The Use of CCK vs PS in Revision TKAs

Inclusion criteria: * Patients between 18-80 years of age * Patients who are undergoing both femoral and tibial component revisions, or isolated femoral component revisions with a retained tibial component that is compatible with PS or CCK bearings * Patients who are at least 6-weeks out from primary TKA surgery, with complete pre-operative and post-operative knee radiographs obtained at standard of care perioperative visits (AP/lateral and patellar views) * Patients undergoing rTKA for indications including aseptic component loosening, flexion or extension coronal or sagittal instability, component malalignment, arthrofibrosis, patellar maltracking, reimplantation following single or two-stage exchange revision for prosthetic joint infection or bearing surface wear when femoral or tibial component revision is indicated. * The use of revision total knee arthroplasty systems which have PS and CCK bearing options including different degree options of coronal and rotational constraint (to be individually randomized per constrained option): * Zimmer Biomet Persona, NexGen, or Vanguard * Smith and Nephew Legion * DJO / Enovis Empowr * Stryker Triathlon * Link SymphoKnee * Depuy Attune sion Criteria: Exclusion Criteria: Patients undergoing rTKA with a hinged implant, or pre-operatively determined to require CCK bearing rTKA, \> 80 years of age, or those requiring rTKA less than 6-weeks from the primary TKA, Patients undergoing rTKA for bearing exchange only rTKA, isolated tibia…