Elsevier

Injury

Volume 36, Issue 6, June 2005, Pages 788-792
Injury

Early diagnosis of occult hip fractures: MRI versus CT scan

https://doi.org/10.1016/j.injury.2005.01.024Get rights and content

Summary

Objective:

We compared Computerised Tomography (CT) and Magnetic Resonance Imaging (MRI) in diagnosis of a painful hip in elderly patients after trauma. We report on accuracy, efficiency and benefits.

Design:

We assessed 13 patients, average age 73 years, after fall with plain X-rays showing no evidence of fracture. There were two groups: Group A (six patients) underwent CT and MRI; Group B underwent MRI only.

Results:

In Group A where all of the six patients underwent CT and MRI, four of the CT images resulted in misdiagnosis due to inaccuracy. In Group B where all the seven patients underwent only MRI, all the results were accurate and enabled a precise and fast diagnosis.

Conclusions:

MRI was found to be a more accurate modality than CT scan for obtaining early diagnosis of occult hip fractures. These results point out the advantage of immediate MRI imaging in patients with occult hip fracture enabling a more effective treatment, a shorter hospitalisation period entailing decreased medical costs.

Introduction

Hip fractures have become a widespread health and economic problem in the western world. Longer lifespan has increased the incidence of hip fractures in older people. In the USA, each year 250,000 patients sustain hip fractures. Most of them are treated in community hospitals. Estimates show that the number of hip fractures will double or triple in the coming 20–50 years.1, 2, 3, 4, 22 In 2–10% of the patients presenting with painful hip after trauma initial radiographs may not show the fracture.7, 17, 19

The first year mortality rate of hip fracture patients ranges between 14 and 36%.12 Early diagnosis is essential for improving the care and the recovery of the elderly patients,3, 10, 15, 20, 22 and the mortality rate doubles when the operation is performed after a delay of more than 2 days.13

Most hip fractures diagnosed on clinical history and physical examination are confirmed by plain radiographs. When initial X-rays are negative or equivocal, and there is a clinical suspicion of occult hip fracture, additional diagnostic tests are necessary.9 Failure to diagnose the fracture may result in displacement of a previously undisplaced fracture which may lead to a more complicated operation, longer hospitalisation and delayed rehabilitation.12

Re-assessment of the undiagnosed painful hip includes repeated X-rays several days later and a bone scan at 72 h; the reported sensitivity and specificity of bone scans in occult hip fractures is 93 and 95%, respectively.11, 14 However, a bone scan may produce false positive or false negative results,11 and therefore, it cannot serve as a sole indicator. Moreover, a bone scan does not provide the anatomical location of the fracture, and often necessitates further imaging. CT scan is usually available and very effective in the assessment of acetabular and pelvic fractures, but has not been reported as a diagnostic tool for occult hip fractures. An alternative is MRI examination5, 8, 9, 16, 18 but this is expensive,21 and is not readily available in many community hospitals. Early diagnosis of occult hip fractures would shorten hospitalisation by expediting definitive treatment, leading to reduced costs.

We compared the accuracy of CT Scan and MRI in diagnosing occult hip fractures.

Section snippets

Materials and methods

The study was conducted at a university hospital, treating 400 hip fractures a year.

Between May 2001 and October 2002, we admitted 590 patients with a suspected hip fracture. Of these, 13 (2.2%) had no evidence of fracture on plain radiographs (AP, lateral and full internal rotation X-rays). These patients were divided into two groups. Patients in Group A had CT followed immediately by an MRI (Table 1). Patients in Group B only had an MRI (Table 2).

CT Scan was conducted with an MX8000

Results

We studied 13 patients (11 women and two men) with clinically suspected hip fracture, eight in the left hip, and five in right hip, with no evidence of fracture according to plain films. The ages ranged from 58 to 82 years, mean 73 years. Ten patients were admitted within the first 24 h after the injury, one 3 days later, one 10 days later and one 30 days after the fall.

Discussion

The incidence of occult hip fracture is estimated to be 2–10%.7, 17, 19, 22 In this study, we examined the efficacy of MRI in the early diagnosis of occult hip fractures compared to CT Scan. Our experience shows that MRI provides a definitive early diagnosis in patients with painful hips, whereas a CT is liable to lead to misdiagnosis. The MRI results changed the treatment and ambulation instructions in eight out of the 13 patients. The CT led to misdiagnosis in 66% of patients. Out of the

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