Populations and Risk Factors
- Individuals sustaining FOOSH (fall on outstretched hand) injuries with the wrist extended and pronated
- Contact sport athletes and individuals involved in high-energy trauma
- Risk of progression to Kienbock disease if left untreated (disrupted blood supply leads to avascular necrosis)
- Associated with scapholunate dissociation and dorsiflexed intercalated segment instability (DISI)
Causes and Pathophysiology
- FOOSH mechanism: Impact force transmitted through the extended, pronated wrist displaces the lunate anteriorly (volar direction) while the rest of the carpals remain in their normal position
- Carpal tunnel compression: Anterior displacement pushes the lunate directly into the carpal tunnel, compressing the median nerve and producing acute CTS symptoms
- Carpal instability: The lunate forms the central part of the proximal carpal row. Its displacement destabilizes the entire wrist architecture, often associated with DISI pattern
- "Terry Thomas" sign: Widened gap (> 4 mm) between scaphoid and lunate on imaging indicates scapholunate ligament disruption
- Kienbock disease risk: Chronic untreated instability or repeated dislocation can disrupt the lunate's already precarious blood supply, leading to avascular necrosis and progressive bone collapse
Signs and Symptoms
- Murphy's Sign: When making a fist, the 3rd metacarpal head is level with the 2nd and 4th (normally it projects distally) — hallmark clinical indicator
- Deep, localized pain in the center of the wrist, aggravated by extension
- Median nerve signs: Numbness, tingling in thumb and first three fingers (acute CTS from carpal tunnel compression)
- Flick sign: Patient shakes the wrist to relieve numbness (secondary CTS indicator)
- Possible "dinner fork" appearance or loss of the hand's transverse arch
- Significant grip weakness
- Red flags: Median nerve compression symptoms require medical referral; reduction must only be performed by a specially trained provider — never attempt manipulation
CMTO Exam Relevance
- CMTO Appendix category A1 (MSK conditions)
- Murphy's Sign is a key clinical indicator for lunate displacement
- Essential to screen for secondary carpal tunnel syndrome (Phalen, Tinel tests)
- "Terry Thomas" sign on imaging confirms scapholunate dissociation
- Red flag: median nerve compression symptoms require medical referral
Massage Therapy Considerations
- Acute phase: Locally contraindicate massage at the site to avoid exacerbating damage. Reduction is a medical procedure
- Subacute/chronic: Address protective muscle hypertonicity in muscles crossing the wrist (forearm flexors, extensors, pronators)
- CTS management: If displaced lunate compresses the median nerve, stretch wrist flexors to decompress the carpal tunnel. Passive joint movements within painless range
- Kienbock disease awareness: Chronic untreated instability can lead to avascular necrosis of the lunate — refer for medical management if symptoms persist
- Focus: Restore wrist joint play through gentle accessory mobilization. Address forearm muscle imbalances contributing to wrist instability
Key Takeaways
- Murphy's Sign (3rd metacarpal head level with 2nd and 4th when making a fist) is the hallmark clinical indicator
- Anterior lunate displacement into the carpal tunnel can cause acute CTS — screen with Phalen and Tinel tests
- Reduction must only be performed by a specially trained provider. Never attempt manipulation
- Acute phase is locally contraindicated. Subacute work addresses protective muscle hypertonicity in wrist muscles
- Chronic untreated instability risks progression to Kienbock disease (avascular necrosis of the lunate)