Table Of ContentClinSportsMed25(2006)xi
CLINICS IN SPORTS MEDICINE
FOREWORD
Imaging of Upper Extremities
Mark D. Miller, MD
ConsultingEditor
Itissomucheasier tosee somethingifyou know what you arelooking for!
That is the purpose of the next two issues of the Clinics in Sports Medicine.
Dr. Tim Sanders, whom I have known and had the pleasure of working
with over the last 10 years, has put together a pair of absolutely outstanding
issuesonmusculoskeletalimaging.Thisfirstissuefocusesontheupperextrem-
ity, and it will be followed by a lower extremity issue. Tim has already edu-
cated many of us with his excellent current concepts articles in the American
Journal of Sports Medicine and his podium presentations, including his recent
review at the Colorado Orthopaedic Review Course.
Dr. Sanders has assembled an ‘‘all star’’ panel of radiologists, who know
what they are talking about and, more importantly, can teach even the most
imaging-illiterate of us. From the fingers to the shoulder, from kids to adults,
from radiographs to ultrasound to MRI, this issue covers it all. This is per-
haps one issue thatorthopaedic surgeons may enjoy even more than ournon-
operative colleagues, because there are more pictures! Please enjoy this issue.
I know I will!
Mark D. Miller, MD
University of Virginia
Department of Sports Medicine
McCue Center – 3rd Floor
Emmet St. & Massie Rd.
Charlottesville, VA 22903, USA
E-mail address: [email protected]
0278-5919/06/$–seefrontmatter ª2006ElsevierInc.Allrightsreserved.
doi:10.1016/j.csm.2006.04.001 sportsmed.theclinics.com
ClinSportsMed25(2006)xiii–xiv
CLINICS IN SPORTS MEDICINE
PREFACE
Imaging of Upper Extremities
Timothy G. Sanders, MD
GuestEditor
Theroleofimagingintheevaluationofsports-relatedinjuriesoftheupper
extremities has evolved significantly over the past decade, with MRI
becoming the imaging modality of choice for the evaluation of most soft-
tissue injuries ranging from overuse injuries to acute traumatic injuries.
Ultrasoundhasalsoemergedasausefulproblem-solvingtoolthatcanbeused
inthetargetedevaluationofcertainupper-extremityinjuries.Tomaximizethe
diagnosticvalueofthesetools,thetreatingphysicianmustpossessasolidfund
ofknowledgeregardingtherolesofthevariousimagingmodalitiesandanun-
derstanding of which studies are best suited for the evaluation of specific
injuries.
ThisissuedealsprimarilywiththemorecompleximagingmodalitiesofMRI
and ultrasound. First, excellentreview articles providea basic approachto the
evaluationofanMRexaminationoftheshoulder,elbow,andwrist.Thesear-
ticles provide a framework for the interpretation of these complex exams, re-
viewing the pertinent imaging anatomy as well as specific injury patterns that
canbeseenonMRI.Next,theroleofMRIisdiscussedasitpertainstospecific
clinicalproblemsthatinvolvetheshoulder,includinganarticleontheMReval-
uationofshoulderpaininthehigh-performancethrowerandareviewofthecom-
plexitiesofimagingthepostoperativeshoulder.Next,areviewofthenumerous
nerveentrapmentsyndromesoftheupperextremityspecifictotheathleteispro-
vided,andtheroleofMRIinestablishingthesesometimes-elusivediagnosesis
discussed.Stressfracturesoftheupperextremityareuncommonandoftenover-
lookedclinically.Thevariousstressfracturesoftheupperextremityandtheirim-
aging appearance are comprehensively reviewed. The hand and wrist are at
0278-5919/06/$–seefrontmatter ª2006ElsevierInc.Allrightsreserved.
doi:10.1016/j.csm.2006.02.004 sportsmed.theclinics.com
xxiivv PPRREEFFAACCEE
increasedriskforinjuryinmanysports,andimagingofthesmallanatomicsoft-
tissuestructuresoftheseareascanbechallenging.Twoarticlesdiscusstheroleof
compleximagingmodalitiesintheseanatomicareas.Thefirstprovidesacompre-
hensivereviewofMRIofulnar-sidedwristpain,andtheseconddealswiththe
imaging of the fingers and thumb. Several unique upper-extremity injuries are
seen in the pediatric age group, and these are mostly related to the immature
and developing skeleton. Special imaging considerations of pediatric sports-
relatedinjuriesarediscussedinaseparatearticle.Thenextarticlereviewstheutil-
ity of ultrasound in the evaluation of upper-extremity injuries and provides a
comparison of the sensitivity and specificity of ultrasound as it compares to
MRI. Finally, in response to the proliferation of low-field-strength magnets,
particularly in the outpatient setting, a thorough literature review is provided
comparingtheuseoflow-field-andhigh-field-strengthMRI.Thisarticlediscusses
thebenefitsanddrawbacksoftheuseoflow-field-strengthmagnets.
Iwouldliketothankthemanyauthorswhohavecontributedtheirtimeand
expertise to make this issue a reality, and I would also like to thank Deb Del-
lapenaofElsevierforhersupportinputtingthisissuetogether.Finally,Ihope
that the readers find this issue helpful in furthering their understanding of the
role of imaging as it pertains to the evaluation of sports-related injuries of the
upper extremities.
Timothy G. Sanders, MD
National Musculoskeletal Imaging
1930 N. Commerce Parkway
Suite #5
Weston, FL 33326, USA
E-mail address: [email protected]
ClinSportsMed25(2006)371–386
CLINICS IN SPORTS MEDICINE
Shoulder Magnetic Resonance Imaging
Lida Chaipat, MD, William E. Palmer, MD*
MusculoskeletalImaging,MassachusettsGeneralHospital,55FruitStreet,YAW6030,Boston,
MA02114,USA
MRI provides excellent soft tissue contrast and allows for multiplanar
imaginginanatomicplanes.BecauseoftheseadvantagesMRIhasbe-
come the study of choice for imaging of shoulder pathology. Some
structures, such as the rotator cuff, humeral head contour, and glenoid shape,
areevaluatedwellwithconventionalMRI.Whenmoresensitiveevaluationof
thelabrum,capsule,articularcartilage,andglenohumeralligamentsisrequired
or when a partial-thickness rotator cuff tear is suspected, magnetic resonance
(MR)arthrographywithintra-articularcontrastcanbeperformed.ForMRar-
thrographycontrastisinjecteddirectlyintotheglenohumeraljoint.Thisarticle
reviewstheappearancesofnormalanatomicstructuresinMRIoftheshoulder
and disorders involving the rotator cuff and glenoid labrum.
TECHNIQUE
Imaging is performed with the patient in the supine position, arm at the side,
and the shoulder slightly externally rotated [1]. A dedicated surface coil is
placed close around the shoulder to optimize signal-to-noise ratio. Imaging
time usually is 1 hour or less.
Specific imaging protocols vary by institution. At our hospital the standard
shoulder MRI protocol includes triplanar imaging. The following sequences
are obtained: coronal oblique proton density (PD), coronal oblique T2 with
fatsaturation,sagittalobliqueT2,sagittalobliqueT1,andaxialgradientecho.
Axial (transverse) images are obtained perpendicular to the long axis of the
body. From an axial image through the supraspinatus muscle, the coronal
oblique sequences are prescribed parallel to the supraspinatus tendon. Sagittal
oblique sequences then are oriented perpendicular to the coronal images.
ForMRarthrographygadoliniumcontrastisinjecteddirectlyintothegleno-
humeral joint under fluoroscopic guidance. The injected solution distends the
capsule, separates the glenohumeral ligaments, and outlines intra-articular
structures.
*Corresponding author. E-mail address: [email protected] (W.E. Palmer).
0278-5919/06/$–seefrontmatter ª2006ElsevierInc.Allrightsreserved.
doi:10.1016/j.csm.2006.03.002 sportsmed.theclinics.com
372 CHAIPAT &PALMER
Attheauthors’hospitala22-or20-gauge3.5inspinalneedleisinsertedinto
the glenohumeral joint and approximately 12 mL of a solution containing ga-
dolinium, normal saline solution, iodinated contrast, and lidocaine is injected.
(Solution is made by mixing 0.4 mL of gadopentate dimeglumine with 50 mL
ofnormalsaline.Then10mLofthissolutionismixedwith5mLofiodinated
contrastand5mLofpreservative-freelidocaine1%.)MRIisinitiatedwithin30
min before fluid in the joint can be resorbed [1].
TriplanarT1sequenceswithorwithoutfatsuppressionareobtainedtotake
advantageofthecontrastprovidedbytheinjectedsolution.AT2-weightedse-
quence is performed to evaluate the extra-articular structures for pathology,
such as bursal surface partial-thickness rotator cuff tear, soft tissue mass, and
bone marrow abnormality.
NORMAL ANATOMY
Theshoulderiscomposedoftwoarticulations:theglenohumeraljointandthe
acromioclavicular (AC) joint [2]. Glenohumeral articulation is maintained by
the joint capsule, glenohumeral ligaments, rotator cuff musculature, and la-
brum. The labrum is a ring of fibrocartilage that is adherent to the glenoid
rim.Theintactlabrumincreasestheconcavityofthebonyglenoidandthesu-
periorlabrumservesastheanchorforthelongheadofthebicepstendon.The
jointcapsulemayinsertvariablyontheperipheryofthelabrumorontheneck
of the scapula [3]. Distally, the capsule inserts on the anatomic neck of the
humerus.
The glenohumeral ligamentsarecordlike thickeningsin the anterior and in-
feriorjointcapsule.Theyincludethesuperior,middle,andinferiorglenohum-
eral ligaments. The superior and middle glenohumeral ligaments attach to the
anterior labrum. The inferior glenohumeral ligament has anterior and poste-
rior bands that attach to the anterior inferior and posterior inferior labrum,
respectively. The size of glenohumeral ligaments varies from patient to
patient.
Therotatorcuffiscomprisedoftendonsfromthesupraspinatus,infraspina-
tus, teres minor, and subscapularis muscles. The supraspinatus, infraspinatus,
and teres minor muscles arise from the posterior surface of the scapula, cross
posteriortothehumeralhead,andinsertonthegreatertuberosity.Thesupra-
spinatus insertion is most superior and the teres minor insertion most inferior
on the tuberosity. The infraspinatus and teres minor tendons may appear
fused, and a separate teres minor tendon may not be seen [4].
The subscapularis muscle arises from the anterior surface of the scapula,
crosses anterior to the humeral head, and inserts on the lesser tuberosity.
Thedeepfibersofthesubscapularistendonblendwiththetransversehumeral
ligament across the bicipital groove and help maintain the normal position of
the biceps tendon.
The supraspinatus and teres minor muscles have single muscle bellies and
tendons. The subscapularis and infraspinatus are made up of multiple muscle
bellies and small tendons that coalesce to form common tendon insertions.
SHOULDER MAGNETIC RESONANCE IMAGING 373
The rotator cuffintervalisthe space between the supraspinatusand subsca-
pularis tendons along the anterior superior humeral head. Through this space
run the intracapsular portion of the biceps tendon, coracohumeral ligament,
and the superior glenohumeral ligament.
On their course to their insertion sites on the humeral head the rotator cuff
tendonspassunderthecoracoacromialarchandACjoint.Thecoracoacromial
archismadeupofthecoracoidprocess,coracoacromialligamentandtheacro-
mion.HypertrophicabnormalitiesoftheACjointorarchstructuresmaycause
mechanicalimpingementontheunderlyingrotatorcuffmuscleortendon,par-
ticularly the supraspinatus tendon.
Interposed between the coracoacromial arch and supraspinatus tendon lies
thesubacromial-subdeltoidbursa,whichnormallydoesnotcontainfluid.Fluid
may be seen within the bursa when there is bursitis or when fluid leaks into it
from the glenohumeral joint through a full-thickness cuff tear.
Becauseofnormalopeningsinthejointcapsule,theglenohumeraljointisin
communicationwiththesubscapularrecess(beneaththesubscapularismuscle)
andthelongheadofthebicepstendonsheath.Whenajointeffusionispresent
fluidoftenisseenintherecessortendon sheathanddoesnothave pathologic
significance.
The AC joint is a synovial joint surrounded by a fibrous capsule. This cap-
sule is reinforced by fibers of the AC ligament. The coracoacromial and cora-
coclavicularligamentsalsoareimportantinmaintainingnormalpositionofthe
clavicle andacromialprocess.Tearingoftheseligamentsresultsinvarious de-
grees of AC joint separation.
NORMAL MRI APPEARANCE
The fibrous structures in the shoulder are highly organized tissues with nor-
mallylowsignalonallpulsesequences.Thesestructuresincludethejointcap-
sule, glenohumeral ligaments, rotator cuff tendons, and the labrum. When
there is disruption of the organization structure because of tendinopathy or
tear, the signal intensity increases. Unfortunately, there are confounding fac-
torsthatmaycauseartifactuallyincreasedsignalintensityintheabsenceofpa-
thology. These are discussed in more depth elsewhere in this article.
ArticularcartilageisintermediateinsignalintensityonT2andspinechose-
quences.FluidappearsashighinsignalintensityonT2-weightedandshorttau
inversionrecoveryimaging,whichisafluid-sensitivesequence.Normalmuscu-
lature is intermediate in signal intensity on all pulse sequences. Increased T1
signal may be seen with fatty atrophy and increased T2 signal may be seen
with edema.
Normal cortical bone is dark on all pulse sequences because of the lack of
mobileprotons,whereasthemarrowspaceusuallyisT1hyperintensebecause
offatcontent.HeterogenousareasoflowT1signalmaybeseenwithredmar-
rowconversion.Thisfindingiscommonparticularlyinpatientswhohavesys-
temicdiseaseandincreasedredbloodcellturnover.Examplesincludesmokers
and patients who have chronic obstructive pulmonary disease or renal
374 CHAIPAT &PALMER
insufficiency.Themarrowofpatientswhohavehematologicdisorders,suchas
multiple myeloma, may have an identical appearance.
APPROACH TO ROTATOR CUFF EVALUATION
One approach to evaluating the rotator cuff on MRI is to begin by reviewing
thecoronalobliquePDimagestogetanoverviewoftheanatomy(Fig.1).Pro-
ton density images are weighted intermediately between T1 and T2 signal.
They provide superior signal-to-noise ratio and spatial resolution, albeit at
the expense of soft tissue contrast. Large cuff tearsand distortionsof the anat-
omy may be identified. Shoulder alignment may be evaluated also.
Occasionallybecauseofimproperpositioningorpatientmotiontheshoulder
isimagedininternalrotation.Thisimagingleadstooverlapofthesupraspina-
tus and infraspinatus tendons on coronal oblique images [5]. The coronal ob-
lique plane usually is the most useful plane for cuff evaluation because it
parallelsthecourseofthemostcommonlytorncufftendons,thesupraspinatus
and infraspinatus [6]. The subscapularis often is seen well in the coronal obli-
queplanebutisevaluatedbestonaxialimages.Theteresminortendonisseen
best in the sagittal oblique plane but rarely is torn.
After a general overview of anatomy is obtained by reviewing the coronal
obliquePD images, the T2-weightedimages with fatsuppressionmay beeval-
uatedforabnormallyincreasedsignalinthetendonsorbones(Fig.2).Thecor-
onal and sagittal oblique fast spin echo (FSE) T2 fat-suppressed images are
highly sensitive for pathology; however, they are prone to artifactually in-
creased signal and artifact unless the time to echo (TE) is greater than 30
msec. Once a potential abnormality is identified on one of the fat-suppressed
sequences the finding should be confirmed on orthogonal images.
Next, the axial images should be reviewed with particular attention to the
subscapularis muscle. Finally, review of the sagittal T1 sequence is useful to
evaluate for muscle atrophy and mechanical impingement of the rotator cuff
by hypertrophic degenerative changes in the coracoacromial arch structures.
Fig.1. Normalrotatorcufftendon.OnPDobliquecoronalimage,thesupraspinatustendon
(arrow)showsuniformthicknessandsignalintensity.Thetendonisintactonthegreatertuber-
ositywithoutmuscleatrophyorfattychange.H,humeralhead.
SHOULDER MAGNETIC RESONANCE IMAGING 375
Fig.2. Severebonemarrowedemainpatientwithsuspectedrotatorcufftear.Fat-suppressed
T2-weightedobliquecoronalimage(A)showshigh-signalbonemarrowedemainvolvingthe
distalclavicle(arrow)andadjacentacromion.OnT1-weightedobliquesagittalimage(B),the
distalclavicularmarrowedema(arrow)islowinsignalintensity.Thecufftendon(A)andcuff
muscles(B)arenormal.G,glenoid;H,humeralhead.
ROTATOR CUFF TEARS
The spectrum of rotator cuff pathology rangesfrom tendinopathy and fraying
topartial-orfull-thicknesstearing.Partial-thicknesstearsmaybeclassifiedfur-
ther asoccurring onthe articularor bursal surface ofthe tendon. Athird type
ofpartial-thicknesstearistheintrasubstancetear,whichoccurswithinthesub-
stanceofthetendonwithoutextendingtothetendonsurface.Thistypeoftear
is uncommon but is important to identify on MRI because the tendon surface
may appear normal at arthroscopy and the tear may be missed.
Tendinopathy is identified by increased signal within the tendon substance.
The abnormally increased signal intensity remains below that of fluid on T2-
weightedsequences[7].Tendinopathymaybepresentwithorwithouttendon
thickening or thinning. [1]. Fraying is described when the normal linear dark
signal at the margin of a tendon becomes indistinct, but no gap in the tendon
fibers is identified.
Themostspecificsignofacufftearisdiscontinuityofthecufffiberswithfluid
signalintheinterveninggap(Figs.3and4).Unfortunately,thisgapmayonlybe
seeninfairlylargetearsthatmeasuremorethanseveralmillimeters.Forsmaller
tears the signal on T2-weighted imaging and secondary signs of cuff tearing
shouldbeconsideredcarefully.Secondarysignsincludefluidinthesubacromial
or subdeltoid bursa, tendon retraction, and muscular atrophy. The latter two
signs may have implications for the type of surgical repair that is required
and so should be evaluated routinely on every MRI obtained for rotator cuff
evaluation. The appearance of the torn fibers also should be noted, because
poor quality, diffusely torn tendon may not be suitable forrepair (Fig.5).
ThemyotendinousjunctionnormallyislocatedbeneaththeACjoint.When
itismoreproximalafull-thicknesstearshouldbesuspected.Incasesofpartial-
thickness tearing only the torn fibers retract. Some partial- and full-thickness
376 CHAIPAT &PALMER
Fig.3. Full-thicknessrotatorcufftearin54-year-oldpatient.Onfat-suppressedT2-weighted
oblique coronal image (A), distal supraspinatus tendon (arrow) is disrupted by focal high-
signalfluidandismildlyretractedfromthegreatertuberosity.Moreposteriorslice(B)shows
intactinfraspinatustendon(arrow)andnormalattachmenttothegreatertuberosity.H,humeral
head.
cuff tears may have a delaminating component with the tear dissecting proxi-
mallybetweenthedeepandsuperficialtendonfibers.Thetornfibersmaydem-
onstratedifferentdegrees ofretraction(Fig. 6).The degree of retractionofthe
cufffibersshouldbemeasuredbecausethishasadirectrelationshiptoprogno-
sis. The anterior–posterior dimension of the tear also is important and is mea-
sured best on the sagittal sequences.
Anintrasubstancetearisdescribedwhenthereisfluidintensitysignalwithin
thesubstanceofthetendonthatdoesnotextendtoeitherthearticularorbursal
surface.
In some chronic cuff tears and following rotator cuff repair, granulation tis-
sueandfibrosismayfillthegap,resultinginisointenseordarksignal.Inthese
Fig.4. Largepartial-thicknessbursalsurfacerotatorcufftearin56-year-oldpatient.OnT2-
weightedobliquecoronalimage,distalsupraspinatustendonshowsfocalfluid(straightarrow)
disruptingbursalfibersfromgreatertuberosity.Articularsurfacefibers(curvedarrow)remain
intactongreatertuberosity.H,humeralhead.
