Meniscal Root Tears: An Update Focused on Preoperative and Postoperative MRI Findings.

Meniscal root tears represent radial tears or avulsions of the meniscal cartilage at the tibial attachment site that profoundly affect meniscal biomechanics and kinematics. Meniscal root tears have the functional effect of a total meniscectomy and can lead to rapid degenerative change with development of early knee osteoarthritis (OA). A growing range of arthroscopic surgical techniques have been developed to repair meniscal root tears with the aim of restoring joint kinematics and contact pressures and delaying the development of OA. With increased understanding of the anatomy and biomechanics of the meniscal root, meniscal root injury repair has become the treatment of choice in knees with nonadvanced OA. This article reviews the anatomy and biomechanics of the meniscal roots, clinical and imaging diagnostic criteria of meniscal root tears, correlation between arthroscopy and MRI in the diagnosis and classification of meniscal root tears, and expected and abnormal MRI findings after meniscal root repair. Familiarity with MRI signs and classifications of meniscal root tears, as well as with root repair surgical techniques, can aid radiologists in correctly reporting preoperative and postoperative MRI findings.

Multimodality Imaging of Foreign Bodies: New Insights into Old Challenges.

Traumatic wounds and lacerations are a common reason for patients to present to emergency departments, with retained foreign bodies (FBs) accounting for 7%-15% of cases, particularly those involving the extremities. These retained materials result in a granulomatous tissue response known as an FB reaction, a pathologic attempt to isolate the FB from the host. The most common FB materials are glass, metal, and wood, but other compositions can also be found, such as plastic and animal-derived materials. Clinical history, physical examination, and wound exploration are essential in investigation of retained material but are not sufficient to exclude an FB, and additional investigation is required. Imaging evaluation is a useful tool to help depict and locate an FB, assess possible complications, and guide removal. Conventional radiography, the first-line method in this scenario, is a widely available low-cost depiction method that has good sensitivity for depicting FBs. If the retained material is not depicted at conventional radiography, US can be performed. US is highly sensitive in depicting both radiolucent and radiopaque FBs in superficial locations. For deeper objects, CT may be necessary. MRI is the best imaging modality to delineate local soft-tissue and osseous complications. Retained FBs can result in early and delayed complications, with infection being the most frequent complication. To avoid preventable morbidities related to FBs, radiologists should be familiar with imaging findings and provide essential information to help the attending physician treat each patient. Online supplemental material is available for this article. ©RSNA, 2020.