Research Basis

Dr. Bodner's Planning Algorithm

The scientific foundation behind CupCalc's Potential Normalized Center and spinopelvic planning framework.

AAOS 2023 Poster

The Potential Normalized Center (PNC) and the biplanar functional planning algorithm implemented in CupCalc were first presented by Dr. Russell J. Bodner at the American Academy of Orthopaedic Surgeons Annual Meeting in 2023. The poster introduces a novel framework for predicting postoperative spinopelvic normalization and incorporating that prediction into preoperative cup positioning.

Bodner AAOS 2023 Poster — A Novel Biplanar Functional THA Planning Algorithm
Bodner RJ. A Novel Biplanar Functional THA Planning Algorithm Including Age and Predictive Postoperative Changes. AAOS Annual Meeting 2023. Las Vegas, NV.

What is the Potential Normalized Center?

The PNC is the predicted center of the 1-year postoperative safe zone — where the functional cup target is expected to land once spinopelvic mobility normalizes after THA.

Total hip arthroplasty relieves hip impingement, allowing femoral flexion to recover. As the hip regains range of motion, the pelvis no longer needs to compensate with excessive posterior tilt in sitting. This normalization shifts the functional acetabular index (AI) and modifies the effective cup orientation relative to the pre-operative state.

The PNC predicts where the cup will functionally land at one year, based on the patient's preoperative mobility class, pelvic incidence, and age-adjusted recovery coefficient (K). Planning toward the PNC rather than only the preoperative target can reduce the risk of functional mismatch as the patient's kinematics evolve postoperatively.

Supporting Literature