Authors: R. Bruce Simpson M.D. Brett Barrick, M.D. Emil Azer M.D. Darryl Auston, M.D. Ph.D.
Author Affiliations: RBS: Trinity Health of New England, Hartford, CT; BB: Orthopedic & Trauma Services of Oklahoma, Tulsa, OK; EA: Upstate Orthopedics, Syracuse, NY; DA: OrthoOne, Thornton, CO

Introduction: The Moore classification of fracture dislocations of the knee remains relevant in identification of these injuries. Historic rates of neurovascular compromise and long-term prognosis are poorer than tibial plateau fractures. Correct identification of these injuries, therefore, is critical for proper treatment of these injuries. This report identifies four unique radiographic characteristics of Moore type 1 and 2 fracture dislocations. 1) lateral dislocation of the lateral tibial condyle, 2) valgus impactation of the lateral tibial spine, 3) tibial varus malalignment, and 4) a cortical fallen leaf fragment. We analyze the frequency of each radiographic finding and compare them to the radiographic features of medial (Schatzker 4) tibial plateau fractures.

Methods / Materials: Retrospective review of 34 patients who underwent operative fixation for a Moore 1 or 2 knee fracture-dislocation or Schatzker 4 medial tibia plateau fracture during an eight year period. Injury radiographs and computed tomography (CT) scans were reviewed to assess the percentage of patients with and quantitatively analyze the 4 radiographic patterns between the two groups.

Results: The radiographic differences between knee fracture-dislocations and medial tibia plateau fractures was as follows, (1) lateral dislocation of the lateral tibial condyle (90% vs 0%, p=0.0003);(2) valgus impaction of the lateral tibial spine (71% vs 0%, p =0.007); (3) tibial varus malalignment (90% vs. 0%, p=0.0003); (4) cortical “fallen” leaf fragment (66% vs. 0%, p=0.012).

Discussion / Conclusion: Moore type 1 and 2 knee fracture dislocations can be reliably distinguished from medial tibial plateau fractures based on all four radiographic characteristics. Identification of knee fracture dislocation can help guide surgical decision making and educating patients on poorer long term prognosis.

Description: Plain film demonstrating four unique radiographic findings of Moore-type knee fracture dislocations