Learning objectives
To present the imaging features which help in the differential diagnosis of the femoral head bone marrow edema pattern.
Background
The term bone marrow edema pattern of the femoral head refers to a non-specific MRI finding characterized by an ill-defined area of hypointensity on T1 W images and hyperintensity on T2 W and STIR images, extending to the femoral head and neck. This pattern is consistent with idiopathic transient osteoporosis (ITOH), migratory osteoporosis, transient bone marrow edema syndrome (TBME) and early osteonecrosis (ON). Similar signal alterations are observed in other pathologic entities including trauma, inflammation, osteoarthritis and malignancies. These latter conditions can usually be excluded...
Imaging findings OR Procedure details
For each clinical entity a representative case is illustrated with emphasis on the imaging criteria leading to diagnosis.A 35-year-old man presented with painful hip and motion restriction without history of trauma and no predisposing factors for ON.Plain radiographs showed osteopenia of the left femoral head and neck, without joint space loss, contour deformity or areas of osteosclerosis.Bone scintigram showed increased isotope uptake without any cold spots within it.A DEXA study showed a 17-20% decrease in the bone mineral density.In T1 W MRI images the left...
Conclusion
Bone marrow edema of the hip has to be correctly interpreted in order to avoid overtreatment in transient and self-limiting conditions. The presence of subtle subchondral lesions and the temporal evolution are usually key to diagnosis. Unfortunately, there are cases in which, even in the absence of specific subchondral lesions, ON cannot be excluded from the differential diagnosis and follow-up examination (in 6-12 months), or biopsy is required to set the final diagnosis.
References
Resnick D, Kang HS. Internal derangements of joints. Emphasis on MR imaging. WB Saunders CO Philadelphia 1997; pp 512-520 Stoller D. ed. Magnetic Resonance Imaging in Orthopaedics and Sports Medicine, 2nd ed. Lippincott-Raven, Philadelphia 1997; pp 127-145 and 196-198 Curtiss PH Jr, Kinkaid WE. Transient demineralization of the hip in pregnancy: A report of three cases. J Bone Joint Surg (Am) 1959; 41A:1327 Wilson AJ, Murphy WA, Hardy DC, et al. Transient osteoporosis: Transient bone marrow edema? Radiology 1988; 167:757 Hofman S, Engel A, Neuhold...
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