Perilunate and lunate dislocations
Lunate and Perilunate Dislocation
Background
• Perilunate Dislocation
· Dorsal displacement of capitate in relation to lunate
· Note that the radius, capitate, lunate, and third metacarpal form a straight line on lateral x-ray
• Lunate Dislocation
· Volar dislocation of the lunate in relation to the radius, spilled teacup
Clinical Features
• FOOSH injury with excessive hyperextension, ulnar deviation, and intercarpal supination
• On exam, decreased range of motion with focal swelling
· Dorsal swelling with mass in perilunate dislocation
· Volar swelling with palpable mass in lunate dislocation
• Median nerve compression possible, perform thorough neurovascular exam
• Scaphoid fractures and scaphoid rotary subluxation are common
• Degenerative arthritis is very common, 60% incidence
Workup
• X-ray, wrist series, minimum of three views
• Perilunate dislocation
· Lateral view, dorsal dislocation of capitate when an imaginary line is drawn through radius, luante, and capitate
· PA view, capitate and lunate overlap
• Lunate dislocation
· Lateral view, lunate displaced and tilted volarly
· PA view, lunate is triangular in shape
Differential Diagnosis
• Fractures of the distal radius
• Fractures of the carpal bones, the scaphoid being the most common
• Scapholunate dissociation
• Ligamentous injury
• Septic arthritis
Treatment
• Immediate orthopedic consult for closed vs open reduction
· The longer the dislocation is left unreduced, the lower the likelihood of reduction
• In ED, volar splint in neutral
