Modern Study Review (AI-Generated)
High-Yield Summary
Scapholunate Advanced Collapse (SLAC) wrist is the most common pattern of wrist osteoarthritis resulting from chronic scapholunate ligament injury and subsequent carpal instability. It leads to progressive degenerative changes primarily involving the radioscaphoid joint, followed by adjacent intercarpal joints. Early recognition and staging guide treatment, which ranges from radial styloidectomy to complex salvage procedures such as four-corner fusion or proximal row carpectomy. The ultimate goal is to relieve pain while preserving wrist motion and function.
Key Diagnostic Findings
| Aspect | Details |
|---|---|
| Anatomy | Scapholunate ligament disruption ? rotary subluxation of scaphoid (palmar flexion) |
| Pathomechanics | Palmar flexed scaphoid causes abnormal joint contact and increased pressure on radius and capitate; capitate migrates into scaphoid-lunate gap |
| Clinical Presentation | Chronic wrist pain, decreased range of motion, weakness, and possible dorsal wrist swelling |
| Imaging | – X-rays: Scapholunate dissociation, rotary subluxation, joint space narrowing, osteophytes – Advanced stages show radioscaphoid and intercarpal arthritis – CT/MRI for detailed cartilage and ligament assessment |
| Classification (Modern SLAC Staging) | |
| Stage I | Degeneration limited to radial styloid and distal radial scaphoid |
| Stage IIa | Entire radioscaphoid joint involved |
| Stage IIb | Radioscaphoid plus scapho-trapezial-trapezoidal (STT) joint arthritis |
| Stage III | Radioscaphoid, scaphocapitate, and lunocapitate joints involved |
Current Gold Standard Treatment
| Stage | Non-Operative Indications | Operative Indications & Procedures |
|---|---|---|
| Stage I | NSAIDs, splinting, activity modification | Radial styloidectomy ± distal scaphoid excision; STT fusion or scapho-capitate fusion if instability present |
| Stage IIa/b | Failed conservative management, persistent pain | Scaphoid excision + limited intercarpal fusion (four-corner fusion or lunocapitate fusion); proximal row carpectomy (PRC) may preserve more motion |
| Stage III | Advanced arthritis with significant pain and dysfunction | Scaphoid excision + four-corner fusion or lunocapitate fusion; wrist arthrodesis for salvage in severe cases |
Technical pearls for intercarpal fusion:
- Complete cartilage and subchondral bone removal
- Preservation of carpal height
- Generous bone grafting
- Correction of DISI deformity by restoring lunate alignment to improve wrist extension and reduce impingement
Modern Complications & Outcomes
| Complication | Notes |
|---|---|
| Nonunion after fusion | Rates vary; meticulous technique and bone grafting reduce risk |
| Persistent pain or stiffness | Common; PRC may preserve more motion but can lead to progressive arthritis |
| Carpal height loss | Leads to decreased wrist function; preservation critical during surgery |
| Progression of arthritis | Possible after limited fusion or PRC; requires long-term monitoring |
| Hardware irritation or failure | Possible with fusion plates or screws; may require removal |
Outcomes:
- Four-corner fusion and PRC provide reliable pain relief with moderate preservation of wrist motion.
- Wrist arthrodesis offers definitive pain relief but sacrifices motion.
- Early intervention before advanced collapse yields better functional outcomes.
Classic Clinical Notes
SLAC
Scapho-Lunate Advanced Collapse – SLAC Wrist
- Primary injury is a disruption of the scapholunate ligament
- This results in rotary subluxation of the scaphoid – it flexes in a palmar direction
- When flexed palmarly, there is incongruous joint contact between the proximal scaphoid and distal radius, with significantly increased contact pressures
- Abnormal forces are transmitted from the scaphoid to distal radius, and from the capitate to lunate
- As the scaphoid shortens, the capitate experiences increased load and begins to fall into the gap between the scaphoid and lunate
Stages
| Stage | Description |
|---|---|
| Stage I | Radial styloid and distal-radial aspect of scaphoid degeneration |
| Stage IIA | Entire radioscaphoid articulation involved |
| Stage IIB | Radioscaphoid and STT joint arthritis |
| Stage III | Radioscaphoid, scaphocapitate, and lunocapitate articulations involved |
Surgical Treatment – SLAC Wrist
| Stage | Treatment Options |
|---|---|
| Stage I | Radial styloid excision to remove impingement on the radial side of the wrist – may be done alone or combined with distal scaphoid fusion: STT or scapho-capitate fusion – Scaphoid-trapezium-trapezoid fusion (STT) – Scaphoid-capitate fusion |
| Stage II | Radioscaphoid ± scaphotrapezial/trapezoidal – Scaphoid excision plus limited intercarpal fusion (“four-corner” capitate-lunate-hamate-triquetrum fusion, or lunocapitate fusion) – Proximal row carpectomy – some evidence that PRC may preserve more motion than intercarpal fusion |
| Stage III | Radioscaphoid, scaphocapitate, lunocapitate – Scaphoid excision and four-corner fusion – Scaphoid excision and lunocapitate fusion – Wrist arthrodesis |
Technical Points for Intercarpal Fusions
- Thoroughly excise the cartilage and subchondral bone
- Preserve carpal height
- Bone graft generously
- Correct capitate-lunate alignment; in particular, if a DISI pattern has developed, it is important to get the lunate out of its extended position to restore wrist extension and reduce radiocapitate impingement
Last Updated on January 24, 2026 by orthonet
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