Lunate Dislocation: A Case Presentation for FRCS (Tr & Orth) Oral Examination
1. Describe this radiograph. What additional imaging might you request and what would you expect this to show?
This is a lateral radiograph of the left wrist that shows a volar dislocation of the lunate while the capitate is articulating with the radius. To further evaluate the injury, a PA view of the wrist should be taken to look for malalignment in the carpus and of the radiocarpal axis. Interruption of Gilula’s lines may also be observed, and the lunate might appear ‘wedge’- or ‘slice of pie’-shaped and overlap with the capitate. Radiographs should also be assessed for any evidence of fractures and intercarpal widening.
A lateral radiograph of the left wrist is indicative of a volar lunate dislocation with capitolunate articulation. Gilula's lines should be observed on the PA view of the wrist, which may reveal malalignment in the carpus and radiocarpal axis and confirm the condition. Interruption of Gilula's lines may be noticed, and the lunate may appear 'wedge' or 'slice of pie'-shaped and overlap with the capitate. Plain radiographs should also be examined for evidence of fractures and intercarpal widening.
2. How many Gilula lines are there?
There are three Gilula lines. The first line follows a smooth curve outlining the proximal convex surfaces of the scaphoid, lunate, and triquetrum. The second line traces the distal concave surfaces of the same bones. The third line follows the proximal curvatures of the capitate and hamate.
Gilula's lines are used for evaluating the alignment of the wrist. Three Gilula lines are taken into account, with the first line outlining the proximal convex surfaces of the scaphoid, lunate and triquetrum in a smooth curve. The second line traces the distal concave surfaces of the same bones, while the third line follows the proximal curvatures of the capitate and hamate.
3. How would you manage this injury in the emergency department?
This injury is a potentially high-energy injury and requires assessment using ATLS guidelines. The patient needs to undergo a circumferential examination to ensure it is a closed injury. Next, the neurovascular status of the hand should be evaluated, with the median nerve being of particular concern. The patient should be provided with suitable analgesia and prepared for closed reduction, which should be performed under conscious sedation. This should be achieved by applying longitudinal traction across the wrist with slight wrist extension while applying direct thumb pressure over the lunate from palmar to dorsal. The wrist should then be gently flexed, and the lunate 'thumbed' back into place. The traction should be relaxed, and the wrist placed in a below elbow backslab, with the wrist immobilized at 10 degrees of palmar flexion. The reduction should be confirmed and the position determined using PA and lateral radiographs. If closed reduction fails, the patient should be placed in a wrist splint and the limb elevated in a Bradford sling to minimize swelling. The patient would need to be admitted, and open reduction would need to be performed with palmar carpal tunnel approach and stabilized surgically on the next available operating list by an experienced upper limb surgeon.
Assessment of this condition should follow ATLS guidelines, owing to its potential high-energy nature. A circumferential examination of the patient is required to ensure the injury is a closed one. The neurovascular status of the hand needs to be evaluated, specifically for the median nerve. Closed reduction would then involve longitudinal traction across the wrist with slight wrist extension, combined with direct thumb pressure over the lunate from palmar to dorsal. The wrist should then be gently flexed, and the lunate reduced back to its position. Patients should be given suitable analgesia and immobilized with wrist splints, a below elbow backslab, and observation. In cases of failed closed reduction, open reduction is necessary whereby stabilization is performed through dorsal approach to the wrist and carpus.
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