Effect of weightbearing on medial meniscal extrusion: dynamic ultrasound with MRI correlation

BackgroundMeniscal damage compromises its capacity to resist load transmission. However, little is known about the effects of different meniscal injuries on meniscal extrusion under femorotibial loading conditions.PurposeTo evaluate meniscal extrusion in the medial compartment using ultrasound (US), with and without axial loading, and correlate to individual factors (age, body mass index [BMI], osteoarthritis [OA], and type of meniscal tear with different degrees of extrusion).Material and MethodsThe study involved 104 volunteers (53 men, 51 women; mean age = 41.5 ± 1.8 years; age range = 18-70 years; mean BMI = 28.7 ± 5.8 kg/m²; range = 20-47 kg/m²). Meniscal extrusion was evaluated using US in the supine and standing positions, and tears were confirmed by magnetic resonance imaging (MRI).ResultsOur study shows significant variation in meniscus extrusion between supine and standing positions (P = 0.0002). In the supine position, mean values of medial meniscal extrusion within the meniscal tear group (2.281 ± 2.03 mm) were higher than the group without tears (0.55 ± 0.68 mm) (P < 0.0001). From a total of 104 knees studied, 57 (54.8%) demonstrated meniscal injuries. All menisci with ≥3 mm of extrusion presented tears confirmed on MRI. Painful medial compartment showed higher extrusion values (P < 0.0001). OA and age had a greater impact on extrusion (P = 0.001).ConclusionThe presence of extrusion ≥3 mm predicts meniscal tear. In addition, OA and age have a greater impact on increasing extrusion. This research provides valuable insights into the effects of axial body load and associated factors on meniscal extrusion.