Stage 2, Perilunate dislocation Test Cases Introduction Role of Plain Films in Diagnosing Wrist Dislocations/Ligamentous Injuries: Often an Underutilized Modality That Can Diagnose Complex/Rare Cases Utilizing Simple Rules Rami E Eldaya, Jorge Lee-Diaz, Glen M. Garcia University of Texas Medical Branch Stage 2, Perilunate dislocation Test Cases Introduction Value of frontal image for detection of carpal ligamentous injuries Gilula’s lines Wrist Dislocation Summary Stage Pathophysiology Radiographic appearance Miscellaneous Stage 1, sacpholunate dissociation rupture of the scapholunate ligament Frontal:   widening of the scapolunate interval > 3mm can see ring sign on AP secondary to rotatory subluxation of the scaphoid Lateral: typically normal Normal scapholunate interval is less than 3 mm Stage 2, Perilunate dislocation Capitate dorsal Lunate can appear triangular in appearance (not specific) Disruption of Gilula’s lines capitate dislocates dorsally and the lunate maintains a normal articulation with the radius Much more common than lunate dislocation High association with transcaphoid fractures Triquetrum, capitate and ulnar styloid fractures can also be seen Stage 3, midcarpel dislocation Triquetral ligaments disruption lunate dislocates volarly and the capitate and carpus dislocate dorsally. Stage 4, lunate dislocation Lunate dislocation lunate overlaps the capitate and has a triangular or piece of pie appearance lunate seen displaced and angulated volarly the capitate remains aligned with the radius Can lead to median nerve entrapment Most of carpal ligamentous / dislocation injuries present acutely to the emergency department with pain or deformity after recent traumas. Plain films are the initial modality of evaluation. Also, carpal and carporadial  dislocations/ligamentous injuries have been described in literature since 1970s yet they remain puzzling  plain film diagnosis for a lot of junior residents. This is likely due to relative rarity of the injury, complex nature of the injury, and lack of familiarity of radiographic findings of such injuries secondary to growing dependence on MR for evaluation of these injuries Frontal radiographs depicting Gilula’s Lines: Black arc: outlining the proximal convexities of the scaphoid, lunate, and triquetrum Orange arc: outlines the distal surfaces of the scaphoid, lunate, and triquetrum Green line: outlines the proximal capitate and hamate Disruption of any of these lines is suggestive of carpus injury with two exceptions: A triquetrum that is shorter than the lunate leads to a step-off in the first arc (the second arc remains normal) Bi-lobed appreance of the second arc secondary to lunate type II morphology Note on frontal images disruption of the second (blue) and third (green) Gilula lines suggestive of carpus dislocation/ligamentous injury. The red arrow highlights a scaphoid fracture, a typical associated injury. Lateral image demonstrate disruption of the radius, capitate, and lunate line (blue arrow). The lateral image is imperative in differentiating stage 2 from 4 based on displacement of bones. In this case dorsal capitate displacement is present. Purpose of Abstract We will review the complex-ligamentous anatomy of the wrist on plain film We will introduce a systemic method to help detect these injuries on radiographs We will review the pathophysiology of such injuries with emphasis on the perilunate-lunate injury complex 4 stages We will test the attendant knowledge with complex rare case Value of the lateral image for evaluating of carpal ligamentous injuries Stage 4, Lunate dislocation Lateral view is the optimal view to diagnose carpal dislocations. Normal wrist should exhibit alignment between the radius, capitate, and lunate as suggested by a line drawn through the radius (red line). If the line fails to intersect any of the three bones, a carpal dislocation injury is suggested. Stage 1, Scapholunate dissociation References Note widened scapholunate interval (arrow). The Stage 1 SLD is best appreciated on frontal radiographs 1) Mayfield JK. Mechanism of carpal injuries. Clin Orthop Rel Res. 1980;149:45–54 2) NA Siddiqui, SP Sarkar Isolated Dorsal Dislocation of the Lunate Open Orthop J. 2012; 6: 531–534. Published online 2012 November 30 3)Gilula LA. Carpal Injuries: Analytic approach and case exercises. Am J Roentgen. 1979;133:503–17 4). Bilos ZJ, Hui PW. Dorsal dislocation of the lunate with carpal collapse. Report of two cases. J Bone Joint Surg. 1981;63-A(9):1484–6. [PubMed] 5). Seidenstein H. Two Unusual dislocations at the wrist. J Bone Joint Surg. 1956;38-A:1137–41. Frontal Image demonstrate disruption of the second Gilula’s line (blue arrow) Lateral Image demonstrate volar displacement of the lunate (blue arrow)