Standard X-rays are not a reliable indicator of hip and pelvic fractures, according to an article published in the April issue of the American Journal of Roentgenology.

"Hip fractures cause high morbidity and mortality, especially in the elderly population, in which the 1-year mortality has been reported to be 12-37%," write Matthew Kirby, MD, and Charles Spritzer, MD from the Department of Radiology, Duke University Medical Center, Durham, North Carolina. "The patient population among whom this problem often arises is elderly women with a history of minor trauma."

In a retrospective study, investigators sought to determine the accuracy of hip and pelvic X-rays in patients who arrived at the Duke emergency department with pain or suspected trauma, and who later had a magnetic resonance imaging scan (MRI). The researchers studied the records of 92 patients whose treatment occurred between July 2005 and June 2008. Seventy-seven were women and 15 were men, with an average age of 70.8 years. Sixty-five had a history of trauma, typically a fall or automobile accident.

X-ray Has False Positives and False Negatives

The results showed that X-ray missed a number of fractures and that MRI revealed many fractures undetected by X-ray. Among other findings:

• 13 patients (14%) had 23 fractures (6 hip, 17 pelvic) undetected by X-ray but confirmed by MRI
• 11 patients (12%) whose X-ray suggested the presence of fractures had MRIs that showed none
• 15 patients (16%) with X-rays that did reveal fractures had MRIs that depicted additional breaks missed by X-ray

Of the 59 patients whose MRIs showed no fractures, 43 (73%) had other conditions revealed by MRI, including muscle edema and tears, trochanteric bursitis, and hamstring tendinopathy. An area under the curve of 0.74 was calculated for receiver operating characteristics analysis for hip fracture detection through X-ray.

The researchers concluded that MRI paves the way for better patient care.

"We found a large number of both false-positive and false-negative diagnoses based on radiographic findings alone," the authors write. "Use of MRI has a substantial advantage in the detection of pelvic and femoral fractures, helping to steer patients to appropriate medical and surgical therapy."

Several limitations were noted by the investigators. First, the retrospective study design offers innate limitations, including the fact that work-up bias may have existed, as only patients who underwent MRI were evaluated. Second, no separate examination was done for trauma patients alone. Third, the study included no cost analysis for the added expense of MRI and other factors that might offset it. Finally, variation existed among MRI protocols and requested X-rays.

Future implications for the study include benefits for patients as well as healthcare management, according to the study authors.

"Accurate diagnosis of hip and pelvic fractures in the emergency department can speed patients to surgical management, if needed, and reduce the rate of hospital admissions among patients who do not have fractures," Dr. Spritzer said in a press release. "This distinction is important in terms of health care utilization, overall patient cost, and patient inconvenience."

Duke University Medical Center supported the study. The study authors have disclosed no relevant financial relationships.

AJR Am J Roentgenol. 2010;94:1054-1060.
Nancy Fowler Larson, March 23, 2010 • Medscape Medical News © 2010 Medscape, LLC