High Yield Overview

SCAPHOLUNATE LIGAMENT RECONSTRUCTION - DORSAL CAPSULODESIS

Dorsal longitudinal approach over scapholunate interval | advanced

Critical Danger Structures - 5 Specific Anatomical Zones

Superficial Radial Sensory Nerve

Location: Branches cross dorsal-radial wrist 2-5mm from skin incision, superficial to extensor retinaculum Protection: Identify in subcutaneous tissue during approach, retract radially with vessel loops, protect throughout case

Dorsal Sensory Branch Ulnar Nerve

Location: Emerges 5cm proximal to ulnar styloid, courses near 6th extensor compartment on ulnar wrist Protection: Identify during subcutaneous dissection ulnar side, retract and protect with moist sponge

Extensor Pollicis Longus Tendon

Location: Third extensor compartment, courses around Lister's tubercle - can be attenuated or frayed at this point Protection: Gentle retraction radially after opening retinaculum, avoid excessive traction on potentially weakened tendon

Radial Artery Dorsal Carpal Branch

Location: Supplies dorsal wrist capsule and ligaments, runs within capsular layers over scapholunate interval Protection: Preserve distal pedicle when creating capsular flap - distally-based design maintains vascular supply

Radiocarpal and Midcarpal Joint Surfaces

Location: Immediately deep to dorsal capsule, exposed after capsulotomy - scaphoid and lunate articular cartilage Protection: Avoid direct instrument contact with articular surfaces, careful K-wire insertion avoiding cartilage penetration

Mnemonic

DORSALDORSAL - Components of SL Ligament Strength

Mnemonic

REPAIRSREPAIRS - Post-operative Protocol Essentials

Procedure Overview

Indications

Primary Indication: Chronic scapholunate ligament tear with carpal instability

Specific Patient Selection Criteria:

Scapholunate ligament injury confirmed on MRI or arthroscopy
Symptomatic instability with pain, weakness, clicking
REDUCIBLE scapholunate malalignment and DISI deformity
Timeline: 6 months to 2 years from injury (sub-acute to chronic)
Failed conservative management (splinting, activity modification, therapy)
NO radiographic evidence of SLAC arthritis (critical exclusion)
Adequate tissue quality for capsular flap reconstruction
Patient compliance for extended immobilization and rehabilitation

Radiographic Indications:

Scapholunate interval greater than 3mm (Terry Thomas sign)
Scapholunate angle greater than 60-70 degrees on lateral (DISI pattern)
Cortical ring sign on PA view (flexed scaphoid viewed end-on)
Intact radioscaphoid, radiolunate, and capitolunate joints (no SLAC)

Contraindications

Absolute Contraindications:

SLAC wrist Stage II or higher (radioscaphoid arthritis present)
Irreducible scapholunate deformity (fixed malalignment)
Active infection in wrist or hand
Severe osteoporosis with fragile bone (K-wire fixation would fail)
Medical comorbidities precluding prolonged immobilization

Relative Contraindications:

SLAC Stage I (radial styloid arthritis only) - consider with styloidectomy
Very chronic injuries (greater than 2-3 years) - poor tissue quality
Scaphoid malunion or lunate pathology complicating reduction
High-demand manual laborers (higher failure risk)
Poor patient compliance (will not maintain immobilization)
Revision surgery after failed previous SL reconstruction
Inflammatory arthropathy (rheumatoid arthritis)

Alternative Procedures When Contraindicated:

SLAC Stage II-III: Four-corner fusion (scaphoid excision, capitate-lunate-hamate-triquetrum fusion)
SLAC Stage III-IV: Proximal row carpectomy or total wrist fusion
Acute SL tears (less than 6 weeks): Primary ligament repair
Chronic irreducible: Scaphoid-trapezium-trapezoid fusion with ligament reconstruction

Operative Technique - Step by Step

Step 1: Positioning & Preoperative Imaging Assessment

Position supine with arm extended on radiolucent hand table. Apply upper arm pneumatic tourniquet (not inflated yet). Position mini C-arm for PA and lateral wrist imaging. May use finger trap traction (5-10 lbs) or towel roll under distal forearm for wrist extension positioning.

Preoperative Fluoroscopic Assessment:

PA view: Measure scapholunate interval (normal less than 3mm, pathologic greater than 3mm to 5mm or more)
Identify Terry Thomas sign (widened SL gap), cortical ring sign (flexed scaphoid)
Lateral view: Measure scapholunate angle (normal 30-60 degrees, DISI greater than 70 degrees)
Assess lunate position (extended in DISI pattern)
Critical: Confirm NO radioscaphoid or capitolunate arthritis (contraindication for reconstruction)
Document reducibility: Apply manual pressure and stress views to confirm deformity is reducible

Inflate tourniquet to 250mmHg after exsanguination with Esmarch bandage.

Exam Pearl

Technical Tip: EXAM KEY - 'Scapholunate ligament injury causes DISI deformity: lunate extends dorsally, scaphoid flexes palmarly. Diagnostic criteria: SL interval greater than 3mm on PA (Terry Thomas sign), SL angle greater than 70 degrees on lateral. Cortical ring sign shows flexed scaphoid viewed end-on. Must have NO arthritis for reconstruction - if SLAC wrist present (radioscaphoid or capitolunate arthritis), reconstruction will fail and patient needs salvage procedure like four-corner fusion.'

Critical Assessment Points

Proceeding with reconstruction when SLAC arthritis present leads to predictable failure
Missing irreducible deformity (fixed malalignment requires different procedure or bone grafting)
Inadequate preoperative imaging assessment of arthritis status

Step 2: Incision & Superficial Dissection

Make longitudinal dorsal wrist incision centered over scapholunate interval, extending from just proximal to Lister's tubercle distally to midcarpal level (approximately 6-8cm total length).

Incise skin and subcutaneous tissue with sharp dissection. Identify and protect superficial radial sensory nerve branches on radial side of incision - typically 2-3 small branches cross the operative field 2-5mm from skin incision. Use vessel loops to retract branches radially. Identify and protect dorsal sensory branch of ulnar nerve on ulnar side near 6th extensor compartment - retract ulnarly.

Identify extensor retinaculum. The longitudinal fibers of retinaculum are visible overlying extensor tendons.

Exam Pearl

Technical Tip: EXAM KEY - 'I use longitudinal dorsal incision centered over scapholunate interval. This provides direct access to dorsal capsule. During subcutaneous dissection, I identify and protect superficial radial nerve branches on radial side and dorsal ulnar sensory branches on ulnar side - these are the most common nerves injured in dorsal wrist surgery. I use vessel loops for gentle retraction.'

Nerve Injury Prevention

Superficial radial sensory nerve branches: Typically 2-3 branches cross operative field, can cause painful neuroma if injured
Dorsal sensory branch ulnar nerve: Emerges 5cm proximal to ulnar styloid, courses near 6th compartment
Use loupe magnification for nerve identification in subcutaneous layer

Step 3: Extensor Retinaculum Division & Tendon Management

Incise extensor retinaculum longitudinally between 3rd compartment (EPL) and 4th compartment (EDC/EIP). This internervous interval provides direct access to dorsal capsule.

Identify EPL tendon in 3rd compartment coursing around Lister's tubercle - retract radially with moist sponge or small retractor. Note: EPL can be attenuated or frayed at Lister's tubercle, especially in chronic cases - handle gently.

Identify 4th compartment containing EDC and EIP tendons. Can retract these tendons ulnarly OR split the compartment longitudinally and pass between tendons for better exposure.

The dorsal wrist capsule is now visible beneath the extensor tendons.

Exam Pearl

Technical Tip: EXAM KEY - 'I open extensor retinaculum between 3rd and 4th compartments - this is internervous interval giving direct access to dorsal capsule over scapholunate. I retract EPL radially (protect carefully as it can be attenuated over Lister's tubercle) and retract EDC/EIP ulnarly. Can repair retinaculum at closure with Z-lengthening if needed to prevent extensor adhesions.'

Tendon Complications

EPL tendon injury: Can be attenuated over Lister's tubercle, avoid excessive traction
Extensor tendon adhesions: Minimize trauma to paratenon, gentle tissue handling
Retinaculum closure too tight: Can impair extensor tendon gliding

Step 4: Capsulotomy & Creation of Distally-Based Capsular Flap

Identify dorsal wrist capsule architecture. The dorsal radiocarpal ligament and dorsal intercarpal ligament form characteristic V or inverted-Y pattern converging on dorsal lunate.

Create Distally-Based Capsular Flap:

Start proximally at distal radius dorsal rim
Incise longitudinally creating rectangular flap approximately 10-15mm wide
Extend distally 20-25mm to capitate/lunate level
Leave distal attachment intact - this is the vascular pedicle
Elevate flap from proximal to distal, preserving distal blood supply

The flap incorporates dorsal radiocarpal ligament and portion of dorsal intercarpal ligament. Flap dimensions: 10-15mm wide, 20-25mm long, distally-based with hinge point over capitate-lunate region.

After elevating flap, the scapholunate interval is fully exposed. May see frayed, attenuated, or completely absent dorsal SL ligament tissue. Scaphoid and lunate clearly visible.

Exam Pearl

Technical Tip: EXAM KEY - 'I create DISTALLY-BASED dorsal capsular flap that will bridge the scapholunate interval and substitute for torn dorsal SL ligament. Flap dimensions approximately 10-15mm wide by 20-25mm long. Critical to preserve DISTAL pedicle - this maintains blood supply to flap. The dorsal SL ligament's dorsal component is the strongest portion providing 80% of stability - the capsulodesis recreates this anatomic restraint.'

Capsular Flap Technical Points

Flap too thin or narrow: Will tear during tensioning or fixation - ensure adequate tissue thickness
Disrupting distal vascular pedicle: Leads to flap necrosis and reconstruction failure
Inadequate flap length: Won't reach both scaphoid and lunate with adequate tension
Damage to underlying articular cartilage: Avoid deep dissection into joint

Step 5: Assess & Reduce Scapholunate Deformity

With scapholunate interval exposed, assess pathology:

Scapholunate gap: Typically widened (greater than 3mm, often 5-8mm)
Scaphoid position: Flexed (palmar tilt) - see abnormal orientation
Lunate position: Extended (dorsal tilt) - DISI deformity

Reduction Maneuvers:

Scaphoid reduction: Insert 0.062 inch K-wire into scaphoid waist as joystick handle. EXTEND scaphoid (dorsiflex, lift proximally) to correct flexion deformity
Lunate reduction: Manipulate lunate into FLEXION (palmar tilt) using instrument or direct pressure
Close SL gap: Apply manual pressure or use pointed reduction forceps/bone clamp to approximate scaphoid to lunate
Fluoroscopic confirmation: PA view shows SL interval less than 3mm, no cortical ring. Lateral view shows SL angle 30-60 degrees, corrected DISI

Temporary K-wire Fixation:

Place two 0.062 inch K-wires across scapholunate joint in DIVERGENT pattern (prevents rotation)
Place one 0.062 inch K-wire from scaphoid into capitate (scaphocapitate wire for additional stability)
Leave K-wires proud of skin 1cm for later removal
Confirm position on fluoroscopy (wires cross joint but don't penetrate far cortex excessively)

Exam Pearl

Technical Tip: EXAM KEY - 'Reduction is critical before reconstruction. I use K-wire joystick in scaphoid to EXTEND it (correct abnormal flexion). I flex the lunate. I close SL gap with reduction forceps. I confirm anatomic reduction on fluoroscopy: SL interval less than 3mm on PA, SL angle 30-60 degrees on lateral. I hold reduction with 3 temporary K-wires (2 scapholunate divergent, 1 scaphocapitate) while performing capsulodesis. This ensures healing in correct anatomic position.'

Reduction Complications

Inability to achieve reduction: May need bone graft in SL interval or consider different procedure
K-wire penetrating articular cartilage: Confirm extraarticular position on both views
Loss of reduction during reconstruction: Ensure K-wires adequately hold position
Scaphoid or lunate fracture: Avoid excessive force, especially in osteoporotic bone

Step 6: Prepare Bone Surfaces for Capsular Flap Attachment

With reduction maintained by K-wires, prepare scaphoid and lunate dorsal surfaces for capsular flap fixation.

Bone Surface Preparation:

Use small rongeur or 2-3mm burr to gently roughen dorsal cortex of proximal scaphoid
Roughen dorsal surface of lunate similarly
Create slight trough or bed in bone to accept capsular flap (enhances contact and healing)
Depth: Superficial only (1-2mm) - do NOT penetrate joint or weaken bone structure
Purpose: Roughened bone surface promotes fibrous ingrowth and flap-to-bone healing

Alternative: Suture Anchor Preparation:

If using suture anchors for stronger fixation (recommended for chronic or severe cases):
Place two 2.0mm or 2.4mm suture anchors in dorsal proximal scaphoid
Place two 2.0mm or 2.4mm suture anchors in dorsal lunate
Position anchors to allow capsular flap to bridge interval when sutured
Load anchors with 2-0 or 3-0 non-absorbable braided suture (FiberWire, Ethibond)

Exam Pearl

Technical Tip: EXAM KEY - 'I prepare bone surfaces to enhance capsule-to-bone healing. I use small rongeur or burr to roughen dorsal cortex of scaphoid and lunate - creates bleeding bone surface promoting fibrous tissue ingrowth. Alternatively, I prefer suture anchors for more secure fixation, especially in chronic cases - 2 anchors in scaphoid, 2 in lunate, positioned dorsally to accept capsular flap. Anchors provide stronger fixation than sutures through bone tunnels.'

Bone Preparation Risks

Scaphoid or lunate fracture: Especially with anchor insertion - predrill carefully
Penetrating radiocarpal or midcarpal joint with burr: Stay superficial on dorsal cortex
Anchor malposition: Should be dorsal surface, not articular - confirm on fluoroscopy
Weakening bone excessively: Keep preparation superficial (1-2mm depth maximum)

Step 7: Dorsal Capsulodesis - Secure Capsular Flap

The distally-based capsular flap is now secured to both scaphoid and lunate, bridging the scapholunate interval. The flap acts as a tether preventing scaphoid flexion and lunate extension.

Fixation Technique Option 1: Suture Anchors (Preferred)

Pass sutures from scaphoid anchors through capsular flap at appropriate position
Tie sutures to secure flap to dorsal scaphoid with firm tension
Pass sutures from lunate anchors through capsular flap
Tie sutures to secure flap to dorsal lunate
Flap should bridge scapholunate interval under appropriate tension
Add additional interrupted sutures along flap edges for reinforcement

Fixation Technique Option 2: Transosseous Bone Tunnels

Drill small (1.5-2.0mm) bone tunnels through scaphoid (dorsal to palmar)
Drill similar tunnels through lunate (dorsal to palmar)
Pass 2-0 or 3-0 braided non-absorbable suture through capsular flap
Pass suture through bone tunnels
Tie sutures on palmar side or over palmar cortex (may need small palmar incision)
Ensures strong fixation but technically more demanding

Flap Tension Assessment:

Too loose: Won't prevent recurrent scapholunate gapping - inadequate restraint
Too tight: Will tear flap tissue or pull through bone - leads to failure
Appropriate tension: Flap under visible tension, approximates bones, no excessive blanching
Test: Gently stress scapholunate interval - should have minimal gapping with flap restraining

Exam Pearl

Technical Tip: EXAM KEY - 'I secure dorsal capsular flap to both scaphoid and lunate using suture anchors - this provides strongest fixation. The flap bridges scapholunate interval creating TETHER that prevents pathologic motion. Appropriate tension is critical - too loose fails to prevent instability recurrence, too tight causes tissue failure. The flap substitutes for torn dorsal SL ligament which provided 80% of scapholunate stability. This is why dorsal capsulodesis works biomechanically.'

Capsulodesis Fixation Complications

Capsular flap tearing: Ensure adequate tissue thickness, avoid excessive tension, use multiple sutures
Suture pulling through bone: Use anchors or ensure bone tunnels positioned to distribute force
Bone tunnel fracture: Keep tunnels small (1.5-2.0mm), avoid excessive number
Inadequate tension: Most common cause of reconstruction failure - flap must restrain motion

Step 8: Augmentation Options (If Indicated)

For severe chronic instability, high-demand patients, or revision cases, consider adding augmentation to simple capsulodesis.

Modified Brunelli (Bone-Retinaculum-Bone) Augmentation:

Use additional strip of dorsal wrist capsule (separate from main flap)
Drill bone tunnel through scaphoid waist (dorsal to palmar, 3-4mm diameter)
Pass capsular strip through scaphoid tunnel
Loop strip back and secure to dorsal capsule or proximal scaphoid with suture anchors
Creates dynamic tether resisting scaphoid flexion

SLAM (Scapholunate Axis Method) Tendon Graft Augmentation:

Harvest palmaris longus tendon (or toe extensor if palmaris absent)
Drill bone tunnels in scaphoid (dorsal to palmar) and lunate (dorsal to palmar)
Pass tendon graft in figure-8 pattern through both tunnels
Tension graft appropriately and secure with suture or interference screw
Provides strong internal brace augmenting capsulodesis

Decision Making: Simple capsulodesis adequate for most subacute/early chronic cases. Consider augmentation if: revision surgery, severe chronic instability (greater than 2 years), poor tissue quality, high-demand manual laborer, competitive athlete.

Exam Pearl

Technical Tip: EXAM KEY - 'For augmentation in severe cases, I use Bone-Retinaculum-Bone technique where capsular strip passes through scaphoid tunnel creating additional dynamic restraint, or SLAM procedure using tendon graft in figure-8 through scaphoid and lunate tunnels. These add strength for high-demand patients or revision surgery. However, simple dorsal capsulodesis is sufficient for most moderate instability cases caught relatively early (within 6 months to 2 years).'

Augmentation Risks

Scaphoid fracture through bone tunnel: Higher risk with larger tunnels for tendon grafts
Tendon graft necrosis: Avoid excessive tension, maintain vascularity
Over-constraining joint: Can limit wrist motion excessively
Increased technical complexity and operative time

Step 9: Final Reduction Assessment & K-Wire Position Confirmation

After capsulodesis secured, perform final fluoroscopic assessment to confirm anatomic reduction and appropriate K-wire positioning.

PA Fluoroscopy View Assessment:

Scapholunate interval: Should measure less than 3mm (normal 2-3mm)
Cortical ring sign: Should be ABSENT (indicates scaphoid reduced from flexion)
Gilula lines: Three smooth carpal arcs should be restored and parallel
No carpal step-off or malalignment
K-wire position: Wires cross scapholunate joint, adequate purchase in both bones

Lateral Fluoroscopy View Assessment:

Scapholunate angle: Should measure 30-60 degrees (corrected from DISI)
Radiolunate angle: Should be 0 degrees ± 10 degrees (corrected lunate extension)
Capitate-lunate alignment: Should be colinear (no VISI or DISI pattern)
K-wire position: Adequate penetration but not excessively through far cortex

K-Wire Configuration:

Two scapholunate K-wires in DIVERGENT pattern (prevents rotation)
One scaphocapitate K-wire for additional stability
Wires bent and cut outside skin with 1cm proud for later removal
Alternative: Bury wires under skin if preferred (requires mini-open for removal)
Protect wire ends with plastic guards and dressing

Exam Pearl

Technical Tip: EXAM KEY - 'I confirm anatomic reduction on final fluoroscopy before closing. SL interval should be 2-3mm on PA view. SL angle 30-60 degrees on lateral - this corrects the DISI deformity. I use 3 K-wires total: 2 scapholunate divergent (prevent rotation), 1 scaphocapitate (additional stability). These wires protect the capsulodesis during healing for 8-12 weeks. I leave wires outside skin with bent ends and protective guards - easier for later removal than buried wires.'

Final Assessment Critical Points

Loss of reduction: If alignment inadequate, re-reduce before closing - don't accept suboptimal position
K-wire migration risk: Ensure adequate bending and secure dressing to prevent movement
Overcorrection: Excessive scaphoid extension can limit wrist extension - aim for normal alignment
Pin tract infection prevention: Educate patient on pin care, protective covering

Step 10: Wound Closure

Irrigate wound thoroughly with normal saline (3-6 liters) to remove bone debris and blood.

Layered Closure:

Capsule: Attempt to close dorsal wrist capsule over reconstruction with 3-0 absorbable suture (Vicryl) if adequate tissue remains. Often capsule is thin after flap harvest - if inadequate tissue, leave capsule open (acceptable)
Extensor Retinaculum: Close retinaculum over extensor tendons with 3-0 absorbable suture - can perform Z-lengthening if tight to prevent extensor tendon adhesions and maintain smooth gliding
Subcutaneous Layer: Close with 4-0 absorbable suture (interrupted or running)
Skin: Close with 4-0 nylon interrupted vertical mattress or running subcuticular 4-0 absorbable suture
K-wire Protection: Apply sterile dressing around K-wire sites with protective plastic guards to prevent catching on clothing

Apply soft sterile dressing (fluffs and gauze).

Exam Pearl

Technical Tip: EXAM KEY - 'I close extensor retinaculum over tendons to provide smooth gliding surface - may Z-lengthen retinaculum if tight after reconstruction. Often don't have enough capsule to close after creating flap - this is acceptable, don't force tension closure. I protect K-wire sites with sterile dressing and plastic guards to prevent pin catching and reduce infection risk. Standard layered skin closure.'

Closure Complications

Extensor tendon adhesions: Avoid tight retinaculum closure, gentle tissue handling, early mobilization after immobilization period
K-wire site infection: Proper pin care education, protective covering, remove wires at 8-12 weeks
Wound dehiscence: Avoid excessive tension on skin closure, ensure adequate hemostasis

Step 11: Immobilization

Apply LONG ARM CAST or well-molded LONG ARM SPLINT immediately after surgery.

Immobilization Position:

Wrist: Neutral position (0 degrees flexion-extension)
Forearm: Neutral rotation (midposition between pronation-supination)
Elbow: 90 degrees flexion
Fingers: FREE for metacarpophalangeal and interphalangeal ROM exercises

Rationale for Long Arm Immobilization: Prevents forearm rotation (pronation-supination) which creates torsional stress on scapholunate reconstruction. Short arm cast allows rotation and risks early failure.

Duration: Long arm immobilization for 4 weeks, then transition to short arm cast for additional 4-8 weeks (total immobilization 8-12 weeks minimum).

Exam Pearl

Technical Tip: EXAM KEY - 'I use LONG ARM immobilization for first 4 weeks because forearm rotation (pronation-supination) creates torsional stress on scapholunate reconstruction - short arm cast allows this rotation and risks failure. After 4 weeks, transition to short arm cast for 4-6 more weeks. Total casting 8-10 weeks minimum. K-wires remain during this entire period, protecting the healing capsulodesis. This extended immobilization is critical for success but will cause some stiffness requiring therapy later.'

Immobilization Complications

Inadequate immobilization: Most common cause of reconstruction failure - ensure compliance
Short arm cast initially: Allows forearm rotation stressing repair - must use long arm
Prolonged immobilization: Necessary evil - causes stiffness but prevents failure
Cast complications: Monitor for pressure sores, compartment syndrome in early period

Step 12: K-Wire Removal & Therapy Initiation

At 8-12 weeks post-operatively, obtain radiographs to assess scapholunate alignment.

Radiographic Criteria for K-Wire Removal:

Scapholunate interval maintained at less than 3mm on PA view
Scapholunate angle maintained at 30-60 degrees on lateral view
No loss of reduction or hardware failure
No signs of infection or complications

K-Wire Removal Technique:

Typically performed in clinic or minor procedure room (not operating room)
Clean pin sites with chlorhexidine or betadine
Infiltrate local anesthetic (1% lidocaine) around each wire site
Use needle driver or wire removal pliers to grasp wire ends
Back out wires with gentle twisting and pulling motion
Remove scapholunate wires first, then scaphocapitate wire
Pin sites typically heal by secondary intention (small puncture wounds)
Apply sterile dressing, no sutures needed

Hand Therapy Initiation:

Begin immediately after wire removal
Focus: Gentle ROM (active, active-assisted, gentle passive)
Wrist flexion-extension, radial-ulnar deviation, forearm rotation
NO strengthening initially
Removable wrist splint for protection between therapy sessions

Exam Pearl

Technical Tip: EXAM KEY - 'K-wires removed at 8-12 weeks after confirming maintained reduction on radiographs. This is in-office procedure with local anesthetic - grasp wire ends with needle driver and back out with gentle rotation. Pin sites heal quickly without sutures. I start hand therapy immediately after wire removal for gentle ROM only - no strengthening until 12+ weeks. Extended immobilization causes stiffness, so early ROM important, but must wait for adequate healing time before removing wire protection.'

Wire Removal Complications

K-wire breakage during removal: If wire breaks, may need fluoroscopy to locate fragment, occasionally requires operative removal
Loss of reduction after wire removal: Indicates inadequate healing - may need revision surgery
Pin tract infection: Rare if good hygiene maintained - treat with oral antibiotics, earlier removal if needed

Complications Management

Scapholunate Capsulodesis Complications - Recognition, Prevention, and Management

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 32-year-old rock climber presents 8 months after wrist injury with clicking, pain, and weakness. PA radiograph shows 5mm scapholunate interval and cortical ring sign. Lateral shows SL angle of 75 degrees. How do you interpret these findings and what is your management approach?"

EXCEPTIONAL ANSWER

This patient has chronic scapholunate ligament dissociation with DISI deformity based on radiographic findings. Let me interpret systematically: **Radiographic Interpretation**: PA view shows widened scapholunate interval at 5mm (normal less than 2-3mm) - this is the Terry Thomas sign indicating scapholunate dissociation. The cortical ring sign represents the proximal pole of the scaphoid viewed end-on, indicating pathologic scaphoid flexion. Lateral view shows scapholunate angle of 75 degrees (normal 30-60 degrees), diagnostic of DISI deformity where the lunate is extended dorsally and scaphoid flexed palmarly. **Pathophysiology**: The scapholunate ligament has torn (likely dorsal component which provides 80% of stability), allowing scaphoid to flex abnormally and lunate to extend. The 8-month timeline makes this chronic but potentially still within reconstruction window. **Critical Assessment Points**: (1) Is the deformity REDUCIBLE - I would assess with stress views or fluoroscopy applying manual pressure to see if SL interval closes and alignment corrects. (2) Is there SLAC arthritis present - carefully examine PA view for radial styloid or radioscaphoid arthritis, lateral for capitolunate changes. Any arthritis is contraindication to reconstruction. (3) Patient factors - occupation (rock climber = high demand), compliance with prolonged immobilization, expectations. **Management Approach**: If reducible deformity and NO arthritis: Candidate for scapholunate ligament reconstruction - I would offer dorsal capsulodesis creating distally-based capsular flap to tether scaphoid and lunate. Procedure involves open reduction, temporary K-wire fixation, capsular flap creation and secure fixation to both bones, 8-12 weeks immobilization. Alternative: Could consider augmented reconstruction with tendon graft (SLAM procedure) given high-demand athlete status. If SLAC present: reconstruction contraindicated, would require salvage (four-corner fusion or PRC). If irreducible: may need bone grafting in SL interval or different procedure. Counsel patient: 10-30% failure rate, expect 30-40% ROM loss, 6-12 month recovery, may need activity modification long-term.

VIVA SCENARIOStandard

EXAMINER

"Explain the biomechanics of scapholunate ligament injury, why DISI deformity develops, and the rationale for why dorsal capsulodesis works to restore stability."

EXCEPTIONAL ANSWER

**Normal Scapholunate Biomechanics**: The scapholunate ligament connects scaphoid and lunate, maintaining them as a linked unit during wrist motion. The scaphoid naturally tends to FLEX (palmar tilt) because it bridges the proximal and distal carpal rows with distal row forces pushing it palmarly. The lunate naturally tends to EXTEND (dorsal tilt) because the capitate pushes it dorsally. The INTACT scapholunate ligament prevents these deforming forces, keeping scaphoid and lunate moving together synchronously. **SL Ligament Anatomy**: The ligament has three components - dorsal (strongest, 2-3mm thick, provides 80% of stability), proximal/membranous (thinnest, tears first acutely), and palmar (intermediate strength). The DORSAL component is the primary restraint - this is why dorsal-based repairs work. **DISI Deformity Development**: When scapholunate ligament is completely torn (especially dorsal component), the linkage between scaphoid and lunate is lost. The scaphoid FLEXES abnormally due to unopposed distal row forces - on PA radiograph you see cortical ring sign (flexed scaphoid viewed end-on) and foreshortened appearance. The lunate EXTENDS abnormally, following the triquetrum which tilts dorsally - on lateral radiograph you see increased lunate tilt. The scapholunate ANGLE increases to greater than 70 degrees (normal 30-60 degrees) - this is DISI or Dorsal Intercalated Segment Instability. The scapholunate GAP widens to greater than 3mm (Terry Thomas sign). **Why DISI Leads to SLAC**: The abnormal carpal alignment creates abnormal contact pressures and load distribution across radiocarpal and midcarpal joints. Progressive arthritis develops in predictable pattern: Stage I radial styloid, Stage II entire radioscaphoid joint, Stage III capitolunate joint. This is SLAC - Scapholunate Advanced Collapse. Key point: radiolunate joint SPARED even in advanced disease because lunate remains congruent with radius. **Dorsal Capsulodesis Biomechanical Rationale**: The procedure creates distally-based dorsal capsular flap that bridges scapholunate interval and is secured to both scaphoid and lunate. This flap acts as a TETHER that: (1) Prevents scaphoid flexion by restraining dorsal scaphoid when it tries to tilt palmarly. (2) Prevents lunate extension by connecting it to reduced scaphoid. (3) Maintains reduced scapholunate gap by physically bridging interval. (4) Recreates function of torn DORSAL SL ligament component which provided primary restraint. The flap substitutes for the strongest portion (dorsal component) in the anatomically correct position (dorsal aspect). This is why it works biomechanically - addresses the primary stabilizer that was lost.

VIVA SCENARIOStandard

EXAMINER

"Describe your step-by-step technique for creating and securing a distally-based dorsal capsular flap for scapholunate capsulodesis, including fixation options and how you assess appropriate flap tension."

EXCEPTIONAL ANSWER

**Surgical Approach and Exposure**: I use longitudinal dorsal wrist incision centered over scapholunate interval, approximately 6-8cm from Lister's tubercle to midcarpal level. After protecting superficial radial nerve branches and dorsal ulnar sensory nerve, I incise extensor retinaculum between 3rd compartment (EPL) and 4th compartment (EDC/EIP). I retract EPL radially and EDC/EIP ulnarly, exposing dorsal wrist capsule. **Capsular Flap Creation**: The dorsal radiocarpal ligament and dorsal intercarpal ligament form V or inverted-Y pattern converging on lunate - I incorporate this into my flap. I create DISTALLY-BASED rectangular capsular flap: Start proximally at distal radius dorsal rim. Make two parallel longitudinal incisions creating flap 10-15mm WIDE. Extend distally 20-25mm to capitate/lunate level. CRITICAL - leave DISTAL attachment intact - this is the vascular pedicle maintaining blood supply. I elevate flap from proximal to distal using sharp dissection, preserving distal hinge point. **Exposure of Scapholunate Interval**: After elevating capsular flap, the scapholunate interval is fully exposed. I typically see frayed, attenuated, or absent dorsal SL ligament tissue confirming complete tear. Scaphoid and lunate are clearly visible. **Reduction**: Before securing flap, I must reduce the deformity. Insert 0.062 inch K-wire into scaphoid as joystick to EXTEND it (correct flexion). Manipulate lunate into FLEXION. Close scapholunate gap with reduction forceps or manual pressure. Confirm reduction on fluoroscopy: PA view shows SL interval less than 3mm, no cortical ring. Lateral view shows SL angle 30-60 degrees. I hold reduction with 3 temporary K-wires: 2 scapholunate (divergent pattern), 1 scaphocapitate. **Bone Surface Preparation**: With reduction held by K-wires, I prepare dorsal surfaces of scaphoid (proximal pole) and lunate for flap attachment. Use small rongeur or 2-3mm burr to gently roughen cortex creating bleeding surface - promotes healing. Alternatively (my preference), I place suture anchors: 2 anchors in dorsal proximal scaphoid, 2 anchors in dorsal lunate, loaded with 2-0 FiberWire or Ethibond. **Flap Fixation - Suture Anchor Technique (Preferred)**: Pass sutures from scaphoid anchors through capsular flap at appropriate position to bridge to scaphoid. Tie sutures securing flap to scaphoid with appropriate tension. Pass sutures from lunate anchors through flap. Tie sutures securing flap to lunate. The flap now bridges scapholunate interval under tension. Add interrupted 2-0 sutures along flap edges for reinforcement. **Alternative Fixation - Transosseous Bone Tunnels**: Drill 1.5-2.0mm bone tunnels through scaphoid and lunate (dorsal to palmar). Pass 2-0 or 3-0 braided suture through capsular flap and through tunnels. Tie on palmar side or over palmar cortex. More technically demanding but avoids anchor cost. **Assessing Appropriate Tension**: This is CRITICAL. Too loose - won't prevent recurrent gapping (failure). Too tight - tears flap or pulls through bone (failure). Appropriate tension: Flap should be under visible tension when tied, approximates scaphoid to lunate, some blanching acceptable but not excessive ischemia. I test by gently stressing scapholunate interval - should have minimal gapping with flap restraining motion. The flap should feel taut but not so tight it's ready to tear. **Final Confirmation**: Fluoroscopy after capsulodesis to confirm maintained reduction - SL interval less than 3mm, SL angle 30-60 degrees, K-wires in good position.