Post on 11-Jul-2015
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Four-Dimensional Computed Tomography Imaging of the Wrist
A Novel Technique to Evaluate Dynamic Instabilities
Marc Garcia-Elias MD Josep Monill MD ; Xavier Alomar MDInstitut Kaplan, Barcelona, Spain Creu Blanca, Barcelona, Spain
Aquilion One, Toshiba Medical Systems
0.5 mm detectors- 16 cm of z-axis volume
Gantry rotation time: 350 milliseconds
Minimum temporal resolution: 175 milliseconds
100 kVp-80 mA
14 image series obtained for 14 seconds
DLP 240mGy. cm
Technical parameters in 320-MDCTTechnical parameters in 320-MDCT
Carpal kinematics Carpal kinematics
FLEXION - EXTENSION
RADIAL INCLINATION - ULNAR INCLINATION
ULNAR FLEXION - RADIAL EXTENSION (DART-THROWING)
RADIAL FLEXION – ULNAR EXTENSION
FLEXION-EXTENSION
Y’
Y
X’X
Y’
Y
X’X
RADIAL CUBITAL INCL.
ECRL
FCU
DART-THROWING
ULNAR FLEXION – RADIAL EXTENSIÓN
Carpal kinematics Carpal kinematics
FLEXION - EXTENSION
RADIAL INCLINATION - ULNAR INCLINATION
ULNAR FLEXION - RADIAL EXTENSION
RADIAL FLEXION - ULNAR EXTENSION
The proximal row hasn´t tendinous attachments
The movement always begins in the distal row
The fibers of midcarpal ligaments increase in tension
The forces of compression generated on the bone force it to move
In the central movements the radiocarpal joint is slightly active
Flexion Neutral Extension
Carpal kinematics Carpal kinematics
FLEXION - EXTENSION
RADIAL INCLINATION - ULNAR INCLINATION
ULNAR FLEXION - RADIAL EXTENSION
RADIAL FLEXION - ULNAR EXTENSION
RADIAL INCLINATION ULNAR INCLINATION
FLEXION EXTENSION
The proximal row, from a flexed position in radial deviation becomes extended in ulnar deviation
RADIAL INCLINATION-ULNAR INCLINATION
VIDEO (Please wait)
In radial deviation the trapezium is pushing the scaphoid towards flexion and ulnar translation.
In ulnar deviation it‘s the triquetral-hamate joint the one forcing the proximal row towards extension and radial translation.
Radial dev Neutral Ulnar dev
25º
0º
-25º RA
DIO
LU
NA
TE
AN
GL
E
Smooth curve from flexion to extension
Which structures ensure a smooth progression from flexion to extension?
The most important ligament inducing progressive extension of the proximal row in ulnar deviation is the palmar triquetrum-capitate-hamate ligament that increase in tension. The triquetrum is pulled by this ligament against the proximal pole of the hamate with which the triquetrum extends.
The scaphotrapezial ligament causes extension and pronation to the scaphoid.
If the proximal row extends too much the capitate would sublux dorsally. This is prevented by the portion of the dorsal intercarpal ligament.
1 Scaphoid-Trapezium 2 Dorsal Intercarpal 3 Triquetrum-Capitate
1
2
3
The contraction of the flexor carpi ulnaris generates a dorsal directed vector on the triquetrum that helps
extending the proximal row in ulnar deviation.
VIDEO (Please wait)
Carpal kinematics Carpal kinematics
FLEXION - EXTENSION
RADIAL INCLINATION - ULNAR INCLINATION
ULNAR FLEXION - RADIAL EXTENSION (DART-THROWING)
RADIAL FLEXION - ULNAR EXTENSION
extension-radial inclinationextension-radial inclinationflexion-ulnar inclinationflexion-ulnar inclination
“Dart-throwing” motion
“Dart-throwing” motion
In the dart-throwing motion the wrist rotates from an extended radial deviation position to a flexed ulnar deviated position.
This oblique plane of motion is the one most commonly used in activities of daily living.
The contribution of the radiocarpal joint to dart-throwing motion is minimal, most rotation occurring at the midcarpal level.
In the dart-throwing plane the proximal row does not rotate.
NEUTRAL RADIAL INCLINATION
RADIAL INCL. + EXTENSION
NEUTRAL ULNAR INCLINATION
ULNAR INCL.+ EXTENSION “ “Dart-throwing motion” Minimal radiocarpal joint rotationDart-throwing motion” Minimal radiocarpal joint rotation
ERD FUD
DART-THROWING MOTION
Midcarpal rotation VIDEO (Please wait)
“ “Dart-throwing motion” Minimal radiocarpal joint Dart-throwing motion” Minimal radiocarpal joint rotationrotation
ERD FUD Moritomo et al,2004
VIDEO (Please wait)
Non-dissociative Instability Non-dissociative Instability
Pathomechanics
Clinical forms
Non-dissociative Instability- PathomechanicsNon-dissociative Instability- Pathomechanics
The wrist exhibits a radiocarpal and/or a midcarpal subluxation of the entire proximal row during non-resisted wrist motion without injury of the interosseous ligaments of the proximal row.
This result in a clunking wrist. Clunking is a low-pitched dull sound produced by sudden subluxation and/or reduction of a partially or totally dislocated carpal bone.
In the clunking non-dissociative wrist the proximal row remains flexed until the wrist is ulnarly deviated at which point it suddenly jumps into extension.
Non-dissociative Instability- Clinical formsNon-dissociative Instability- Clinical forms
There are two major types of non-dissociated carpal clunking: extrinsec and intrinsec.
The extrinsec clunking results from injury or bone alteration outside the carpal area (dorsal malunited radial fractures).
The intrinsec clunking derives from insufficiency or injury of one, or several, carpal ligaments: scaphotrapezoid, triquetrum-capitate-hamate, dorsal scaphotriquetral, palmar radiolunate or ulnolunate.
There are three major patterns of intrinsic carpal clunking: anterior midcarpal, dorsal midcarpal and combined radiocarpal-midcarpal.
Anterior midcarpalAnterior
midcarpalDorsal
midcarpalDorsal
midcarpal
Intrinsic Clunking
Extrinsic Clunking
Radiocarpal-midcarpal
Radiocarpal-midcarpal
Non-dissociative Instability- Clinical formsNon-dissociative Instability- Clinical forms
Anterior midcarpal clunkingAnterior midcarpal clunking The ligaments mostly involved in the palmar midcarpal
instability are the scaphotrapezial ligament, and the triquetrum-capitate-hamate ligament.
The proximal row remains tilted palmarly until near the end of ulnar deviation, where it suddenly rotates into extension, sometimes with a palpable thud (catch-up clunk).
In most cases there is a combination of medial and lateral ligament insufficiency.
There are cases where the dysfunction clearly derives from a predominant injury at the scaphotrapezial ligament (anterolateral midcarpal instability) or from a predominant injury ot the triquetrum-capitate-hamate ligament (anteromedial midcarpal instability). Stress views are recommended to assess the location of the predominant injury.
25º
0º
-25º
Clunk !
Radial dev Neutral Ulnar dev
RA
DIO
LU
NA
TE
AN
GL
E
CLUNK
Anterior midcarpal clunking
VIDEO (Please wait)
12
1: Triquetrum - Hamate 2: Triquetrum - Capitate
Tq
CH
Palmar triqutetrum-capitate-hamate ligament
Anteromedial midcarpal instabilityAnteromedial midcarpal instability
Anterior midcarpal clunking after injury ot the triquetrum-capitate-hamate ligament
Anteromedial midcarpal instabilityAnteromedial midcarpal instability
Scaphoid-Trapezium ligament (STT)
Anterolateral midcarpal instabilityAnterolateral midcarpal instability
Anterior “drawer” test
STT subluxation
(“open mouth” sign)
Anterolateral midcarpal instabilityAnterolateral midcarpal instability
Dorsal midcarpal clunkingDorsal midcarpal clunking
The ligaments mostly involved in the dorsal midcarpal instability are the radioscaphocapitate ligament, and the dorsal scaphotriquetral ligament.
As the wrist rotates toward ulnardevation the capitate subluxes over the edge of the scapholunate socket inducing hyperextension of the proximal row.
Once the capitate is subluxed dorsally there is a reactive contraction of wrist extensors and the distal row tends to return abruptly to its normal alignment often with an audible clunk.Dorsal Intercarpal
Ligament
Dorsal midcarpal instability Dorsal midcarpal instability Dorsal midcarpal instabilityDorsal midcarpal instability
Radiocarpal- midcarpal clunkingRadiocarpal- midcarpal clunking
The pattern of clunking is similar to the anterior midcarpal instability but adding an increased mobility at the RC joint implying an abnormally flexed and ulnarly translocated proximal row in radial deviation.
This form of clunking is frequent among teenagers with hyperlax radio-ulno-carpal ligaments.
In the radiocarpal (or proximal) type of clunking, the ligaments mostly involved are the palmar long and short radiolunate and the dorsal radiotriquetral.
Palmar-dorsal radiocarpal ligaments
CLUNK
Combined radiocarpal-midcarpal instabilityCombined radiocarpal-midcarpal instability
CLUNK
Combined radiocarpal-midcarpal instabilityCombined radiocarpal-midcarpal instability
Combined radiocarpal-midcarpal instabilityCombined radiocarpal-midcarpal instability
Scapholunate instability
Lunotriqueteal instability
Dissociative Instability Dissociative Instability
Dissociative Instability- PathomechanicsDissociative Instability- Pathomechanics
This instability is secondary to rupture of the linkage between the bones of the proximal row.
In the scapholunate instability the scaphoid has lost its ligament connections and exhibits dorsoradial subluxation over the edge of the radius during radial deviation.
It is important to distinguish between partial and complete scapholunate interosseous ligament (SLIL) tears. Partial tears are benign, often asymptomatic. Complete disruptions evolve into progressive carpal collapse and joint degeneration.
The dart-throwing plane of motion allows easy discrimination between partial and total SLIL injury.
Scapholunate instability
Scapholunate inteosseous ligament (SLIL)
Can we differentiate complete from partial rupture?
“Dart-throwing” motion
Complete SLIL rupture
Complete SLIL rupture
Scaphoid and distal row rotated as one single functional unit.
Reduced position of scaphoid in radial extesion.
Dorsolateral subluxation of scaphoid in ulnar flexion. Wide gap between the scaphoid and lunate in ulnar
flexion. Trapezium does not rotate about the distal scaphoid.
No scaphocapitate motion.
“Dart-throwing” motion
Complete SLIL rupture
Complete SLIL rupture
“Dart-throwing” motion“Dart-throwing” motion
Partial SLIL rupture
Partial SLIL rupture
Increased rotation of scaphoid relative to normal wrist.
The lunate rotate and translate laterally but less than the scaphoid.
Subtle gapping of the scapholunate joint in ulnar flexion.
Reduced trapezium rotation about the distal scaphoid.
Scaphocapitate motion slightly reduced.
“Dart-throwing” motion
Complete SLIL rupture
Complete SLIL rupture
“Dart-throwing” motion
Partial SLIL rupture
Partial SLIL rupture
VIDEO (Please wait)
“Dart-throwing” motion“Dart-throwing” motion
Partial SLIL rupture
Partial SLIL rupture
.Clunking of the wrist is the result of a radiocarpal and midcarpal ligament insufficiency.There are three major patterns of intrinsic non-dissociative carpal clunking: anterior midcarpal, dorsal midcarpal and combined radiocarpal-midcarpal. The four-dimensional Computed Tomography allows to detect subtle motion abnormalities to characterize the different types of non-dissociative wrist instability.In the dissociative instability four-dimensional Computed Tomography provide diagnostic criteria that help differentiating between partial and complete tears of scapholunate ligament.
SummarySummary