Defining “Paradoxical Instability” and Other Indications for Aseptic Single-Component Polyethylene Revision: A Cohort Study Including Mid-flexion Instability and Limited Arc of Motion

SCPR demonstrated effectiveness in treating all 3 indications, with particularly promising results for paradoxical instability cases. This study establishes paradoxical instability as a distinct clinical entity characterized by knee imbalance, mid-flexion instability, recurrent effusions, and limited motion arc. This limited motion arc is paradoxically treated with an increase of polyethylene thickness. The findings support SCPR as a viable treatment option for carefully selected patients with these conditions.