Prevalence of traumatic hip and pelvic fractures in patients with suspected hip fracture and negative initial standard radiographs--a study of emergency department patients.

OBJECTIVES To determine the prevalence of hip and pelvic fractures in emergency department (ED) patients with hip pain and negative standard initial radiographs. METHODS This was a retrospective, cohort study at an academic, community-based ED. ED patients presenting during a one-year period with hip pain for whom a plain-film radiograph was obtained were included. Eligible patients were identified by query of electronic records. Plain radiographs and magnetic resonance images (MRIs) were ordered at the discretion of the treating physician. Initial plain radiographs were read at the point of care by board-certified radiologists. MRI images were reviewed by radiologists with fellowship training in musculoskeletal imaging. Structured follow-up at more than one month postvisit was conducted to rule out a subsequent diagnosis of hip fracture. Ninety-five-percent confidence intervals (95% CIs) and kappa (kappa) were calculated as appropriate. RESULTS Seven hundred sixty-four of 895 patients (85.3%) had follow-up completed (study group). Within the study group, 219 patients (29%) had evidence of fracture on initial radiographs. Of the 545 patients with negative initial radiographs, 62 patients (11.4%) underwent hip MRI during the ED visit. MRI identified 24 additional patients with hip fractures. Interobserver agreement for the presence of fracture on MRI was very good (kappa = 0.847). For patients with negative initial plain radiographs who did not have a hip MRI, follow-up did not identify any of these patients as having a subsequent diagnosis of fracture. Thus, 24 of 545 (4.4%; 95% CI = 3.0% to 6.5%) patients with negative initial plain radiographs had a hip fracture. CONCLUSIONS In this cohort of ED patients with symptoms suspicious for hip fracture who had negative standard radiographs, the authors found that 4.4% were subsequently diagnosed as having fracture. Further studies are warranted to identify characteristics of patients requiring advanced hip imaging studies.