Mastering Lunate Dislocation: A Case for FRCS Success
Key Takeaway
In this comprehensive guide, we discuss everything you need to know about Mastering Lunate Dislocation: A Case for FRCS Success. A volar lunate dislocation involves significant wrist injury, presenting as a specific dislocation a case where the lunate bone displaces volarly. The capitate typically remains articulated with the radius. Radiographic assessment reveals characteristic findings like carpal malalignment, interrupted Gilula’s lines, and the lunate appearing 'wedge'-shaped, requiring further imaging for confirmation.
A 35-year-old male presents following a high-energy motorcycle accident. He has severe pain, global wrist swelling, and paresthesia in the median nerve distribution. You are presented with his initial AP and lateral radiographs.
Describe the injury pattern seen on these radiographs and outline the emergency management steps required before definitive fixation.
Candidate: "This is a perilunate dislocation. On the lateral view, the capitate is dorsally dislocated from the lunate, while the lunate maintains its articulation with the distal radius. This indicates an unstable carpal injury. For emergency management, I would perform an immediate closed reduction under sedation, as there is evidence of acute median nerve compression, followed by urgent orthopaedic referral for open reduction and internal fixation."
Candidates often fail to describe the specific radiographic signs (e.g., the "spilled teacup" vs. "piece of pie"). They frequently skip the urgent clinical assessment, focusing only on the imaging, or fail to mention that this is a time-sensitive, potentially limb-threatening injury due to the median nerve compression.
The perfect candidate identifies this as a Mayfield Stage II/III perilunate dislocation. They describe the lateral "spilled teacup" vs. "piece of pie" on AP, but crucially state the four-step management plan:
- Urgent Neurovascular Status: Document median nerve deficit clearly.
- Reduction: Immediate closed reduction under regional/sedation (longitudinal traction + dorsal/volar pressure) to decompress the carpal tunnel.
- Post-Reduction Imaging: CT scan to assess for occult scaphoid fractures (Trans-scaphoid perilunate dislocation).
- Definitive Care: Early ORIF (combined volar and dorsal approach) to address the ruptured scapholunate and long radiolunate ligaments.
