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Upper 3 The

Donald Sammut Surgeon

Kings plus lecture notes

• Unlike'many'other','the'wrist'surface'anatomy'gives'away'little'of' the'bony'structures'beneath'the'surface.'

• Still'less'does'it'suggest'the'complex''structures' Carpus'

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• The'wrist'is'surrounded'by'vital'structures,',','.''

• Pathology'in'these'structures'can'give'symptoms'mistaken'for'problems' with'the'wrist''

• 8'wrist''form'the'carpus.'

• Proximally'these'articulate'with'the'' • Distally'they'articulate'with'the'metacarpals.'

• The'carpal'bones'articulate'with'each'other'in'a'particular'configuration'of' bony'shapes'and''which'dictate'the'complex'function.' Trapezoid' Capitate' ' Hamate'

Scaphoid' Pisiform' Lunate' Triquetral' • Proximally'the'carpus'articulates'with'the'distal'radius'and'with'the' triangular'fibrocartilage.'

• The'TFC'separates'the'carpus'from'the'ulna'

• The'distal'ulna'does'not'participate'in'the'articulation'with'the'carpus'

• View'of'the'distal'radius.'Proximal'aspect'of'the'RadioKcarpal'joint'

• Note'' 'the'Scaphoid'fossa'

'the'Lunate'fossa'

'the'triangular'fibrocartilage'

PROXIMAL)ARTICULAR)SURFACE)OF)THE)WRIST:)RADIUS'AND'TRIANGULAR'CARTILAGE' ' THE'ULNA'IS'EXCLUDED.' • Distal'aspect'of'the'RadioKcarpal'joint'

The'radius'and'triangular'fibrocartilage'articulate'with'the'scaphoid,'lunate' and'triquetral' DISTAL)ARTICULAR)SURFACE)OF)THE)WRIST:)SCAPHOID,'LUNATE','TRIQUETRAL' ' • The'bony'shapes'of'the'radiocarpal'joint'make'for'an'unstable'arrangement' • There'are'no'bony'confines'(as'in'the')'to'give'the'joint'stability' • Much'stability'is'conferred'by'the'surrounding'ligaments'and'tendons'

Note' • For$any$joint,$stability$is$in$inverse$proportion$to$mobility.$The$more$mobile$the$ joint,$the$less$stable$it$is$and$the$more$it$relies$on$soft$tissue$for$stability.$ • Compare$$and$hip.$The$shoulder$has$a$wide$arc$of$movement,$the$hip$ less.$The$shoulder$is$regularly$dislocated$in$contact$sports,$the$hip$is$rarely$ dislocated.$The$shoulder$requires$the$support$of$the$rotator$cuff$for$its$stability$

• On'the'ulnar'side,'ligaments'front'and'back'produce'a'cup'shape,'overall''

• The'triangular'fibrocartilage'forms'the'base'of'this'cup' • The'whole'arrangement'is'called'the'TFCC:'Triangular'Fibrocartilaginous' Complex'

• This'complex'cups'the'ulnar'part'of'the'carpus' TFCC' Triangular' FibroKCartilaginous' Complex' MOVEMENTS'OF'THE'WRIST:'

• Flexion'and'Extension' • Radial'Abduction'

• Ulnar'Abduction'

• Pronation'and'supination'enormously'increases'the'versatility'of'the' wrist.'This'movement'occurs'at'the'Distal'and'Proximal'radioKUlnar'joints' and'not'at'the'wrist.' Wrist'Flexion' Wrist'Extension'

85°' 85°'

Plus' Pronation'and'Supination'' at'DRUJ'

Radial'Abduction'''''''''''''''Ulnar'Abduction' • The'commonest'composite'movement'of'the'wrist:'

• DorsoKRadial'to'PalmarKUlnar' '(The'DartKThrowing'movement)' Ulnar'Deviation'' and' Flexion'

Radial'Deviation'' and'' Extension' The'SCAPHOID'

• Largest''in'the'proximal'carpus' • At'an'angle'to'the'axis'of'the'radius'(average'73°)'

• The'obliquity'may'explain'its'vulnerability'to'injury'

• 80%'covered'in'articular'cartilage'

• A'palpable'bony'prominence'on'the'palmar'surface'is'called'the'Tubercle' of'the'Scaphoid.'The'Flexor'Carpi'Radialis'curves'over'it'into'the'palm'

• THE'SCAPHOID''

• Commonest'carpal'bone'to'fracture' • Vulnerable'in'landing'on'the'outstretched'hand'

• Notoriously'difficult'to'diagnose.'The'fracture'is'often'not'visible'on'first' Xray'

• 80%'of'its'blood'supply'comes'through'the'arrowed'middle'segment,'the' .''

• This'may'deprive'the'proximal'part'of'the''bone'of'blood'when'the'waist'is' fractured.'This'may'lead'to'AVASCULAR'NECROSIS'of'the'proximal'pole'

Scaphoid:'Gr.$skaphos$='boat' 80% surface - articular cartilage 80% blood supply – waist of scaphoid Proximal pole fracture Avascular necrosis of proximal pole

The'LUNATE'

• So'named'because'of'its'half'moon'shape'on'lateral'Xray' • The'Keystone'of'the'carpus'

• Important'ligamentous'links'to'scaphoid'and'triquetral' Palmar' Dorsal'

Lunate'

The'TRIQUETRAL'

• Completes'the'proximal'carpal'row'' • Articulates'with'the'triangular'fibrocartilage'

• Carries'the'Pisiform'on'the'palmar'surface' Palmar' Dorsal'

Triquetral' The'PISIFORM'

• Not'a'true'Carpal'bone'–'a'sesamoid'for'distal'insertion'of'Flexor'Carpi' Ulnaris'

• The'PisoKhamate'and'PisoKmetacarpal'ligaments'give'the'FCU'strong' insertion'into'the'entire'ulnar'half'of'the'carpus.' Palmar' Dorsal'

Pisiform' Insertion'of'Flexor'Carpi'Ulnaris'

PisoKHamate' PisoKMetacarpal' Ligament' Ligament' The'TRAPEZIUM'

• The'most'mobile'of'the'distal'carpal'row' • Distal'surface'the'saddle'shaped'CarpoKmetacarpal'joint'with'the'' metacarpal'

• On'the'palmar'surface'has'a'ridge'(the'Trapezial'ridge)'beneath'which'the' Flexor'carpi'radialis'courses'on'its'way'to'insertion'into'the'bases'of' Metacarpal'2'and'3.' Palmar' Dorsal'

Trapezium'

The'TRAPEZOID'

• Smallest'bone'of'the'distal'carpal'row' • Trapezoidal'in'shape'and'wedged'in'between'Trapezium''and'Capitate' wider'on'the'dorsum'and'narrower'on'the'palmar'surface.' Palmar' Dorsal'

Trapezoid' The'CAPITATE'

• Largest'bone'of'the'carpus' • Important'insertion'point'for'a'number'of'stabilising'ligaments.'

• The'proximal'part'is'called'the'Head'of'the'Capitate'and'articulates'with'a' deep'concavity'formed'by'scaphoid'and'lunate,'in'the'midcarpal'joint.' Palmar' Dorsal'

Capitate' The'HAMATE'

• So'called'because'of'the'prominent'Hamulus'(hook)'on'the'palmar'aspect' • This'hamulus'receives'insertion'of'the'flexor'retinaculum'and'the'pisoK hamate'ligament'

• The'flexor'tendons'to'the'little'finger'change'angle'around'the'Hook'of' the'hamate' Palmar' Dorsal'

Hamate'

Three'levels'of'joints'in'the'wrist'

• CarpoKMetacarpal'Joints:'Between'carpus'and'metacarpals' • MidKcarpal'joint:'between'proximal'and'distal'carpal'rows'

• RadioKCarpal'Joint:'between'Radius'and'proximal'carpal'row' CarpoKMetacarpal' 'Joints'

MidKCarpal'Joint'

RadioKCarpal'Joint' The'8'Carpal'bones'are'organised'in'two'rows:'

• PROXIMAL'CARPAL'ROW:'Sacphoid,'Lunate,'Triquetral'(+pisiform)'

• DISTAL'CARPAL'ROW:'Trapezium,'Trapezoid,'Capitate,'Hamate' Proximal Carpal Row Distal Carpal row Mid Carpal Joint

Radio Carpal Joint • The'carpus'is'more'proximal'than'the'surface'anatomy'might'suggest'

• There'are'two'creases'on'the'palmar'surface'of'the'wrist.' • The'proximal'crease'coincides'with'the'Radio'Carpal'Joint' Proximal'' Wrist'' crease' • The'(palpable)'four'bony'landmarks'of'attachment'of'the'flexor' retinaculum'

Radial:' ' 'The'ridge'of'trapezium' ''The'tubercle'of'the'scaphoid''

Ulnar: ' 'The'hook'of'the'hamate'

''The'Pisiform'

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' ' The'Pisiform' Ridge of Hook of trapezium Hamate

Pisiform Tubercle of scaphoid • The'strong'Flexor'Retinaculum'holds'the'columns'of'the'concave'carpus'

• Division'of'the'Flexor'Retinaculum,'as'in'carpal'tunnel'release,'causes' surprisingly'little'functional'impairment'(the'Flexor'retinaculum'rapidly' reforms)'

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• The'carpal'bones'are,'as'a'group,'concave'on'the'palmar'aspect.'

• The'rest'of'the'hand'reflects'this'concavity' • Most'hand'function'involves'the'palm'and'the'digits'curving'around'an' object'and'this'concavity'forms'the'basis'of'function.'

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• Cross'section'of'the'palm'also'shows'this'palmar'concavity'and'dorsal' convexity'

• This'means'that'the'extensors'are'spread'over'a'wide'area'on'the'back'of' the'carpus'and'need'to'be'held'in'separate'compartments'to'maintain' alignment'

• The'flexors'are'bunched'up'inside'the'carpal'tunnel'and'need'no'such' separation'

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IV III V II VI I • The'flexor'retinaculum'is'much'shorter'than'the'Extensor'retinaculum'as'a' result'of'the'carpal'concavity'towards'the'palm'

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' Dorsal Palmar

Xrays'of'the'wrist' • Xrays'of'the'wrist'present,'on'superficial'examination,'complex'bony' shapes'superimposed'on'each'other'

• It'is'not'difficult'to'follow'each'bony'outline'and'analyse'the'Xray' appearance.'

• The'distal'Carpal'row'and'the'proximal'Carpal'rows'are'easy'to'make'out'

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Distal'Carpal'Row' Proximal'Carpal'Row' • Gilula’s'Lines'are'a'useful'quick'check'of'alignment'or'loss'of'normal' relations'

• These'radiological'arcs'most'be'followed'to'detect'any'step'or' interruption'

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' ' Gilula’s'Lines'(Radiological'Arcs'of'the'wrist)'

• The'ulnar'tilt'of'the'radius'can'be'checked'on'the'PA'view'

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' Ulnar'Tilt'

20-25° • The'true'lateral'of'the'wrist'shows'the'tip'of'the'radial'styloid' superimposed'on'the'centre'of'the'lunate' this'view'also'shows'the'volar'tilt'of'the'radius'

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Volar'Tilt'

10 - 15° • The'axis'of'the'scaphoid'is'drawn'bisecting'the'scaphoid'

• The'axis'of'the'lunate'is'obtained'by'joining'the'tips'of'the'two'peaks'of' the'lunate'on'lateral'view'and'drawing'a'line'at'90°'to'this.'

• The'angle'between'Lunate'and'scaphoid'is'a'good'guide'to'the'integrity' of'the'scaphoKlunate'ligament'(see'later)'

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' ' Axis'of'' Scaphoid' Axis'of'' Lunate' Scapho'Lunate' Angle:'avge'47°' (30'K60)'

• The'ligaments'that'clothe'the'carpus'are'not'immediately'visible'even'on' removal'of'the'covering'tendons.''

• They'are'covered'by'a'thin'fibrofatty'film'which'must'be'removed'before' the'orientation'of'ligament'fibres'is'seen'

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Intrinsic'Ligaments' ' Carpal'bone'to'Carpal'bone' Carpal'bone'to'Metacarpal' ' ' ' ' Extrinsic'Ligaments' ' Radius/Ulna'to'Carpus'' Intrinsic ligaments

Extrinsic Ligaments • The'extrinsic'Ligaments''(from'radius'and'Ulna'to'Carpus)'seem' bewildering'and'complex'but'there'is'a'logic'to'their'orientation'

• The'key'is'the'Ulnar'tilt'of'the'radius.'

• The'carpus'has'a'tendency'to'slide'in'an'ulnar'direction'

• All'major'intrinsic'ligaments'are'orientated'to'prevent'this'slide'

• They'slant'from'proximal'radius'to'ulnar'carpus'

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' Ulnar Tilt 20 - 25°

Radioscaphoid Radioscaphocapitate

Long RadioLunate

Short Radio Lunate Radio Triquetral • The'same'reason'for'the'orientation'of'extrinsic'ligaments'applies'dorsally'

• There'is'only'one'major'extrinsic'ligament:'The'Dorsal'RadioKCarpal' Ligament'

• This'slants'across'the'back'of'the'carpus'connecting'radius'to'the'back'of' Triquetral.'Again,'this'resists'the'tendency'of'the'carpus'to'slide'in'an' ulnar'direction.'

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Dorsal intercarpal (intrinsic) Dorsal Radio Carpal (extrinsic) • The'long'tendons'that'insert'into'the'carpus'and'the'bases'of'the' metacarpals'perform'a'vital'role'in'the'stability'of'the'wrist.'

• At'the'moment'of'impact'of'a'fist'with'a'solid'surface,'all'of'these'tendons' are'taut.''

• This'tension'of'‘guy'ropes’'all'around'the'wrist'stabilises'and'protects'it' from'dislocation'or'ligament'tear.'

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' ' ECRL ECRB

APL FCR

FCU ECU ECRL ECRB

APL FCR

FCU ECU • Note'that'all'tendons'that'leave'the''and'travel'into'the'hand' BYPASS'the'proximal'Carpal'row.''

• NO''inserts'into'the'Proximal'Carpal'row.'

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• Laxity'of'the'extrinsic'ligaments'of'the'carpus'produces'MIDKCARPAL' INSTABILTY,'a'possible'source'of'pain'

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' Mid'Carpal'Instability' Wrist biomechanics • The'Proximal'carpal'row'is'knows'as'an'INTERCALATED'SEGMENT'

• It'is'intercalated'between'the'distal'carpal'row'and'the'radius'

• It'receives'NO'tendon'insertion'but'moves'passively'in'response'to' movement'distal'and'proximal'to'it.'

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' ' Proximal'Carpal'Row'=' ' INTERCALATED'SEGMENT' APL ECRL/B FCU FCR ECU

• The'key'aspects'of'Wrist'Biomechanics'

1.'The'proximal'Carpal'row'is'not'moved'directly'by'any'tendon'

2.'No'tendon'inserts'into'the'proximal'carpal'row'

3.'The'proximal'carpal'row'confirms'to'the'changing'shapes'around'it'(distal' 'carpal'row'and'radius)'

4.'It'acts'as'a'variable'shaped'filler'that'changes'shape'so'as'to'maintain' 'maximum'bony'contact'in'all'positions.'

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' PROXIMAL)CARPAL)ROW) ' A'VARIABLE'SHAPE'' STRUCTURE' THAT'MAINTAINS'' MAXIMUM'BONY' CONTACT'IN'ALL'POSITIONS'

• The'proximal'carpal'bones'act'as'a'‘springKloaded’'group'

• The'ligaments'and'shape'dictate'that':'

1.'The'Scaphoid'is'constantly'tending'to'flex'

2.'The'Triquetral'is'constantly'tending'to'extend'

3.'The'Lunate'follows'whichever'of'its'neighbours'is'prevailing'

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Lunate Scaphoid Triquetral Extension/'dorsal'

Flexion/ palmar Radial Abduction: Ulnar abduction: Scaphoid Flexion/ Triquetral Extension/ Triquetral follows Scaphoid follows • In'Radial'abduction,'the'Scaphoid'flexes:'The''Lunate'and'Triquetral'follow'

• In'Ulnar'abduction,'the'Triquetral'extends:'The'Lunate'and'Scaphoid' follow'

• This'alteration'in'shape'is'easily'visible'on'Xray'

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Scaphoid'flexed' Scaphoid'extended'

• This'‘spring'loaded’'arrangement'can'only'work'if'the'three'proximal' carpal'row'bones'are'linked'together.'

• There'are'strong'intercarpal'ligaments'which'are'essential'to'function:'

• ScaphoKlunate'ligament'links'Scaphoid'and'lunate'

• LunoKTriquetral'Ligament'links'lunate'to'Triquetral'

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Scapholunate Lunotriquetral • A'tear'of'the'ScaphoKlunate'ligament'(partial'or'complete)''may'follow'a' Fall'on'to'the'Outstretched'hand'(often'seen'in'Emergency'records'as' FOOSH)'

• This'is'easily'missed'and'the'absence'of'visible'fracture'is'falsely' reassuring.'

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• The'scaphoid'is'normally'flexed'I'Radial'abduction'

• If'it'is'flexed'in'the'neutral'position'of'the'wrist,'this'is'abnormal'and' suggestive'of'a'scaphKlunate'tear.'

• The'scaphoid'is'seen'end'on,'in'the'Xray.'The'tubercle'gives'it'a'‘signet' ring'appearance’'

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Signet'Ring'sign'(flexed'Scaphoid)' • The'loss'of'integrity'of'the'scaphoKlunate'ligament'drives'scaphoid'and' lunate'apart'

• The'scapho'lunate'gap'widens' • This'is'known'as'the'Terry$Thomas$sign$after'a'film'star'of'the'1950’s' famous'for'his'gapKtoothed'grin'

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The'Terry'Thomas'Sign'

Terry Thomas Lara'Stone'

Diastema$(gap$in$front$teeth)$ Georgia'Jagger' In'scapho'lunate'instability:'

'The'scaphoid'soon'becomes'fixed'in'Flexion;'' 'The'lunate'and'the'Triquetral'fix'in'extension.''

'The'scapholunate'angle,'measureable'on'lateral'Xray,'increases' 'beyond'normal'range'

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In'Luno'triquetral'Instability'(less'common)'

'The'Scaphoid'and'lunate'fix'in'flexion'and'the'Triquetral'fixes'in' 'extension'

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• Why'does'it'matter'if'the'proximal'carpal'row'loses' this'ability'to'conform'to'altered'shapes?'

• The'proximal'carpal'row'and'the'distal'radius'have'been'likened'to'two' conforming'spoons'

• If'their'axes'do'not'conform,'the'incongruous'shapes'will'develop'wear,' inflammation'and'eventual'deterioration'of'the'joint.'This'affects'first'the' Radio'Carpal'joint'and'later'the'midcarpal'joint'

• This'is'known'as'SLAC':'Scapholunate$Advanced$Collapse$

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SLAC'1' SLAC'2' SLAC'3' The'Thumb'' CarpoKMetacarpal'joint'

The'saddle'shaped'thumb'carpoKmetacarpal'joint'is'set'at'an'angle'to'the' axis'of'the'hand'

This'is'an'essential'feature'that'enables'the'thumb'to'stand'away'from'the' plane'of'the'digits'

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• The'slope'of'the'joint'surface'produces'a'radial'vector'when'force'is' applied'to'the'thumb'column'

• The'thumb'metacarpal'thus'tends'to'slide'down'the'slope' '

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• The'strongest'ligament'in'this'joint'is'on'the'ulnar'side,'countering'the' tendency'of'the'metacarpal'to'slide'off'the'surface.'This'is'called'the'Volar' Beak'ligament'(the'ulnar'base'of'the'metacarpal'is'beakKshaped)'

• This'is'comparable'to'the'orientation'of'the'strongest'extrinsic'ligaments' in'the'carpus'(see'above).'

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' ' Volar'' Beak'Ligament'

• The'continuity'of'Carpus,'beak'ligament'and'metacarpal'is'crucial.''

• If'this'is'interrupted,'as'in'a'Bennett’s'fracture,'the'structure'becomes' unstable'

• Treatment'aims'at'restoring'this'continuity'

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' ' Bennett'Fracture'

'of'the'basal'joint'of'the'thumb'is'common'since'the'thumb'takes' so'much'pressure'and'counters'four'long'digits'

• Wear'of'the'joint'surface'sets'up'inflammation' • This'loosens'the'beak'ligament'

• The'joint'becomes'incongruous'and'a'self'reinforcing'cycle'of'wear'sets' up.'

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• Clinically,'the'metacarpal'of'the'thumb'is'seen'to'slide'down'the' trapezium'

• The'1st'web'space'narrows'and'the'Metacarpo'phalangeal'joint'goes'into' compensatory'extension'

• This'is'known'as'the'Z'deformity'of'the'thumb'

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' ' arthritic''at'rest.jpg'

• Deterioration'of'this'basal'joint'is'treated'by'trapeziectomy'

• The'trapezium'is'removed'and'a'tendon'is'often'interposed'between' metacarpal'and'scaphoid.'

• The'removal'of'grating'bone'surfaces'relieves'pain.'

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• Osteoarthritis'of'the'base'joint'of'the'thumb'may'also'present'with' symptoms'of'carpal'tunnel'syndrome'

• This'is'because'the'trapezium'is'one'of'the'columns'of'the'carpal'tunnel' • The'median''curves'around'it'before'giving'off'its'terminal'branches.'

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• On'the'ulnar'side'of'the'wrist,'the'pisiform'is'the'‘landing'pad’'when'the' hand'places'on'a'flat'surface.''

• Pisotriquetral'arthritis'is'common' • First'line'treatment'is'injection'with'steroids'usually'under'Xray'control'

• Resistant'cases'may'require'removal'of'the'pisiform.'

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