Perilunate Injuries

Introduction

Severe carpal injury resulting from wrist hyperextension.

Anatomy

Space of Poirier: Inherently weak area palmarly between the lunate and capitate that lacks substantial ligamentous connections.

Nomenclature

There are many variations of injury that include combinations of fractures and dislocations. When describing an injury the prefix, "trans", is used when describing a fracture. For instance when a fracture passes through the scaphoid and there is a perilunate dislocation one would say, "transscaphoid perilunate dislocation".

• Lesser arc injuries: refers to a purely ligamentous injury about the lunate.
• Greater arc injuries: involve fractures of some of the bones surrounding the lunate.

Pathogenesis

The injury typically propagates from radial to ulnar through the carpus. The injury force typically enters the carpus through the scaphoid (transscaphoid fracture) or through the scapholunate interval followed by the space of Poirier and finally the lunatotriquetral articulation. Variations of this pattern include fractures through the carpal bones surrounding the lunate, as well as trans-radial styloid fractures.

Four stages of progressive instability:

1. Disruption of scapholunate articulation or scaphoid fracture
2. Force continues through the space of Poirier (lunatocapitate articulation)
3. Disruption of lunotriquetral articulation and separation of the carpus from the lunate (typically dorsally)
4. The lunate dislocates from the lunate fossa and rotates into the carpal tunnel, hinged on the palmar ligaments ("spilled teacup sign"). The images below demonstrate a trans-radial styloid, trans-scaphoid, Stage IV perilunate dislocation

Natural History

Describe the natural history,epidemiology and prognosis

Patient History and Physical Findings

History:

Physical Findings:

Imaging and Diagnostic Studies

Radiography:

• AP and lateral X-rays

Differential Diagnosis

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Treatment

Initial Management:

• Closed vs. open reduction
• Open reduction preferred if swelling is not excessive
• Consider carpal tunnel release with some injuries

Definitive Management:

• Closed reduction and percutaneous pinning may be employed when an acceptable closed reduction can be achieved
• Perilunate dislocations: Open reduction is the preferred technique 
• Dorsal approach:
  
  • scapholunate joint pin fixation and ligament repair
  • scaphocaptiate pin fixation
  • lunotriquetral reduction and pinning
    
    • ligament typically nonrepairable
• Volar approach:
  
  • carpal tunnel release
  • capsular repair
• Transscaphoid perilunate dislocation
• ORIF of the scaphoid
• CRPP of lunotriquetral joint
• Consider repairing the volar ligaments

Pearls and Pitfalls

Tips and problems to avoid

Postoperative Care

Include immediate postoperative care and rehabilitation

Outcome

Include functional and prosthetic survivorship data as applicable

Complications

• carpal tunnel syndrom
• chondrolysis
• carpal instability 
• scaphoid nonunion

References