112 Trans-Scaphoid Perilunate Dislocation. Two Atypical Presentations with Enucleation of The Proximal Pole

This article describes two cases of tran-scaphoid perilunate dislocation, both of which have an atypical presentation. In both cases, the proximal pole of the scaphoid was enucleated, one into the carpal tunnel, the other into the distal forearm. In addition, the capitolunate alignment was preserved, with dorsal dislocation of the entire carpus. These cases are presented for educational purposes, as these injuries are highly unstable, and require a different operative approach to a typical perilunate dislocation. In a typical Mayfield II perilunate dislocation, the lunate remains within the lunate fossa, and acts as a 'keystone' for fixation of the dislocated carpus. These cases do not fit the classic Mayfield classification. Given the lunate was also unstable, K-wires were placed through the distal radius into lunate, then from the scaphoid into the lunate. Another learning point for all training levels is that the referring orthopaedic hospital referred one of these injuries incorrectly as a 'lunate dislocation'. This article provides an opportunity to re-cap the Mayfield classification, and clarify the distinction between lunate and perilunate dislocation. In all cases, stringent monitoring for any carpal tunnel syndrome is required, and urgent decompression should be performed if there is any concern.