Varus stress MRI in diagnosis of medial meniscal posterior root tear

Background: Early and accurate diagnosis of medial meniscal posterior root tear (MMPRT) via magnetic resonance imaging (MRI) is crucial to prevent the development of medial meniscus extrusion (MME) and subsequent osteoarthritic changes. The study aims to assess the role of MRI in diagnosing the medial meniscal posterior root tear (MMPRT) as well as to investigate the additive value of a new MRI technique (varus stress position technique) in measuring the accurate degree of a truly extruded meniscus, during normal daily activities like standing or walking. This prospective study included 70 patients who had an episode of posteromedial knee pain. All patients underwent conventional MRI, whereas only 35 of them underwent MRI with varus stress loading position. Results: The study included 70 patients, of which 56 were female (80.0%), with a mean age of 49.1 +/- 8.5 years. According to duration onset of MMPRT, 39 patients were in the chronic stage (4-12 months), 16 patients were in the acute stage (early < 1 month), and 15 patients were in the subacute stage (1-3 months). It was found that varus stress position could detect 100% of the patients (35/35) with positive medial meniscus extrusion (MME) (>= 3 mm), whereas the MRI with the traditional position could detect only 62.9% of the cases (22/35) (P < 0.000). Regarding the chronicity of MMPRT, a significant increase was observed in the amount of MME in post-varus MRI compared with that in pre-varus MRI for each stage (acute, subacute, and chronic) (P < 0.000). Conclusion: MRI is considered a superior imaging modality in diagnosing MMPRT through several characteristic MRI findings. The varus stress position showed a valuable role in assessing the presence and degree of severity of true extruded meniscus using positional varus stress load.