What is the diagnosis?

Lunate dislocation. Note the loss of articulation with the radius and volar displacement of the lunate with on the lateral view.

What is this commonly confused with?

Perilunate dislocation (Image 2). Note the dorsal displacement of the other carpal bones in relation to the lunate, which maintains its articulation with the radius (Image 3). Management, disposition, and prognosis are the same for both. Read more about perilunate dislocations here.

• Pearl: 25% of cases are reportedly missed on initial presentation [1].

Image 2. Author’s image

What physical exam finding should you monitor?

Pay close attention to the neurologic exam. Numbness in fingers 1-4 signifies median nerve entrapment as the lunate compresses the carpal tunnel. This can indicate acute carpal tunnel syndrome, which requires urgent correction. 

• Pearl: 24-45% of cases are found to eventually have some type of median nerve damage [2].

What is your management?

Urgent closed reduction with placement in a sugar tong splint. This is done by hyperextending the wrist, pulling traction, then simultaneously placing dorsally directed pressure on the lunate while bringing the wrist over the top. See example here (1:00-1:30).

• Pearl: These can be difficult reductions that may require open fixation. If orthopedics is readily available, don’t be afraid to consult early.

What is your disposition? When does this patient need orthopedics?

After successful reduction and normal neurologic exam, the patient can be discharged with follow-up within the week with a hand surgeon as guided by institutional protocols. 

• Pearl: Without surgery, patients are at high risk for long term complications such as arthritis and loss of function, so be sure there is early follow-up in place [3].