Double column acetabular fractures fixation using a novel dynamic anterior plate-screw system: A biomechanical analysis

According to the classification of Judet and Letournel, all double column acetabular fractures will certainly involve the disruption of the quadrilateral plate (QLP). Accurate reduction and reliable fixation of QLP is the key to obtain a normal congruent hip joint and avoid postoperative arthritis. The aims of this study were to assess the biomechanical properties of a novel dynamic anterior plate-screw system (named DAPSQ) and to compare its biomechanical stability with buttress-plate construct.Double column acetabular fractures involving the QLP were created on cadaveric pelvic specimens and subsequently stabilized with (1) a pre-contoured side-specific DAPSQ titanium plate and 4 quadrilateral screws (Group A) or a 12-hole suprapectineal pelvic reconstruction plate combined with a 9-hole 1/3 tube buttress plate (Group B). These constructs were mechanically loaded on ZwickZ 100 testing machine. Construct stiffness and displacement amounts of the two fixation methods in the condition of dynamic axial loading conditions were measured.As the axial loading force increased from 200 N to 800 N, the longitudinal displacement of each pelvic specimen increased linearly and Group B was found to have significantly higher displacement than Group A (p0.05). In the 600 N physiological loading, the construct stiffness values of Groups A and B were 139.4 ± 37.4 N/mm and 101±18.3 N/mm, respectively. Group A is 27% stiffer than Group B(p0.05).In this in vitro biomechanical study, DAPSQ plate and quadrilateral screws fixation of a double column acetabular fracture involving the QLP resulted in a better fixation construct than the traditional suprapectineal pelvic reconstruction plate and 1/3 tube buttress plate fixation.