The relationship between the survival of total knee arthroplasty and postoperative coronal, sagittal and rotational alignment of knee prosthesis

Purpose Our study sought to address four issues: (1) the relationship between postoperative overall anatomical knee alignment and the survival of total knee prostheses; (2) the relationship between postoperative coronal alignment of the femoral and tibial component and implant survival; (3) the relationship between postoperative sagittal alignment of the femoral and tibial components and implant survival; and (4) the relationship between postoperative rotational alignment of the femoral and tibial component and implant survival. We reviewed 1,696 consecutive patients (3,048 knees). Radiographic and computed tomographic examinations were performed to determine the alignment of the femoral and tibial components. The mean duration of follow-up was 15.8 years (range, 11-18 years). Thirty (1.0 %) of the 3,048 total knee arthroplasties failed for a reason other than infection and periprosthetic fracture. Risk factors for failure of the components were: overall anatomical knee alignment less than 3A degrees valgus, coronal alignment of the femoral component less than 2.0A degrees valgus, flexion of the femoral component greater than 3A degrees, coronal alignment of the tibial component less than 90A degrees, sagittal alignment of the tibial component less than 0A degrees or greater than 7A degrees slope, and external rotational alignment of the femoral and tibial components less than 2A degrees In order to improve the survival rate of the knee prosthesis, we believe that a surgeon should aim to place the total knee components in the position of: overall anatomical knee alignment at an angle of 3-7.5A degrees valgus; femoral component alignment, 2-8.0A degrees valgus; femoral sagittal alignment, 0-3A degrees; tibial coronal alignment, 90A degrees; tibial sagittal alignment, 0-7A degrees; femoral rotational alignment, 2-5A degrees external rotation; and tibial rotational alignment, 2-5A degrees external rotation.