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Objective: To determine the efficacy of a thromboprophylaxis protocol that included deep venous thrombosis (DVT) prophylaxis (subcutaneous heparin), preoperative screening with magnetic resonance venography (MRV), and therapeutic management (vena caval interruption preoperatively, therapeutic heparin anticoagulation postoperatively) when indicated., Design: Prospective, consecutive., Setting: Tertiary referral, teaching hospital in New York City., Patients: One hundred one patients with acutely displaced acetabular fractures., Main Outcome Measure: Preoperative MRV was performed to assess vascular structures. Patients with proximal DVT received vena caval filter interruption preoperatively and therapeutic warfarin postoperatively. Patients without proximal DVT received only subcutaneous heparin preoperatively and low-dose warfarin postoperatively., Results: Forty-nine asymptomatic thrombi were identified in thirty-four of 101 patients (34 percent). Location of thrombi were in the popliteal vein in four of forty-nine patients (8 percent), superficial femoral vein in eight of forty-nine (16 percent), common femoral vein in thirteen of forty-nine (27 percent), external iliac vein in six of forty-nine (12 percent), internal iliac vein in fourteen of forty-nine (29 percent), and common iliac vein in four of forty-nine (8 percent). Thrombi were isolated to the injured extremity in twenty-six of thirty-four patients (76 percent), bilateral in four of thirty-four (12 percent), and isolated to the uninjured extremity in four of thirty-four (12 percent). Twenty-six of the thirty-four patients with proximal thrombi received preoperative vena caval filters. As a result of this protocol, only one patient (1 percent) developed a nonfatal pulmonary embolism., Conclusion: MRV is a sensitive screening examination that allows the placement of inferior vena caval filters based on documented proximal thrombosis. We anticipate that preoperative DVT screening with MRV will significantly decrease the incidence of fatal pulmonary embolism in this high-risk population.

We performed a prospective, blinded study to assess and compare the values of preoperative contrast venography and magnetic resonance venography in the detection of deep venous thrombosis in the thigh and pelvis of forty-five consecutive patients who had a displaced acetabular fracture. The magnetic resonance venography and contrast venography were performed an average of seven days (range, one to twenty-nine days) after the injury. Twenty-four asymptomatic thrombi were identified with magnetic resonance venography in fifteen (33 percent) of the patients. Four of the thrombi were in the superficial femoral vein, nine were in the common femoral vein, one was in the external iliac vein, seven were in the internal iliac vein, and three were in the common iliac vein. Ten (42 percent) of the twenty-four thrombi were confirmed with contrast venography; nine of them were located in the thigh. The remaining fourteen thrombi (58 percent) that had been noted on magnetic resonance venography could not be seen with contrast venography because they were located either in the deep pelvic veins or in the uninjured extremity. The thrombi in the internal iliac vein were identified only with magnetic resonance venography. Twelve of the fifteen patients who had thrombi had a filter placed in the inferior vena cava preoperatively. In eight of these patients, the filter was placed because of the findings of magnetic resonance venography alone. Magnetic resonance venography resulted in a change in the therapeutic management of ten (22 per cent) of the forty-five patients. There were no pulmonary emboli. We concluded that magnetic resonance venography is superior to contrast venography for the preoperative evaluation of proximal deep venous thrombosis in patients who have an acetabular fracture. Magnetic resonance venography is non-invasive, does not require the use of contrast medium, images the proximal aspects of both lower extremities simultaneously, and, most importantly, allows for the identification of deep venous thrombosis in the pelvis.

Objective: The purpose of this prospective study was to compare the value of MR imaging in the detection of injuries associated with acute acetabular fractures (femoral head fracture, free fragments within the hip joint, and injury to the sciatic nerve) with the value of preoperative CT examinations, intraoperative inspection, intraoperative somatosensory evoked potentials (SEP), and clinical neurologic examinations., Subjects and Methods: Coronal fat suppressed long TR/TE and unenhanced and contrast-enhanced T1-weighted MR images were obtained preoperatively in 37 patients with acetabular fractures. The sciatic nerve was assessed for injury and the femoral head was assessed for fracture, dislocation, and contusion. MR results were compared with CT findings for acetabular fractures and fractures of the femoral head. The appearance of the sciatic nerve on MR images was correlated with intraoperative changes in SEP and results of the clinical neurologic examination., Results: Although MR images showed acetabular fractures, intraarticular fragments were often obscured. Fragments were readily apparent on CT scans. MR images showed fracture of the femoral head in 10 (27%) of 37 cases. Nine of these fractures also were seen on CT scans. MR images showed subchondral contusion of the femoral head in 24 (65%) of 37 cases. The same areas appeared normal on CT scans. MR images of the sciatic nerve obtained after injection of contrast material showed intraneural or perineural enhancement in all patients with either changes in baseline SEP (n = 19) or preoperative neurologic deficit (n = 10). Although baseline changes in SEP were more common with intraneural enhancement, the difference in the prevalence of neurologic deficits was not significant. The preoperative enhancement pattern alone could not be used to predict a neurologic deficit., Conclusions: MR imaging of acetabular fractures can be used to detect subclinical injury of the sciatic nerve and occult injuries of the femoral head not readily apparent on CT scans. However, intraarticular fragments may be obscured.