Optimization of total hip arthroplasty implantation: is the anterior pelvic plane concept valid?

The anterior pelvic plane (APP) is currently used as superficial anatomical landmark for three-dimensional orientation during total hip arthroplasty (THA), specifically when using computer aided surgery. However, the actual parameter for characterizing the pelvic orientation is the sacral slope, which correlates with other functional spinal parameters. The goal of the paper was to investigate relationships between APP and sacral slope. Both were measured on 328 lateral radiographs of the pelvis in standing position by two observers. The poor correlation between APP and sacral slope suggest keeping using the reference to the APP for the per-operative orientation in the 3D space, while individually adjusting the preoperative planning to the sacral slope.