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Three Part Question

In [patient with suspected fracture of neck of femur and normal plain xray of the hip in emergency department] is [MR scanning more sensitive than Bone scan] in [detecting occult fractures] ?

Clinical Scenario

An 82 year old lady has been brought to ED complaining of hip pain having been found on the floor at her residential home. Clinical examination indicates likely fractured neck of femur. Plain AP and lateral radiographs of the hip demonstrate to obvious fracture. What is the most accurate investigation to rule out fracture?

Search Strategy

Pubmed 19/7/2010, OVID Medline 1950-July week 1 2010, Web of Knowledge 19/7/2010
Pubmed: fracture$.mp AND ((MRI$.mp) OR bone scan$.mp)
OVID: exp Hip fractures /cl,di,ra AND (MRI$ OR bone scan$).mp
Web of Knowledge:Topic=(fracture$) AND Topic=(MRI) AND Topic=(bone scan)
Refined by: Languages=( ENGLISH ) AND Subject Areas=( ORTHOPEDICS )

Search Outcome

PudMed:149 articles found, 147 irrelevant to the study question.

OVID:109 articles, no new articles relevant to the study question.
Web of Knowledge: 167 articles, no new articles relevant to the study question.
Reference review: 1 further article

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Evans PD, WIlson C, Lyons K. 1994 UK	37 pateints with suspected occult hip fractures investigated with MRI scan (within 24 hours) and bone scan (after 48 hours)	Prospective cohort study	Senstivity and accuracy of MRI compared with bone scan in detecting fracture of proximal femur	8 of 37 patients had fractures. All 8 diagnosed by MRI. 6 of 8 diagnosed by bone scan.	Small study numbers. No blinding of investigators to outcome of other scan reported.
Rubin et.al. 1998 USA	40 patients with suspected occult hip fracture underwent either MRI within (24 hours) or bone scan( within 72 hours). 21 patients recieved bone scan, 19 MRI.	Retrospective cohort study	Sensitivity	MRI: 100% bone scan:90.9%	Retrospective study. No criteria for allocating pateints to a group, bone scan patients diagnosed during first half of study, MRI second half.
			Specificity	MRI: 100% bone scan: 100%
			Accuracy	MRI: 100% bone scan: 95%
			Time to Diagnosis	MRI: .0368+/-0.587 days. bone scan: 2.21+/-1.30 days p=<0.0001
			Cost effectiveness	MRI:$3050.75 bone scan:$7543
Rizzo et.al 1993 USA	66 patients with occult fractured neck of femur. All investigated with limited MRI within 24 hours and bone scan within 72 hours	Prospective cohort study	accuracy of MRI compared with bone scan in detecting fracture of proximal femur	23 patients had negative MRI and bone scan. 36 patients had evidence of fracuture with both MRI and bone scan. 1 patient had positive MRI and negaive bone scan (re-scan at 6 days demonstrated fracture)	No blinding of investigators to outcome of other scan.
			Sensitivity of MRI compared with bone scan in detecting fracture of proxiaml femur	MRI with in 24 hours showed greater sensitivity then bone scan at 72 hours

Comment(s)

Only a few small cohort studies comparing the two investigations directly however all reach the same conclusion that MRI demonstrates equal or greater sensitivity at detecting fractures. The speed and availability of MRI is a major factor as fractures are evident immediately with MRI whereas bone scans incur a delay before investigation and evidence of fracture is not guaranteed by 72 hours. The British Orthopaedic Association guidelines recommend that fractured neck of femur should be operated within 48 hours of admission, clearly this is not always possible with bone scan.

Clinical Bottom Line

MRI is more sensitive, cost effective and accurate at detecting a fracture in an occult hip fracture than bone scans. Where available MRI should be the investigation of choice.

References

1. Evans PD, Wilson C, Lyons K Comparison of MRI wih Bone Scanning foir Suspected Hip Fracture in Elderly Patients Journal od Bone and Joint Surgery 1994; 76-B: 158-9
2. Rubin SJ, Marquardt JD, Gottlieb RH, Meyers SP, Totterman SMS, O'Mara RE Magnetic Resonance Imaging: a cost effective alternative to bone scintigraphy in the evaluation of patients with suspected hip fractures Skeletal Radiology 1998;27:199-204
3. Rizzo PF, Gould ES, Lyden JP, Asnis SE Diagnosis of Occult Fractures about the Hip Journal od Bone and Joint Surgery 1993; 75:395-401