Magnetic resonance imaging of knee menisci: Diagnostic interpretation and pitfalls

Abstract

Magnetic resonance imaging (MRI) was recognized early on as a useful tool in the evaluation of patients with suspected internal derangement of the knee. The superb soft tissue contrast afforded by MRI provides clear visualization of the normal anatomic structures, as well as an accurate depiction of common pathological conditions and traumatic injuries of the knee. Both the capabilities and diagnostic accuracy of MRI of the knee have evolved rapidly over the past few years. Consequently, it continues to be one of the most frequently performed musculoskeletal imaging studies. With the exception of the physical examination, MRI has become the most important diagnostic tool to aid in the evaluation of the patient with suspected internal derangement of the knee. To gain the most benefit from this diagnostic tool, the orthopaedic surgeon must have a basic understanding of the imaging techniques and planes commonly used to evaluate the knee. In addition, it is important to possess a thorough knowledge of the appearance of the normal meniscus on MRI scans, the MRI criteria for meniscal tears, and the pitfalls that commonly mimic meniscal pathology. Finally, with an ever-increasing number of patients having undergone meniscal repair, a basic approach to interpreting MRI scans of the postoperative knee is essential.