An orthopaedic surgical instrument for positioning an acetabular prosthetic component in a patients surgically-prepared acetabulum has a base configured to engage the patients pelvis, a first linkage pivotally coupled to the base, a locking mechanism operable to lock the first linkage in position relative to the base, and a second linkage removably coupled to the first linkage. The second linkage has an alignment axis corresponding to a desired abduction angle and a desired anteversion angle of the acetabular axis of the acetabular prosthetic component.
