Anterior impingement caused by synovial tissue in the intercondylar notch after robot-assisted cruciate-retaining total knee arthroplasty: a case report

Abstract

Background Anterior knee pain and impingement are recognized complications after total knee arthroplasty (TKA), with causes including patella baja, patellofemoral maltracking, and implant design–related factors. However, synovial impingement in the intercondylar notch after cruciate-retaining TKA (CR-TKA) is rare and poorly characterized. Case presentation A 75-year-old woman underwent robotic-assisted cruciate-retaining TKA using a Triathlon® condylar-stabilizing insert. The postoperative alignment and early recovery were uneventful. At 3 months postoperatively, she developed anterior knee pain and a catching sensation during extension from 20° flexion. Conservative treatment failed to relieve the symptoms. Imaging studies showed no implant malposition, loosening, or patella baja. At 10 months postoperatively, synovectomy and insert exchange were performed. Intraoperatively, hypertrophic synovial tissue in the intercondylar notch impinged against the anterior lip of the insert. Tissue resection resolved the symptoms. Conclusions Synovial impingement should be considered a potential cause of anterior knee symptoms after CR-TKA with a CS insert.