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A long-term radiographic follow-up study was conducted on 24 patients (34 hips) who underwent core decompression of the femoral head for avascular necrosis (AVN). The purpose of the study was to assess the potential correlation between the extent of AVN, as determined with preoperative magnetic resonance (MR) imaging, and development of collapse. The preoperative MR results were classified into four categories: group A, no AVN; group B, less than 25% involvement of the weight-bearing portion of the femoral head; group C, 25%-50% involvement; and group D, more than 50% involvement. Histologic evidence of AVN was found in all 34 hips. Collapse occurred in none of the hips in groups A and B (n = 12), in three of seven hips (43%) in group C, and in 13 of 15 hips (87%) in group D. It is concluded that MR estimation of the extent of femoral head involvement with AVN may help in predicting which femoral heads will collapse shortly after core decompression, so that this invasive procedure can be avoided in patients at risk.

High-field surface coil magnetic resonance (MR) images were obtained of 12 ankles: two from healthy volunteers, seven from patients, and three from fresh cadavers. The cadaver ankles were sectioned in the coronal, sagittal, and axial planes for direct comparison with the MR images. Plain film confirmation of pathologic conditions was obtained in all patients, and five underwent arthroscopy or surgery, or both. MR imaging provided excellent delineation of ligaments and cartilaginous structures in all cases.

A retrospective evaluation of magnetic resonance (MR) imaging for the detection of avascular necrosis (AVN) of the femoral head was performed in 49 patients (85 hips) with clinical suspicion of AVN. Positive findings at bone biopsy or evidence on plain radiographs was considered proof of AVN. Absence of clinical symptoms and of radiographic findings for a minimum of 18 months after MR imaging was considered evidence of the absence of AVN. All patients were studied with plain radiography and technetium-99m methylene diphosphonate bone scintigraphy. Five hips had negative MR images, positive findings at bone marrow biopsy, positive bone pressure measurement (BMP), and positive bone scans. A comparison between MR images and bone scans showed MR imaging to be superior, with a sensitivity of 88.8% (vs. 77.5%) and a specificity of 100% (vs. 75%). BMP was the most sensitive (92%) but least specific test (57%).