Session IV - Femur

Detection of Cerebral Fat Embolism in Patients with Femoral Fractures

Gregory A. Zych, DO; Alejandro Forteza, MD; Sebastian Koch, MD; Iszet Campo, MD; James J. Hutson, Jr., MD, University of Miami School of Medicine, Miami, FL

Purpose: To detect cerebral fat embolism in patients with femoral fractures and observe associated symptoms and signs.

Methods: Adults with femoral shaft fractures admitted to the University of Miami/ Jackson Memorial/Ryder Trauma Center were considered for entrance into the prospective study. Inclusion criteria were:skeletal maturity with a femoral shaft fracture that required operative stabilization. Exclusion criteria were: traumatic brain injury, inability to provide informed consent and deep venous thrombosis. Transcranial Doppler(TCD) studies of the middle cerebral artery were performed generally within twenty four hours of admission, during operative fixation of the femoral fracture, the first postoperative day and prior to discharge or one week post-injury. Detection of a patent foramen ovale was performed with a Contrasted TCD using micro bubbles of air. If necessary, this was confirmed with echocardiography.

Serial physical examination focused on the symptoms and signs of fat embolism, chest radiographs and arterial blood gas analysis.

Neurologic examination was performed serially.

There were twenty one patients enrolled in the study, males-sixteen and females-five. The mean age was twenty nine years, range seventeen to fifty one. Mechanism of injury was motor vehicle crash-seventeen, pedestrian-two, fall-one and gunshot-one. All patients had femoral fractures OTA 32:A-2,B-17,C-3. One patient had bilateral fractures. Twenty fractures were closed and two were open, Grade 1-1,Grade 2-1. Associated fractures were present in ten patients, with three patients having either tibia or pelvic fractures.

Results: The initial TCD showed fat emboli in sixteen patients. The intraoperative TCD was positive for fat emboli in eighteen cases, three of which did not show emboli preoperatively. Femoral fracture stabilization was performed utilizing intramedullary nails in twenty two fractures. Postoperative TCD was positive in fourteen patients. No patient had fat emboli only after the femoral fixation.

Arterial blood gas analysis on admission yielded a mean pO2=78mm, with a range from 49-103. Initial chest radiograph was positive in only one patient with probable pulmonary contusion, which was later read as chronic changes. Subsequently six patients developed pulmonary compromise and five had some form of central neurologic deficit. All of these patients had other signs consistent with fat embolism such as petechiae etc. Of the patients with pulmonary dysfunction or neurologic deficits, six had positive postoperative TCD studies.

Nine patients had a patent foramen ovale(PFO) as detected by Contrasted TCD. Six of these had pulmonary compromise. Five patients with PFO had neurologic changes.

All patients survived with aggressive treatment and neurologic recovery was achieved in all cases.

Discussion and Conclusion: This ongoing study is the first to evaluate a high risk trauma population for cerebral fat embolism. Initially, cerebral fat emboli were seen in seventeen of twenty two fractures, 77%. The results indicate that these emboli occur soon after femoral fracture and are not necessarily produced during fracture stabilization. Only three patients first developed the emboli intraoperatively.

There was a close association between the presence of fat emboli as seen with TCD and the obvious manifestations of fat emboli syndrome. Both pulmonary and neurologic changes were, in the majority, attributable to the fat emboli. Recovery from this fat embolism syndrome was observed in all patients.

Theoretically, a patent foramen ovale would predispose to any type of pulmonary embolism due to the cardiac shunting and more direct route to the systemic circulation. The prevalence of a patent foramen ovale in the general population is approximately 15%. Nine of our patients were found to have this cardiac anomaly which may be associated with clinically symptomatic fat embolism.

The major risk factor for early fat embolism is a femoral shaft fracture caused by blunt trauma. The prevalence of this entity could not be determined, in this study, since it was not possible to enroll every patient admitted with a femoral shaft fracture. The rate of fat emboli in this group was surprisingly high.