Ro rtRe , Lt.

Tthewrsofsiotiopre

AOThradandcartheziubomewitlateartanacol

ArThbyTh

intfyipa

mecombethesueradthepisnacavsidtriqtiorecanpropreasp(arthe radial styloid. These relationships become importantwhen articular diseases such as rheumatoid arthritis affect the

2

*Department of Radiology, University of Texas Health Science Center, SanAntonio, TX.

DD

The

Add

248wrist.Themidcarpal compartment (Fig. 2) includes articulations

between the proximal and the distal carpal rows. The distalpole of the scaphoid articulates with the two trapezial bones,termed the trapezioscaphoid space. The proximal end of thescaphoid combines with the lunate and triquetrum to form aconcavity that articulates with the combined capitate and

epartment of Radiology, Wilford Hall Medical Center, Lackland AFB, TX.epartment of Radiology, University of Texas Health Science Center, SanAntonio, TX.opinions and assertions expressed herein are the private views of theauthors and are not to be construed as official or as representing theviews of the Air Force or the Department of Defense.ress reprint requests to Rebecca A. Loredo, MD, Associate Professor andChief of Musculoskeletal Imaging, Department of Radiology, Universityadiographic Evaluationf the Wrist: A Vanishing Abecca A. Loredo, MD,* David G. Sorge, MD

he intricate anatomy and compartmentalization of struc-tures in thewrist are somewhat daunting. As in other joints,radiographic appearance of disease processes affecting the

ist is very much dependent on the articular and periarticulart tissue and osseous anatomy. Therefore, abbreviated discus-ns of the pertinent anatomy are includedwithin the introduc-nwithmore specific anatomic discussionswithin the text as alude to certain conditions affecting the wrist.

natomy of the Wristsseous Anatomye osseous structures of the wrist are the distal portions of theius and ulna, the proximal and distal rows of carpal bones,the bases of the metacarpals (Fig. 1). The proximal row of

pal bones consists of the scaphoid, lunate, triquetrum, andpisiform. The distal row of carpal bones contains the trape-m, trapezoid, capitate, and hamate bones. The distal row ofnes articulates with the metacarpal bases. The bases of thetacarpals articulate with the distal row of carpal bones andh each other. The proximal carpal row is termed an interca-d segment because forces acting on its proximal and distaliculations determine its position.1 This aspect of the osseustomy becomes important when considering the pattern oflapse that occurs in the different types of wrist instability.

ticular Compartmental Anatomye wrist joint is separated into a number of compartmentsthemany ligaments that attach to the carpal bones (Fig. 2).ese compartments are of considerable significance for thehaof Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio,Texas 78284. E-mail: loredo@uthscsa.edu

0037-198X/05/$-see front matter 2005 Elsevier Inc. All rights reserved.doi:10.1053/j.ro.2005.01.014Colonel, and Glenn Garcia, MD

erpretation of standard or MR arthrograms and for identi-ng various patterns of arthritic involvement.2 The com-rtments are as follows:

1. Radiocarpal compartment2. Midcarpal compartment3. Pisiform-triquetral compartment4. Common carpometacarpal compartment5. First carpometacarpal compartment6. Intermetacarpal compartments7. Inferior (distal) radioulnar compartment

In daily clinical practice, the most important compart-nts are the radiocarpal, midcarpal, and distal radioulnarpartments. The radiocarpal compartment (Fig. 2) lies

tween the proximal carpal row and the distal radius andtriangular fibrocartilage, which is fibrocartilaginous tis-that extends from the ulnar side of the distal aspect of theius to the base of the ulnar styloid. A meniscus attaches totriquetrum and is located between the radiocarpal andiform-triquetral compartments, in most cases. In the coro-l plane, the radiocarpal compartment forms a C-shapedity bordered by the radial collateral ligament on the radiale and the point at which the meniscus is attached to theuetrum on the ulnar side.2 On its ulnar side, two projec-ns are noted from the joint space, a proximal prestyloidess between the meniscus and the triangular fibrocartilaged a distal recess that extends to the triquetrum; these latterjections form a Y-shaped area toward the ulnar wrist. Thestyloid recess abuts the ulnar styloid and, on its radialect, the radiocarpal compartment contacts the bare areaea unprotected by articular cartilage) of the scaphoid and

2mate.2

The inferior radioulnar compartment (Fig. 2) lies between

theanartis iThsharadpagu

LiDebelimmemelig

extthetheterscaamqutheligsisnecar

larplepromenonisextTF

cominsFrostrwetheTFulnananOnflo

Figuosslunrowham5thava

Figuintradpalcom

Figuscamequaracartracap

Radiographic evaluation of the wrist 249cartilage-covered surfaces of the radius (sigmoid notch)d the ulnar head, surrounded by a loose capsule.When theiculating surface between the ulna and the sigmoid notchntact, the radius translates on the seat of the ulnar head.e synovial cavity of this compartment is described as L-ped in coronal section, as it extends between the distalius and ulna and then across the distal ulna.2 This com-rtment is separated from the radiocarpal joint by the trian-lar fibrocartilage.

gamentous Anatomytailed review of the ligamentous anatomy of the wrist isyond the scope of this article. Rather, the discussion will beited to the scapholunate ligament, lunotriquetral liga-nt, and the triangular fibrocartilage complex. The liga-nts of the wrist have been classified into intrinsicaments because they arise and insert on carpal bones and

re 1 Gross anatomic section through the wrist illustrating theeous anatomy. The proximal row consists of the scaphoid (S),ate (L), triquetrum (tq), and pisiform (not shown). The distalincludes the trapezium (tm), trapezoid (tz), capitate (C) andate (H). R radius, U ulna, 1st base of thumbmetacarpal, base of small finger metacarpal. (Color version of figure isilable online.)

re 2 Articular compartmental anatomy. The wrist is separatedo compartments by ligaments that attach to carpal bones. Theiocarpal, midcarpal, pisiform-triquetral, common carpometacar-

, first carpometacarpal, intermetacarpal, and inferior radioulnarpartments are shown. (Reproduced with permission.19)

domerinsic ligaments because they connect the distal portion ofradius and the carpal bones. Two intrinsic ligaments joinbones of the proximal carpal row, the scapholunate in-

osseous ligament (joining the proximal surfaces of thephoid and lunate) and the lunotriquetral interosseous lig-ent (joining the proximal surfaces of the lunate and tri-etrum) (Fig. 3).1 These ligaments connect the bones fromir palmar to dorsal surfaces. The intrinsic scapholunateament complex and the lunotriquetral complex each con-t of dorsal, palmar, and proximal (membranous) compo-nts.3 When intact, they separate the radiocarpal and mid-pal compartments of the wrist.The ulnar ligamentous complex (ulnocarpal ligaments) isgely synonymous with the triangular fibrocartilage com-x (TFCC), comprising the triangular fibrocartilage (TFC)per (the articular disk) and the dorsal radioulnar liga-nt, volar radioulnar ligament, ulnolunate ligament, ul-triquetral ligament, ulnar collateral ligament, and the me-cus homologue.4 The literature includes the sheath of theensor carpi ulnaris tendon in the description of theCC.5

The distal radioulnar joint is stabilized by the TFCC.5 Theplex arises from the medial margin of the distal radius to

ert in the fovea at the base of the ulnar styloid process.m the ulnar side, the ulnocarpal ligaments arise and insertongly on the triquetrum (the ulnotriquetral ligament) andakly on the lunotriquetral interosseous ligament and onlunate (the ulnolunate ligament). Further ulnarly, the

CC becomes thickened again as it is joined by fibers of thear collateral ligament to form the meniscus homologue,d it courses distally to insert on the triquetrum, hamate,d base of the fifth metacarpal bone (meniscus reflection).its dorsolateral side, the TFCC is incorporated into the

or of the sheath of the extensor carpi ulnaris tendon. The

re 3 Intrinsic ligaments. Joining the proximal surfaces of thephoid (S) and lunate (L) is the scapholunate interosseous liga-nt; and, joining the proximal surfaces of the lunate (L) and tri-etrum (T) is the lunotriquetral interosseous ligament. They sep-te the radiocarpal and midcarpal compartments. In the distalpal row, three intrinsic ligaments unite the trapezium (TR) andpezoid (TZ) bones, the trapezoid and capitate bones, and theitate with the hamate bones. These distal interosseous ligaments

not prohibit midcarpal and common carpometacarpal compart-nt communication. (Reproduced with permission.1)

TFanulndis

ImanRaInwrgradeciaavoniqvie

PoThthe

250 R.A. Loredo, D.G. Sorge, and G. GarciaC may be fenestrated centrally, especially in middle-agedd elderly persons. It functions as a cushion between thea proximally and the carpus, primarily the triquetrum,tally. It is a major stabilizer of the distal radioulnar joint.2,5

aging of Osseousd Articular Structures

diographic Viewsmost situations, standard radiographic evaluation of theist includes posteroanterior, oblique, and lateral radio-phs (Fig. 4). Additional exams may include radial or ulnarviation views, carpal tunnel view, carpal bridge view, spe-l scaphoid views, or other specialized techniques.1,6 Toid diagnostic errors, the routine and specialized tech-ues and significant points of plain film evaluation are re-wed.

steroanterior Projection

Figure 4 Standard radiographic evaluation of the wrist. Theposteroanterior, lateral, and oblique radiographs.e posteroanterior (PA) projection (Fig. 5) is obtained witharm abducted 90 from the trunk and the forearm flexed

wipro90 to the arm.6 With the forearm in this pronated posi-n, the ulnar styloid is seen in profile.When views are takensupination, the ulnar styloid overlaps the central portion ofdistal ulna. With the wrist in the neutral position, one-

lf or more of the lunate should contact the distal radialicular surface.1

rmal Arcs of the Wristree smooth carpal arcs are formed on the neutral PA viewng the radiocarpal and midcarpal joints (Fig. 6). Arc 1lows the proximal surfaces of the scaphoid, lunate, anduetrum; arc 2 is along the distal surfaces of these samepal bones, and arc 3 follows the curvature of the proximalfaces of the capitate and hamate.7 In the normal situation,a neutral PA view, these curvilinear arcs are roughly par-el, without disruption, and the interosseous spaces arearly equal in size. Disruption of these arcs or abnormalerlapping of adjacent bones on the PA view commonlyicates carpal subluxation or dislocation. There are, how-r, two common normal variants that mimic step-offs

e radiographic evaluation includes (from left to right)attiointhehaart

NoThalofoltriqcarsuronallneovindeve

routinthin the carpal arcs (Fig. 7): (1) a triquetrum shorter in itsximal-distal dimension than the adjacent lunate creates a

lunsecwithacartheto

NoThwiatfroInanrad

UlChradtiofouthethiulnpoinflsho

Figuproviepoonart

Figu1 s(L)of tthe

Figuthedimstearchambilhamseccre

Figuvarlinwhartthe

Radiographic evaluation of the wrist 251otriquetral step-off of the first carpal arc and a normalond carpal arc and (2) a proximally prominent hamateth an apposing hamate facet on the lunate (type II lunate)t produces a bilobate third carpal arc and a smooth secondpal arc if the radial portion (capitate facet), rather thanhamate facet, of the distal lunate articular surface is usedcreate the second carpal arc.7,8

rmal Scapholunate Joint Spacee normal scapholunate joint space width is the same as thedth between pairs of the other carpal bones. It is measuredthe center of the scapholunate joint with the beam angledm the dorsal ulnar aspect of the wrist approximately 10.9

its midportion, this space normally measures 2 mm or lessd usually remains constant evenwithin the normal range ofial or ulnar deviation of the wrist.9

re 5 Posteroanterior (PA) views. (A) With the forearm in anated position, the ulnar styloid is seen in profile. (B) Whenws are taken in supination, the ulnar styloid overlaps the centralrtion of the distal ulna. With the wrist in a neutral position,e-half or more of the lunate (L) should contact the distal radialicular surface.

re 6 PA view illustrating the normal three arcs of the wrist. Arcpans the proximal articular surfaces of the scaphoid (S), lunate, and triquetrum (tq). Arc 2 connects the distal concave surfaces

hese same bones. Arc 3 outlines the proximal articular surfaces ofcapitate (C) and hamate (H).

varPosnar Varianceanges in the length of the ulna relative to the length of theius, designated ulnar variance (Fig. 8), alter the distribu-n of compressive forces across the wrist. Ulnar variance isnd by extending a line along the distal articular surface ofradius toward the ulna and measuring the distance froms line to the distal ulna2 (Fig. 8A). Normally, the radius anda are almost the same length, although wrist and forearmsition and centering of the x-ray tube have been noted touence the measurements obtained.1 When the ulna isrter than the radius, the term negative ulnar variance is

re 7 Two common normal variants that mimic step-offs withincarpal arcs: (A) a triquetrum (tq) shorter in its proximal-distalension than the adjacent lunate (L) creating a lunotriquetral

p-off (arrow) of the first carpal arc and a normal second carpal, and (B) a proximally prominent hamate (H) with an apposingate facet on the lunate (L type II lunate) that produces a

obate second and third carpal arc using the capitate (C) facet andate (H) facet along the distal lunate articular surface to create the

ond carpal arc and the proximal capitate and hamate facets toate the third carpal arc (shown).

re 8 Ulnar variance on PA wrist views. (A) Normal or neutraliance. Perpendicular to the long axis of the radius, tangentiales are drawn along the ulnar-most extent of the subchondralite line of the distal radius and the distal-most extent of theicular surface of the ulnar dome. The shortest distance betweense two lines is the measure of ulnar variance. (B) Negative ulnar

iance or ulna minus variance (measurement of dotted line). (C)itive ulnar variance (measurement of dotted line).

usearetonevarareulnsynthiatilun

CaCacarPAheiindparbyinddisbeltec

LaOntheaxipis

LoRaInmethecomlin

Figupolonpis

Figuaxeto 3axicenperpothebetcon

FiguhanlincarIntharig

252 R.A. Loredo, D.G. Sorge, and G. Garciad (Fig. 8B). The consequences of negative ulnar varianceincreased force applied to the radial side of the wrist andthe lunate bone, which may explain the association ofgative ulnar variance and Kienbcks disease.2 With suchiance, the TFC is thicker, and abnormalities of the TFCCuncommon. A consequence of a long ulna, or positivear variance, is the ulnar impaction or ulnar abutmentdrome, with resulting limitation of rotation. The TFC isnner in instances of positive ulnar variance, and degener-ve perforation of this structure (as well as disruption of theotriquetral interosseous ligament) may be observed.2

rpal Heightrpal height is the distance between the base of the thirdmeta-pal and the distal radial articular surface as determined on aradiograph of the wrist (Fig. 9). Measurement of carpalght allows comparative quantification of carpal collapse in anividual patient over time.7 The carpal height ratio allows com-ison between individuals and it is the carpal height dividedthe length of the third metacarpal. Similarly, a carpal heightexmay be obtained by dividing the carpal height ratio of theeased wrist by that of the normal hand. Some investigatorsieve the carpal height index to be the most sensitive for de-tion of abnormal carpal height in a specific hand.7

teral Projectiona true lateral view of a normalwrist (Fig. 10), the long axis ofthird metacarpal should be coaxial (parallel) with the longs of the radius. Another clue to a true lateral view is that theiform projects directly over the dorsal pole of the scaphoid.5

ngitudinal Axes of thedius, Lunate, and Capitateneutral position, the longitudinal axes through the thirdtacarpal, the capitate, the lunate, and the radius all fall onsame line (Fig. 11A). This ideal situation is actually un-

re 9 Carpal height relative measurements in the left and rightds of the same patient. (A) Left hand carpal height is shown as ae (a) that spans the distance between the base of the third meta-pal and the distal radial articular surface on a PA radiograph. (B)the right hand, the carpal height (b) is comparatively shorter thant measured in the left hand due to chronic arthritis affecting theht left hand.mon, but in most cases the axes are within 10 of thise. The axis of the radius is constructed as a line parallel to

axiprore 11 Normal lateral views illustrating measurements. (A) Thes of the radius, lunate, and capitate should superimpose, with 00 described as the capitate-lunate angle in normal patients. Thes of the capitate (C) is drawn from the center of its head to theter of its distal articular surface. The lunate axis (L) is drawn aspendicular to a line through the center of its proximal and distalles. (B) The scapholunate angle formed between the long axis oflunate and that of the scaphoid (the scapholunate angle) rangesween 30 and 60. The axis of the scaphoid (S) is shown as a linenecting the proximal and distal convex margins. The lunate (L)re 10 Normal lateral views of the wrist. (A) Normal. The distalle of the scaphoid (S) is seen. (B) Example of parallelism of theg axis of the radius with the long axis of the thirdmetacarpal. Theiform (P) is overlying the distal pole of the scaphoid.s is shown as a perpendicular to a line through the center of theximal and distal poles.

thecandisdrasurshona

LoThthr11sisthafortheran

DionThmona12mebepothefro(Fi(rasurtanart

OThtioindopeshojoi

RaRawrpaAsmaoidapdisAsitsThthrAlt2 aab

RaRaof

Figu

Figuvolintpomidoavebetsur

Radiographic evaluation of the wrist 253center of the radial shaft (Fig. 11A). The axis of the lunatebe drawn through the midpoints of its proximal and

tal articular surfaces (Fig. 11A). The axis of the capitate iswn through the centers of its head and its distal articularface (Fig. 11A). The axes of the radius, lunate, and capitateuld superimpose, with 0 to 30 described as the capitolu-te angle in normal patients.1

ngitudinal Axis of the Scaphoide long axis of the scaphoid is represented by a line drawnough the midpoints of its proximal and distal poles (Fig.B).1 Another method, proposed by Gilula andWeeks, con-ts of connecting the ventral convexities of the scaphoidt are visible on the lateral view.10 Normally, the anglemed between the long axis of the radius, the lunate, andcapitate and that of the scaphoid (the scapholunate angle)ges between 30 and 60 and averages 47.1

stal Radial MeasurementsLateral and Posteroanterior Viewsere are three radiographic measurements that are com-nly used to assess the anatomy of the distal radius,mely, palmar tilt, radial inclination, and radial length (Fig.).1,11 The normal palmar or volar tilt of the radius can beasured on lateral views by noting the angle of intersectiontween a line drawn tangentially across the most distalints of the radial articular surface and a perpendicular tomidshaft of the radius (Fig. 12A). This normally rangesm 11 of volar tilt to 4 of dorsal tilt.1 Radial inclinationg. 12B) is measured on PA radiographs and averages 22nge 13 to 30). Radial length (Fig. 12C) can be mea-ed along the longitudinal axis of the radius. It is the dis-

re 12 Normal measurements of the distal radius. (A) Palmar orar tilt of the radius can be measured by obtaining the angle ofersection between a line drawn tangentially across the most distalints of the radial articular surface and a perpendicular to thedshaft of the radius. Normal range is 11 of volar tilt to 4 ofrsal tilt. (B) Radial inclination is measured on PA radiographs andrages 22 (range 13 to 30). (C) Radial length is the distanceween the tip of the radial styloid and the ulnar head articularface. Radial length averages 11 to 22 mm.ce between the tip of the radial styloid and the ulnar headicular surface. Radial length averages 11 to 22 mm.11

lowscablique Viewe standard oblique view (Fig. 13) is taken in the PA posi-n, with the hand in partial pronation. This view is helpfuldetection of scaphoid tuberosity and waist fractures andrsal margin triquetral fractures. It profiles the scaphotra-zial, trapeziotrapezoidal, and capitolunate joints and willw the first carpometacarpal and the scaphotrapezoidalnts to best advantage.12

dial and Ulnar Deviation Viewsdiographs obtained with radial and ulnar deviation of theist (Fig. 14) are useful for visualizing the carpal bones,rticularly the scaphoid, and for assessing carpal mobility.the wrist is radially deviated, palmar flexion of the proxi-l carpal row occurs and the distal pole of the distal scaph-rotates into the palm. This causes the normal scaphoid to

pear foreshortened and exhibit a ring-like appearance of itstal pole as the distal aspect of the scaphoid is seen end-on.the wrist is placed in ulnar deviation, the scaphoid rotatesdistal pole dorsally and ulnarly and it appears to elongate.1

e distances between the carpal bones are normally equaloughout and are unchanged by radial or ulnar deviation.hough widening of the scapholunate distance to betweennd 4 mm may be abnormal, more than 4 mm is definitelynormal.1,6

diocarpal Joint Viewdiographs obtained by angulating the beam along the axisthe radiocarpal joint (Fig. 15) allow better visualization of

re 13 Normal semipronated oblique radiograph: this view al-

s examination of the radial aspect of the wrist, particularly thephoid (S) and radial styloid (RS).

thithefrobescavis

APTointhabeofon

SeInpro16inclugoaspanviehade

LaThcarcanpatruanlonvo

Figu(B)towproscadev(itselo

FiguplaangLisensmiibl

FiguoblfrotriqseeNoinaand

254 R.A. Loredo, D.G. Sorge, and G. Garcias articulation; a PA roentgenogram may be obtained withbeam angulated 10 proximally, and a lateral radiographm the radial side of the joint may be obtained with theam angulated 15 proximally. The PA view elongates thephoid and shortens the capitate, and it may provide betterualization of abnormalities of the scaphoid.12

re 14 Normal radial and ulnar deviation views. (A) Radial andulnar deviation. In radial deviation, the scaphoid (S) rotatesard the palm and appears foreshortened. The distal scaphoid isjected end-on and appears as a circular density (asterisk). Thepholunate distance remains normal (less than 2 mm). In ulnariation, the scaphoid is seen in full length. The scaphoid rotatesdistal pole moving dorsally and toward the ulna) and appears tongate (arrows). The scapholunate interval may increase slightly.

re 15 Normal radiocarpal joint view. (A) The wrist and palm areced flat on the cassette, as in the PA view. The central beam isled 25 to 30 toward the elbow and is centered just distal toters tubercle.12 (B) This view elongates the scaphoid and short-the capitate. The radiocarpal (R-C) joint should demonstrateulnthe

nimum bony overlap with parallelism at the (R-C) joint still vis-e. (Reproduced with permission.12)Projectionmore reliably profile the scapholunate and lunotriquetralerspaces, an AP view can be obtained. The dorsum of thend and wrist are flat against the cassette and the centralam is perpendicular to the cassette, centered over the headthe capitate. The ulnar styloid projects over the ulnar headan adequate examination.6,9

misupinated Oblique Viewsome cases, oblique projections are taken in both a semi-nated oblique and a semisupinated oblique position (Fig.). The latter is an anteroposterior oblique view that is takenpartial supination. Synonymous names for this view in-de the Norgaard view, the ball-catchers or Youre inod hands with Allstate view. It shows the pisiform, palmarect of the triquetrum, palmar ulnar surface of the hamate,d it profiles the pisiform-triquetral joint. The Norgaardw is optimal for evaluation of early erosive changes in thends and wrists of patients with inflammatory arthriti-s.1,12,13

teral Flexion and Extension Viewsese views demonstrate extension and flexion at the radio-pal and midcarpal joints in normal wrists (Fig. 17). Theybe used in evaluation of carpal instability patterns. In

rticular, these views can assist in distinguishing between ae instability pattern versus normal variance.12 Extensiond flexion of the wrist is recognized by observation of theg axis of the thirdmetacarpal extended dorsally and flexedlarly, respectively, relative to the long axis of the radius and

re 16 Normal oblique views. (A) Normal AP semisupinatedique radiograph: in this view, the pisiform bone is separatedm the remaining carpal bones. The hamate (H), pisiform (P),uetrum (tq), and pisiform-triquetral joint (arrow) are specificallyn on this view when evaluating for inflammatory disease. (B)rmal semipronated oblique radiograph: This view allows exam-tion of the radial aspect of the wrist, particularly the scaphoid (S)radial styloid (arrow).a. In extension, the pisiform remains closely apposed totriquetrum and projects over the scaphoid as in the neu-

tratriq

CaAdo(1)tacsuost

Thcas30do

ScThturnopromathetedvieviesemvieprotexthe

CaThdoferplaprotistubthetun

Figutenmithe

FiguwitsupofThinepro(ar

Figuis pis daxiscaham

Radiographic evaluation of the wrist 255l lateral view. In flexion, the pisiformmoves away from theuetrum, projecting anterior to the scaphoid.12

rpal Boss View or Off-Lateral Viewslightly supinated off-lateral view (Fig. 18) shows thersal carpal boss on a tangent and enables distinction ofa separate os styloideum, (2) a bony prominence at-hed to the second or third metacarpal base or apposingrface of the trapezoid or capitate bones, (3) degenerativeeophytes, or (4) a fracture of the dorsal prominence.12

re 17 (A) Normal lateral volar flexion and (B) dorsiflexion (ex-sion) of the wrist occur with motion at the radiocarpal and thedcarpal joints. The distal pole of the scaphoid (S) rotates towardpalm in volar flexion.

re 18 Carpal boss view. (A) The wrist is slightly ulnar-deviatedh the ulnar side of the wrist on the cassette. Approximately 30ination of the wrist is performed to place the dorsal prominencethe second to third CMC joints tangent to a vertical central ray.e central beam is passed through or tangent to the dorsal prom-nce. (Reproduced with permission.12) (B) In this case, the dorsaltheart

minence is profiled to show a separate bone, the carpal bossrow), in tangent.e view is taken with the ulnar side of the wrist on thesette, in slight ulnar deviation and with approximately supination. The central beam passes tangent to thersal prominence.12

aphoid Viewse standard pronated oblique view generally shows frac-es of the scaphoid tubercle. However, the detection ofn-displaced scaphoid fractures can be significantly im-ved with the use of dedicated scaphoid views. Thesey include magnification views or any combination offollowing: PA or AP ulnar deviation view, semiprona-oblique view with ulnar deviation, lateral scaphoid

w, stecher position view, ulnar oblique scaphoidw, 30-degree semipronated oblique PA view, 60-degreeipronated oblique PA view, and elongated obliquew.12 For a more detailed technical discussion of thesejections, the reader is referred to standard imagingts that detail the position and technique for obtainingse views.12

rpal Tunnel Viewe carpal tunnel view (Fig. 19) is obtained with the wristrsiflexed and either the ventral aspect of the wrist (in-osuperior view) or the palm (superoinferior view)ced on the film cassette. The x-ray beam is angled tofile the carpal tunnel. This view shows the palmar softsues and the palmar aspects of the trapezium, scaphoiderosity, capitate, hook of the hamate, triquetrum, andentire pisiform.6,12 It should be noted that the carpalnel view obtained using the inferosuperior projection,

re 19 Normal carpal tunnel view. (A) The long axis of the handlaced in a vertical direction (hyperextended) and the central rayirected along the volar aspect at an angle of 25 to 30 to the longs.6 (B) and (C) In the normal situation, the trapezium (tm),phoid (S), triquetrum (tq), pisiform (P), and the hook of theate (h) can be delineated. (Reproduced with permission.1)GaynorHart method, may create a confusing ringifact representing an end-on view of the fifth metacarpal

suolu

CaThchdesofviequibl

ClThscaItbeWcreprowiwi

DiIfde(Fibecap

FiA dtiomeviecisBe

Figuappinfdemandsw

FiguingthewitIn

Figucastowop

256 R.A. Loredo, D.G. Sorge, and G. Garciaperimposed on the carpal bones, with the central radi-cent area corresponding to the medullary canal.6

rpal Bridge Viewis view profiles dorsal surface fractures of the scaphoid,ip fractures of the dorsum of other carpal bones, and itmonstrates calcifications and foreign bodies in the dorsalt tissues. On an adequate examination, there is tangentialw of the dorsal aspect of the scaphoid, lunate, and tri-etrum (Fig. 20). The superimposed capitate should be vis-e.12

enched Fist Viewe clenched fist view (Fig. 21) is used to widen thepholunate joint in cases of scapholunate joint diastasis.can be obtained in a PA or AP position as the centralam passes through the center of the capitate head.ith a tight fist, the contracting tendons and musclesate a force within the wrist that drives the capitateximally toward the scapholunate joint.3,12 In wriststh a lax or disrupted scapholunate ligament, the jointll widen.

stal Tilt Viewthere is suspicion of a capitate waist fracture that is notmonstrated on the standard PA view, the distal tilt viewg. 22) may be utilized. It is a PA projection with the central

re 20 Normal carpal bridge view. (A) The wrist is flexed toroximately 90 and the central ray is angled at 45 in a supero-erior direction (Reproduced with permission.12) (B) This viewonstrates the scaphoid (S) and lunate (L) and triquetrum (tq)is useful for diagnosing fractures, foreign bodies, and soft-tissue

elling within the dorsum of the wrist.am angled 25 to 30 toward the fingers, centered on theitate.12

gatmirst Carpometacarpal Joint Viewedicated anteroposterior projection with beam angula-n has been used to define changes in the first carpo-tacarpal joint (Fig. 23).12 Coned frontal and lateralws of the first carpometacarpal joint allow a more pre-e analysis of arthritis and traumatic lesions, such as thennetts fracture.6

re 21 Normal clenched fist view. With a tight fist, the contract-tendons and muscles create a force within the wrist that drivescapitate (C) proximally toward the scapholunate joint. In wristsh a lax or disrupted scapholunate ligament, the joint will widen.this case, the S-L interval did not abnormally widen.

re 22 Normal distal tilt view. (A) The wrist is placed flat on thesette, as it is for a PA view. The central beam is angled 25 to 30ard the fingers, centered on the capitate. (B) This view is used fortimal evaluation of the capitate waist. The capitate (C) is elon-

ed and the scaphoid (S) is foreshortened. (Reproduced with per-ssion.12)

REv

De

ThgratusratmulatshFravoof

guofbreisfropatheoftstr

carsucthitiss

WDMaclipawrhisthe

Figu(A)hotowdiodig

Figufatcre(arshoatio

Figualle

Radiographic evaluation of the wrist 257adiographicaluation of Soft Tissues

ep and Superficial Fat Planes

ere are two deep fat planes that are useful in the radio-phic evaluation of wrist trauma: the pronator quadra-fat pad and the scaphoid fat pad. The pronator quad-us fat pad (Fig. 24) lies between the pronator quadratusscle and the volar tendon sheaths. It is seen on theeral radiograph of the wrist as a linear or crescent-aped lucency just anterior to the distal radius and ulna.ctures involving the distal radius or ulna often showlar displacement, blurring, irregularity, or obliterationthis fat plane.The scaphoid fat plane or fat stripe (Fig. 25) is a trian-lar or linear collection of fat that is bounded by tendonsthe abductor pollicis longus and the extensor pollicisvis and by the radial collateral ligament.1 This fat planeseen on the PA radiograph as a lucent stripe extendingm the radial styloid to the trapezium and almostralleling the radial aspect of the scaphoid. Fractures ofscaphoid, the radial styloid, and the first metacarpal

en result in displacement or obliteration of this fatipe.On the ulnar aspect of the wrist, fat along the extensorpi ulnaris tendon is often visible. Inflammatory processesh as rheumatoid arthritis may obliterate this fat stripe and

re 23 Normal first carpometacarpal joint: specialized view.The hand is hyperextended and the thumb is placed in a

rizontal position. The central ray is angled approximately 45ard the elbow. (Reproduced with permission.6) (B) The ra-graph shows that the axis of the thumb differs from the otherits.cken the tendon shadow, increasing the amount of soft-ue density along the ulnar styloid.1

plafatrist Pain ifferential Diagnosisny wrist disorders are readily identified during the initialnical evaluation. Alternatively, the patients history may bethognomonic of a certain injury, such as acute volar ulnarist pain in a golfer after a dubbed swing; this being atory that is typically associated with fracture of the hook ofhamate. However, some disorders such as carpal instabil-

re 24 The pronator quadratus fat pad. The pronator quadratusstripe is seen on the lateral radiograph of the wrist as a linear orscent-shaped lucency just anterior to the distal radius and ulnarowheads). Fractures involving the distal radius or ulna oftenw volar displacement (arrows), blurring, irregularity, or obliter-n of this fat plane.

re 25 Scaphoid fat stripe. (A) The normal fat stripe is seen par-ling the lateral aspect of the scaphoid (arrows). (B) A non-dis-

ced fracture of the scaphoid is associated with obliteration of thestripe (circle).

ityconamaregralow

TFranFracomthepadeframatiorad(orframo(dipatio

po(2)paalothepresolagediafraint

clocasfrafradochsalshothenoclomoorsee

onwivome

FiguTh(3)

258 R.A. Loredo, D.G. Sorge, and G. Garciaand ulnar-sided wrist pain are less specific; and theseditions are conclusively diagnosed only after careful ex-ination supported by appropriate imaging studies. Theremany varied causes of wrist pain and methods of radio-phic evaluation, as will be discussed throughout the fol-ing pages of this writing.

raumaticactures of the Radiusd UlnaPatterns of Injuryctures of the distal aspect of the radius are one of the mostmon skeletal injuries treated by orthopedic surgeons andy account for 17% of all fractures seen in emergency de-rtments.14 A multitude of classification systems have beenvised based on extraarticular or intraarticular involvement,cture complexity (degree of displacement and angulation),nagement issues, mechanism of injury, and treatment op-ns.15 Intraarticular fractures of the distal portion of theius have been described as two-, three-, four-, or five-partmore) fractures. Based on stability and reducibility of thecture, consistent radiographic observations have led to are universally accepted description of articular injuriesscussion of fracture parts), whereby analysis of the fracturettern and creation of a subset of articular injury classifica-

re 26 Basic components of an articular fracture of the radius.e basic fracture parts are (1) the radial shaft, (2) the radial styloid,a dorsal medial fragment, and (4) a palmar medial fragment.n has facilitated their treatment.15

Despite frequent comminution, there are four basic com-Figuclonents or parts of an articular fracture: (1) the radial shaft,the radial styloid, (3) a dorsal medial fragment, and (4) almar medial fragment (Fig. 26). The twomedial fragments,ng with their ligamentous attachments to the carpus andulnar styloid, are termed the medial complex. Anatomicservation of this medial complex is recognized as an ab-ute requirement for optimal fracture reduction and man-ment. Displacement of these strategically positioned me-l fragments also forms the basis for categorizing articularctures into a classification system (type I, II, III, IV), takingo account features of previous classification systems.15

Type I fractures are minimally displaced, stable aftersed reduction, and effectively treated by a short period oft immobilization (Fig. 27). More commonly, an articularcture is Type II, which is the dorsally displaced die-punchcture. In such a fracture, the lunate selectively impacts thersal medial component, resulting in an unstable fracturearacterized by varying degrees of comminution of the dor-metaphysis, marked dorsal tilting, and considerablertening of the radius.15 In the majority of type II fractures,medial complex components are neither widely separatedr rotated (Type IIA), and they are generally amenable tosed reduction and skeletal fixation (Fig. 28). Less com-nly, a more comminuted and displaced pattern of dorsalpalmar displacement, the type IIB fracture (Fig. 29), isn, irreducible by closed methods.15

A third type of pattern, the type III spike fracture, dem-strates articular disruption similar to that in type II injuriesth added displacement of a spike fragment, from thelar metaphysis (Fig. 30). Displacement of the spike frag-nt may occur at the time of injury or during fracture ma-re 27 Type I fractures are minimally displaced and stable aftersed reduction.

nipinj

arawi31typendirtenysiwi

Figutofra

Figu

Figupoam

Figuviedis

Radiographic evaluation of the wrist 259ulation, which worsens fracture stability and may causeury to adjacent nerves and tendons.15

The type IV fracture pattern is characterized by wide sep-tion or rotation of the dorsal and palmar medial fragmentsth severe disruption of the distal radius articulations15 (Fig.). A more violent injury accounts for the occurrence of thee V explosion fracture. This severe injury results from anormous force, composed of both axial compression andect crush, with resultant severe comminution often ex-ding from the articular surface of the radius to the diaph-s.15 The latter two patterns usually occur in associationth severe surrounding soft-tissue trauma.

re 28 Type IIA die-punch fracture. The medial complex com-nents are neither widely separated nor rotated and are generallyenable to closed reduction and/or skeletal external fixation.

re 29 Type IIB die-punch fracture. (A) PA view and (B) oblique

widme

w show a more comminuted and displaced pattern of dorsalplacement.re 30 Type III spike fracture. The articular disruption is similarthat in type II injuries with the added displacement of a spikegment (arrow), from the volar metaphysis.

re 31 Type IV fracture. (A) PA view and (B) lateral view show

e separation or rotation of the dorsal and palmar medial frag-nts with severe disruption of the distal radius articulation.

repepstaagescrincradofBapaoftur

CoThmohameThtheturticpla

comartradpaflealianmetiosom

excres

imartcaume(3)thebuoffac

SmThradvotiothefrainc

BaA BthefracauA vthemoa rtio

Figu

Figua mlati

260 R.A. Loredo, D.G. Sorge, and G. GarciaThe classification system described above is not meant tolace the common fracture descriptions and use of theironyms; it is a method of discussion that increases under-nding of fracture reducibility, stability, and ultimate man-ment. Common eponyms are consistently used to de-ibe fractures of the distal end of the radius. Exampleslude Colles fracture (fracture of the distal aspect of theius with dorsal displacement), Smiths fracture (fracturethe distal portion of the radius with palmar displacement),rtons fracture (fracture of the dorsal rim of the radius),lmar or reverse Bartons fracture (fracture of the palmar rimthe radius), and Hutchinsons or chauffeurs fracture (frac-e of the radial styloid process).

lles Fracturee well-known Colles fracture (Fig. 32) is the most com-n injury to the wrist caused by a fall on an outstretchednd causing axial compression together with a bending mo-nt. The combination leads to dorsiflexion of the joint.16

e frequency of this fracture increases with advancing age ofpatient. The classic Colles fracture is a transverse frac-e, with or without comminution, with or without intraar-ular extension, accompanied by impaction and dorsal dis-cement of the distal surface of the radius.16

Complications of Colles fractures are diverse and fairlymon. Such complications include unstable reduction,

icular incongruity, subluxation or dislocation of the distalioulnar joint, median nerve compression resulting in car-l tunnel syndrome, ulnar nerve injury, entrapment ofxor tendons, reflex sympathetic dystrophy, carpal mal-gnment or fracture, posttraumatic osteolysis of the ulna,d malunion, delayed union, or nonunion.16 Therefore,asurement of such parameters as radial tilt, radial inclina-n, and ulnar variance on routine radiographs assumese importance17 in evaluation of fracture stability.

Markers of fracture instability are (1) radial shortening in

re 32 Colles fracture. (A) PA oblique and (B) lateral views showetaphyseal fracture of the radius (arrows) in mild dorsal angu-onwith associated ulna styloid tip avulsion fracture (arrowhead).ess of 6 to 10 mm, as this predisposes to further collapse,ulting in distal radioulnar instability and ulnocarpal joint

strainspaction (Fig. 33); (2) angulation or tilting of the radialicular surface exceeding 20 in the sagittal plane, whichses a serious disturbance of radiocarpal collinear align-nt as well as incongruity of the distal radioulnar joint; andmetaphyseal comminution involving both the volar anddorsal radial cortices as this eliminates an intact bony

ttress on which a stable reductionmust hinge. Recognitionthese radiographic signs of instability is essential for satis-tory management of these injuries.15

iths Fracturee less common Smiths fracture is a fracture of the distalial metaphysis or epiphysis, with or without articular in-lvement, demonstrating palmar displacement or angula-n. The mechanism of injury is hyperflexion from a fall onpalmar-flexed wrist (Fig. 34). Complications of Smiths

ctures are similar to those of Colles fractures and maylude injury to the extensor tendons.16

rtons Fractureartons fracture is a marginal fracture of the dorsal rim ofradius that displaces along with the carpus, producing a

cture-subluxation (Fig. 35). The fracture results from a fallsing dorsiflexion and forearm pronation on a fixed wrist.ariant of the Bartons fracture involves the palmar rim ofdistal end of the radius (Fig. 36) and may be more com-n than its dorsal counterpart. It is sometimes referred to aseverse Bartons or a palmar Bartons fracture. Complica-ns of fractures of the dorsal or palmar rim of the radius are

re 33 Result of Colles fracture instability. A PA view demon-

tes radial shortening resulting in both disabling distal radioulnartability and ulnocarpal joint impaction (ellipse).

simin

HuFratonacrafireatteratheoftPAgranothe

linfosarc

con

Figuframa

Figushodis

Figudemcarsub

Figu(B)

Radiographic evaluation of the wrist 261ilar to those of a Colles fracture with increased difficultymaintaining stable reduction.15

tchinsons or Chauffeurs Fracturecture of the styloid process of the radius is often referredas a Hutchinsons fracture or a chauffeurs fracture (origi-lly described as a fracture that occurred when the startingnk of an engine suddenly reversed during an engine back-) (Fig. 37). It is an avulsion injury related to the sites ofachment of the radiocarpal ligaments or the radial collat-l ligament. It may also result from a direct blow.18 Becausefragment is most often non-displaced, this fracture is

en difficult to visualize. The fracture is best identified on aradiograph and may not be apparent on a lateral radio-ph. On the PA view, it should not be confused with thermal irregularity along the lateral surface of the radius atexpected site of previous physeal closure. The fracture

re 34 Smiths fracture. (A) PA view and (B) lateral view of acture of the distal radial metaphysis that is angulated in the pal-r direction.

re 35 Bartons fracture. (A) Lateral and (B) AP oblique views

w a marginal fracture of the dorsal rim of the radius that isplaced along with the carpus, producing a fracture-subluxation.

radthee may enter the space between the scaphoid and lunatesae, thereby causing scapholunate dissociation and lesserinjury of the wrist.16

It is critical to restore the articular surface to anatomicgruency following the described various fracture patterns

re 36 Reverse Bartons fracture. (A) Lateral and (B) PA viewsonstrate a volar rim fracture with palmar displacement of the

pus with the rim fragment (arrow), consistent with a fractureluxation pattern.

re 37 Hutchinsons fracture or chauffeurs fracture. (A) PA andPA oblique views demonstrate a fracture through the base of the

ial styloid (arrows). The fracture approaches the space betweenscaphoid and lunate fossae (arrowheads).

tomaob(Cusemoothtalsioligtho

UlWshofrapeeraingtom(luwrasgenphinf38

ChInovtwplathe

turshoplanotyp

OThbocreofno

Figuulnfraph

Figuun

Figulate

262 R.A. Loredo, D.G. Sorge, and G. Garciaprevent the development of instability and late posttrau-tic arthritis. In addition to diagnostic PA, lateral andlique plain x-rays, thin-section computed tomographyT) scans with multiplanar reconstruction of images can bed to assess the intraarticular extent and fracture fragmentrphology in preparation for percutaneous pinning ander methods of reduction. In particular, coronal and sagit-images are especially helpful in measuring cortical depres-n or offset. MR imaging has been useful in evaluation ofamentous, nerve, tendon, and surrounding soft-tissue pa-logy associated with wrist fractures.

na Styloid Fracturehen an ulnar styloid fracture is present, another fractureuld be sought (Fig. 38A), because only 6% of ulnar styloidctures occur alone.19 In isolation, an ulna styloid fracture isrhaps related to an avulsion produced by the ulnar collat-l ligament or triangular fibrocartilage complex. The result-ossific fragment should not be confused with the ana-ic variant appearance of the normal ossification centernula) that may appear in the meniscus homologue of theist. The irregular contour of the fracture fragment, as wellthe irregularity of the donor site along the styloid process,erally allows accurate diagnosis of the fracture. Hypertro-y of the fragment with fracture nonunion is encounteredrequently andmay be a source of chronic wrist pain16 (Fig.B).

ildhood Fractureschildren, injuries may result from acute trauma or chroniceruse. Due to the fact that the capsule and ligaments areo to five times stronger than the growth plate, the growth

re 38 Ulna styloid fractures. (A) PA view shows a fracture of thea styloid (arrow). This fracture is associated with a scaphoidcture (arrowheads). (B) Oblique view demonstrating hypertro-y of the ulna fragment with ulna fracture nonunion.te is more often involved. Acute fractures typically involveradial and ulnar physes; in younger children, torus frac-

(arplaes commonly occur (Fig. 39). The radiographs of childrenuld be inspected carefully in at least two orthogonalnes in an effort to avoid misdiagnosis or incomplete diag-sis of fractures. Physeal fractures are usually SalterHarrise II (Fig. 40).

ccult Wrist Fracturesere are a number of common and not-so-common carpalne fractures that are more often missed than others. In-asing awareness of these injuries and more consistent useCT scanning and MR imaging have improved their diag-sis.

re 39 Torus fracture. (A) PA view and (B) lateral views show aicortical fracture of the metaphysis of the radius (arrow).

re 40 Salter Harris, type II fracture of the radius. (A) PA and (B)ral views of the wrist demonstrate fracture of the metaphysis

rows) that extends into the physis (arrowhead) with dorsal dis-cement of the epiphysis with the dorsal metaphyseal fragment.

ScTh(65Sev20potheincch

inPAvietheofchscdisbelat

ismelacfraplaeranoexccougrathi

avaunoid

thaitsfrapeofbeeveanhe

inCopreoidachsom

bospaTenocleten

Figuunmoscathithrrow

Radiographic evaluation of the wrist 263aphoid Fracturee majority of fractures of the wrist involve the scaphoid%). However, radiographic diagnosis may be difficult.enty percent of these fractures occur through the waist;% involve the proximal third, and 10% occur in the distalle. In children, avulsion fractures of the distal portion ofscaphoid are typical. Unusual patterns of scaphoid injurylude dorsal avulsion fractures and fractures of the osteo-ondral interface in young children.16

Radiographically, multiple views of the wrist are indicatedpatients with suspected scaphoid fractures. In addition to, lateral and oblique projections, angled andmagnificationws, and views with the wrist in ulnar deviation will showwaist of the scaphoid to best advantage. Soft-tissue signsfracture include dorsal swelling and scaphoid fat padanges. Obliteration, distortion, or displacement of theaphoid fat stripe may occur (Fig. 25B). In the case of aplaced scaphoid fracture or suboptimal healing, there maydorsal tilting of the lunate (humpback deformity) simu-ing that occurring in dorsal segmental instability.16

Themajor factor leading to nonunion of scaphoid fracturesdelayed or inadequate immobilization. Therefore, treat-nt is often begun even when radiographic confirmation isking. Individuals without radiographically demonstrablectures who are clinically suspected of having non-dis-ced scaphoid fractures are immobilized in a cast for sev-l weeks and then reexamined. Ganel and coworkers, whoted that a negative bone scan 24 to 72 hours after injuryludes fracture at this site, have suggested an alternativerse.20 In clinically suspicious cases with negative radio-phs, a bone scan (with the cast on) is performed and, ifs is negative, immobilization is discontinued.Complications of a scaphoid fracture (Fig. 41) includescular necrosis of the proximal pole, delayed or non-

re 41 Scaphoid fracture avascular necrosis (AVN) and non-ion. (A) Avascular necrosis of the proximal fragment (arrow) isre prevalent in fractures that involve the proximal third of thephoid and less frequent with fractures that involve the middlerd. (B) A PA view of the wrist demonstrates a chronic fractureough the waist of the scaphoid, consistent with nonunion (ar-).ion, and an unusual form of osteoarthritis, termed scaph-nonunion advanced collapse16 (SNAC). Due to the fact

Figudot the entire blood supply to the scaphoid enters throughdistal pole, avascular necrosis (AVN) may occur followingctures through the waist of the scaphoid and it is an ex-cted sequela of proximal pole fractures. Increased densitythe proximal fragment, indicating avascular necrosis, hasen noted on radiographs in about 30% of patients.1 How-r, sclerosis alone does not indicate inevitable nonunion,d both the fracture and the avascular area may go on toal.Nonunion of scaphoid fractures is due primarily to a delaydiagnosis or lack of adequate immobilization, or both.21

ntributing factors include anatomical features such as thesence of articular cartilage covering five of the six scaph-surfaces, healing by endosteal reaction only, failure toieve anatomical reduction, and a tenuous blood supply ine cases.21,22

Radiographic abnormalities of scaphoid nonunion includene sclerosis, cyst formation, widening of the scapholunatece, bone resorption, and, subsequently, osteoarthritis.ndon ruptures may occur as a complication of scaphoidnunion, and CT may reveal hypertrophy of Listers tuber-in the dorsum of the radius, which may predispose todon disruption.16re 42 Triquetral dorsal avulsion fracture. A lateral view shows arsal-avulsion fracture of the triquetrum (ellipse).

FrThbo(Fiwidooftiotencautriqan

framaCTIt imo(FiofswtheprealstraligneheMRcludiapafusfratheexc

a dmathemiAPdeseeAne

arethefradisdro

Figulatebet

FigudemCo(ar

Figuof a

264 R.A. Loredo, D.G. Sorge, and G. Garciaactures of Other Carpal Bonese triquetrum is the second most commonly injured carpalne (3 to 4% of all carpal bone injuries). The dorsal fractureg. 42) may be caused by forceful contact of the triquetralth the hamate or ulnar styloid process or to avulsion of thersal radiotriquetral ligaments.16 The dorsal-avulsion typeinjury is not often missed on the lateral or oblique projec-ns. However, a less common triquetral fracture that is of-missed involves the body of the triquetrum (Fig. 43),sed by a direct blow in most cases.16 This rare type ofuetral injury may be missed on conventional radiographyd better diagnosed with CT.Fractures of the hamate make up 2 to 4% of all carpalctures.16 Sagittal or coronal fractures through the bodyy occur and these may be detected on plain x-ray or with. CT scans are often necessary to define the fracture plane.smore difficult to clinically and radiographically detect there common fracture involving the hook of the hamateg. 44). Therefore, this injury deserves attention. Fracturesthe hook often occur in association with a dubbed golfing or in sports that use rackets or bats. The grip may placeend of the club handle or bat against the hook, therebydisposing the hook to direct trauma. These injuries mayo result from a fall on a dorsiflexed wrist, with the forcensmitted through the transverse carpal and pisohamateaments.16 Aside from standard radiographs, a carpal tun-l view, computed tomography, or a bone scan may belpful in detecting fractures of the hook of the hamate, as isimaging (Fig. 45). Complications of these fractures in-

de nonunion, osteonecrosis, injuries to the ulnar or me-n nerve, tenosynovitis or tendon rupture, and chronicin. A bipartite hook or os hamuli proprium (incompleteion of the ossification center of the hook) may mimic acture.16 On an MR imaging study, it is recommended thataxial and sagittal images be completely reviewed before

re 43 Fracture of the body of the triquetrum. (A) A conventionalral x-ray may not show this rare type of triquetral injury. It ister diagnosed with (B), computed tomography (arrow).luding a fracture of the hamate.23

Fractures of the pisiform (Fig. 46) are usually the result of(C)rowirect blow to the volar surface of the wrist. The fracturey be transverse (usually a chip fracture of the distal end ofbone) or longitudinal. Occasionally, the fracture is com-nuted. The fracture is best visualized on a 30 supinatedview, carpal tunnel view, lateral oblique view, or a radialviation PA view. When no other soft-tissue swelling isn, paraulnar fat pad swelling suggests a pisiform fracture.complication of fractures involving the pisiform is ulnarrve damage.16,24

Isolated fractures of the capitate, trapezium, and trapezoidinfrequent. Capitate fractures (Fig. 47) usually involveneck of the bone and may be associated with metacarpalctures, scaphoid fractures, and trans-scaphoid perilunatelocations, at times resulting in the scaphocapitate syn-me (Fig. 48).16 In scaphocapitate syndrome, the head of

re 44 Hamate fracture. (A) A pronated oblique view of the wristonstrates a fracture of the hook of the hamate (arrow). (B)

rresponding CT scan image shows the fracture to best advantagerow). (Courtesy of Donald Resnick, MD, San Diego, CA.)

re 45 Hamate hook fracture. (A) Sagittal T1-weighted MR imagehamate hook fracture (arrows). (B) T1-weighted axial image and

T2-weighted axial image show the fracture line (circle and ar-).

thepreprodisProprosupfilm

cappro

bo(pathefirsziathoproThligtunavu(Firadzia(Fifra

CaAnbacomcluturThanthechtur

Figutra(ar

Figuwetra(C)straa scap

Figuscapeais tcappatare

Radiographic evaluation of the wrist 265capitate is fractured and rotated 180. Difficulty inter-ting the radiographs in this situation can result in im-per treatment of a fracture fragment that is considerablyplaced or a fracture fragment that is markedly rotated.per radiographic interpretation often requires multiplejections, including PA, lateral, and oblique views, oftenplemented with CT scan images. When interpreting thes, the squared-off appearance of the proximal end of the

re 46 Pisiform fracture. A 30 supinated AP view demonstrates ansverse fracture (chip fracture) of the distal end of the bonerows).

re 47 Capitate fracture. (A) A Capitate (C) neck fracture is notll seen on a PA view. (B) An axial T1-weighted MR image illus-tes a low signal intensity fracture line within the capitate (arrows).In the same patient, a coronal T2-weighted MR image demon-tes high marrow signal intensity within the capitate (circle) andlevubtle high signal intensity fracture line within the waist of theitate (arrow).itate, best seen on a PA view, is the key to making theper diagnosis.24

The trapezium may fracture in various places, the verticaldy, dorsoradial tubercle, dorsoulnar tubercle, and anteriorlmar) ridge.25,26 The vertical split fracture of the body oftrapezium is associated with lateral subluxation of thet metacarpal, which remains attached to the lateral trape-l fragment. The fracture of the palmar trapezial ridge, al-ugh rare, is important to recognize as these fractures arene to nonunion27 if not promptly diagnosed and treated.e anatomy is such that a portion of the transverse carpalament attaches to this ridge and extends across the carpalnel to the hook of the hamate. In a setting of trauma, anlsion fracture of the trapezial ridge may be produced26

g. 49). Because the ridge is not well visualized on routineiographs, the diagnosis can be easily overlooked. Trape-l ridge fractures can best be seen on the carpal tunnel viewg. 49B). CT scans also are very useful in evaluation of thesectures.

rpometacarpal Injuriesatomically, the osseous structures of the wrist include theses of the metacarpals. Within the first carpometacarpalpartment of the wrist, relatively common injuries in-

de the Bennetts fracture-dislocation and Rolandos frac-e that occur at the base of the thumb metacarpal (Fig. 50).e Bennetts fracture and Rolandos fracture are two-partd three-part (or comminuted) fractures, respectively, andy are usually well recognized on radiographs. A moreallenging diagnosis is that of a beak ligament avulsion frac-e.

re 48 Scaphocapitate syndrome status post transscaphoid, tran-pitate perilunate fracture dislocation. (A) The squared-off ap-rance of the proximal end of the capitate, best seen on a PA view,he key to making the proper diagnosis of the syndrome. C itate. (B) A lateral view shows the perilunate fracture dislocationtern. The lunate (L), capitate (C), and two scaphoid fragments (S)labeled.The beak ligament avulsion fracture (Fig. 51) occurs at theel of the thumb carpometacarpal joint. At this articulation,

themeThulnligtherioguwisalmeit bstaredrad

frapu

StRaInmainthi52rotcomRaseechortrepo

Figuclecarrowlab

Figunetcle(th

Figucarmefor

Figu

266 R.A. Loredo, D.G. Sorge, and G. Garciare is a major strong ligament that connects the beak of thetacarpal base to the anterior tubercle of the trapezium.is ligament has been referred to as the anterior oblique, thear, the ulnar-volar, and the beak ligament.28 Two otheraments in the capsule include the lateral ligament beneathabductor pollicis longus tendon insertion, and the poste-r oblique ligament that is under the extensor pollicis lon-s.2 Although rare, pure dislocation of the first metacarpalthout fracture can occur. The dislocations are always dor-and the beak ligament strips subperiosteally along thetacarpal. The ligament is lax in the dislocated position, butecomes tight again if the thumb is reduced. Chronic in-bility can result if unrecognized and not treated with rigiduction (pinning) for a 6- to 8-week time interval.2 Carefuliographic examination may demonstrate the tiny avulsed

re 49 Trapezial ridge fracture. (A) A PA wrist view does notarly demonstrate the fracture of the trapezium (circle). (B) Apal tunnel view clearly illustrates a trapezial ridge fracture (ar-). The trapezium (tm), scaphoid (S), and hamate hook (h) areeled.

re 50 Fracture of the base of the thumb metacarpal. (A) A Ben-ts fracture is consistent with a two-part fracture-dislocation (cir-

). (B) A Rolandos fracture is consistent with a comminutedree-part) fracture (circle).

viesecgment(s) adjacent to the metacarpal base unless there isre ligamentous avulsion.

ress Fracture of thedial Epiphyseal Platethe skeletally immature, a stress reaction can develop pri-rily at the distal radial growth plate and to a lesser degreethe distal end of the ulna. Gymnastics is the major cause ofs injury; hence it bears the name, gymnasts wrist29 (Figs.and 53). The condition is due to chronic compression andational forces that are applied as the upper extremity be-es the weight-bearing limb during this sport activity.

diographically, the changes at the physis resemble thosen in rickets. The physeal plate shows irregularity, cysticange, and widening, consistent with a SalterHarris type III injury. There may be adjacent bone fragmentation. If notated, the condition can lead to early physeal closure andsitive ulnar variance with dysfunction of the distal radio-

re 51 Beak ligament avulsion fracture. (A) The first carpometa-pal (CMC) joint is subluxed (circle) and an adjacent bone frag-nt is seen (arrow). (B) Pinning of the first CMC joint is necessaryadequate reduction and prevention of instability.

re 52 Gymnasts wrist (SH I injury). (A) PA and (B) lateral wrist

ws demonstrate widening of the physis of the radius (arrows)ondary to chronic stress reaction in a gymnast.

ulncom

WCaalicarimformiageanprewhresturtioinsscasivins

PeModoasstaureoidresdioprostafai

ligruplun

FiguPA(arresmefra

Figuscadolinsur

Radiographic evaluation of the wrist 267ar joint and abnormalities of the triangular fibrocartilageplex.29

rist Instabilityrpal instability occurs when there is symptomatic mal-gnment between the rows of carpal bones and between thepal bones and the radius. Figuratively speaking, the prox-al carpal row is termed an intercalated segment becauseces acting on its proximal and distal articulations deter-ne its position.30 Collapse is normally prevented by link-of the proximal and the distal carpal rows by the scaphoid

d its connecting ligaments.1 When the system is com-ssed, a zigzag pattern of collapse occurs, analogous toat happens to cars in a train if the first car stops short. Theultant instability may be due to traumatic injuries (frac-es or ligamentous disruption) or to inflammatory condi-ns such as rheumatoid arthritis. When the term carpaltability was first coined, it was almost synonymous withpholunate instability. Since then, descriptions of progres-e perilunate instabilities have evolved with scapholunatetability representing the first stage of perilunate injuries.3

rilunate Dislocationst wrist injuries, including dislocations, result from forcedrsiflexion of the wrist. The resultant lesions are predictablethey are all progressive stages of the same injury pattern. Age I injury is secondary to scapholunate ligamentous fail-and dissociation with rotatory subluxation of the scaph-.16 Stage II injury is characterized by perilunar instabilityulting from capitolunate failure of the palmar ra-scaphocapitate ligament or a fracture of the radial styloidcess, leading to perilunate dislocation16 (Fig. 54). The

re 53 Gymnasts wristSH II injury of radius and ulna. (A) Aview shows mild widening of the physes of the ulna and radiusrows) with possible minimal metaphyseal sclerosis. (B) The cor-ponding coronal T2-weighted image shows high signal intensitytaphyseal bands that are consistent with stress reaction or stressctures of the radius and ulna (arrows).ge III injury results from lunotriquetral partial or completelure or avulsion of the volar and dorsal radiotriquetral

Figuwitaments.24 The final stage IV injury is associated with dis-tion of the dorsal radiocarpal ligaments, which frees theate and allows it to become volarly displaced (lunate dis-

re 54 Perilunate dislocation. (A and B) Widening of thepholunate joint (arrow) secondary to ligamentous injury andrsal perilunate dislocation (arrows) are shown. The anterior-moste depicts the lunate (L) sitting within the radial (R) articularface with the second line spanning the dorsally displaced carpus.re 55 A lateral x-ray depicts palmar lunate dislocation (arrow)h minimal dorsal tilt of the capitate (lines drawn).

locisgrescainjcujur

ScScaaccscadiscurheisotyptiemaPAAPwilatvieaticlecapananna

the

Figuwid

Figuwid(cirwitme

268 R.A. Loredo, D.G. Sorge, and G. Garciaation)16 (Fig. 55).When the perilunate dislocation patternassociated with fractures, these injuries are then calledater arc injuries as the arc of injury passes through thephoid, capitate, hamate, and/or triquetrum. The lesser arcuries affect the ligaments and joint spaces about the cir-mference of the lunate and begin with scapholunate in-y.16

apholunate (SL) Instabilitypholunate instability or scapholunate dissociation mayompany tears of the palmar radiocarpal ligaments andpholunate interosseous ligament complex. Scapholunatesociation (rotatory subluxation of the scaphoid) may oc-r as a complication of lunate or perilunate dislocation,umatoid arthritis, and other articular diseases, or as anlated injury.16 Although characteristic abnormalities areically identified on routine radiographic examination, pa-nts who are suspected of having ligamentous instabilityy require additional views. The full series may include (1)views in neutral, ulnar deviation, and radial deviation; (2)clenched fist view; (3) an oblique view; (4) lateral viewsth the wrist in neutral, flexion, and extension; and (5)eral view in neutral position with the fist clenched.1 Thews in flexion and extension and in radial and ulnar devi-on help to demonstrate the dynamics of wrist motion. Thenched-fist views compress the wrist, tending to force theitate into the space between the scaphoid and the lunate,d to rotate the scaphoid toward the palm, thus revealingy tendency for abnormal scaphoid rotation or scapholu-te separation.1,3

re 56 A PA view demonstrates marked scapholunate joint spaceening (double arrow), a foreshortened scaphoid with a ring signcle) due to palmar rotary subluxation of the scaphoid, consistenth scapholunate dissociation. Incidentally noted is first carpo-tacarpal osteoarthritis.Abnormal findings on standard radiographic views or onadditional views include the following1 (Fig. 56):

ingdef1. A wide scapholunate distance (Terry Thomas sign).Normally, the scapholunate distance is less than 2 mm.Ligamentous disruption is suggested when the distancebetween the scaphoid and lunate is greater than 2 mmand can be diagnosed almost unequivocally when thisdistance is 4 mm or more.1,16

2. Foreshortened appearance of the scaphoid. On a PAview, this appearance is due to rotation of the distalpole of the scaphoid toward the palm. In contrast to thenormal wrist, this foreshortening does not appear onulnar deviation.

3. Ring sign. This sign refers to the density produced bythe cortex of the distal pole of the scaphoid seen end-onbecause of the abnormal scaphoid rotation. Normal in-dividuals may exhibit this finding on PA views takenwith the hand in radial deviation; however, this appear-ance should not persist when the hand is in ulnar de-viation.1

4. Dorsiflexion instability. On a continuum of progressiveseverity of scapholunate injury or dissociation is theoccurrence of secondary changes such as capsular con-tracture, scaphoid and midcarpal fixation, dorsal inter-calary segment instability (DISI), scapholunate ad-vanced collapse (SLAC), and pancarpal degenerativearthritis.1,16 Radiographic findings of DISI include (1)on a PA view, overlap of the lunate and the capitate and(2) on a lateral view (Fig. 57), scapholunate angle80

re 57 A lateral view demonstrates dorsal tilt of the lunate and aened scapholunate angle to near 90 (normal 30 to 60) suggest-

disruption of the scapholunate ligament resulting in a DISIormity.

sparandisextfol

noob(scsalsicizeweintampecarcomradmephratneinsingMR

LuLutionacarpomePasymThpanothoartsiti

luntragraatieliThnotriqrup

ulntriqcaprelWstaincovstrinclunquthe

noSeqhapomispadifUlels

M

Figumavollatetra

Radiographic evaluation of the wrist 269(normal 30 to 60), lunate dorsally tilted, and scaph-oid flexed toward the palm.1,16 A wrist with SLAC has apattern of osteoarthritis, characterized by narrowing ofboth the radioscaphoid and the capitolunate spaces.1

During videofluoroscopy, widening of the scapholunatece may be demonstrated, as the wrist is observed during age of motion.30 Conventional arthrography can confirmruption of the scapholunate ligament by demonstratingension of contrast medium into the midcarpal joint spacelowing radiocarpal joint injection.CT scanning and MR imaging can be useful for the diag-sis of scapholunate dissociation. Aside from the expectedservations that can be extrapolated from radiographsapholunate gap2 mm, palmar flexion of scaphoid, dor-tilting of lunate), abnormalities of the intrinsic and extrin-components of the scapholunate ligament can be visual-d with the use of specific MR imaging parameters. T2-ighted image findings include hyperintense linear signalensity in partial or complete ligament tears, complete lig-entous disruption with a hyperintense fluid-filled gap, hy-rintense synovial fluid communication between the radio-pal and midcarpal compartments, disruption of the dorsalponent of the SL ligament, synovitis of the extrinsic volariocarpal ligaments, and degenerative perforations in thembranous (proximal) ligamentous portion. MR arthrogra-y has been successful in identification of flap tears, perfo-ion, and assessment of the integrity of the dorsal compo-nt of the SL ligament.23 With all methods of assessment fortability, caution must be exercised as improper position-of the wrist during routine radiography, CT scanning, orimaging may simulate the instability patterns.16

notriquetral Instabilitynotriquetral instability may be seen after sprain or disrup-n of the lunotriquetral interosseous ligament, with perilu-te injury, excision of the triquetrum, sprains of the mid-pal joint that attenuate the extrinsic ligaments, with ulnarsitive variance associated with degenerative lunotriquetalmbranous tears, and in patients using wheelchairs.16,23

tients with this injury usually progress from minimalptoms to ulnar wrist pain and the sensation of instability.

ey develop ulnar nerve paresthesias and eventual midcar-l instability. A similar pattern of instability is seen as armal variant in persons with ligamentous laxity and inse with various articular disorders, including rheumatoidhritis and calcium pyrophosphate dihydrate crystal depo-on disease.14

Standard radiographs may appear normal in patients withotriquetral tears or sprains and in those with lunotrique-l dissociation and dynamic instability.16 Stress radio-phs, ie, clenched-fist AP view in pronation or ulnar devi-on or the clenched-fist lateral view, may be necessary tocit the abnormality in patients with dynamic instability.e abnormalities encountered include disruption of thermal smooth convexity of the proximal carpal rowwith the

uetrum displaced proximally on the AP radiograph. Dis-tion of the normal arc is particularly pronounced with

Inresar deviation, producing overlapping of the lunate anduetrum.31 On the lateral view, the lunate is tilted volarly,itate directed dorsally, and the triquetrum dorsiflexed ination to the lunate compared with the other wrist.1,18,31

ith progressive instability, volar intercalated segmental in-bility (VISI) deformity occurs and radiographic findingslude the following: (1) PA views show that the lunateerlaps the capitate and (2) lateral views (Fig. 58) demon-ate a scapholunate angle 30 (normal 30 to 60),reased capitolunate angle to 30 (normal 0 to 30),ate tilted volarly, capitate directed dorsally, and the tri-etrum dorsiflexed in relation to the lunate compared withother wrist.1,16,30

Standard arthrography is probably the most helpful diag-stic aid in the evaluation of lunotriquetral tears30 (sprains).uential injection of the midcarpal and radiocarpal spacess been shown to be the best method of evaluation.16 Asitive study demonstrates communication between thedcarpal and radiocarpal joints through the lunotriquetralce. Patients with isolated lunotriquetral tears need to beferentiated from those with ulnar impaction syndrome.nar impaction syndrome is discussed more extensivelyewhere in this writing.

idcarpal InstabilityIntrinsic to Carpus

re 58 A lateral view demonstrates capitolunate angle30 (nor-l 0 to 30), lunate tilted volarly, capitate directed dorsally,ar tilting of the lunate most consistent with a VISI (volar interca-d segment instability) often due to disruption of the lunotrique-l ligament.midcarpal instability, laxity of certain carpal ligamentsults in lack of support for the proximal carpal row and

mijoirowulnmi(RLinowulntiotoincapthesnacliatefistprestrby

napaenionanPMAwhdisne

condetraaninsviafortralunpoattintscavitarmradconval

nathemohawrlig

itathetur

MExsaltheuncaprelulnallradsalthewi

RaAltchputhecomlatbe

ingresorbilassThartthe

oringalldisfeastyslidthaShrad

DiAnpaagaradagntiv

270 R.A. Loredo, D.G. Sorge, and G. Garciadcarpal joint, which in turn leads to a loss of the normalnt reactive forces between the proximal and distal carpals. The proposed etiology is injury toor laxity ofthear arm of the arcuate ligament (a major stabilizer of thedcarpal joint) and laxity of the dorsal radiolunotriquetralT) ligament.32 A dynamic flexion deformity (VISI) occursthe proximal row as the distal row translates palmarlying to the lax ligament. As the wrist moves from radial toar deviation, there is no longer the normal coupled rota-n of the carpus and smooth transition from flexion (VISI)extension (DISI). Instead, the proximal row remains flexeda VISI-like pattern for a period with the head of theitate [subluxed] volarly into the space of Poirier.32,33 Asdistal row/capitate abruptly reduces, the proximal rowps into extension in a DISI-like pattern creating thenical finding called the catch-up clunk. This is accentu-d by increasing the load on the capitolunate joint when theis clenched and relieved by either splints which applyssure in a dorsal direction to the pisiform or by surgery toengthen the volar arcuate ligament and dorsal ligaments orfusion of the lunate-triquetrum-capitate-hamate bones.33

The dynamic pattern of instability described above ismed palmar midcarpal instability (PMCI) because of thelmar translation of the distal row. In earlier reports, thistity was termed ulnar midcarpal instability.34 Dorsiflex-injury, compression, rotation, and distraction injuries

d ulnar minus variance have been associated with PMCI.35

CI is the most common pattern of midcarpal instability.36

much less common variant of midcarpal instability, inich the proximal carpal row is extended (DISI) and thetal carpal row is subluxed dorsally when the wrist is inutral, is termed dorsal midcarpal instability (DMCI).32

The radiographs may be normal as PMCI is a dynamicdition. Lateral radiographs in neutral, radial, and ulnar

viation may demonstrate VISI deformity and mild palmarnslation of the distal carpal row. Videofluoroscopy in PAd lateral planes may show the dynamic palmar flexiontability (VISI) with wrist motions from radial to ulnar de-tion.32 CT scan and MR image findings include VISI de-mity with volar tilt of the scaphoid and the lunate, palmarnslocation of the distal row, sclerosis between the distalate and proximal capitate, and dorsal tilting of the distalle of the capitate. The T2-weighted MR images show anenuated or disrupted lunotriquetral ligament with hyper-ense fluid extending across the lunotriquetral (LT) orpholunate (SL) interval. There may be hyperintense syno-is versus ligament attenuation associated with the ulnarof the arcuate ligament and the dorsal radiotriquetral (or

iolunotriquetral) ligament. MR arthrography will showtrast directly communicating across the SL or LT inter-.32

The natural history of midcarpal instability is that the dy-mic instability becomes a fixed VISI deformity with loss ofnormal physiologic VISI to DISI wrist motion with wristtion from radial to ulnar deviation. Louis and associates37

ve described the capitolunate instability pattern (CLIP

ist) where there is laxity of the palmar radioscaphocapitateament in patients in whom dorsal subluxation of the cap-

motrate on the lunate and the scaphoid on the scaphoid fossa ofradius could be demonstrated. These patients have fea-es similar to those of patients with DMCI.17

idcarpal InstabilityExtrinsic to Carpustrinsic midcarpal instability is often associated with rever-of the normal volar tilt of the distal articulating surface ofradius. This is most often observed in patients with mal-ion of a distal radial fracture. Subsequently, the lunate anditate are tilted dorsally; however, theymaintain a collinearationship with each other on neutral lateral views. Withar deviation, the capitate rotates volarly and becomes par-el and slightly dorsally displaced, relative to the shaft of theius on the lateral view. However, the lunate remains dor-ly tilted. The inability of the lunate to rotate volarly withcapitate is thought to cause the pain and clunk associated

th extrinsic midcarpal instability.32

diocarpal or Proximal Carpal Instabilitieshough a rare occurrence, proximal carpal instabilities arearacterized by subluxation or dislocation of the entire car-s in a dorsal, palmar, ulnar, or radial direction relative todistal radius. Dorsal and palmar instabilities are mostmonly related to trauma and ulnar dislocations are re-

ed to ligamentous laxity. Radial translocations have noten reported.32

Dorsal carpal instabilities may appear as an isolated find-or in association with Colles or Bartons fractures, whichult in either dorsal tilt of the distal radial articular surfacedorsal displacement of the dorsal lip. Palmar carpal insta-ities are less common, as one might expect, given theirociation with the rare palmar or reverse Bartons fracture.is results in increased palmar tilt or displacement of theicular surface. Both are treated with osteotomy to correctmalalignment.18,38

Ulnar carpal instabilities are generally from capsular injuryany type of synovitis, such as rheumatoid arthritis result-in weakening and laxity of the extrinsic ligaments.32 This

ows the carpus to migrate down the inclined plane of thetal radius in an ulnar direction33 (Fig. 59). A diagnosticture is an abnormally wide space between the radialloid process and the scaphoid29 as the carpus begins toe ulnarly along the radius. The scapholunate angle is lessn 30. PA views show that the lunate overlaps the capitate.ift of the entire carpus dorsal to the midpoint of the distalial articular surface is seen.1

stal Radioulnar Joint Instabilityatomically, in full supination, the ulnar head rests on thelmar aspect of the notch, and in full pronation, it restsinst the dorsal lip of the notch.2 Acute injuries of the distalioulnar joint (DRUJ) frequently go undiagnosed or misdi-osed. Early recognition of DRUJ injury is crucial to effec-e treatment because chronic DRUJ conditions are much

re difficult to manage.39 Injuries to the DRUJ can involveuma to the bone, joint, and the surrounding soft tissues.

DRDRwebolocarmducomofradnifihaartdisfreconverdisDRlocintdistalradareabthedis

60sty

PAtheofcatmetecbeshiontinandisanno

noornatom

Figuvieabning

Figuenitio

Radiographic evaluation of the wrist 271UJ Dislocation/SubluxationUJ dislocations have been reported as isolated injuries asll as with Galleazzi fractures, Essex-Lopresti injuries, bothne forearm fractures, distal radius fractures, fracture-dis-ation of the elbow, and in plastic deformation of the fore-.39 DRUJ dislocation can be categorized as simple (re-

ces spontaneously or with minimal manipulation), orplex (irreducible, incomplete reduction, or interposition

soft tissue or bone). Isolated dislocations of the inferiorioulnar joint are uncommon, usually resulting from sig-cant rotatory force applied to the forearm about a fixednd, as in a fall or twisting injury. At the distal radioulnariculation, dislocations of the ulna most often occur in atal, dorsal, and medial direction; volar dislocation is lessquent.16 Most dislocations of this articulation occur injunction with Galeazzi fractures, short oblique, or trans-se fractures that occur at the junction of the middle andtal third of the radius accompanied by dislocation of theUJ. An Essex-Lopresti injury is a fracture or fracture-dis-ation of the radial head associated with disruption of theerosseous membrane between the radius and ulna andlocation of the DRUJ.40 DRUJ injuries also occur with dis-radius fractures. Poor results following treatment of distalius fractures with symptoms at the distal radioulnar jointtypically from chronic disruption of the TFCC, ulnar

utment due to radial shortening, posttraumatic arthritis ofdistal radioulnar joint, and/or persistent instability or

location of the DRUJ.39

Radiographic findings of distal radioulnar dislocation (Fig.

re 59 A coronal T1-weighted MR image with scapholunate wid-ng, proximal migration of the capitate (C), and ulnar transloca-n of the carpus.) include (1) abnormal rotation of the ulna with the ulnarloid overlying the central portion of the distal ulna on the

tisstenradiograph; (2) widening of the radioulnar distance onPA view in ulna dorsal dislocations; (3) superimpositionthe radius and ulna on the PA view in ulna ventral dislo-ions; and (4) posterior or anterior (less common) displace-nt of the ulna on lateral radiographs.27 Unfortunately, de-tion of subluxation on radiographs may be quite difficultcause slight variations in wrist position alter the relation-p of the radius and ulna. Because of the difficulty in dem-strating the anatomy of the distal radioulnar joint on rou-e radiographs, the associated complex injuries that occur,d the infrequent occurrence of isolated subluxations orlocations, CT of the bilateral wrists in neutral, pronated,d supinated positions may be utilized to confirm the diag-sis.46

Due to the fact that DRUJ dislocation or subluxation mayt occur until the patient reaches the extremes of pronationsupination, most institutions study the DRUJ in full pro-tion, neutral position, and in full supination. The asymp-atic wrist is included in the same positions.5 On transax-

re 60 Distal radioulnar joint (DRUJ) dorsal dislocation. A PAw demonstrates widening of the radioulnar distance (diamond),ormal rotation of the ulna with the ulnar styloid (arrow) overly-the central portion of the distal ulna. Incidentally noted is soft-

ue calcification in the expected location of the flex carpi ulnarisdon (asterisk).

ialevaThlinmeradtheconlindorecmepecenrotlineresig61assadtur

canthecomthe

conatepelag

TrPaasforTFhoTFthe

Figu(A)shotiocenrotsigmowit

Figuim(arguldis

Tab

Cl

Cl

Tra

272 R.A. Loredo, D.G. Sorge, and G. Garciaimages, there are methods of objective CT or MRluation of the position of the ulna relative to the radius.e methods (Fig. 61) require construction of a number ofes that are drawn along the radius and ulna. In onethod, a line is drawn through the dorsoulnar and dorso-ial aspects of the radius and another line is drawn throughpalmoulnar and palmoradial aspects of the radius; thegruent ulnar head should lie between these two divergentes5,46 (Fig. 61A). If the ulnar head crosses the respectiversal or palmar line, subluxation in a dorsal or palmar di-tion is diagnosed. Another method is the epicenterthod.41 In this method, with the DRUJ in supination, arpendicular line is drawn from the midpoint between theter of the ulnar head and the ulnar styloid (center of DRUJation) to the chord of the sigmoid notch (Fig. 61B). If thise is in the center of the sigmoid notch, the joint is consid-d congruous.5 With the arm in pronation, the arcs of themoid notch and the ulnar head should be congruous (Fig.C). CT and MR imaging share diagnostic advantages inessment of this joint. However, MR imaging has the addedvantage of evaluation of the surrounding soft-tissue struc-es.In equivocal cases, arthrography of the radiocarpal jointbe helpful in establishing the diagnosis, as disruption ofinferior radioulnar joint requires injury to one or more

re 61 Objective methods of evaluation of normal DRUJ on CT.With the forearm in neutral rotation, the congruent ulnar headuld lie between the two divergent lines drawn.46 (B) In supina-n, a perpendicular line drawn from the midpoint between theter of the ulnar head and the ulnar styloid (center of DRUJation) to the chord of the sigmoid notch falls in the center of themoid notch. (C) With the arm in pronation, the arcs of the sig-id notch and the ulnar head should be congruous. (Reprintedh permission.5)ponents of the TFCC, the major stabilizing structure ofdistal portion of the ulna.16 On arthrographic images,trast opacification of the radiocarpal joint will be associ-d with filling of the inferior radioulnar joint as a result ofrforation or detachment of the intervening articular carti-e (Fig. 62).

iangular Fibrocartilage Complex Tearsthologic conditions affecting the TFCC can be categorizedtraumatic or degenerative and Palmer has devised a systemcategorizing the abnormalities42 (Table 1). Lesions of theCC are variable in location; they may be confined to therizontal, or flat, portion of the TFCC (referred to as theC or articular disc) or involve one or more components ofTFCC with or without instability of the distal radioulnar

re 62 A coronal T1-weighted fat suppressed postgadoliniumMRage following radiocarpal contrast injection demonstrating a tearrow) just ulnar to the cartilaginous attachment of the TFC (trian-ar fibro-cartilage) onto the radius with contrast spilling into thetal radioulnar joint from a radiocarpal injection.

le 1 Palmer Classification of TFCC Abnormalities42

ass 1. TraumaticA. Central perforationB. Ulnar avulsionC. Distal avulsionD. Radial avulsionass 2. Degenerative (ulnocarpal abutment syndrome)A. TFCC wearB. TFCC wear (lunate /or ulnar chondromalacia)C. TFCC perforation (lunate /or ulnar chondromalacia)D. TFCC perforation (chondromalacia lunotriquetral

ligament perforation)E. TFCC perforation (chondromalacia, ligament

perforation, ulnocarpal arthritis)

umatic and degenerative TFCC abnormalities/tears exist and are

listed according to the most often used classification systemdescribed by Palmer.42

joitharesstuappe

noarepoasssiosite

is wgarNonodismaradofFigthestrresTFateartere

UlThmesynloa

ofttoulnThheingciaintalmitivmaofthewiwi

najoichqumeadwrchVidtrupuonuln

Figuchapro(se

Figustratheme

Radiographic evaluation of the wrist 273nt.2 Degenerative lesions of the TFCC are more commonn traumatic lesions and are thought of as chronic injuriesulting from load on the ulnar side of the wrist. Anatomicdies have shown that perforation of the TFCC occurs inproximately one-third to one-half of cadaveric specimens,rhaps due to degenerative changes.1

Radiography is not useful in characterization of TFCC ab-rmalities. However, there are radiographic findings thatassociated with abnormalities of the