The Role of Polar Axis Angle in Acetabular Component Positioning: A Case Report on Revision Total Hip Arthroplasty

A seventy-six-year-old woman with a prior total hip arthroplasty (THA) presented with instability requiring component revision. Seated imaging was used to understand functional component orientation in a position of high risk for posterior dislocation. Successful acetabular revision was performed using a polar axis angle (PAA)-driven approach to optimize postoperative stability. THA stability was maintained at 1-year and 2-year follow-up by imaging and clinical examination.

This case report applies the novel concept of the PAA, a method for assessing the mechanical stability of hip prostheses, in preoperative planning for a revision THA secondary to instability. This report highlights the utility of the PAA to guide acetabular revision, reduce dislocation risk, and achieve favorable short-term clinical outcomes.