hand•opsurg-cmc-lrti-enhanced

Thumb CMC Arthroplasty - LRTI (Ligament Reconstruction Tendon Interposition)

advanced Level

Exam Relevance: VERY HIGH

90 mins

Primary Indication

Symptomatic thumb CMC arthritis Eaton stage II-IV, failed conservative management (splinting, NSAIDs, intra-articular steroid), disabling pain affecting function, radiographic arthritis with narrowing/subluxation

Danger Structures

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undefined - Surrounding operative field
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Visual Atlas

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Step-by-Step Technique

Preoperative Assessment and Marking: EATON STAGING: Stage I (normal contour, widening), II (slight narrowing, <2mm osteophytes), III (marked narrowing, >2mm osteophytes), IV (STT joint involved). Assess STT joint tenderness. Mark: CMC joint (base thumb metacarpal), FCR at wrist, radial sensory nerve course. Document thumb ROM, opposition, pinch strength.

Surgeon's Tip

EXAM KEY: 'EATON classification predicts procedure: I-II may consider osteotomy, II-III ideal for LRTI, IV consider fusion if young/high demand. Assess STT joint - if arthritic may need excision/denervation.'

Danger Zone

Missing STT arthritis (persistent pain postop)
Not documenting baseline function

Dorsoradial Incision and Nerve Protection: WAGNER APPROACH: Dorsoradial longitudinal incision 3cm long, centered over CMC joint (base 1st metacarpal). Curve slightly toward anatomic snuffbox. Careful subcutaneous dissection to identify RADIAL SENSORY NERVE branches. Typically 3-5 branches cross field. Preserve ALL branches - gently retract with vessel loops.

Surgeon's Tip

EXAM KEY: 'RADIAL SENSORY NERVE is most at risk - multiple branches. LONGITUDINAL incision protects nerves better than transverse. Use loupe magnification. Retract nerves gently with vessel loops - not forcefully.'

Danger Zone

Nerve injury causing neuroma (10-20% incidence)
Excessive retraction causing neuropraxia

Exposure of CMC Joint: Identify APL and EPB tendons (1st dorsal compartment). Retract radially to protect. Incise joint capsule LONGITUDINALLY over CMC joint. Create capsular flaps that can be repaired later. Expose trapezium and base of thumb metacarpal. Assess articular surfaces - confirms diagnosis.

Surgeon's Tip

EXAM KEY: 'CAPSULAR INCISION longitudinal between APL/EPB radially and thenar muscles volarly. Preserve capsule for later repair. APL inserts on base metacarpal - landmark for joint.'

Danger Zone

Radial artery injury if dissection too deep volarly
Inadequate exposure leading to difficulty

Trapezium Excision: Complete TRAPEZIECTOMY: Use combination of sharp dissection, rongeur, and osteotome. Remove trapezium piecemeal if needed (easier than en bloc). Start dorsally, work volarly. Protect FCR tendon volarly. Smooth all bony edges. Ensure COMPLETE excision - retained trapezial fragments cause pain. Check for STT arthritis.

Surgeon's Tip

EXAM KEY: 'COMPLETE trapezium excision essential - retained fragments = pain. Piecemeal removal is acceptable. Protect FCR volarly, scaphoid radially, 2nd MC ulnarly. Smooth all edges with rongeur.'

Danger Zone

Scaphoid fracture during excision
FCR tendon injury
Incomplete excision (retained fragments)
Injury to 2nd CMC joint ulnarly

FCR Harvest for Ligament Reconstruction: Separate volar wrist incision over FCR at wrist crease (2cm). Identify FCR tendon. Harvest RADIAL HALF (or entire slip) distally-based. Length 8-12cm. Keep distal insertion intact (2nd/3rd MC base). Split FCR longitudinally in half using scissors. Maintain continuity with distal insertion.

Surgeon's Tip

EXAM KEY: 'FCR HARVEST: radial HALF slip, 8-12cm length, DISTALLY-BASED (insertion intact). Provides donor for reconstruction while preserving some wrist flexion. Need adequate length for weaving and interposition.'

Danger Zone

Harvesting wrong tendon (FDS, PL)
Inadequate length
Complete FCR division (lose distal insertion)

Metacarpal Bone Tunnel Creation: Create bone tunnel through base of thumb metacarpal. Entry: ULNAR base (volar-ulnar cortex). Exit: DORSAL-RADIAL cortex. Use 2.0-2.5mm drill. Smooth tunnel edges. This tunnel allows FCR to pass through and provide suspension.

Surgeon's Tip

EXAM KEY: 'Bone tunnel ULNAR-to-RADIAL through base thumb metacarpal. Size 2.0-2.5mm. Allows FCR suspension. Direction ulnar volar to dorsal radial gives proper vector for stability.'

Danger Zone

Tunnel too large (inadequate fixation)
Tunnel misdirection
Metacarpal fracture

FCR Passage and Ligament Reconstruction: Pass FCR slip through metacarpal tunnel ulnar-to-radial. Pull snug to suspend metacarpal - eliminates space left by trapezium. Anchor FCR to periosteum on RADIAL side of metacarpal with multiple non-absorbable sutures (2-0 Ethibond). Tension to maintain thumb length and height.

Surgeon's Tip

EXAM KEY: 'SUSPENSION: FCR through tunnel, anchored radially. Creates SUSPENSIONPLASTY - prevents metacarpal subsidence. Tension with thumb in opposition, slight traction. This is LIGAMENT RECONSTRUCTION component.'

Danger Zone

Inadequate tension (subsidence)
Over-tensioning (stiffness)
Suture failure

Tendon Interposition (Anchovy): Take remaining FCR length and fold into ball ('ANCHOVY' technique). Stuff anchovy into trapezial space - fills void left by excision. Suture anchovy to surrounding capsule to secure. This is spacer and prevents contact between scaphoid and metacarpal.

Surgeon's Tip

EXAM KEY: 'ANCHOVY = FCR rolled into ball, stuffed into trapezial space. TENDON INTERPOSITION component. Acts as spacer and biological cushion. Some surgeons omit this step (simple trapeziectomy + suspension).'

Danger Zone

Anchovy too bulky (limits motion)
Inadequate interposition (bone-on-bone contact)

Temporary K-wire Fixation: Place 1.6mm K-wire from thumb metacarpal to index metacarpal (or trapezoid). Maintains space and thumb position during healing. Position thumb in PALMAR ABDUCTION and slight opposition. Leave wire percutaneous for easy removal at 4-6 weeks.

Surgeon's Tip

EXAM KEY: 'Temporary K-WIRE thumb MC to index MC or trapezoid. Maintains SPACE while suspensionplasty heals. Remove at 4-6 weeks. Position thumb in functional position (slight opposition, palmar abduction).'

Danger Zone

Wire migration
Pin tract infection
Wire breakage

Capsular Repair and Closure: Repair joint capsule over reconstruction with absorbable sutures. Close subcutaneous layer. Skin closure with nylon or subcuticular suture. Apply THUMB SPICA SPLINT incorporating wrist and thumb (IP joint free). Splint maintains thumb in opposition and protection.

Surgeon's Tip

EXAM KEY: 'Capsular REPAIR important for stability. Thumb spica splint with IP FREE. Immobilize 4-6 weeks to allow suspensionplasty healing. Then remove K-wire and begin gentle ROM.'

Danger Zone

Splint too tight (compartment syndrome)
Inadequate immobilization (construct failure)

Postoperative Protocol: Thumb spica 4 weeks. K-wire removal 4-6 weeks (in clinic). Begin gentle ROM at 4-6 weeks with hand therapist. Strengthening at 8-12 weeks. Avoid heavy pinch/grip for 3 months. Full recovery 4-6 months. Most patients: 80-90% pain relief, improved function, slight loss of pinch strength.

Surgeon's Tip

EXAM KEY: 'Results: 80-90% pain relief, improved function, but 20-30% loss pinch strength vs pre-op (but less pain = net functional gain). Subsidence 2-3mm normal. Significant subsidence >40% suggests technical issue.'

Danger Zone

Early loading (subsidence)
Inadequate therapy (stiffness)

Perform intraoperative imaging/fluoroscopy to confirm adequate position and alignment

Surgeon's Tip

EXAM KEY: Documentation of intraoperative findings is crucial for Thumb CMC Arthroplasty - LRTI (Ligament Reconstruction Tendon Interposition).

Danger Zone

Radiation exposure
Inadequate imaging

Irrigate wound thoroughly and achieve meticulous hemostasis

Surgeon's Tip

EXAM KEY: Copious irrigation reduces infection risk. Bipolar for hemostasis near neurovascular structures.

Danger Zone

Hematoma formation
Wound complications

Close wound in layers with appropriate suture technique

Surgeon's Tip

EXAM KEY: Layered closure with deep absorbable sutures and skin closure appropriate for location.

Danger Zone

Wound dehiscence
Skin necrosis from tension

Apply sterile dressing and appropriate immobilization as indicated

Surgeon's Tip

EXAM KEY: Post-operative immobilization tailored to procedure stability and patient compliance.

Danger Zone

Pressure injuries
Excessive immobilization