Medial-Pivot Design Improved Knee Symptoms From Anteroposterior Instability in Early-Range Flexion and Resolved Anterior Knee Pain in Revision Total Knee Arthroplasty.

Abstract

Instability can lead to poor functional results after tricompartmental total knee arthroplasty (TKA). We identified a group of patients who appeared to have anteroposterior (AP) instability in early-range flexion (ie, 20 to 30° range) associated with anterior knee pain and feelings of instability. The purpose of this study was to assess the clinical results in terms of stability and anterior knee pain after revision TKA with a medial-pivot implant and to assess the effect of the implant positioning used in the revision technique. There were 45 patients (45 knees) evaluated retrospectively to assess standing lower extremity alignment and functional results by generating a knee stability score after revision TKA with medial pivot implant design. Revision TKA using the medial-pivot TKA lowered the joint line by 3.6 millimeters (mm) (P < .001) and positioned the tibia anteriorly by 3.5 mm (P < .001) on radiographic measurements as compared with results after primary TKA. Moreover, medial pivot revision TKA improved AP stability by a 56-point change in score (P < .001). Revision TKA using a medial pivot design improved AP stability and anterior knee pain after failed primary procedures.