatomy and terminology is provided, along with examples of meniscal injuries ranging from simple linear tears to more complex entities such as ramp lesions.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The menisci have a concave superior margin conforming to the femoral condyles and a flat base attaching to the tibial plateau via central anterior and posterior roots. The meniscal body is thicker and lies in between the horns, constituting the middle third of the meniscus. The inner margin is referred to as the free edge. The periphery, or outer margin, of the menisci is vascular and is also known as the red zone. There are various, commonly encountered, supporting ligaments that are intimately related to meniscal function and stability. For example, the transverse geniculate, meniscocapsular, meniscotibial, and meniscofemoral ligaments. Normal menisci produce homogenously low signal on MRI with smooth, well-defined margins. On sagittal images, a bowtie configuration is seen. Coronal images demonstrate a wedge or triangle shape depending on the imaging plane. A true tear, or grade 3 signal change, is defined as linear hyperintense signal reaching the articular surface on two consecutive images. The morphology of a tear is also an important consideration having an impact on clinical outcome. Horizontal tears are orientated parallel to the tibial plateau and split the meniscus into superior and inferior portions. Vertical tears have a perpendicular orientation, splitting the meniscus into inner and outer portions. Radial tears involve the inner margin and extend towards the periphery, splitting the meniscus into anterior and posterior components. More complex injury patterns can occur, including degenerative tears, displaced meniscal fragments, or injury to supporting ligaments.

Conclusion
In summary, meniscal injuries are commonly encountered in clinical practice. Accurate assessment and communication of findings is important to guide further management. It is important to highlight the exact location and morphology of meniscal tears and associated complications.