Modern Study Review (AI-Generated)
High-Yield Summary
Scaphoid-Trapezium-Trapezoid (STT) fusion is a surgical procedure primarily indicated for advanced Kienböck’s disease and select cases of wrist arthritis such as Scapholunate Advanced Collapse (SLAC). It aims to stabilize the wrist by fusing the scaphoid to the trapezium and trapezoid, thereby offloading the lunate and preserving partial wrist motion. Mastery of the surgical anatomy and technique is critical to avoid neurovascular injury and optimize functional outcomes.
Key Diagnostic Findings
| Aspect | Details |
|---|---|
| Anatomy | Scaphoid, trapezium, trapezoid, EPL (extensor pollicis longus), ECRB (extensor carpi radialis brevis), radial styloid, superficial branch of radial nerve |
| Clinical Presentation | Patients present with wrist pain, decreased range of motion, and weakness, often with lunate collapse (Kienböck’s) or degenerative changes (SLAC wrist) |
| Imaging | X-rays show lunate sclerosis/collapse (Kienböck’s), scapholunate gap, and arthritic changes; MRI for early avascular necrosis; CT for joint surface evaluation |
| Classification Systems | Lichtman classification for Kienböck’s disease; Watson classification for SLAC wrist |
Current Gold Standard Treatment
- Non-operative: Reserved for early-stage Kienböck’s disease (Lichtman I-II) with immobilization and activity modification.
- Operative Indications: Advanced Kienböck’s (Lichtman III-IV) with lunate collapse or SLAC wrist with scaphoid instability.
- Surgical Technique Highlights:
- Transverse dorsal wrist incision.
- Interval between EPL and ECRB to minimize soft tissue disruption.
- Careful identification and protection of the superficial branch of the radial nerve.
- Radial styloidectomy performed if SLAC wrist is present.
- Fixation typically with K-wires or headless compression screws between scaphoid and trapezoid; trapezium fixation often unnecessary.
- Alternatives: Proximal row carpectomy, lunate replacement, or complete wrist fusion depending on disease severity.
Modern Complications & Outcomes
| Complication | Notes |
|---|---|
| Nonunion or delayed union | Most common; requires rigid fixation and bone grafting if needed |
| Radial nerve injury | Superficial branch injury leads to sensory deficits; meticulous dissection required |
| Persistent wrist stiffness | Partial wrist fusion preserves some motion but stiffness is common |
| Progression of arthritis | Adjacent joint arthritis can develop over time |
| Pain relief and function | Generally good pain relief; functional outcomes depend on disease stage and surgical technique |
Classic Clinical Notes
STT Fusion
Technique of STT Fusion (For Kienbock’s Disease)
- The exposure is a transverse incision.
- The initial interval goes between EPL and ECRB.
- Watch out for superficial branch of the radial nerve.
- Take EPL radially first to deal with the scaphoid and trapezoid.
- Then take EPL ulnarly to deal with the trapezium, which is quite deep in the wound.
- Take off the radial styloid if doing it for SLAC wrist.
- K-wire trapezoid to scaphoid – don’t actually need to K-wire to trapezium.
Last Updated on January 24, 2026 by orthonet
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