Biomechanical consequences of anterior column fracture of the acetabulum.

OBJECTIVES

To measure biomechanical consequences of a high anterior column acetabular fracture.

DESIGN

A benchtop biomechanical model using quasi-static loading of the hip joint in a simulated single-leg stance. Pressure-sensitive prescale (Fuji) film was used to determine hip joint loading parameters.

PARTICIPANTS

Six cadaveric hemipelvi with one hip tested in each specimen. Three right and three left hips were tested.

INTERVENTION

Creation of an anterior column fracture with anatomic reduction and fixation, followed by gap malreduction/fixation, and subsequently step malreduction/fixation.

MAIN OUTCOME MEASUREMENTS

Contact pressure, contact area, and load distribution throughout the hip joint in each experimental condition.

RESULTS

There were significant increases in load (p<0.01) and peak pressures (p<0.01) in the superior acetabular region after gap malreduction and in peak contact pressures after step malreduction (p<0.01) as compared with the intact acetabulum. Anatomic reduction was not associated with increased mean or peak contact pressures (in any region).

CONCLUSIONS

Both step and gap malreductions of a high anterior column fracture resulted in significantly increased peak contact pressures in the superior acetabular region. These biomechanical data cannot be directly extrapolated to clinical applications, but these data suggest that anatomic reduction of anterior column fracture affords the best opportunity to restore contact pressures, contact area, and load distribution within the hip to levels similar to those seen in the intact acetabulum.