The Importance of Proper Acetabular Component Positioning and the Challenges to Achieving It

The importance of proper cup placement cannot be overemphasized, regardless of the bearing material or diameter. Unsatisfactory acetabular component position has been associated with instability, increased wear, and pain. Pelvic, acetabular, and femoral anatomy are all variable, so it is illogical to have the same fixed target position for all patients. The hip arthroplasty surgeon actually faces 2 challenges: (1) determining the desired acetabular component position for each patient (the target), and (2) how to reasonably obtain that position in surgery (hitting the target). An abduction angle of 40° ± 10° is generally satisfactory. Anteversion is more complex. The desired amount of anteversion is influenced by (a) the amount of femoral anteversion and (b) the cup abduction angle. A combined anteversion of 25° ± 10° is generally satisfactory. A combination of internal and external landmarks can be used to assess the relative component position. Routine evaluation of intraoperative range of motion is an additional check. When in doubt, we try to obtain a quality intraoperative image.