No difference in the anteroposterior stability between the GRADIUS and multi-radius designs in total knee arthroplasty

This retrospective study aimed to compare stability and clinical and radiological outcomes of total knee arthroplasty (TKA) for the GRADIUS and multi-radius femoral designs after minimum of two-year follow-up.

A total of 142 patients who underwent TKA using ATTUNE posterior stabilized (PS) implants (68 patients, GRADIUS group) or Persona PS implants (74 patients, multi-radius group) for degenerative osteoarthritis were included. After an average of 2-year follow-up, the anteroposterior (AP) stability at 30°, 60°, and 90° was measured using KT 2000 device and compared between the two groups. The clinical outcome measurements included range of motion (ROM) of the knee, patient-reported outcomes and anterior knee pain (AKP). For the clinical evaluation of mid-flexion instability, pain was evaluated using the visual analog scale (VAS) score recorded during climbing up or going down stairs. The radiolucent lines on knee radiographs obtained at final follow-up were evaluated and compared between two groups.

The average AP stability at 30° knee flexion was 5.7 mm in the GRADIUS group and 5.9 mm in the multi-radius group; however, the difference was not significant. The AP stability at 60° and 90° knee flexion was also similar in both groups. There were no significant differences in the ROM, patient-reported outcomes at follow-up, incidence of AKP and VAS scores between the two groups. There were no differences in the incidence of radiolucency around the components between the two groups.

The GRADIUS design did not show any advantage with respect to the stability or clinical outcomes compared with the multi-radius design in TKA.