Magnetic resonance imaging for acute hip pain in the emergency department

Clinical utility of a focused hip MRI for assessing suspected hip fracture in the emergency department

PURPOSE

A focused hip MRI (FHMR) for the detection of radiographically occult hip fractures was implemented in our emergency department (ED) in 2013. The goal of this study was to assess the clinical utility of this protocol.

METHODS

We retrospectively reviewed radiology reports of 262 unique patients who underwent 263 FHMR (coronal T1, coronal STIR, axial T2 fat saturated) for suspected hip fracture in the ED from October 2013 to March 2020. Electronic medical records were reviewed for the ED course, follow-up imaging, and clinical management within 90 days.

RESULTS

Seventy-one patients had one or more fractures identified by FHMR: one-third had proximal femoral fractures; two-third had pelvic fractures. Of these 71 patients, 53 (74%) had radiographically occult fractures, including 14 (20%) with occult proximal femoral fractures; 4 patients had fractures occult on CT. Nineteen patients with a suspected fracture on radiography were found to have no fracture on FHMR. Four fractures not reported on FHMR were later seen on follow-up imaging: these included 1 isolated greater trochanter, 1 additional ischial tuberosity, 1 additional superior pubic ramus, and 1 additional sacrum. All four fractures were treated non-operatively. Muscle/tendon injury was the most common type of injury, seen in 50% (130/262) patients with the most commonly torn tendons being the hamstring (44%; 15/34) followed by gluteus medius tendon (18%; 6/34). A full-hip or pelvis MRI was done after FHMR in only 5 patients, primarily for the purpose of better characterizing findings already identified on FHMR (2 for fracture, 2 for tendon injury, 1 for soft tissue metastasis). Only one of these five studies provided new information: ruling out a previously questioned fracture. Clinical management of the vast majority of patients was based solely on findings from the FHMR.

CONCLUSIONS

FHMR offers reliable identification of radiographically occult hip fractures and muscle/tendon injuries. The protocol is well trusted in guiding patient management in our ED.

Dedicated MRI in the emergency department to expedite diagnostic management of hip fracture

PURPOSE

To determine the effect on time to diagnosis of making MRI imaging for hip fractures available directly in the emergency department (ED).

METHODS

We conducted a retrospective observational study of patients with MRI imaging of the hip for suspected occult fracture, comparing time to diagnosis and time to disposition of populations imaged in the year preceding and the year following installation of an MRI scanner in the ED.

RESULTS

Time to diagnosis of hip fractures was 709 min before installation of a dedicated ED MRI scanner and 280 min after, a 60% reduction. Including the MRI in the diagnostic workup did not increase ED throughput time, and we were able to save 48% of the patients who had an ED-based MRI from an admission to the hospital.

CONCLUSION

Implementation of an MRI scanner for dedicated emergency department use enables faster hip fracture diagnosis and surgical consultation, or definitive disposition without increasing ED throughput time.

Magnetic Resonance Imaging in Symptomatic Children With Hereditary Multiple Exostoses of the Hip

BACKGROUND

Magnetic resonance imaging (MRI) is useful in evaluating nontraumatic hip pain. It provides information about associated injuries like labral/chondral tears or ischiofemoral impingement (IFI). However, in hereditary multiple exostoses (HME) there has been no report about MRI findings in symptomatic children with hip involvement.

METHODS

Records of children with HME and hip osteochondromas, who had hip MRI/magnetic resonance arthrography, were reviewed. The presence of chondral lesions and labral tears, as well the presence of IFI, was recorded. IFI was defined as edema or fatty replacement/atrophy in the quadratus femoris muscle or decrease of the space for this muscle between the ischium and the proximal femur. The measurements used to determine the space included the ischiofemoral space, the quadratus femoris space, and the minimum ischiofemoral space (MIFS). All measurements were performed on axial T1-weighted images.

RESULTS

Ten children were included (4 males, 6 females). In 2 patients, MRI was unilateral, therefore a total of 18 hips were analyzed. The indication for MRI was hip pain. Mean age, when MRI was performed, was 11.7 years. Labral tears were found in 44% (8/18) and chondral lesions in 33% (6/18) of the hips. The mean ischiofemoral space was 17.2 mm (SD, 7.3), the mean quadratus femoris space was 14.9 mm (SD, 5.3), and the mean MIFS was of 12.8 mm (SD, 5.9). IFI was seen in 44% (8/18) of hips. Two patients had bilateral IFI. MIFS was <10 mm in all hips with IFI (8/8). Of these hips, 88% (7/8) had edema of the quadratus femoris muscle and 38% (3/8) had fatty replacement/atrophy in the muscle. Osteochondromas were seen in the lesser trochanter in all hips with IFI (8/8) and in the ischium in 50% of them (4/8).

CONCLUSIONS

In symptomatic children with HME of the hip, MRI is helpful in detecting the source of pain. A high percentage of these children have IFI and intra-articular lesions. These findings can play an important role in the indication and planning of the surgical approach.

LEVEL OF EVIDENCE

Level IV-diagnostic study.