Download Stress Fractures

Chealon Miller, HMS IV
Gillian Lieberman, MD
November 2005
Stress Fractures
Chealon Miller, Harvard Medical School Year IV
Gillian Lieberman, MD
Chealon Miller, HMS IV
Gillian Lieberman, MD
Our Patient G.F.
• 29 year old female runner
• c/o left shin pain and swelling
• Evaluated at OSH with MRI showing a “mass”
• Referred to BIDMC for further evaluation
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Initial Referral Workup
• History and Physical Exam
• Plain Radiograph
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Chealon Miller, HMS IV
Gillian Lieberman, MD
History & Physical Exam
• PMH/PSH: Right ACL allograft repair
• Medications: OCP, Bactrim, Ciprofloxacin
• Allergies: PCN Angioedema
• Physical Exam: Patient has FROM; TTP at proximal
tibia; neurovascularly intact; no palpable mass felt at
left leg
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Chealon Miller, HMS IV
Gillian Lieberman, MD
After the initial physical exam, a plain
radiograph was obtained
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Plain Radiograph*
• Findings:
– No evidence of fracture line
– Indistinctness of the outer periosteum
• Impression:
– Possible subtle stress fracture at the medial
cortical surface of the tibia at point of tenderness
• Recommendation:
– Bone scan if needed
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* Radiograph not available on PACS
Chealon Miller, HMS IV
Gillian Lieberman, MD
Let’s Review the Anatomy
of Long Bone and The
Lower Extremity
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Anatomy of Long Bone
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pharyngula.org/ index/weblog/2003/11
Chealon Miller, HMS IV
Gillian Lieberman, MD
Anatomy of Lower Extremity
www.foottrainer.com/foot/
anatomy.uams.edu/.../ xrays/xra_atlas42.html
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Menu of Tests for Stress Fractures
• Plain Film
• MRI
• Nuclear Imaging
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Let’s review the
characteristics of various
tests and look at them in
different patients with stress
fractures
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Stress Fracture Imaging:
Plain Film
• Advantages:
– inexpensive
– first modality used in the evaluation of a possible
fracture
• Disadvantage:
– may not demonstrate nondisplaced fractures and
microfractures
• Appearance:
– dark streak within the bone
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Companion Patient One-Plain Film of Stress Fracture
www.injuryupdate.com.au/ injuries/shin_&_calf/...
Arrows indicate fracture line
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Stress Fracture Imaging:
MRI
• Advantages:
– better spatial resolution
– better specificity
– detects bone contusions
• Disadvantages:
– more expensive
– requires patient cooperation
– can be difficult to differentiate stress fracture from bone
contusion
• Appearance:
– Bone contusion: low T1 signal, high T2 signal intensity
– Stress Fracture: low T1 signal, low T2 signal intensity
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Companion Patient Two-MRI of Stress Fracture
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Logan and Hardy,www.footdoc.com/main. cfm?pg=how_to&fn=bonestim
Chealon Miller, HMS IV
Gillian Lieberman, MD
Stress Fracture Imaging:
Nuclear Imaging
• 3 phase skeletal scintigraphy with 99mTc
• Advantages:
– The entire skeleton can be imaged
– Scintigraphy changes can precede plain film
changes by weeks
• Disadvantage:
– Specificity is poor
• Appearance:
– Increased tracer uptake at affected site in the
third phase
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Companion Patient Three-Bone Scan of Stress Fracture
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Oliphant, www.uwec.edu/.../AT/ aidil/lowerextremity.htm
Arrow (left image) and circle indicate increased tracer uptake
Chealon Miller, HMS IV
Gillian Lieberman, MD
Let’s return to our patient
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Our Patient G.F.:
Revisited
• Interpretation of plain films taken at initial presentation:
– Indistinctness of the outer periosteum
– Possible stress fracture
• Subsequent MRI (10 days later)
– Anterior Tibia:
• Increased intramedullary signal in the anterior
aspect of the proximal tibia
• Compatible with early stress reaction
– Posterior Tibia:
• Abnormal enhancement in the posterior cortex of
the proximal tibia
• Surrounding enhancement in the soft tissues
• Not typical for stress fracture
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Initial plain film unavailable,
but let’s review the MRI
findings
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Chealon Miller, HMS IV
Gillian Lieberman, MD
MRI Anterior Lesion
Arrows indicate increased signal intensity
PACS, BIDMC
Coronal STIR
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Differential Diagnoses:
Anterior Lesion
•
•
•
•
•
Stress Fracture
Stress Reaction (Bone Contusion)
Bone Metastases
Osteomyelitis
Probable Diagnosis:
– History: Long Distance Runner
– Radiology: No linear lucency indicative of
fracture
***Stress Reaction***
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Chealon Miller, HMS IV
Gillian Lieberman, MD
MRI Posterior Lesion
Normal Bone on T2 weighted image
Abnormal T2 weighted image
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PACS, BIDMC
Chealon Miller, HMS IV
Gillian Lieberman, MD
MRI Posterior Lesion
Increased signal intensity (bone)
Increased signal intensity (soft tissue)
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PACS, BIDMC
Chealon Miller, HMS IV
Gillian Lieberman, MD
Differential Diagnoses:
Posterior Lesion
•
•
•
•
•
Scar of a prior stress fracture
Sessile osteochondroma
Periosteal chondroma
Non-ossifying fibroma
Definitive Diagnosis:
– non-ossifying fibroma based on radiologic
appearance
• Follow Up:
– X-rays in 2 months
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Follow Up X-rays were
obtained at 2 and 5 months
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Follow Up X-Rays: 2 months Later
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PACS, BIDMC
Chealon Miller, HMS IV
Gillian Lieberman, MD
Follow Up X-ray:
2 Months Later
• Anterior
– No soft tissue masses
– No bone lesions
• Posterior
– Focally sclerotic, slightly
expansile area in the
posterior upper tibia
– Not changed when
compared with previous
films
– Non-aggressive
appearance
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PACS, BIDMC
Chealon Miller, HMS IV
Gillian Lieberman, MD
Follow Up X-ray: 5 months later
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PACS, BIDMC
Chealon Miller, HMS IV
Gillian Lieberman, MD
Follow Up X-ray:
5 Months Later
• Anterior
– No soft tissue masses
– No bony lesions
• Posterior
– Focal density in proximal
tibia posteriorly
– Density abuts the
posterior cortex
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PACS, BIDMC
Chealon Miller, HMS IV
Gillian Lieberman, MD
Let’s review information about
stress fractures
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Stress Fractures:
General Information
• Definition:
– Failure of the skeleton to withstand submaximal
forces over time
• Two Types:
– Fatigue Fracture: normal bone is exposed to
repeated abnormal stresses
– Insufficiency Fracture: normal stress is applied to
abnormal bone
• Epidemiology
– Most are located in the tibia
– Distal Tibia: long distance runners
– Proximal Tibia: children and elderly
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Stress Fractures:
Radiologic Considerations
•
MRI with diffuse edema, but without
dark fracture line
– Bone contusion: microfracture of
cancellous bone
– Could also be osteonecrosis or
transient osteoporosis
• Best modality for follow up of stress
fractures
– Plain radiographs
• Computed Tomography
– High rate of false negatives
– Often skipped with preference for
MRI or bone scan
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pharyngula.org/ index/weblog/2003/11
Chealon Miller, HMS IV
Gillian Lieberman, MD
Final comments about our patient
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Our Patient G.F.:
Revisited
• Patient’s follow-up X-rays show no abnormalities in
the region of the anterior tibial cortex
• Posterior cortex shows non-ossifying fibroma
• Stress fractures have occurred in non-ossifying
fibromas
• Patient no longer experiences pain in left lower
extremity; however, clinical change should be
investigated
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Chealon Miller, HMS IV
Gillian Lieberman, MD
References
• Groves et al. 16-Detector multislice CT in the detection
of stress fractures: a comparison with skeletal
scintigraphy. Clin Radiol. 2005 Oct;60(10):1100-5.
• Novelline, R. Squire’s Fundamentals of Radiology: Sixth
Edition, 2004; 362
• Pretorius, E, Solomon, J. Radiology Secrets: 2nd Edition,
2006; 337-339
• Reeder, M. Gamuts in Radiology: Comprehensive Lists
of Roentgen Differential Diagnosis: 4th edition, 2003; 331
• Reeser, J. http://www.emedicine.com/pmr/topic134.htm
• Alice Fisher, MD
• Eric Stein, MD
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Chealon Miller, HMS IV
Gillian Lieberman, MD
Acknowledgments
•Larry Barbaras our Webmaster
•Gillian Lieberman, MD
•Pamela Lepkowski
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