The Effect of Lateralization of a Pelvic Brim Plate on the Fixation of an Anterior Column Fracture: A Biomechanical Analysis

Objectives Anterior column fractures can be seen as either isolated or accompanied by many types of complex acetabulum fractures. The aim of this study was to biomechanically compare the stability of a standard pelvic brim plate with a more laterally located suprapectineal plate, which is more commonly used in minimally invasive application, on an intermediate height anterior column fracture model under dynamic and static loading. Materials and methods Right side, adult, foam cortical shell artificial hemipelvis models were used (Sawbones, Pacific Research Laboratories, Vashon, WA, USA). Twenty-four (24) pieces of foam cortical shell artificial hemipelvis models were separated into three groups (M, L, and control). In group "M," a suprapectineal plate was placed medially just adjacent to the pelvic brim. In group "L," a laterally located suprapectineal plate was placed 2 cm lateral of the pelvic brim at its most proximal point. Then, dynamic load testing of 1000 cycles between 50 N and 500 N force and a static load test of 1.2 kN at 2 mm/minute were applied. Dynamic and static tests were conducted on an axial compression device. Displacements were measured after dynamic and static loading conditions. Results In the dynamic loading test at the AL point (superior intersection of the fracture line with the acetabular roof), the median displacement was significantly higher in group L than in group M (0.12 (IQR: 0.058-0.8125) mm and 0.04 (IQR: 0.03-0.065) mm (p = 0.02)). There was no other statistically significant difference in the displacement amounts in both dynamic and static loading conditions at other measurement points. The comparison of the stiffness of the M and L groups showed no statistically significant results, while the control group was significantly more rigid than both the M and L groups (p = 0.04 for both). None of the artificial hemipelvis models was found to be fractured at the end of the test. Conclusion Suprapectineal plates, placed on either the medial or lateral aspect of the pelvic brim, may be used for the fixation of anterior column-type fractures to provide rigid fixation and stability. As plate location did not impact stiffness and stability, the results suggest that surgeons have flexibility in determining the fixation based on accessibility, fracture pattern, and surgeon experience.