Radiographic Evaluation of Blunt Ankle Trauma

Jack Casey, HMS III Gillian Lieberman, MD

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Jack Casey, HMS IVGillian Lieberman, MD

Radiographic Evaluation of Blunt Ankle Trauma

Jack Casey, HMS III Gillian Lieberman, MD

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Overview

• Importance of ankle injuries• Imaging– when, how, and what to look for• Anatomy review• Common ankle injuries

– Patient cases to illustrate mechanisms of injury and radiologic classification

Focus on radiology

Jack Casey, HMS III Gillian Lieberman, MD

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Historical Context

Jack Casey, HMS III Gillian Lieberman, MD

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Blunt Ankle Trauma – Still A Major Problem

• Most common MSK injury• Less that 15% of patients have clinically

significant fractures• Ankle films are 3rd most common radiologic study

ordered in many hospitals• > $500 million spent annually on ankle

radiographs in North America• Clinical guidelines can help guide management

Steill et al. JAMA, 1993.

Jack Casey, HMS III Gillian Lieberman, MD

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Indications for Imaging The Ottawa Ankle Rules

• Set of clinical guidelines, designed to have sensitivity of 100% for detecting fractures s/p blunt ankle trauma.– willing to accept trade-off of lower specificity

• Expected benefits: Limit radiation exposure, health care costs, ED waiting time.

• Designed to be easy to use

Jack Casey, HMS III Gillian Lieberman, MD

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Ottawa Ankle Rules - The basics

Ankle x-ray series is only necessary if there is pain near the malleoli and any of these findings:

1. Inability to bear weight both immediately and in the ED (four steps)

2. Bone tenderness at posterior edge or tip of medial or lateral malleoli.

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Jack Casey, HMS III Gillian Lieberman, MD

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Ottawa Ankle Rules - The basics

Foot x-ray series is only necessary if there is pain in the mid-foot and any of these findings:

• Inability to bear weight both immediately and in the ED (four steps)

2. Bone tenderness at base of fifth metatarsal or the navicular.

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Jack Casey, HMS III Gillian Lieberman, MD

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Ottawa Ankle Rules - How good are they?

• Systemic review of 27 studies (15,581 patients) – Sensitivity 96.4 - 99.6 %– Specificity varied widely (10-79%)– Less than 2% of patients who were negative for fx according to

ankle rules actually had a fracture.– Missed fractures were almost always minor, did not affect long

term outcomes.

• 28% reduction in use of ankle radiography• No decrease in patient satisfaction

Bachmann et al. BMJ, 2003.Steill et al. JAMA, 1993.

Jack Casey, HMS III Gillian Lieberman, MD

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Ottawa Ankle Rules - A few limitations

• Not applicable to:– <18 y/o– Altered mental status– Multi-system trauma– Chronic/ subacute injuries

• Always trust clinical judgment

Jack Casey, HMS III Gillian Lieberman, MD

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Implementing the OAR

• Thorough (but brief) H+PEvaluate skin/ soft tissue. Assess for open fx.Check and document neurovascular statusPalpate entire distal 6 cm of both malleoli before asking patient to bear weightPalpate over 5th metatarsal and navicular for tendernessPalpate for tenderness over proximal fibula to exclude potential Maisonneuve fracture

• Think about underlying anatomy and mechanism of injury

Jack Casey, HMS III Gillian Lieberman, MD

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Basic Anatomy 1- Bones

Interactive Foot and Ankle. Primal Pictures, Ltc.

Anterior Process of Calcaneus

Jack Casey, HMS III Gillian Lieberman, MD

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Basic Anatomy 2- Ligaments

Greenspan, Orthopedic Radiology

THREE principal sets of ligaments support the ankle, all of which are essential to its stability.

Jack Casey, HMS III Gillian Lieberman, MD

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Basic Anatomy 3- Tendons

Greenspan, OrthopedicRadiology

Jack Casey, HMS III Gillian Lieberman, MD

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Anatomy- Putting it All Together

Bones and connective tissue give rise to ring- like structure surrounding the talus.

Rosen’s Emergency Medicine: Concepts and Clinical Practice.

Jack Casey, HMS III Gillian Lieberman, MD

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Ankle Injuries-Inversion

Greenspan, Orthopedic Radiology

Remember Ring- Like Structure in Conceptualizing Injury.

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Jack Casey, HMS III Gillian Lieberman, MD

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Ankle Injuries- Eversion

Greenspan, Orthopedic Radiology

Remember Ring- Like Structure in Conceptualizing Injury.

www.x-strap.com

Jack Casey, HMS III Gillian Lieberman, MD

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Appropriate Views

• Must always include:1) AP2) Mortise (ankle in 10 - 25 degrees of internal rotation)3) Lateral

• May add additional views in questionable cases (i.e. stress views, comparison views with uninjured ankle)

Jack Casey, HMS III Gillian Lieberman, MD

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Regions of Interest

• Bones of ankle joint• The fifth metatarsal tuberosity should be

seen in at least one projection. • Important to visualize anterior process of

the calcaneus.

Jack Casey, HMS III Gillian Lieberman, MD

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Normal AP Radiograph

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Jack Casey, HMS III Gillian Lieberman, MD

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Normal Mortise Radiograph

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Foot internally rotated 10- 35 degrees to allow for improved visualization of the mortise.

Jack Casey, HMS III Gillian Lieberman, MD

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AP vs. Mortise Views

AP Mortise

Images from Greenspan, Orthopedic Radiology

Jack Casey, HMS III Gillian Lieberman, MD

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Normal Lateral Radiograph

Note: ROI not fully included (5th

metatarsal absent)

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Jack Casey, HMS III Gillian Lieberman, MD

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Classifying Fractures

• Anatomic• Weber (AO)• Other

Jack Casey, HMS III Gillian Lieberman, MD

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Anatomic Classification of Fx

Identifying additional sites of fracture is not just an academic exercise– as bi/tri malleolar fx usually require othopedics eval, surgical management.

Greenspan,Orthopedic Radiology

Jack Casey, HMS III Gillian Lieberman, MD

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Unimalleolar Fx

Patient 1–s/p eversioninjury, fallfrom 10 feet

Small fx, medial malleolus

Also note dislocation talus

Image from BIDMC PACS

Jack Casey, HMS III Gillian Lieberman, MD

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Bimalleolar FxPatient 2-“Fall with ankle inversion. Please r/o fracture”

Images from BIDMC PACS

Mortise View AP view

Jack Casey, HMS III Gillian Lieberman, MD

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Trimalleolar FxPatient 3-“Eversion injury. r/o fx” (ED films)

Images from BIDMC PACS

Jack Casey, HMS III Gillian Lieberman, MD

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Trimalleolar Fx ORIF

Images from BIDMC PACS

Patient 3 (Intra-op)

Jack Casey, HMS III Gillian Lieberman, MD

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Weber Classification of Fx

• Based on the level of fibular fracture• Used to determine extent of syndesmotic

injury. A<B<C

Jack Casey, HMS III Gillian Lieberman, MD

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Weber A

Patient 4- s/pfall with ankleinversion. r/o fx.

BIDMC PACS.

Avulsion fx below joint line

Jack Casey, HMS III Gillian Lieberman, MD

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Weber B

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Spiral fibular fx: assoc. with partial disruption of tibiofibular ligament

Jack Casey, HMS III Gillian Lieberman, MD

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Weber C

How would you classify anatomically?

Patient 6—“s/p ankle trauma r/o fx”

Bimalleolar (comminuted)

BIDMC PACS.

Jack Casey, HMS III Gillian Lieberman, MD

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Recap of Classifications

• Anatomic- Uni/ Bi/ Tri Malleolar

• Weber- A/ B/ C

Jack Casey, HMS III Gillian Lieberman, MD

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Fracture 5th Metatarsal

BIDMC PACS

Patient 7—“s/p ankle inversion injury. r/o fx”

Jack Casey, HMS III Gillian Lieberman, MD

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Fracture 5th Metatarsal

Mechanism of Injury

Jack Casey, HMS III Gillian Lieberman, MD

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Beyond Simple Radiographs

If pain persists in 6-8 weeks, consider otherimaging modalities:

- MRI (for evaluation of ligaments/ tendons)- CT

Jack Casey, HMS III Gillian Lieberman, MD

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Summary

• Indications for RadiographsOttawa Ankle Rules:

o 4 sites for bony tenderness, 4 stepso Save time, money, and avoid radiation exposure, without

sacrificing quality

• Appropriate views, ROI• Think about anatomy• Always look for additional fx

Jack Casey, HMS III Gillian Lieberman, MD

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Acknowledgements

• Gillian Lieberman, MD• Pamela Lepkowski• Mary Hochman, MD• Larry Barbaras

Jack Casey, HMS III Gillian Lieberman, MD

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References• American College of Radiology. ACR appropriateness criteria. Imaging evaluation of

suspected ankle fractures. www.acr.org• Anis AH et al. Cost-effectiveness analysis of the Ottawa Ankle Rules. Annals of

emergency medicine. 1995.; 26:422-428.• Bachmann, LM et al. Accuracy of Ottawa ankle rules to exlude fractures of the ankle

and the mid-foot: systematic review. BMJ 2003; 326: 417.• Greenspan, A. Orthopedic radiology. A practical approach. Lipincott, Williams and

Williams. Philadelphia, PA. 2000. • Marx: Rosen’s Emergency Medicine. Concepts and clinical practice. Fifth ed. 2002,

Mosby, Inc. • Steill IG et al. Implementation of the Ottawa ankle rules. JAMA 1994; 271: 827-832.• Steill IG et al. Decision rules for the use of radiography in acute ankle injuries.

Refinement and prospective validation. JAMA 1993; 269:1127.• www.aafp.org/afp/20020901/785.html• www.rad.washington.edu• www.x-strap.com/pix/eversion.jpg