https://youtu.be/w2QemJqJBfsTitle: Unraveling the Complexities of the Lateral Meniscus and ACL on MRI
๐ Deep Dive into Anatomy and Injury: the intricate relationship between the anterior root of the lateral meniscus (LM) and the anterior cruciate ligament (ACL) in the knee, as revealed by MRI.
Unique Structure:
- The anterior root of the LM is distinct with its fan-shaped, multi-fiber (≥ 3 bundles) composition. Unlike the medial meniscus, it often presents a fissured appearance similar to the posterior root of the medial meniscus on MRI.
Fissured Appearance:
- This characteristic look is due to fibrofatty tissue interspersed among the insertional collagen fibers and the interwoven fibers at the ACL insertion.
Proximity and Overlap:
- Remarkably, the ACL’s footprint and the anterior root of the LM are just 8 mm apart on MRI. At the microscopic level, their fibers overlap by up to 40%.
Alignment Insights:
- The anterior horn of the LM shows a fascinating alignment with the ACL's bundles. The anterior aspect aligns with the AM bundle center, while the posterior aspect aligns with the PL bundle center.
Fibrous Connections:
- These connections from the anterior horn of the LM to the ACL bundles are consistent and vital for knee stability.
๐ค Case Study - Type IV Tibial Spine Fracture:
- A complex tibial eminence fracture (Type IV according to the Meyers and McKeever classification) showcases the challenges in fracture reduction. In an adult case, MRI showed comminuted, displaced fragments, no longer in contact with the bone. Significantly, the anterior root of the LM was attached to one of these fragments, adding complexity to the treatment.
๐ฏ The Takeaway: Understanding these detailed anatomical relationships is crucial for accurate diagnosis and effective treatment planning in sports injuries and other knee-related conditions.