Wrist Carpal Instability Examination
Carpal instability examination requires understanding the complex carpal ligament anatomy and different instability patterns. Examiners expect you to perform Watson's test correctly, understand the difference between DISI and VISI patterns, and assess the DRUJ systematically.
Quick Reference One-Pager
Scapholunate (SL)
- Watson's scaphoid shift test
- SL ballottement test
- DISI pattern on lateral X-ray
- Most common carpal instability
Lunotriquetral (LT)
- Shuck test (ballottement)
- Shear test
- Ulnar deviation pain
- VISI pattern (less common)
DRUJ Instability
- Piano key test
- Ballottement test
- TFCC assessment
- Compare with contralateral
Key Points
- Compare both wrists
- Assess for clicks and clunks
- Pain reproduction is key
- Dynamic instability may need stress views
Anatomy and Instability Patterns
Carpal Ligament Anatomy
Intrinsic Ligaments (Between Carpal Bones):
- Scapholunate (SL) ligament: Strongest dorsally, prevents scaphoid flexion
- Lunotriquetral (LT) ligament: Prevents lunate extension
Extrinsic Ligaments (Radius/Ulna to Carpus):
- Volar: Radioscaphocapitate, long radiolunate, short radiolunate
- Dorsal: Radiotriquetral (dorsal radiocarpal)
Carpal Rows:
- Proximal: Scaphoid, lunate, triquetrum (pisiform)
- Distal: Trapezium, trapezoid, capitate, hamate
- Scaphoid spans both rows (link bone)
DISI vs VISI Patterns:
DISI (Dorsal Intercalated Segment Instability):
- Lunate dorsiflexed (tilted dorsally greater than 15°)
- Scapholunate angle greater than 70° (normal 30-60°)
- Caused by SL ligament injury (scaphoid flexes, lunate extends)
VISI (Volar Intercalated Segment Instability):
- Lunate palmarflexed
- Scapholunate angle less than 30°
- Caused by LT ligament injury (less common)
Clinical Presentation
History Clues
Scapholunate Instability:
- Fall on outstretched hand (FOOSH)
- Dorsal wrist pain (anatomical snuffbox deep)
- Weakness with grip
- Clicking with movement
- "My wrist just doesn't feel right"
Lunotriquetral Instability:
- Ulnar-sided wrist pain
- Pain with ulnar deviation
- Clicking on the ulnar side
DRUJ Instability:
- Pain with forearm rotation
- Weakness with pronation/supination
- Prominent ulnar head
- History of distal radius fracture
Scapholunate Instability Tests
Special test
Watson's Test (Scaphoid Shift Test)
Scapholunate instability
Technique
- 1Patient seated, forearm pronated
- 2Examiner's thumb on scaphoid tubercle (volar wrist)
- 3Apply dorsal pressure to scaphoid tubercle
- 4Move wrist from ulnar to radial deviation while maintaining pressure
Positive Sign
Painful clunk or click as scaphoid subluxates dorsally, or apprehension
Indicates
Scapholunate ligament injury - scaphoid shifts dorsally due to lack of ligamentous restraint
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Watson's Test Interpretation:
- Clunk may occur in normal patients (hyperlaxity)
- MUST compare with contralateral wrist
- Pain with the maneuver is the key finding
- Positive = painful clunk on AFFECTED side (not contralateral)
- May need to repeat test several times
Special test
Scapholunate Ballottement Test
SL ligament integrity
Technique
- 1Stabilize lunate between thumb and finger of one hand
- 2Grasp scaphoid with other hand
- 3Apply dorsal-volar shear force between bones
Positive Sign
Increased translation, pain, or crepitus between scaphoid and lunate
Indicates
Scapholunate ligament injury or disruption
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Finger Extension Test
SL instability screening
Technique
- 1Patient extends middle finger against resistance
- 2Examiner resists extension at the MCP joint
Positive Sign
Dorsal wrist pain over SL interval
Indicates
Scapholunate injury (ECRB and ECRL load the scaphoid during finger extension)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Lunotriquetral Instability Tests
Special test
LT Ballottement (Shuck) Test
Lunotriquetral ligament integrity
Technique
- 1Stabilize lunate with one hand
- 2Grasp pisiform/triquetrum with other hand
- 3Apply dorsal-volar shear between lunate and triquetrum
Positive Sign
Increased laxity, painful crepitus, or click
Indicates
Lunotriquetral ligament injury
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
LT Shear Test
LT instability
Technique
- 1Wrist in neutral
- 2Load triquetrum from ulnar side
- 3Apply dorsally directed force
Positive Sign
Pain at LT interval, click
Indicates
LT ligament pathology
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Ulnar Snuffbox Tenderness
LT interval assessment
Technique
- 1Palpate ulnar snuffbox (between ECU and FCU tendons)
- 2Apply pressure at LT interval
Positive Sign
Point tenderness at LT interval
Indicates
LT ligament injury (nonspecific but helpful localizing sign)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
DRUJ Instability Tests
Special test
DRUJ Ballottement Test
DRUJ stability
Technique
- 1Forearm in neutral, pronation, and supination
- 2Stabilize distal radius with one hand
- 3Grasp ulnar head with other hand
- 4Apply dorsal-volar force to ulnar head
Positive Sign
Increased dorsal-volar translation compared to contralateral wrist
Indicates
DRUJ instability (TFCC and/or radioulnar ligament injury)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
DRUJ Testing Positions:
- Pronation: Tests dorsal radioulnar ligaments (tight)
- Supination: Tests volar radioulnar ligaments (tight)
- Neutral: Both ligaments contribute
Test in all three positions and compare with contralateral side!
Special test
Piano Key Test
DRUJ instability
Technique
- 1Forearm pronated on table
- 2Press down on ulnar head from dorsal side
- 3Release pressure
Positive Sign
Ulnar head springs back up like piano key
Indicates
Dorsal DRUJ instability (dorsal subluxation of ulna)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
TFCC Load Test (Press Test)
TFCC integrity
Technique
- 1Patient pushes up from chair using affected hand
- 2Axial load through ulnar side of wrist
Positive Sign
Ulnar-sided wrist pain
Indicates
TFCC pathology (tear, degeneration)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Fovea Sign
TFCC and LT assessment
Technique
- 1Palpate between ulnar styloid and FCU tendon
- 2Apply pressure at foveal region
Positive Sign
Point tenderness at fovea
Indicates
TFCC tear at foveal attachment or LT injury
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Midcarpal Instability Tests
Special test
Midcarpal Shift Test
Midcarpal instability
Technique
- 1Patient seated, forearm pronated
- 2Stabilize forearm
- 3Apply axial compression and palmar translation to metacarpals
- 4Move wrist from radial to ulnar deviation
Positive Sign
Painful clunk as proximal row shifts from VISI to neutral
Indicates
Midcarpal instability (extrinsic ligament laxity)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Midcarpal Instability Patterns
Types:
- CIC (Capitolunate Instability Pattern): Most common
- CIND (Carpal Instability Nondissociative): Ligament laxity between rows
Clinical Features:
- "Catch-up clunk" with movement
- Often bilateral (generalized ligamentous laxity)
- Painful clicking with ulnar deviation
- May improve with strengthening
Imaging Correlation
- view
- PA
- value
- Greater than 3mm (Terry Thomas sign)
- indicates
- SL dissociation
- view
- PA
- value
- Cortical ring from flexed scaphoid
- indicates
- SL dissociation
- view
- Lateral
- value
- Greater than 70° (DISI)
- indicates
- SL ligament injury
- view
- Lateral
- value
- Less than 30° (VISI)
- indicates
- LT ligament injury
- view
- Lateral
- value
- Greater than 30°
- indicates
- Carpal instability
- view
- PA or CT
- value
- Asymmetric compared to contralateral
- indicates
- DRUJ instability
Differential Diagnosis
- location
- Dorsoradial wrist
- mechanism
- FOOSH
- keyTest
- Watson's test +ve
- imaging
- SL gap greater than 3mm, DISI
- location
- Ulnar wrist
- mechanism
- FOOSH, rotation
- keyTest
- LT ballottement
- imaging
- VISI pattern
- location
- Distal RU joint
- mechanism
- DR fracture, trauma
- keyTest
- Ballottement, piano key
- imaging
- DRUJ widening on CT
- location
- Central/ulnar
- mechanism
- Laxity
- keyTest
- Midcarpal shift
- imaging
- May need dynamic views
- location
- Snuffbox
- mechanism
- FOOSH
- keyTest
- Snuffbox tenderness
- imaging
- Scaphoid views/MRI
- location
- Ulnar wrist
- mechanism
- Rotation, load
- keyTest
- Fovea sign, press test
- imaging
- MR arthrogram
Summary Presentation
“35-year-old woman presents 3 months after a fall on outstretched hand with persistent dorsal wrist pain and clicking.”
Examination Sequence
Systematic Approach
- Observation: Swelling, deformity, prominence of ulnar head
- Palpation: SL interval, LT interval, fovea, DRUJ
- Active ROM: Flexion, extension, radial/ulnar deviation
- Grip Strength: Compare with contralateral
- Watson's Test: SL instability
- SL Ballottement: SL integrity
- LT Tests: Shuck test, shear test
- DRUJ Tests: Ballottement, piano key
- Midcarpal Shift: If suspected
- Neurovascular: Complete examination
Examiner Tips
Do
- Perform Watson's test correctly (pressure on tubercle)
- Compare with contralateral wrist (essential)
- Test DRUJ in pronation, neutral, and supination
- Understand DISI vs VISI patterns
- Know the imaging findings (Terry Thomas, ring sign)
Don't
- Accept painless clunk as positive Watson's
- Forget to test DRUJ
- Miss fovea sign for TFCC
- Neglect LT interval assessment
- Forget to correlate with X-ray findings