Does the clinical and radiologic outcomes following total knee arthroplasty using a new design cobalt-chrome tibial plate or predecessor different?

BACKGROUND: This study aimed to compare clinical and radiographic outcomes for a new tibial component (Attune S +) and the previous design (Attune S) in total knee arthroplasty (TKA) patients using ATTUNE® posterior stabilized (PS) prosthesis and also assessed related factors for the development of tibial radiolucent line(RLL). METHODS: This retrospective study included 362 knees (179 Attune S, 183 Attune S +) with an average 4 years (range, 2-8) follow-up. Clinical outcomes, radiologic parameters and the incidence of RLL around the tibial component were compared through the serial assessment. For the subgroup analysis, radiologic parameters were compared between patients with and without RLL. RESULTS: There was no significant difference in terms of clinical outcomes and radiologic parameters between two designs. The incidence of RLL was not different through the serial follow-up (P > 0.05). In the subgroup analysis, the preoperative medial proximal tibial angle (83.7° versus 85.0°, P = 0.01) was smaller and preoperative hip-knee-ankle angle (169.1° versus 171.8°, P = 0.01) has more varus in the group with RLL than those without. CONCLUSIONS: The clinical and radiologic outcomes including the incidence of tibial RLL between new design and predecessor were not significantly different at average 4 years follow-up. The development of tibial RLL was associated with preoperative varus deformity of tibia and lower limb alignment.