BIOMECHANICAL CONSEQUENCES OF ANTERIOR COLUMN FRACTURE OF THE ACETABULUM

Objectives: To measure biomechanical consequences of a high anterior c olumn acetabular fracture. Design: A benchtop biomechanical model usin g quasi-static loading of the hip joint in a simulated single-leg stan ce. Pressure sensitive prescale (Fuji) film was used to determine hip joint loading parameters. Participants: Six cadaveric hemipelvi with o ne hip tested in each specimen. Three right and three left hips were t ested. Intervention: Creation of an anterior column fracture with anat omic reduction and fixation, followed by gap malreduction/fixation, an d subsequently step malreduction/fixation. Main Outcome Measurements: Contact pressure, contact area, and load distribution throughout the h ip joint in each experimental condition. Results: There were significa nt increases in load (p < 0.01) and peak pressures (p < 0.01) in the s uperior acetabular region after gap malreduction and in peak contact p ressures after step malreduction (p < 0.01) as compared with the intac t acetabulum. Anatomic reduction was not associated with increased mea n or peak contact pressures (in any region). Conclusions: Both step an d gap malreductions of a high anterior column fracture resulted in sig nificantly increased peak contact pressures in the superior acetabular region. These biomechanical data cannot be directly extrapolated to c linical applications, but these data suggest that anatomic reduction o f anterior column fracture affords the best opportunity to restore con tact pressures, contact area, and load distribution within the hip to levels similar to those seen in the intact acetabulum.