MRI in Comparison to CT Scan Changes the Treatment Modality in Significant Percentage of Patients with Occult Hip Fracture

Introduction: Patients with clinical presentation of hip fracture but negative radiograph can be misdiagnosed as having no fracture. Missing non displaced hip fracture can be disastrous to the patients. It is well established that MRI is a very sensitive and specific exam for the diagnosis of occult femoral neck fractures. However, in the setting of emergency room its availability is low thus other modalities like bone scan or CT scan are used to evaluate these patients.

Purpose of Study: To compare the diagnostic performance, effect on the operative decision and cost effectiveness of MRI and CT scan in the evaluation of occult hip fracture.

Methods: retrospective study of 53 patients which both MRI and CT scan were conducted in the evaluation of occult hip fracture during the period of 1/1/2012 to 1/7/2016. Comparison of the MRI and CT regarding the diagnosis, influence on operative decision making and cost effectiveness were evaluated.

Results: 10 patients (19%) were operated as a result of a fracture revealed only by MRI and missed by CT. In 5 patients (9%) CT revealed incomplete hairline intertrochanteric fracture. MRI evaluation led to operate 2 patients and 3 others were spared from operation. In 41 patients (77%) non-surgical diagnosis was found in the MRI (pubic rami fracture, hematoma, nonspecific edema, acetabular fracture, osteoarthritis, greater trochanteric fracture, trochanteric bursitis, infection, and muscle contusion). Cost effectiveness analysis showed that over all the MRI exam is less expensive when considering these results.

Discussion /Conclusion: MRI is a superior tool in occult hip fracture diagnosis, helps the operative decision making and should be the modality of choice in the evaluation of occult hip fracture in the emergency room.