Assessment of Femoral and Tibial Component Rotation in Total Knee Arthroplasty Performed Using “Tensioned Gap” and “Free-floating Range of Motion” Techniques: A Computed Tomography-based Observational Study

Abstract

Abstract Background: Total knee arthroplasty (TKA) has an excellent success rate for the treatment of advanced arthritis of the knee. Component malrotation is one of the main causes of poor outcomes. We performed this study to assess the accuracy of the “Tensioned gap” and “Free-floating Range of Motion” techniques in TKA for rotational alignment of femoral and tibial components, respectively, which do not depend on anatomical landmarks. Materials and Methods: This prospective observational study included 64 TKA performed on 36 patients (24 females and 12 males), during 2015–2018. The average age was 59.9 ± 7.12 years (range 50–71 years). All patients were operated on with cemented fixed-bearing cruciate substituting TKA with posterior stabilization. Femoral component rotation was determined by the “Tensioned Gap” technique, and tibial component rotation was determined by the “Free-floating Range of Motion” technique. The measurement of femoral and tibial component rotation was performed on a computed tomography scan. Results: The mean femoral component rotation was 2.73° ± 0.93° of external rotation, range: 1.0°–4.7° of external rotation. The mean tibial component rotation was 0.30° ± 3.97° of internal rotation, range: 10° of internal rotation to 6° of external rotation. Conclusion: We concluded that the “tensioned gap technique” is found to be a reliable and reproducible technique for the rotational alignment of the femoral component. Considering the number of TKA performed annually, and the data derived from the present study, the “Range of Motion” technique is not found to be a notable intraoperative method for determining the rotational position of the tibial component in relation to tibial tuberosity.