Background: Lower limb malalignment is a hallmark of knee osteoarthritis, with surgical correction techniques evolving from traditional mechanical alignment (MA) to kinematic alignment (KA) approaches. Restrictive kinematic alignment (rKA) represents a hybrid strategy combining principles from both techniques. This study evaluated short-term functional outcomes following robotic-assisted total knee arthroplasty (RoTKA), comparing MA versus rKA alignment strategies. Methods: This prospective, randomized, single-center study enrolled 96 patients with grade 3–4 idiopathic knee osteoarthritis (Kellgren–Lawrence classification). Patients were randomized to MA (n = 49, mean age 67 ± 9 years) or rKA (n = 47, mean age 66 ± 7 years) groups. Preoperative hip–knee–ankle (HKA) angles were 172.6° ± 1.1° and 172.9° ± 0.9° for MA and rKA groups, respectively. Outcomes were assessed using Visual Analog Scale (VAS) pain scores, range of motion (ROM), Knee Society Score (KSS), Oxford Knee Score (OKS) (primary outcome), SF-36, and Forgotten Joint Score (FJS-12). Results: Postoperative HKA angles were 179.5° ± 1.2° (MA) and 176.0° ± 1.5° (rKA). At 14 days postoperatively, knee ROM increased by 20.5% in the MA group and 25.7% in the rKA group, with a statistically significant 5.2% intergroup difference, indicating faster postoperative recovery (p = 0.008). VAS pain scores decreased by 7% in the rKA group while increasing by 13% in the MA group (p < 0.001). At one-year follow-up, FJS-12 scores were significantly higher in the rKA group (94.8 ± 3.2 vs. 91.9 ± 2.2, p < 0.001). No significant differences were observed in KSS, OKS, or SF-36 score between groups. Conclusions: Restrictive kinematic alignment demonstrated superior early postoperative outcomes compared to mechanical alignment in RoTKA, with significantly reduced pain and improved ROM. While one-year functional outcomes were comparable between techniques, rKA may offer advantages in the immediate postoperative period, supporting its consideration as a viable alignment strategy in robotic-assisted 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.

Introduction There are two main concepts of total knee arthroplasty: mechanical and anatomical alignment of the lower limb axis. Howell et al. (2013) proposed the concept of kinematic alignment, the main idea of which is to preserve the level of the joint line and the axis of the lower limb that patients had before the onset of osteoarthritis. Initially, kinematic alignment was proposed to be performed with individual guides based on the results of CT/MRI scans but they took a long time to manufacture, were difficult to install, broke down, and were quite expensive. Introduction of robotic orthopaedic systems into clinical practice enabled to plan and perform bone resection with high accuracy, to install the components of the implant system according to the necessary concept thus providing new opportunities for the application of kinematic alignment, which was the purpose of our study.Purpose To study the possibilities of a robotic surgical system in performing restricted kinematic alignment in total knee arthroplasty (TKA).Materials and methods A prospective single-center study was conducted in 47 patients (12 men and 35 women) with knee osteoarthritis in Kellgren – Lawrence grades 3–4, an average age of (65.87 ± 7.4) years, an average BMI of (31.3 ± 4.7) kd/m2 , median HKA angle of 175°, median LDFA of 87°, median MPTA of 87°. The patients underwent robotic total knee arthroplasty (RoTKA) with the method of restricted kinematic alignment.Results On the control whole-leg radiographs, the average HKA angle after surgery was (176 ± 1.5)°. In 42.6 % of cases, the deviation from the plan was within ± 1°, the deviation ± 2° in 44.7 % of cases, and in the remaining 12.7 % of cases the deviation was negative.Discussion In the literature, we did not find the results of radiographic evaluation of the HKA angle in the coronal view before and after robotic total knee arthroplasty and their comparison with the results of preoperative planning using the kinematic alignment method of the limb axis. The results we obtained show high accuracy of the implementation of the preoperative plan.Conclusion A personalized approach to TKA with application of an autonomous robotic system effectively provides kinematic alignment of the axis of the lower limb with an accuracy of up to 2° in 87.3 % of patients.

The objectives of total knee arthroplasty (TKA) are pain relief, increased range of motion, and alignment of the mechanical axis of the limb. The aim of this study was to investigate the accuracy of alignment of the mechanical axis of the lower limb during robotic primary TKA in comparison with computer navigation and manual technique. A prospective double controlled study of 99 patients randomized into groups was performed. Group A (main) included 29 patients who underwent robot-assisted TKA, group B (control) included 32 patients who underwent standard endoprosthetic technique, and group C (control) included 31 patients who underwent computer-navigated arthroplasty. Telerentgenogram and computed tomographic examination were performed, and the accuracy of mechanical alignment of the limb axis was analyzed. In group A, the accuracy of the mechanical axis is up to ± 1° — 72%, from ±1º to ±3º — 28%, in group B up to ± 1° — 30%, from ± 1° to ±3° — 55%, and more than ± 3° — 15%, in group C up to ± 1° — 45%, from ± 1º to ±3º — 48%, more than 3º — 7%. The accuracy of the alignment of the mechanical axis of the limb with robotic TKA up to ±1° is 72%, statistically significantly exceeds manual technique (30%) and computer navigation (45%), which opens up new prospects in the survival of endoprostheses.