The absent bow tie sign

Selective Unique Signs of Meniscus Tears as Visualized by Magnetic Resonance Imaging

The meniscus is an organized collection of fibrocartilaginous tissue that is located between the femoral condyles and the tibial plateau of the knee which primarily assists with load transmission. The complex composition of articulating soft-tissue structures in the knee causes the menisci to become a common source of injury, especially in the realm of athletic trauma. Magnetic resonance imaging (MRI) has become the imaging modality of choice for evaluating patients with suspected meniscal pathology because of its numerous advantages over plain radiographs. Most forms of meniscal tears have classic MRI findings and are used in correlation with physical examination findings to confirm or rule out a diagnosis. These imaging findings are referred to as signs and have been well studied, and the associated eponyms for each sign are well published throughout the literature. This article will review and describe a unique selection of meniscal pathology as visualized by MRI that is more commonly published in musculoskeletal radiology literature when compared with orthopedics and sports medicine literature.

Common Mistakes and Pitfalls in Magnetic Resonance Imaging of the Knee

This pictorial review presents an overview of common interpretation errors and pitfalls in magnetic resonance imaging (MRI) of the knee. Instead of being exhaustive, we will emphasize those pitfalls that are most commonly encountered by young residents or less experienced radiologists.

Symptomatic ring-shaped lateral meniscus. MRI findings

Ring-shaped lateral meniscus is a rare clinical entity that is usually asymptomatic. Moreover, diagnosis is always based on arthroscopic exploration of lateral meniscus. MRI has not been proven useful so far because the inner portion of the ring-shaped lateral meniscus is usually misinterpreted as a bucket-handle tear. The authors report a case of a 16-year-old girl with ring-shaped lateral meniscus in combination with a meniscal cyst. MRI demonstrated a cyst arising from lateral meniscus and meniscal tissue into the inner portion of the lateral compartment mimicking displaced meniscal fragment. Bucket-handle tears have not been reported to cause or accompany meniscal cysts. As a result the diagnosis of a ring-shaped lateral meniscus along with meniscal cyst was assumed based on MRI and confirmed during arthroscopy. The patient was treated with arthroscopic partial lateral meniscectomy and intra-articular cyst debridement.

Meniscal gymnastics: common and uncommon locations of meniscal flip and flop

The majority of knee magnetic resonance imaging examinations are performed for meniscal evaluations. Displaced meniscal tears including free meniscal fragments are an important diagnosis as most of these tears are unstable and require surgical intervention. Magnetic resonance imaging can be an invaluable tool in the arthroscopic search for a free meniscal fragment. In addition to the commonly seen bucket-handle tears flipped into the intercondylar notch, it is important to be aware of less common locations where menisci may be displaced. First, we briefly summarize the basic meniscal anatomy and some of the more common tear patterns. We then investigate the broad range of meniscal migration.