Osteoporotic Compression Fracture of the Thoracolumbar Spine and Sacral Insufficiency Fracture: Incidence and Analysis of the Relationship according to the Clinical Factors

PURPOSE: To evaluate the incidence of sacral insufficiency fracture in osteoporotic patients with compression fracture of the thoracolumbar (T-L) spine on magnetic resonance image (MRI), and to analyze the correlation of variable clinical factors and the incidence of sacral insufficiency fracture. MATERIALS AND METHODS: We retrospectively reviewed 160 patients (27 men, 133 women; age range of 50 to 89 years) who underwent spinal MRI and had compression fracture of the T-L spine. Compression fractures due to trauma or tumor were excluded. We evaluated the incidence of sacral insufficiency fracture according to the patients' age, sex, number of compression fractures, and the existence of bone marrow edema pattern of compression fracture. During the same period, we evaluated the incidence of spinal compression fracture in the patients of pelvic insufficiency fracture. RESULTS: Out of the 160 patients who had compression fracture in the T-L spine, 17 (10.6%) had insufficiency fracture of the sacrum. Compression fracture occurred almost 5 times more frequently in women (27:133), but the incidence of sacral insufficiency fracture was 2/27 for men (7.4%) and 15/133 for women (11.3%), with no statistically significant difference (p = 0.80). According to age, the ratio of insufficiency fracture to compression fracture was 0% (0/23) in the 50's, 10.6% (7/66) in the 60's, 12.5% (7/56) in the 70's, and 20.0% (3/15) in the 80's. In respect of single and multiple compression fracture, the incidence of sacral insufficiency fracture was 8/65 for men (12.3%) and 9/95 for women (9.5%), showing no significant difference (p=0.37). In the patients with and without compression fracture with bone marrow edema, insufficiency fracture occurred in 5/76 (6.6%) and 12/84 (14.3%), respectively. On the other hand, of the 67 patients who had pelvic insufficiency fracture, 27 (40.3%) also had spinal compression fracture. CONCLUSION: About 10% of the patients with osteoporotic compression fracture in the T/L spine also had pelvic sacral insufficiency fracture, which was not uncommon. These findings suggest the need to consider the possibility of pelvic sacral insufficiency fracture in cases of T/L spinal MRI for patients with osteoporotic compression fracture.

Usefulness of MR Imaging in Pathologic Fracture of Long Bone

PURPOSE: The purpose of this study was to evaluate the usefulness of MR imaging of pathologic fractures of the long bones. MATERIALS AND METHODS: In 18 patients aged between four and 75 (mean, 25.8) years with histologically confirmed pathologic fractures of the long bones, plain radiographs and MR images were retrospectively analyzed. The former were examined with regard to location and type of fracture, and the presence or absence of underlying disease causing fracture; and the latter in terms of underlying disease, extraosseous mass formation, and soft tissue change. RESULTS: The long bones involved were the femur in nine patients, the humerus in six, and the tibia in three. Underlying diseases were metastatic tumor (n=6), benign bone tumor (n=5), primary malignant bone tumor (n=4), osteomyelitis (n=2), and eosinophilic granuloma (n=1). Plain radiographs showed the fracture site as the metaphysis in ten cases, the diaphysis in five, and the metadiaphysis in one. Fractures were either transverse (n=10), oblique (n=3), spiral (n=1), vertical (n=1), or telescopic (n=1). In two cases, the fracture line was not visible. MR images revealed underlying diseases in all cases. A solid mass was present in all cases of malignant bone tumor, and an extraosseous mass in five such cases. Two benign bone tumors took the form of a cystic mass, two were a cystic mass containing an enhanced solid portion, and one was a solid mass. A soft tissue hematoma was seen in three cases. CONCLUSION: Where pathologic fracture of a long bone had occurred, or a pathologic fracture in which the findings of plain radiography were equivocal, MR imaging was useful for evaluating the pattern and extent of an underlying lesion.

MR Findings of Sacral Insufficiency Fractures in Osteoporotic Patients: Two Cases Report

Osteoporosis is one of the major causes of insufficiency fractures, and since plain radiographic findings are either unhelpful or misleading, insufficiency fracture in the sacrum is particularly difficult to diagnosis and to differentiate from other disease processes such as metastasis. We report the MR findings of two cases of insufficiency fracture of the sacrum. These were not demonstrable on conventional radiographs, but bone scintigraphy revealed unilateral sacral alar uptake, suggesting an active sacral lesion. Both T1 and T2-weighted MR images demonstrated fractures of the sacrum as bands of low signal intensity, with areas of surrounding increased signal intensity seen on the latter suggesting marrow edema.

Pubic Insufficiency Fracture: MRI Findings

PURPOSE: To evaluate the characteristic MRI findings of pubic insufficiency fracture. MATERIALS AND METHODS: In nine cases of pubic insufficiency fracture, the findings of plain radiography (n=9), MRI (n=9), and bone scintigraphy (n=8) were reviewed. We retrospectively analyzed, with regard to fracture site, the destructive pattern revealed by plain radiography, and uptake by other pelvic bones, as demonstrated by RI bone scanning. The MR findings evaluated were the fracture gap and its signal intensity, the site and signal intensity of the soft tissue mass, and other pelvic bone fractures. RESULTS: Plain radiography revealed osteolysis and sclerosis of pubic bone in eight of nine cases (89%), and parasymphyseal fractures in seven (78%). RI indicated uptake by the sacrum in six cases (66%), and by the ilium in three (33%). MR findings of fracture gap (seven cases, 78%) were hypo to isointensity on T1WI, hyper-intensity on T2WI and the absence of contrast enhancement. Soft tissue masses were found in seven cases (78%); in four of these the location was parasymphyseal, and in three, surrounding muscle was involved. Hypo to isointensity was revealed by T1WI, hyperintensity by T2WI, and there was peripheral enhancement. Other associated pelvic bone fractures involved the sacrum in seven cases and the ilium in four. CONCLUSION: The characteristic MR findings of pubic insufficiency fracture were parasymphyseal location, fracture gap, peripherally enhanced soft tissue mass formation, and fractures of other pelvic bones, namely the sacrum and ilium.

MR Imaging of Fracture: MR Pathologic Correlation of Experimentally Produced Fractures on Rabbit Tibias

PURPOSE: To investigate MR imaging characteristics of the fracture healing process. MATERIALS AND METHODS: We performed MR-pathologic correlation of fractures experimentally produced by the three-point beding system inthe proximal tibias of 24 New Zealand white rabbits. Axial spin echo T1-weighted image(T1WI), T2-weighted image(T2WI) and T1WI after gadopentetate dimeglumine injection were obtained 1-28 days after fracture MR imaging was followed by freezing, sectioning along the MR imaging planes and histopathologic examinations. Changes in MR signal around the fractures were correlated with histopathologic findings. RESULTS: Hematomas and inflammatory tissue around the fractures, noted one day after fracture, showed slightly increased homogeneous signal intensityon T1WI, heterogeneous hyperintensity on T2WI and heterogeneous contrast enhancement. Granulation tissue,cartilage, and immature osteoid, noted 1-4 weeks after fracture, showed iso- or slight hyperintensity on T1WI, hyperintensity on T2WI and contrast enhancement. Hard callus containing ossified osteoid showed hypointensity onboth T1WI and T2WI without contrast enhancement. CONCLUSION: The characteristics of MR signal intensity and contrast enhancing pattern can explain the histopathology of the fracture healing process.