Working Diagnosis:
Trans-Scaphoid Perilunate Dislocation

Treatment:
Once the diagnosis of a Perilunate dislocation was made, and with the patient's presenting/worsening symptoms, it was decided that a closed reduction would be needed. Consent was given by the patient and he was sedated with 38mg of Etomidate, 50mcg of Fentanyl and 4mg of Morphine. The injured hand was then placed in finger straps and the elbow was placed at a 90 degree angle. On the distal part of the arm, the patient had 6lbs of traction and this was applied for 15-17 minutes. The wrist was then placed into extension with more traction applied followed quickly by flexion of the wrist. The patient felt immediate relief and an X-ray was taken to confirm proper reduction of the lunate Case Photo #3 . A sugar tong splint was applied with the wrist in 10 degrees of flexion and a slight radial deviation.

Outcome:
The patient was able to tolerate the procedure well. He was told to follow-up at the Orthopaedic clinic the next day and was referred to a hand surgeon for open reduction with ligament repair fixation with possible carpal tunnel release. Unfortunately the patient was lost to follow-up

Author's Comments:
Usually the mechanism of injury of a high velocity trauma onto a dorsiflexed wrist that has been ulnarly deviated is the most common cause of perilunate dislocations and perilunate fracture dislocations. Unfortunately, these injuries are often missed on initial presentation. Wrist dislocations only account for < 10% of all wrist injuries.

According to Mayfield et.al. there are four stages to describe a lunate instability: 1) Scapholunate dissociation or rotatory subluxation of the scaphoid 2) Perilunate dislocation commonly with scaphoid fractures 3) Midcarpal Dislocation usually with a triquetral fracture and 4) Lunate Dislocation. In the case of a Lunate dislocation, the scapholunate ligament is disrupted, followed by disruption of the capitolunate articulation and lunotriquetral articulation and the lunate will rotate into the carpal tunnel causing median nerve damage

It is important that even after closed reduction, the patient have ORIF. Patients who were operated on earlier than 5 months showed greater overall outcome with quicker return to activity. However, depending on the level of competition, even after the open reduction there is no guarantee the athlete will return to his pre-injury level.

Editor's Comments:
The author highlighted very well that those injuries are often missed initially. Radiographic evaluation is the key. The wrist PA view is useful as it enables to assess the Gilula lines, which are imaginary lines drawn across the proximal and distal aspects of the proximal carpal row and the proximal aspect of the distal carpal row. These lines should appear as 3 smooth arcs running nearly parallel to each other. Any disruption of these lines support carpal incongruity. The wrist lateral view is the most important. Any disruption of the collinearity of the radius, lunate and capitate suggests a perilunate dislocation. The presence of tingling or numbness in the median nerve distribution or acute carpal tunnel syndrome should prompt emergent close reduction but if symptoms persist despite close reduction, emergent open reduction should be performed. Close reduction with sedation followed by open fixation within a few days is preferred to close reduction and casting.
Even with optimal treatment, about 70% of patient will develop complications such as wrist stiffness, diminished grip strength, and post-traumatic arthritis but are often well tolerated.

References:
1) Mayfield JK, Johnson RP, Kilcoyne RK. Carpal Dislocations: pathomechanics and progressive perilunar instability. J Hand Surg AM. 1980;5 (3): 226-41

2) Jebson PJ, Engber WD. Chronic perilunate fracture dislocations and primary proximal row carpectomy. Iowa Orthop J. 1994:14:42:42-8

3) Pappas ND, Lee DH. Perilunate injuries. Am J Orthop (Belle Mead NJ). 2015 Sep;44(9):E300-2.

Acknowledgments:
Special thanks to Dr. David Postelnek, ER and Dr. David Dromsky, Ortho for their teaching and allowing me to be a part of this case.

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