Evaluation of anterior translation in total knee arthroplasty utilizing stress radiographs

Abstract Background Flexion instability is a common cause for revision after total knee arthroplasty (TKA); however, little objective criteria exist to determine excessive laxity in flexion. This study sought to determine the reliability of stress radiographs for flexion laxity using manual stress as well as a commercially available flexion stress device, with the hypothesis that a commercially available force device would provide increased translation compared to manual stress, and radiographic measurements would be reproducible. Methods Ten patients who previously underwent TKA with non-hinged components were prospectively and consecutively enrolled at a single center to undergo stress radiographs. Three lateral radiographs with the knee at 90° of flexion were obtained for each patient: rest, commercial stress device at 150N, and manual stress. Calibrated radiographs were evaluated by two raters, and inter-rater and intra-rater reliability were determined using intraclass correlation coefficients (ICC). Results Ten patients (seven female) with mean age 72 (range 55–82) years and average duration from surgery 36 (range 12–96) months were evaluated. The commercial stress device provided significantly less anterior translation than manual stress (− 0.3 mm vs. 3.9 mm; p