Bone marrow lesions (BML) are readily depicted on MRI as areas of increased edema-like signal in the subchondral bone. New or increasing BMLs are associated with increased knee pain, especially in males or patients with family history of osteoarthritis [22]. Conversely, decreasing BMLs are associated with reduced knee pain [23]. A systematic review of 22 articles concluded that both BMLs and synovitis/effusion may indicate the origin of knee pain in patients with osteoarthritis [24-26]. Some patients with normal knee radiographs and anterior knee pain have abnormal cartilage on 3 T MRI using quantitative imaging [29]. In particular, patients 45 to 55 years of age with knee pain but normal radiographs exhibited elevated T2 mapping values on 3 T MRI [20]. Patellofemoral cartilage loss is also associated with chronic knee pain, with active knee pain correlated with BMLs [30,31]. Similar to CT, MRI can calculate various anatomic measurements associated with patellofemoral subluxation/dislocation and lateral patellofemoral friction syndrome [32-34]. Bone marrow edema in the classic location for patellofemoral dislocation/relocation injuries is also identified by MRI [15]. MRI may also differentiate patients with more severe patellofemoral osteoarthritis who may not benefit from supervised exercise therapy from patients with medial or lateral knee compartment arthritis who might benefit [35]. MR Arthrography Knee MR arthrography performed with an intra-articular injection of dilute gadolinium solution is typically not indicated as a second examination but rather reserved for patients with known prior meniscal surgery, chondral and osteochondral lesions, and suspected loose bodies [10]. US Knee US is not often useful as a screening test or a comprehensive examination. It may be appropriate to confirm a suspected effusion and to guide a potential aspiration [10]. US is as accurate in diagnosing a popliteal cyst and detecting cyst rupture when compared to MRI [10].
Chronic Knee Pain. Bone marrow lesions (BML) are readily depicted on MRI as areas of increased edema-like signal in the subchondral bone. New or increasing BMLs are associated with increased knee pain, especially in males or patients with family history of osteoarthritis [22]. Conversely, decreasing BMLs are associated with reduced knee pain [23]. A systematic review of 22 articles concluded that both BMLs and synovitis/effusion may indicate the origin of knee pain in patients with osteoarthritis [24-26]. Some patients with normal knee radiographs and anterior knee pain have abnormal cartilage on 3 T MRI using quantitative imaging [29]. In particular, patients 45 to 55 years of age with knee pain but normal radiographs exhibited elevated T2 mapping values on 3 T MRI [20]. Patellofemoral cartilage loss is also associated with chronic knee pain, with active knee pain correlated with BMLs [30,31]. Similar to CT, MRI can calculate various anatomic measurements associated with patellofemoral subluxation/dislocation and lateral patellofemoral friction syndrome [32-34]. Bone marrow edema in the classic location for patellofemoral dislocation/relocation injuries is also identified by MRI [15]. MRI may also differentiate patients with more severe patellofemoral osteoarthritis who may not benefit from supervised exercise therapy from patients with medial or lateral knee compartment arthritis who might benefit [35]. MR Arthrography Knee MR arthrography performed with an intra-articular injection of dilute gadolinium solution is typically not indicated as a second examination but rather reserved for patients with known prior meniscal surgery, chondral and osteochondral lesions, and suspected loose bodies [10]. US Knee US is not often useful as a screening test or a comprehensive examination. It may be appropriate to confirm a suspected effusion and to guide a potential aspiration [10]. US is as accurate in diagnosing a popliteal cyst and detecting cyst rupture when compared to MRI [10].