Measurement of acetabular component migration using two-dimensional radiography.

ABSTRACT

The relationships between apparent acetabular component migration, choice of anatomic landmarks, and changes in rotation of the pelvis were determined by examining radiographs of a pelvic model in multiple projections. The minimum apparent migration associated with transverse and longitudinal rotation of 5 degrees from neutral was 2 mm. The least apparent migration was noted when the teardrop was used as the principal anatomic landmark. Determination of component migration in clinical studies from serial radiographs involves a minimum projection and magnification error of 2 mm.