Clinical evaluation and accuracy of mechanical axis alignment in robotic total knee arthroplasty

The first experience in robotic total knee arthroplasty (RoTKA) has been obtained resulting in the questions about clinical efficiency and accuracy of lower limb alignment.Objective To clarify clinical evaluation and accuracy of alignment of the mechanical axis of the lower limb in RoTKA.Materials and methods Twenty-nine patients with osteoarthritis of the knee of Kellgren-Lawrence stage 3-4 underwent RoTKA. The knee joint was assessed with VAS, WOMAC, FJS-12; the range of motion was measured. The changes in the axis of the lower limb were evaluated on the full limb length radiographs.Results Pain before the surgery according to VAS was 5.8 ± 1.5 points, on the first day after the surgery it was 8.5 ± 1.4, on day 3 - 5.9 ± 1.2, on day 12 - 2.9 ± 1.1. The range of motion on the first day after the surgery was 99.5° ± 1.4°, three months later - 115.1° ± 1.1°, six months later - 125.6 ± 1.5°, one year later- 127.5 ± 1.6°. The WOMAC score before the surgery was 32.7 ± 3.3, after the surgery 25.1 ± 2.1, three months later 7.3 ± 1.3, six months later 2.8 ± 0.2, and after one year - 1.3 ± 0.5. The FJS-12 score 3 months after the surgery was 68.2 ± 4.1, after 6 months 80.3 ± 2.9, after one year 94.0 ± 2.1. The analysis of postoperative full length roentgenograms in 72 % of cases (n = 21) did not reveal any deviation of the mechanical axis from the planned one and in 28 % of cases (n = 8) the deviation of the mechanical axis was up to 1° from the planned one.Discussion Neither technical difficulties nor complications inherent to RoTKA were found. According to the results of VAS, WOMAC and FJS-12 questionnaires, and the assessment of the range of motion, a positive dynamics was observed. According to the results of tele-roentgenograms, there was alignment of the limb axis and the accuracy of the position of the endoprosthesis components.Conclusion The study of this technology has demonstrated safety, accuracy of alignment of the mechanical axis, validity of indications and contraindications, and stable early clinical results.