LUNOTRIQUETRAL INSTABILITY
LTIL Injury | VISI Deformity | LT Arthrodesis
INSTABILITY PATTERNS
Critical Must-Knows
- LTIL (Lunotriquetral Interosseous Ligament) injury causes ulnar wrist pain and VISI (Volar Intercalated Segment Instability) deformity
- VISI deformity: Lunate flexes volarly, triquetrum extends dorsally - opposite of DISI (scapholunate)
- LT arthrodesis is gold standard for chronic instability - high union rate (85-90%), minimal motion loss (LT contributes little to wrist motion)
- LT ballottement test (Reagan's test) is key clinical test - stabilise lunate, translate triquetrum dorsally/palmarly
- Acute injuries: Direct repair with suture anchors if less than 6 weeks, better outcomes than chronic
Examiner's Pearls
- "VISI = Volar Intercalated Segment Instability - lunate flexes volarly (opposite of DISI from SL injury)
- "LT arthrodesis preferred over reconstruction - high union rate, minimal motion loss, reliable pain relief
- "LT contributes less than 5% to wrist motion - fusion well-tolerated functionally
- "LT ballottement test: stabilise lunate, translate triquetrum - pain/crepitus = positive
Critical Lunotriquetral Instability Exam Points
VISI Deformity
VISI (Volar Intercalated Segment Instability) = lunate flexes volarly, triquetrum extends dorsally. Opposite of DISI (scapholunate injury). Lateral X-ray shows lunate tilted volarly (less than 0 degrees capitolunate angle).
LT Arthrodesis Gold Standard
LT arthrodesis is treatment of choice for chronic instability - High union rate (85-90%), minimal motion loss (LT contributes less than 5% to wrist motion), reliable pain relief. Preferred over ligament reconstruction.
LT Ballottement Test
Reagan's test (LT ballottement): Stabilise lunate with one hand, translate triquetrum dorsally and palmarly with other. Positive = pain, crepitus, or increased motion. Compare to contralateral side.
Acute vs Chronic
Acute injuries (less than 6 weeks): Direct repair with suture anchors - better outcomes than chronic. Chronic injuries: LT arthrodesis preferred - reconstruction less predictable.
Lunotriquetral Instability - Quick Decision Guide
| Pattern | Clinical Features | Treatment | Outcome |
|---|---|---|---|
| Dynamic | Pain, clicking, no deformity | LT repair or reconstruction | 70-80% good results |
| Static VISI | Fixed VISI deformity | LT arthrodesis | 85-90% good results |
| With arthritis | LT joint arthritis | LT fusion or salvage | 80-85% good results |
VDVISI vs DISI
Memory Hook:VD: VISI = Volar (LT injury), DISI = Dorsal (SL injury)!
VISILT Instability Features
Memory Hook:VISI: Volar Intercalated Segment Instability - lunate flexes volarly!
HIGHLT Arthrodesis Advantages
Memory Hook:HIGH: High union, Insignificant motion loss, Gold standard, High success!
Overview and Epidemiology
Lunotriquetral instability results from injury to the lunotriquetral interosseous ligament (LTIL), causing ulnar wrist pain and VISI (Volar Intercalated Segment Instability) deformity. Treatment depends on acuity and severity, with LT arthrodesis being the gold standard for chronic instability.
Definition
Lunotriquetral instability: Loss of stability between lunate and triquetrum due to LTIL injury, causing:
- Ulnar wrist pain: Pain on ulnar side of wrist
- VISI deformity: Lunate flexes volarly, triquetrum extends dorsally
- Functional impairment: Weakness, clicking, instability
LTIL (Lunotriquetral Interosseous Ligament):
- Connects lunate and triquetrum
- Stabilises ulnar carpus
- Injury causes VISI deformity
Epidemiology
- Incidence: 5-10% of carpal ligament injuries
- Age: Peak 20-40 years (trauma population)
- Gender: No clear predominance
- Mechanism: Fall on outstretched hand with ulnar deviation, or direct trauma
- Associated injuries: Perilunate dislocations, other carpal injuries
VISI vs DISI
VISI (Volar Intercalated Segment Instability) = lunate flexes volarly (LT injury). DISI (Dorsal Intercalated Segment Instability) = lunate extends dorsally (SL injury). Remember: VISI = Volar (LT), DISI = Dorsal (SL).
Anatomy and Pathophysiology
LTIL Anatomy
Lunotriquetral Interosseous Ligament (LTIL):
- Location: Between lunate and triquetrum
- Structure: Dorsal, volar, and interosseous components
- Function: Stabilises ulnar carpus, prevents VISI deformity
- Blood supply: Dorsal and volar carpal arches
Carpal kinematics:
- Proximal row: Scaphoid, lunate, triquetrum move together
- LT joint: Contributes less than 5% to wrist motion
- VISI: Lunate flexes volarly when LTIL disrupted
Pathophysiology
Injury mechanism:
- Fall on outstretched hand: With ulnar deviation
- Direct trauma: To ulnar side of wrist
- Perilunate dislocation: Often associated with LTIL injury
VISI deformity:
- Lunate: Flexes volarly (opposite of DISI)
- Triquetrum: Extends dorsally
- Capitolunate angle: Less than 0 degrees (normal 0-15 degrees)
- Scapholunate angle: Normal (SL intact)
Why VISI occurs:
- LTIL disruption: Loss of stabilisation between lunate and triquetrum
- Lunate unopposed: Flexes volarly (volar ligaments intact)
- Triquetrum: Extends dorsally (dorsal ligaments intact)
Classification Systems
Severity-Based Classification
Dynamic instability:
- Pain, clicking, no fixed deformity
- LTIL partially torn
- Treatment: LT repair or reconstruction
Static VISI:
- Fixed VISI deformity on X-ray
- LTIL completely torn
- Treatment: LT arthrodesis (preferred)
With arthritis:
- LT joint arthritis present
- Chronic instability
- Treatment: LT fusion or salvage procedures
Severity guides treatment approach.
Clinical Assessment
History
Symptoms:
- Ulnar wrist pain: Pain on ulnar side of wrist
- Clicking or clunking: With wrist movement
- Weakness: Grip strength reduced
- Instability: Feeling of wrist giving way
Mechanism:
- Fall on outstretched hand with ulnar deviation
- Direct trauma to ulnar side of wrist
- High-energy trauma (perilunate dislocation)
Physical Examination
Inspection:
- Swelling on ulnar side of wrist
- VISI deformity (if static)
- Prominence of ulnar head (if VISI)
Palpation:
- LT interval tenderness (ulnar to lunate)
- Ulnar wrist pain
- Crepitus at LT joint
Range of Motion:
- Wrist ROM may be limited
- Pain with ulnar deviation
- Clicking with motion
Special Tests
LT Ballottement Test (Reagan's Test):
- Stabilise lunate with one hand
- Translate triquetrum dorsally and palmarly with other hand
- Positive: Pain, crepitus, or increased motion
- Compare to contralateral side
LT Compression Test:
- Ulnar deviation of wrist
- Apply axial load through ring/small finger metacarpals
- Positive: Pain at LT interval
Ulnar Snuffbox Test:
- Palpate ulnar snuffbox (between triquetrum and ulnar styloid)
- Positive: Tenderness indicates LT injury
Clinical Examination Key Point
LT ballottement test (Reagan's test) is the key clinical test - Stabilise lunate, translate triquetrum dorsally and palmarly. Positive = pain, crepitus, or increased motion. Compare to contralateral side.
Investigations
Standard X-ray Protocol
PA view:
- Assess LT interval (may be widened)
- Carpal height (may be reduced in VISI)
- Ulnar variance
Lateral view (critical):
- VISI deformity: Lunate flexed volarly
- Capitolunate angle: Less than 0 degrees (normal 0-15 degrees)
- Scapholunate angle: Normal (SL intact)
- Lunate position: Volar tilt
Clenched fist view:
- May show dynamic instability
- LT interval widening
Lateral X-ray is essential for VISI diagnosis.
Imaging Gallery
Diagnostic Imaging for LT Instability
Management Algorithm
Management Pathway
Lunotriquetral Instability Management
Clinical examination (LT ballottement test), lateral X-ray (VISI deformity), classify as dynamic or static, acute or chronic.
If acute (less than 6 weeks), direct repair with suture anchors via dorsal or palmar approach. Better outcomes than chronic repair. Success rate 70-80%.
If chronic (over 6 weeks) or static VISI, LT arthrodesis is gold standard. High union rate (85-90%), minimal motion loss (LT contributes less than 5%), reliable pain relief. Success rate 85-90%.
If LT joint arthritis present, LT fusion addresses instability and pain. If severe arthritis or failed fusion, consider salvage procedures (PRC, wrist fusion). Success rate 80-85%.
Surgical Technique
LT Arthrodesis Technique (Gold Standard)
Indications:
- Chronic LT instability (over 6 weeks)
- Static VISI deformity
- Failed repair or reconstruction
Approach:
- Dorsal ulnar incision between 4th and 5th extensor compartments
- Identify and protect DRUJ and ECU tendon
- Expose LT joint through dorsal capsulotomy
Technique:
- Exposure: Dorsal approach, expose LT joint
- Preparation: Remove articular cartilage from lunate and triquetrum using curettes or burr
- Graft: Pack autograft or allograft bone graft
- Fixation: Compression screw (headless cannulated) or plate/screws
- Verification: Confirm reduction and hardware position fluoroscopically
Advantages:
- High union rate (85-90%)
- Minimal motion loss (LT contributes less than 5%)
- Reliable pain relief
- Predictable outcomes
LT arthrodesis is gold standard for chronic instability.
Complications
| Complication | Incidence | Risk Factors | Prevention/Management |
|---|---|---|---|
| Nonunion | 10-15% | Smoking, poor fixation, inadequate graft | Rigid fixation, bone graft, smoking cessation |
| Persistent pain | 10-15% | Incomplete fusion, arthritis | Complete cartilage removal, adequate graft |
| Hardware issues | 5-10% | Prominent screws | Countersink screws, remove if symptomatic |
| Loss of correction | 5-10% | Inadequate fixation | Rigid fixation, compression |
Nonunion
10-15% incidence:
- Cause: Inadequate graft, poor fixation, smoking
- Prevention: Rigid fixation, bone graft, smoking cessation
- Management: Revision fusion with bone graft
Persistent Pain
10-15% incidence:
- Cause: Incomplete fusion, arthritis, other pathology
- Prevention: Complete cartilage removal, adequate graft
- Management: Assess for other causes, consider revision
Postoperative Care
Immediate Postoperative
- Immobilisation: Short arm cast (6-8 weeks)
- Weight bearing: Non-weight bearing on hand
- ROM: Finger ROM immediately
- PT: Wrist ROM after cast removal
Rehabilitation Protocol
Weeks 0-6:
- Short arm cast
- Finger ROM exercises
- Elevation to reduce swelling
Weeks 6-8:
- Cast removal
- Begin wrist ROM exercises
- Progressive strengthening
Weeks 8-12:
- Full ROM
- Progressive activity
- Return to sport/activity
Union and Hardware Removal
Union timeline: Typically 8-12 weeks postoperatively.
Hardware removal: Consider if prominent or symptomatic, usually after union confirmed (3-6 months).
Outcomes and Prognosis
Overall Outcomes
LT arthrodesis:
- Success rate: 85-90% (union, pain relief)
- Functional outcomes: 80-85% return to pre-injury level
- Motion loss: Minimal (LT contributes less than 5% to wrist motion)
Direct repair (acute):
- Success rate: 70-80% (if acute, less than 6 weeks)
- Functional outcomes: 70-75% return to pre-injury level
- Motion: Full motion preserved
Functional Outcomes
Return to activity:
- Timeline: 3-6 months postoperatively
- Rate: 80-85% return to pre-injury level
- Factors: Treatment method, timing, rehabilitation compliance
Pain relief:
- LT arthrodesis: 85-90% pain relief
- Direct repair: 70-80% pain relief (if acute)
Long-Term Prognosis
Arthritis progression:
- With arthrodesis: 5-10% develop adjacent joint arthritis
- Without treatment: 20-30% develop arthritis
- Risk factors: Chronic instability, associated injuries
Evidence Base
LT Arthrodesis Outcomes
- 85-90% union rate
- 85-90% good-excellent results
- Minimal motion loss (LT contributes less than 5%)
- Reliable pain relief
VISI Deformity
- VISI = lunate flexes volarly (LT injury)
- DISI = lunate extends dorsally (SL injury)
- Capitolunate angle less than 0 degrees in VISI
Acute vs Chronic Repair
- Acute repair: 70-80% good results
- Chronic repair: 50-60% good results
- LT arthrodesis preferred for chronic
LT Ballottement Test
- Key clinical test for LT instability
- Sensitivity 70-80%, specificity 80-90%
- Compare to contralateral side
Carpal Motion Analysis
- LT contributes less than 5% to wrist motion
- LT arthrodesis causes minimal motion loss
- Supports arthrodesis as treatment of choice
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Chronic LT Instability with VISI
"A 35-year-old woman presents with 3 months of ulnar wrist pain and clicking. Clinical examination shows positive LT ballottement test. Lateral X-ray shows VISI deformity with lunate flexed volarly. The capitolunate angle is negative 10 degrees."
Scenario 2: Acute LT Injury
"A 28-year-old athlete presents 2 weeks after fall on outstretched hand with ulnar deviation. He has ulnar wrist pain and clicking. Clinical examination shows positive LT ballottement test. X-rays show no fixed deformity (dynamic instability)."
MCQ Practice Points
VISI Deformity
Q: What is VISI and how does it differ from DISI? A: VISI (Volar Intercalated Segment Instability) = lunate flexes volarly (LT injury) - Opposite of DISI (Dorsal Intercalated Segment Instability) = lunate extends dorsally (SL injury). Capitolunate angle less than 0 degrees in VISI (normal 0-15 degrees).
LT Arthrodesis
Q: Why is LT arthrodesis the gold standard for chronic LT instability? A: High union rate (85-90%), minimal motion loss (LT contributes less than 5% to wrist motion), reliable pain relief, predictable outcomes - Preferred over ligament reconstruction for chronic instability. LT arthrodesis is treatment of choice.
LT Ballottement Test
Q: How do you perform the LT ballottement test? A: Stabilise lunate with one hand, translate triquetrum dorsally and palmarly with other hand - Positive = pain, crepitus, or increased motion. Compare to contralateral side. Also known as Reagan's test.
Acute vs Chronic
Q: When is direct repair preferred over LT arthrodesis? A: Acute injuries (less than 6 weeks) with good tissue quality - Direct repair achieves 70-80% good results if acute, but only 50-60% if chronic. LT arthrodesis preferred for chronic injuries (over 6 weeks).
Motion Loss
Q: Why does LT arthrodesis cause minimal functional impairment? A: LT joint contributes less than 5% to total wrist motion - Fusion of LT joint causes minimal motion loss functionally. This supports LT arthrodesis as treatment of choice for chronic instability.
Australian Context
Clinical Practice
- LT instability common in hand/wrist practice
- LT arthrodesis standard for chronic
- Direct repair for acute injuries
- VISI deformity well-recognised pattern
Healthcare System
- Public hospitals handle most cases
- Private insurance covers procedures
- Hand therapy accessible through public/private
Orthopaedic Exam Relevance
Lunotriquetral instability is a common viva topic. Know that VISI = Volar Intercalated Segment Instability (lunate flexes volarly, LT injury), LT arthrodesis is gold standard for chronic (85-90% union, minimal motion loss), LT ballottement test is key clinical test, and acute injuries (less than 6 weeks) have better outcomes with direct repair (70-80% vs 50-60% if chronic). Be prepared to discuss VISI vs DISI and LT arthrodesis technique.
LUNOTRIQUETRAL INSTABILITY
High-Yield Exam Summary
Key Concepts
- •VISI = Volar Intercalated Segment Instability (lunate flexes volarly, LT injury)
- •DISI = Dorsal Intercalated Segment Instability (lunate extends dorsally, SL injury)
- •LTIL = Lunotriquetral Interosseous Ligament
- •LT contributes less than 5% to wrist motion
Clinical Features
- •Ulnar wrist pain
- •Clicking or clunking with movement
- •VISI deformity (if static)
- •LT ballottement test positive (Reagan's test)
Treatment
- •Acute (less than 6 weeks): Direct repair with suture anchors (70-80% good results)
- •Chronic (over 6 weeks): LT arthrodesis (85-90% good results, gold standard)
- •Static VISI: LT arthrodesis (preferred)
- •With arthritis: LT fusion or salvage procedures
LT Arthrodesis Technique
- •Dorsal ulnar approach between 4th and 5th extensor compartments
- •Remove articular cartilage from lunate and triquetrum
- •Pack bone graft (autograft or allograft)
- •Fix with compression screw (headless cannulated) or plate/screws
- •Cast 6-8 weeks, then ROM exercises
Complications
- •Nonunion: 10-15% (prevent with rigid fixation, bone graft)
- •Persistent pain: 10-15% (assess for other causes)
- •Hardware issues: 5-10% (remove if symptomatic)
- •Loss of correction: 5-10% (prevent with rigid fixation)