Download Kings Wrist - Donald Sammut

Upper Limb 3
The Wrist
Donald Sammut
Hand Surgeon
Kings Upper Limb Anatomy
plus lecture notes
•  Unlike'many'other'joints,'the'wrist'surface'anatomy'gives'away'little'of'
the'bony'structures'beneath'the'surface.'
•  Still'less'does'it'suggest'the'complex'ligament'structures'
Carpus'
Radius'
Ulna'
•  The'wrist'is'surrounded'by'vital'structures,'tendons,'nerves,'arteries.''
•  Pathology'in'these'structures'can'give'symptoms'mistaken'for'problems'
with'the'wrist'joint'
•  8'wrist'bones'form'the'carpus.'
•  Proximally'these'articulate'with'the'radius'
•  Distally'they'articulate'with'the'metacarpals.'
•  The'carpal'bones'articulate'with'each'other'in'a'particular'configuration'of'
bony'shapes'and'ligaments'which'dictate'the'complex'function.'
Trapezoid'
Trapezium'
Scaphoid'
Lunate'
Capitate'
Hamate'
Pisiform'
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'hip)'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$Shoulder$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'
85°'
Wrist'Extension'
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'bone'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'
waist.''
•  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'
Dorsal'
Palmar'
Lunate'
The'TRIQUETRAL'
•  Completes'the'proximal'carpal'row''
•  Articulates'with'the'triangular'fibrocartilage'
•  Carries'the'Pisiform'on'the'palmar'surface'
Dorsal'
Palmar'
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.'
Dorsal'
Palmar'
Pisiform'
Insertion'of'Flexor'Carpi'Ulnaris'
PisoKHamate'
Ligament'
PisoKMetacarpal'
Ligament'
The'TRAPEZIUM'
•  The'most'mobile'of'the'distal'carpal'row'
•  Distal'surface'the'saddle'shaped'CarpoKmetacarpal'joint'with'the'thumb'
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.'
Dorsal'
Palmar'
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.'
Dorsal'
Palmar'
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.'
Dorsal'
Palmar'
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'
Dorsal'
Palmar'
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:' '
'
Ulnar: '
'
'The'ridge'of'trapezium'
'The'tubercle'of'the'scaphoid''
'The'hook'of'the'hamate'
'The'Pisiform'
'
'
'
The'Pisiform'
Ridge of
trapezium
Tubercle of
scaphoid
Hook of
Hamate
Pisiform
•  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)'
'
'
'
•  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.'
'
'
'
•  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'
'
'
'
III
II
I
IV
V
VI
•  The'flexor'retinaculum'is'much'shorter'than'the'Extensor'retinaculum'as'a'
result'of'the'carpal'concavity'towards'the'palm'
'
'
'
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'
'
'
'
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'
'
'
'
Gilula’s'Lines'(Radiological'Arcs'of'the'wrist)'
•  The'ulnar'tilt'of'the'radius'can'be'checked'on'the'PA'view'
'
'
'
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'
'
'
'
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)'
'
'
'
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'
'
'
'
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'
'
'
'
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.'
'
'
'
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.'
'
'
'
ECRL
ECRB
APL
FCR
FCU
ECU
ECRL
ECRB
APL
FCR
FCU
ECU
•  Note'that'all'tendons'that'leave'the'forearm'and'travel'into'the'hand'
BYPASS'the'proximal'Carpal'row.''
•  NO'tendon'inserts'into'the'Proximal'Carpal'row.'
'
'
'
•  Laxity'of'the'extrinsic'ligaments'of'the'carpus'produces'MIDKCARPAL'
INSTABILTY,'a'possible'source'of'pain'
'
'
'
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.'
'
'
'
Proximal'Carpal'Row'='
'
INTERCALATED'SEGMENT'
APL
FCR
ECRL/B
FCU
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.'
'
'
'
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'
'
'
'
Scaphoid
Lunate
Triquetral
Extension/'dorsal'
Flexion/ palmar
Radial Abduction:
Scaphoid Flexion/
Triquetral follows
Ulnar abduction:
Triquetral Extension/
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'
'
'
'
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'
'
'
'
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.'
'
'
'
•  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’'
'
'
'
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$after'a'film'star'of'the'1950’s'
famous'for'his'gapKtoothed'grin'
'
'
'
The'Terry'Thomas'Sign'
Terry Thomas
Lara'Stone'
Diastema$(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'
'
In'Luno'triquetral'Instability'(less'common)'
'The'Scaphoid'and'lunate'fix'in'flexion'and'the'Triquetral'fixes'in'
'extension'
'
'
'
•  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$
'
'
'
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'
'
'
'
•  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'
'
'
'
•  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).'
'
'
'
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'
'
'
'
Bennett'Fracture'
•  Arthritis'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.'
'
'
'
•  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'
'
'
'
arthritic'hands'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.'
'
'
'
•  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'nerve'curves'around'it'before'giving'off'its'terminal'branches.'
'
'
'
•  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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