Knee MRI often supports clinical assessment and treatment decisions, but inconsistent meniscus terminology can weaken communication between musculoskeletal radiologists and orthopaedic surgeons. Clearer reporting language is needed for tear diagnosis, uncertain findings, tear patterns, location, roots, extrusion and postoperative assessment. A 2026 interdisciplinary Delphi consensus statement in Radiology sets out agreed terminology across these areas, based on input from orthopaedic surgeons and musculoskeletal radiologists at North American institutions. The statements provide a shared framework for common and complex findings while allowing uncertainty when imaging appearances are not definitive.
Building Agreement Across Specialties
The Delphi process began with open-ended responses and then moved to scored statements. Consensus required strong agreement on a structured rating scale. All panellists completed each round, and all proposed statements eventually reached consensus. Agreement improved between the later rounds in several areas where wording can change clinical interpretation. These included possible tears, tear descriptors, MRI criteria for tears, postoperative assessment, tear patterns, intrameniscal descriptors, meniscal roots and retear descriptors.
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The panel included both orthopaedic surgeons and musculoskeletal radiologists. Their clinical exposure differed. Orthopaedic surgeons more often treated patients across different age groups, while radiologists more often evaluated adult patients and interpreted higher numbers of meniscus cases. This gave the process input from both imaging interpretation and operative decision-making.
The agreed language is practical rather than rigid. It does not require one single classification system for every situation. Instead, it supports clearer wording for recurring MRI findings and allows cautious terms when the diagnosis remains uncertain. This is important because some MRI appearances do not necessarily indicate a surgically treatable lesion. Terms such as “possible” or “equivocal” can help clinical providers keep flexibility in management.
Clarifying Tear Diagnosis and Location
Primary MRI criteria for a meniscus tear include abnormal signal reaching the meniscal surface and changes in meniscal shape. A tear diagnosis is stronger when linear high signal clearly reaches the surface on more than one image. In an unoperated meniscus, shape change can support the diagnosis of a displaced tear. Free edge blunting may reflect either a radial tear or degenerative fraying.
When appearances are uncertain, terms such as “possible”, “probable” or “equivocal” can be used. These terms may apply when abnormal signal reaches the surface on only one image, when the signal path is unclear or when chondrocalcinosis, artefact or technical limitations reduce confidence. The aim is to communicate uncertainty without overstating the diagnosis.
Reportable tear patterns include horizontal, longitudinal-vertical, radial, complex, bucket-handle, vertical flap and horizontal flap tears. No tear-pattern terms were completely prohibited, but oblique should be used carefully because it has been applied to different patterns. Tear location should use anatomical wording, including “anterior horn”, “posterior horn”, “anterior root”, “posterior root” and “body”. Location across the meniscus can be described as “peripheral”, “middle third” or “free edge” or with comparable “inner”, “middle” and “outer” zones. MRI reports should avoid “stable”, “unstable”, “reparable” and “unrepairable” because imaging alone cannot reliably determine those points.
Managing Roots, Extrusion and Retear diagnosis
Meniscal roots anchor the anterior and posterior horns to the tibial plateau. Root injuries include avulsions and radial tears. Signal within the root may be seen, but it should not by itself be called a root tear. When a tear extends from a horn into the root, reports should describe the tear shape and extent where possible.
Meniscus ramp lesions involve injuries at the posteromedial meniscocapsular junction. These include injuries to the meniscocapsular attachments, meniscotibial attachments and the peripheral posterior horn of the medial meniscus. MRI appearances linked with these lesions include fluid-like signal at the junction or peripheral third of the meniscus, contour irregularity and posteromedial tibial plateau marrow oedema-like signal as a nonspecific secondary feature.
For suspected meniscus extrusion, knee MRI remains the preferred imaging test. Standard assessment uses a coronal image through the greatest volume of the medial tibial spine. Measurement uses the tibial plateau margin and the outer edge of the meniscus as reference points. For suspected retear after partial meniscectomy or repair, MRI without contrast is preferred. Retear reporting should describe both shape and signal intensity, including whether signal reaches the surface. MR arthrography or CT arthrography may be considered when routine MRI remains equivocal or comparison material is unavailable.
Standardised knee meniscus MRI reporting gives radiologists and orthopaedic surgeons a clearer shared language. The consensus framework reduces ambiguity around tear diagnosis, tear patterns, location, roots, ramp lesions, extrusion and postoperative retears. It also preserves useful uncertainty when MRI findings are not definitive. For healthcare professionals and decision-makers, the main value lies in more consistent communication across imaging and clinical care, with reports that remain structured, cautious and relevant to treatment planning.
Source: Radiology
Image Credit: iStock
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Knee MRI scan with coronal and sagittal views, supporting musculoskeletal imaging, meniscus assessment and orthopaedic diagnosis.
