Bone Marrow Edema Signal

Increased T2-weighted signal from the subchondral bone marrow is a frequent finding in acute traumatic osteochondral injury [86] as well as in the setting of chronic osteochondral injury, or osteoarthritis [87-89]. Similar alteration in bone marrow signal intensity are observed following high intensity exercise or with altered joint biomechanics [90,91]. It is a nonspecific MRI finding, but can be associated with pain [88], and with internal derangement in the knee [91,92].

The characteristics of the MRI signal abnormality in the marrow are similar to those of water, which is dark on short TE sequences and bright on fluid-sensitive sequences such as fat-suppressed proton density or T2-weighted SE or FSE sequences, or STIR images [93]. Because the abnormal signal closely follows water, this finding has been erroneously termed bone marrow edema [94]. Correlation studies with histology indicate that a mixture of tissue types contribute to the abnormal marrow signal. In the setting of acute trauma, areas of fluidlike signal are associated with regions of trabecular microfracture, hemorrhage, necrosis, and edema [95]. In this clinical setting, the marrow

Fat Necrosis Chronic Bone Marrow

Fig. 8. Forty-two-year-old male with persistent pain after blunt anterior knee trauma. (A) Axial fat-suppressed, PD-weighted FSE image demonstrates focally elevated T2 weighted signal intensity with intact articular surface consistent with a Grade I lesion (arrow). (B) Focal T2 elevation of the radial zone with associated subchondral marrow edema is present on the sagital fat-suppressed, T2-weighted image (arrow). This pattern of radial zone T2-elevation is associated with delamination cartilage injury.

Fig. 8. Forty-two-year-old male with persistent pain after blunt anterior knee trauma. (A) Axial fat-suppressed, PD-weighted FSE image demonstrates focally elevated T2 weighted signal intensity with intact articular surface consistent with a Grade I lesion (arrow). (B) Focal T2 elevation of the radial zone with associated subchondral marrow edema is present on the sagital fat-suppressed, T2-weighted image (arrow). This pattern of radial zone T2-elevation is associated with delamination cartilage injury.

findings represent a bone marrow contusion. Follow-up studies have shown that the abnormal marrow signals can persist for several months following resolution of symptoms, and are infrequently associated with long-term sequelae [96,97]. In contrast to lesions with an ill-defined reticular border, bone marrow contusions that have a well-demarcated margin that extends to the subchondral plate have a 50% likelihood of progressing to localized cartilage loss [98]. In the presence of osteoarthritis or chronic focal osteochondral injury, the region of abnormal marrow signal has a heterogeneous histology consisting of necrosis, fibrosis, subchondral cysts, edema, hemorrhage, and granulation tissue [94,99,100]. The presence of elevated T2-weighted signal in bone marrow may be a secondary indication of an overlying full-thickness articular cartilage defect [31]. In correlation with arthroscopic grading of focal cartilage defects, the prevalence of subchondral marrow hyperintense T2-weighted signal is 1% for athroscopically normal cartilage, 10% for partial-thickness defects, and 53% of full thickness articular cartilage defects [31].

Osteoarthritis

Osteoarthritis

Thank you for deciding to learn more about the disorder, Osteoarthritis. Inside these pages, you will learn what it is, who is most at risk for developing it, what causes it, and some treatment plans to help those that do have it feel better. While there is no definitive “cure” for Osteoarthritis, there are ways in which individuals can improve their quality of life and change the discomfort level to one that can be tolerated on a daily basis.

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