To explore whether quantitative, three-dimensional measurements of meniscal position and size are associated with knee pain using a within-person, between-knee study design.
We studied 53 subjects (19 men, 34 women) from the Osteoarthritis Initiative, with identical radiographic OA grades in both knees, but frequent pain in one and no pain in the other knee. The tibial plateau and menisci were analyzed using coronally reconstructed double echo steady-state sequence with water excitation (DESSwe) MRI.
The medial meniscus covered a smaller proportion of the tibial plateau (-5%) and displayed greater extrusion of the body (+15%) in painful than in painless knees (paired t-test; p < 0.05). The external margin of the lateral meniscus showed greater extrusion of the body in painful knees (+22%; p = 0.03), but no significant difference in the position of its internal margin or tibial coverage. Medial or lateral extrusion ≥3 mm was more frequent in painful (n = 23) than in painless knees (n = 12; McNemar's test; p = 0.02). No significant association was observed between meniscal size and knee pain.
These data suggest a relationship between extrusion of the meniscal body, as measured with quantitative MRI, and knee pain in subjects with knee OA. Further studies need to confirm these findings and their clinical relevance.