Metaphyseal and Rib Fractures in Child...

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Jeremy Tucker, HMS IVGillian Lieberman, MD

Jeremy Tucker, Harvard Medical School, Year IV

Gillian Lieberman, MD, Beth Israel Deaconess Hospital and Harvard Medical School

November 2003

Metaphyseal and Rib Fractures in

Child Abuse

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In real life, no one tells you that the topic of the patient presentation is child abuse.

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Presentation of patient:

•5 month old female presented to Children’s hospital with decreased mobility of her right lower extremity.

•The baby was visiting her father when she rolled off a bed.

•After she was returned to her mother, her aunt noticed that she was not using her leg and suggested bringing her to her doctor.

•Her mother called for an appointment several days later.

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Plain films of right leg included the following:

Fibula Tibia

Talus

Case courtesy of Paul Kleinman, Children’s Hospital Boston

Calcaneus

Navicular

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Look again:

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Note the transverse radiolucencies running through the subphyseal regions of the metaphyses.

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Skeletal survey also included the following:

Normal or Abnormal?

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Rib thickening due to callus pushing in pleural surface

Rib thickening due to callus accentuated by bronchus below

Look again: Abnormal

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Osteoschlerosis and sub-periosteal new bone formation are also signs of fracture healing.

A different view of ribs:

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Callus formation

Subperiosteal bone formation

Osteosclerosis

All signs of fracture healing…All signs of fracture healing…Not consistent with new Not consistent with new fracturesfractures

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Conclusion based on Radiology Findings:•Classic metaphyseal lesions NOT consistent with story of patient falling off bed

•Healing of old fractures NOT consistent with story of patient falling off bed

•Both quality and long-standing nature of fractures gave radiologists a high suspicion of child abuse in case of this 5 month old girl.

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Child Abuse

Each Year

•3 million reports to DSS

•1 million substantiated

•600,000 seriously harmed

•2,000 die

Courtesy of Paul Kleinman

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Child Abuse

Each Year

•3 million reports to DSS

•1 million substantiated

•600,000 seriously harmed

•2,000 die

•Psychological morbidity unmeasurable

Courtesy of Paul Kleinman

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Why focus on skeletal injuries?

Skeletal injuries not usually life threatening Skeletal injuries not usually life threatening and usually heal welland usually heal well

High diagnostic valueHigh diagnostic valueCommon findings in abused babiesCommon findings in abused babiesSkeletal survey is highly sensitive test for Skeletal survey is highly sensitive test for abuseabuse

Kleinman, PK. Diagnostic Imaging of Child Abuse, Second Edition. 1998.

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Distribution of 165 inflicted fractures in 31 fatally abused children

•64 Classic Metaphyseal Lesions

•84 rib lesions

Skeletal injuries

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Highly specific bone findings

Classic Classic metaphysealmetaphyseal lesions*lesions*Rib fractures, especially posterior*Rib fractures, especially posterior*Scapular fracturesScapular fracturesSpinousSpinous process fracturesprocess fracturesSternalSternal fracturesfractures

*also highly common, occur in almost all abused *also highly common, occur in almost all abused childrenchildren


Classic metaphyseal lesions

Also know as “corner fractures” and Also know as “corner fractures” and “bucket“bucket--handle fractures”handle fractures”

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Metaphyseal lesion that looks like a bucket handle.

Metaphyseal lesion that looks like a corner of the bone is fractured.


remove from your vocabulary:

““corner fractures” and “bucketcorner fractures” and “bucket--handle handle fractures”fractures”

Now,

Courtesy of Paul Buonano, Boston Children’s Hospital

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The appearance of a corner fracture or a bucket handle fracture depends on the angle of radiograph projection. But these are part of the same fragment which is in the shape of a disc or frisbee. We will therefore refer to this fracture as a Classic Metaphyseal Lesion.


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Physis: Chondrocytes grow in zones of proliferation and hypertrophy and then calcify matrices between their columns in zone of provisional calcification.(growth plate or epiphyseal plate)

Metaphysis: vascular channels invaded chondrocytes but intercolumnar calcification persists, eventually becoming mineralized osteoid.(distal metaphysis = primary spongiosa)

Chondro- Osseous Junction


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Normal COJ

Subphyseal Metaphysis

Physis hypertrophied chondrocytes


COJ

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Physis Physiology1.1. ChondrocytesChondrocytes proliferate and then enlarge in a proliferate and then enlarge in a

columnar organization with a terminal columnar organization with a terminal chondrocytechondrocyte at edge of at edge of physisphysis..

2.2. MetaphysealMetaphyseal vasculature sends a signal to vasculature sends a signal to terminal terminal chondrocytechondrocyte which causes it to undergo which causes it to undergo a a morpholgicalmorpholgical change: cell begins to change: cell begins to apoptoseapoptose or somehow to be released. or somehow to be released.

3.3. MetaphysealMetaphyseal vasculature invades the lacuna of vasculature invades the lacuna of the changing the changing chondrocytechondrocyte..

Kleinman, PK. Diagnostic Imaging of Child Abuse, Second Edition. 1998.Rogers, Lee. Radiology of Skeletal Trauma, Third Edition. 2002.

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Why the physis doesn’t disappear:

Vascular invasion of Vascular invasion of chondrocytechondrocyte lacunae is lacunae is BALANCED by BALANCED by chondrocytechondrocyte proliferation deep in proliferation deep in the the physisphysis plate, distal to the COJ.plate, distal to the COJ.

MetaphysealMetaphyseal vasculature allows for extension of vasculature allows for extension of metaphysismetaphysis into into physisphysisEpiphysealEpiphyseal vasculature allows for proliferation of vasculature allows for proliferation of chondrocyteschondrocytes from mother cellfrom mother cell

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Why the classic metaphyseal lesion forms in the distal metaphysis:

The most vulnerable part of the bone in an The most vulnerable part of the bone in an infant is the distal infant is the distal metaphysismetaphysis (aka primary (aka primary spongiosaspongiosa))Having no Having no chondrocyteschondrocytes makes it weaker makes it weaker than than physisphysis..Fewer organized cells and less calcification Fewer organized cells and less calcification makes it weaker than the more proximal makes it weaker than the more proximal parts of parts of metaphysismetaphysis or the rest of the bone.or the rest of the bone.


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Therefore, Classic Metaphyseal Lesions:

Are planar fractures, not corners or ringsAre planar fractures, not corners or ringsOccur in the Occur in the metaphysismetaphysis, not the , not the physisphysisAre “virtually Are “virtually pathognomonicpathognomonic” for abuse” for abuseResult from repeated Result from repeated torsionaltorsional and shearing and shearing forcesforces

Kleinman et al. “The Metaphyseal Lesion in Abused Infants: A Radiologic-Histopathologic Study.” AJR: 146, May 1986..

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Shearing and torsional forces which lead to CML’s:


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The shape of the calcified segment below the CML

Frisbee or diskFrisbee or disk--likelikeCentrally the calcified segment is thinCentrally the calcified segment is thinPeripherally the calcified segment is thickerPeripherally the calcified segment is thicker

Why?

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Why the CML is shaped like a frisbee:

Thick Thick subperiostealsubperiosteal bone collar surrounds the thin bone collar surrounds the thin cartilage network of the distal cartilage network of the distal metaphysismetaphysis and the and the hypertrophied hypertrophied chondrocyteschondrocytes of the adjacent of the adjacent physisphysisFractures therefore tend to cut under the bone Fractures therefore tend to cut under the bone collar.collar.This produces the corner fracture appearance from This produces the corner fracture appearance from a perspective tangential to the bone.a perspective tangential to the bone.


Kleinman et al. “The Metaphyseal Lesion in Abused Infants: A Radiologic-Histopathologic Study.” AJR: 146, May 1986..

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Normal COJ and CML shape

Bone Collar


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Calcified disc fragment: thin layer of primary spongiosa of metaphysis + zone of hypertrophic chondrocytes within the zone of provisional calcification + bone collar

Subperiosteal bone collar

Subperiosteal bone collar

Acute CML Changes


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The calcified portion of fractured segment:1.1. Thin portion of Thin portion of metaphysealmetaphyseal primary primary

spongiosaspongiosa2.2. Zone of provisional calcification with the Zone of provisional calcification with the

hypertrophic hypertrophic chondrocyteschondrocytes of of physisphysis3.3. Bone collar at the periphery of fragmentBone collar at the periphery of fragment

Courtesy of Paul Kleinman lecture

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Radiographic alterations: acutely

If no displacement of the fragment occurs, or if If no displacement of the fragment occurs, or if angle of projection is oblique to the fracture, the angle of projection is oblique to the fracture, the radiographic image may look normalradiographic image may look normalIf some degree of displacement occurs in the plane If some degree of displacement occurs in the plane of the projection, transverse of the projection, transverse lucencylucency is seen in the is seen in the subphysealsubphyseal region of region of metaphysismetaphysisFracture line may be apparent in one projection Fracture line may be apparent in one projection and invisible in anotherand invisible in another


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Chronically, what happens?MetaphysealMetaphyseal vessels damaged vessels damaged = loss of signal that normally leads to morphologic = loss of signal that normally leads to morphologic death/differentiation of terminal death/differentiation of terminal chondrocytechondrocyte. . PERSISTENCE rather than DEMISE of terminal PERSISTENCE rather than DEMISE of terminal chondrocytechondrocyte = osseous growth arrest= osseous growth arrestEpiphysealEpiphyseal vessels undamaged = vessels undamaged = chondrocytechondrocyte proliferation proliferation continuescontinuesAbnormal survival of cells causes net increase in cell Abnormal survival of cells causes net increase in cell number present within cartilage column.number present within cartilage column.= = MetaphysisMetaphysis does not invade does not invade physisphysis columncolumn

Kleinman, PK. Diagnostic Imaging of Child Abuse, Second Edition. 1998

Rang, Mercer. Rang, Mercer. The growth plate and its disorders.The growth plate and its disorders. Baltimore, Williams and Wilkins Company, 1969.Baltimore, Williams and Wilkins Company, 1969.

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1. Terminal chondrocytes persist ONLY in focally damaged columns where transformation into bone is blocked.

2. Damaged columns blocked from calcification

3. Uncalcified region extends into calcified region

Healing of Focal Metaphyseal Injury


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Radiographic view: Focal Metaphyseal Radiolucencies (inconspicuous fx)

Histologic view: Extension of metaphysis into normal hypertrophic chondrocytes


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Healing of extensive metaphyseal injury

ChondrocytesChondrocytes accumulate accumulate at COJ, resulting in at COJ, resulting in increased thickness in zone increased thickness in zone of provisional calcification of provisional calcification

Fragment appears to Fragment appears to thicken on radiographthicken on radiograph

Cessation of endochondral bone growth

Diffuse widening of physis


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Recall our patient:Healing of an extensive metaphyseal injury led to diffuse widening of the calcified zone of the physis.

Courtesy of Paul Kleinman at Boston Children’s Hospital

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The second major finding in our patient’s radiographs:

Hints of:

Rib Fractures

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Why Get Images of Ribs in a Case involving a leg?

Suspicion of abuseSuspicion of abuseCentral to radiologic diagnosis of abuseCentral to radiologic diagnosis of abuseUsually rib fractures NOT suspected clinicallyUsually rib fractures NOT suspected clinically51% of 51% of fxsfxs in fatally abused children involve ribsin fatally abused children involve ribsPosterior rib fractures are highly specific for child Posterior rib fractures are highly specific for child abuse (especially after ruling out metabolic abuse (especially after ruling out metabolic disorders, skeletal disorders, skeletal dysplasiasdysplasias, and , and MVA’sMVA’s))Therefore a skeletal survey of ribs is both sensitive Therefore a skeletal survey of ribs is both sensitive and specific for child abuseand specific for child abuse


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Let’s Review Anatomy:

Rib Head

Rib TubercleCosto-transverse process articulation Transverse Process facet

Costo-chondral junction


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Rib Head Apophysis

Transverse Process Apophysis


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Which parts of the ribs fracture most often in cases of abuse?

Mostly rib head and rib neckMostly rib head and rib neckIn a study of 63 abused children, 87% of rib In a study of 63 abused children, 87% of rib fractures were either at the head or the neckfractures were either at the head or the neckFractures of rib head and neck are very Fractures of rib head and neck are very rarely from any cause other than abuse or a rarely from any cause other than abuse or a severe motor vehicle accidentsevere motor vehicle accident

Kleinman,PK. “Factors Affecting Visualization of Posterior Rib Fractures in Abused Infants.” AJR 150, March 1988.

Rogers, Lee. Radiology of Skeletal Trauma, Third Edition. 2002.

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Rib head and neck fractures•No fx visible on frontal projection

•Disruption of Ventral bone cortex at rib head (short arrows) and rib neck (long arrows) often difficult to visualize (>50%)

Kleinman,PK. “Factors Affecting Visualization of Posterior Rib Fractures in Abused Infants” AJR 150, March 1988.

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Mechanism of Rib FractureThoracic compression with free posterior motion:


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Mechanism of fracture

Excessive leverage of rib over transverse process Excessive leverage of rib over transverse process consistent with fracture featuresconsistent with fracture featuresClassic type 1 lever: Classic type 1 lever:

Force on ventral portion of ribForce on ventral portion of ribFulcrum at articulation between transverse Fulcrum at articulation between transverse process and ribprocess and ribLoading (pull) on Loading (pull) on costovertebralcostovertebral articulationarticulation

CostovertebralCostovertebral ligaments stronger than rib, so ligaments stronger than rib, so mechanical failure over point of fulcrummechanical failure over point of fulcrum


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•Front to back force with free posterior rib motion

•Excessive leverage over costo-transverse process fulcrum

•Fractures at maximal points of strain (ventral portion of rib at neck and head, dorsal portion elsewhere)

•Studies with rabbits support compression mech.

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Rib Head fracturesExtend from ventral cortex of rib into Extend from ventral cortex of rib into costocosto--osseous junctionosseous junctionConforms to growth plate fractures described by Conforms to growth plate fractures described by Salter and HarrisSalter and HarrisOften not visible on frontal image if no Often not visible on frontal image if no displacement and displacement and fxfx oblique to plane of xoblique to plane of x--rayrayIf visible, subtle If visible, subtle verticleverticle lucencylucency at extreme at extreme medial aspect of ribmedial aspect of ribHeal with fibrosis and increased Heal with fibrosis and increased osteoblasticosteoblasticactivity, visible activity, visible radiographicallyradiographically after several after several weeksweeks


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Right posterior rib, sixth, shows fracture callus at rib head.

Right posterior ribs, third through eighth, show widening on frontal radiograph

Rib Head Fracture Healing

LonerganLonergan GJ. GJ. RadiographicsRadiographics 2003; 23: 8112003; 23: 811--846.846.

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Rib Neck Fractures

•Ventral surface fracture (location of maximal strain)

•Line through medullary cavity

•Reaches dorsal cortex

•In tact rib head cartilage (*)

•In tact rib tubercle cartilage (diamond)


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Rib Neck Fracture Healing

Callus formation over rib neck


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•Acute posterior rib neck fractures: right 4th, 5th, and 6th possible

•Callus indicating healing of rib fractures: right 4th,5th, and 6th rib. (Also callus at inferior margins of left 6th and 7th)

Rib Neck Fracture Healing


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Thoracic compression:

•Gripping is most common cause of compression

•Similar force vector and rib motion if infant slammed on face or hurled face forward at an immobile object, as rib arcs free to move posteriorly, causing excessive leverage

Lonergan, GL, et al. Radiographics, July-Aug 2003, v23, n4.

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Review: Highly specific bone fractures

Classic Classic metaphysealmetaphyseal lesionslesionsRib fractures, especially Rib fractures, especially posteriorlyposteriorly at head at head and neck and neck Scapular fracturesScapular fracturesSpinousSpinous process fracturesprocess fracturesSternalSternal fracturesfractures


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Moderate specificity fractures

Multiple fractures of different agesMultiple fractures of different agesEpiphysealEpiphyseal separations (Salter separations (Salter fxfx of elbow where of elbow where radial line does not intersect radial line does not intersect capitabulumcapitabulum))Vertebral body fractures (C2 pedicle Vertebral body fractures (C2 pedicle fxfx of of “Hangman’s”“Hangman’s”Digital fractures (buckling of cortical bone)Digital fractures (buckling of cortical bone)Skull fractures (occipital region Skull fractures (occipital region fxfx, often ass. w/ , often ass. w/ soft tissue injury)soft tissue injury)


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Common fractures with LOW specificity for child abuse

SubperiostealSubperiosteal new bone formationnew bone formationClavicularClavicular fracturesfracturesLong bone shaft fractures (transverse or Long bone shaft fractures (transverse or oblique/spiraloblique/spiral---- poor correlation shown between poor correlation shown between pattern of shaft pattern of shaft fxfx and inflicted vs. accidental and inflicted vs. accidental injury, although direct forces cause transverse injury, although direct forces cause transverse fxfxand and torsionaltorsional forces cause oblique forces cause oblique fxfx))Linear skull fracturesLinear skull fractures


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Protocol Problem: acutely most Problem: acutely most fxsfxs very difficult to see on very difficult to see on plain filmplain filmSolutions:Solutions:

Full skeletal surveys vs. specific bone filmFull skeletal surveys vs. specific bone filmFollow up surveys needed to see callus Follow up surveys needed to see callus formationformationBone scans (nuclear medicine Bone scans (nuclear medicine scintigraphyscintigraphy) ) needed to see fractures acutelyneeded to see fractures acutely

Rule out metabolic abnormalities and other causesRule out metabolic abnormalities and other causes

Exact protocol depends on age of child and findings.Exact protocol depends on age of child and findings.Protocol decisions will not be addressed here.Protocol decisions will not be addressed here.

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Let’s now return to our patientClassic Classic metaphysealmetaphyseal lesions consistent with repetitive lesions consistent with repetitive torsionaltorsional forces more than 1 week prior to examforces more than 1 week prior to exam

Rib fractures consistent with Rib fractures consistent with compressionalcompressional force more force more than 1 week prior to examthan 1 week prior to exam

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What was the outcome for this 5 month old little baby?

Social worker met with her mother.Child protection team consulted and reviewed her films. Department of social services met with her mother. Her mother disclosed a 2nd fall from a bed a few weeks previously. DSS not satisfied with new explanationChild protection team ultimately went to court on the baby girl’s behalf.

Courtesy of Paul Kleinman, Boston Children’s Hospital

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ReferencesCaffeyCaffey J. Multiple factures in the long bones of infants suffering froJ. Multiple factures in the long bones of infants suffering from chronic subdural hematoma. m chronic subdural hematoma. AJR 1946, 56:163AJR 1946, 56:163--173.173.Keats T, Smith T. An Atlas of Normal Developmental Roentgen AnatKeats T, Smith T. An Atlas of Normal Developmental Roentgen Anatomy. Chicago, Year Book omy. Chicago, Year Book Medical Publishers, 1988.Medical Publishers, 1988.KleinmanKleinman PK. Diagnostic Imaging of Child Abuse, Second Edition. St. LouiPK. Diagnostic Imaging of Child Abuse, Second Edition. St. Louis, Mosby, Inc. 1998.s, Mosby, Inc. 1998.KleinmanKleinman PK, Marks SC, Adams VI, PK, Marks SC, Adams VI, BlackbourneBlackbourne BD. Factors affecting visualization of posterior BD. Factors affecting visualization of posterior rib fractures in abused infants. AJR 1988, 150: 635rib fractures in abused infants. AJR 1988, 150: 635--638.638.KleinmanKleinman PK, Marks SC, PK, Marks SC, BlackbourneBlackbourne BD. The BD. The metaphysealmetaphyseal lesion in abused infants: a radiologiclesion in abused infants: a radiologic--histopathologichistopathologic study. AJR 1986; 146: 898study. AJR 1986; 146: 898--905.905.LonerganLonergan GJ, Baker AM, Morey MK, Boos SC. Child Abuse: RadiologicGJ, Baker AM, Morey MK, Boos SC. Child Abuse: Radiologic--Pathologic Correlation. Pathologic Correlation. RadiographicsRadiographics 2003; 23: 8112003; 23: 811--846.846.Rang, Mercer. The growth plate and its disorders. Baltimore, WilRang, Mercer. The growth plate and its disorders. Baltimore, Williams and Wilkins Company, 1969.liams and Wilkins Company, 1969.Rockwood C, Wilkins K. Fractures in Children, Fourth Edition, VoRockwood C, Wilkins K. Fractures in Children, Fourth Edition, Volume 3. lume 3. PhilidelphiaPhilidelphia, Lippincott , Lippincott Publishers, 1996.Publishers, 1996.Rogers, Lee. Radiology of Skeletal Trauma, Third Edition. Rogers, Lee. Radiology of Skeletal Trauma, Third Edition. PhilidelphiaPhilidelphia, Churchill Livingston, 2002., Churchill Livingston, 2002.

Reading Reading makethmaketh a full man, conference a full man, conference makethmaketh a ready man, and writing an exact man. a ready man, and writing an exact man. --BaconBacon

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Acknowledgements

Paul K Paul K KleinmanKleinman, MD, Boston Children’s , MD, Boston Children’s HospitalHospitalJesse Wei, MD, BIDMC RadiologyJesse Wei, MD, BIDMC RadiologyDamon Damon SoeiroSoeiro, MD, BIDMC Radiology, MD, BIDMC RadiologyCarlo Carlo BuonomoBuonomo, MD, Boston Children’s , MD, Boston Children’s HospitalHospitalGillian Lieberman, MD BIDMCGillian Lieberman, MD BIDMCPamela Pamela LepkowskiLepkowski, BIDMC Radiology, BIDMC Radiology

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