Osteoarthritis of the knee represents a leading cause of pain and disability worldwide, affecting over 528 million individuals globally. In India, radiographic evidence of knee osteoarthritis is observed in 22 – 39% of adults over 40 years, with a higher prevalence noted among postmenopausal women and those with elevated body mass index. [1,2] The pathogenesis of knee osteoarthritis is multifactorial, involving age-related cartilage degeneration, subchondral bone remodelling, meniscal dysfunction, and low-grade synovial inflammation, culminating in progressive joint pain and functional limitation. [3,4] Conventional management integrates weight reduction, physiotherapy, analgesics, and intra-articular injections; however, these measures provide symptomatic relief without addressing structural derangements. [5,6] Total knee arthroplasty (TKA) remains the definitive intervention for end-stage disease, restoring alignment, stability, and mobility with proven long-term durability; yet, manual techniques may yield inconsistent implant positioning, suboptimal soft-tissue balancing, and variable patient satisfaction. [7] Robotic assistance in TKA has emerged to overcome these limitations by combining preoperative three-dimensional planning with intraoperative haptic guidance, thereby enhancing surgical precision, reproducibility, and early recovery. Although several studies have demonstrated improved alignment accuracy and reduced outliers in robotic versus manual TKA, evidence regarding medium-term functional outcomes—particularly in Indian cohorts—remains sparse. [8] The present prospective study evaluates the functional trajectory of patients with Kellgren–Lawrence grade III–IV knee osteoarthritis undergoing robotic-assisted TKA using validated objective and patient-reported metrics. By focusing on range of motion, Knee Society Scores, and complication rates over a six-month follow-up, this work uniquely addresses the clinical efficacy and safety of the CUVIS Joint™ autonomous robotic platform in an Indian tertiary-care setting, thereby filling a critical gap in current literature. Objectives 1. To access the functional outcome of patients undergoing robotic knee arthroplasty for osteoarthritis of knee joint using the Knee Society Score. 2. To analyze the associated complications during follow-up.

Study Design and Setting A single-centre, prospective cohort study was conducted at Sri Aurobindo Medical College and Postgraduate Institute, Indore, from March 2023 to September 2024. Ethical clearance was obtained from the Institutional Ethics Committee prior to patient enrolment. Participants Thirty patients aged ≥25 years with symptomatic primary or secondary osteoarthritis of the knee (Kellgren–Lawrence grade III–IV) scheduled for primary robotic total knee arthroplasty were consecutively recruited. Exclusion criteria included prior patellectomy, extra-articular deformity, malignant or septic joint pathology, revision arthroplasty, and refusal to consent. All participants provided written informed consent. Preoperative Assessment Baseline demographic data, comorbidities, body mass index, and American Society of Anaesthesiologists (ASA) physical status were recorded. Preoperative knee function was quantified using the Knee Society Score (KSS) and active knee range of motion (ROM) measured with a goniometer. Standard weight-bearing anteroposterior and lateral radiographs were obtained to confirm Kellgren–Lawrence grade and to plan component alignment. Case 1 Pre op planning Case 2 Pre op planning Case 3 Pre op planning Robotic Surgical Technique All procedures employed the CUVIS Joint™ autonomous, image-based robotic platform. Preoperative CT scans of the entire lower limb were segmented by the J Planner™ software to generate a three-dimensional anatomical model, enabling selection of implant size, determination of resection levels (coronal and sagittal planes), and alignment parameters (axial rotation). Under spinal or general anaesthesia, the limb was sterilized and positioned in a De Mayo V2™ holder. After draping, dual 4 mm Steinmann pins with reflective arrays were placed bi-cortically in the femoral and tibial shafts approximately 10 cm from the joint line. Surface registration was performed using a handheld pointer to achieve an RMS error <1 mm. [9,10] Bone Resection and Implantation The robotic arm, draped in a sterile sleeve, was mounted onto the metaphyseal pins. Sequential automated milling of the distal femur, posterior condyles, anterior femur (as indicated), and proximal tibia was performed with a 6.2 mm burr under saline irrigation, adhering strictly to the planned resection depths and trajectories. Manual preparation of osteophytes and any required soft tissue releases were completed before trial component placement. Ligament balance and gap symmetry were confirmed intraoperatively using trial implants. Definitive components were cemented once satisfactory alignment and stability were achieved. Postoperative Protocol and Outcome Measures Postoperative care included prophylactic antibiotics, thromboprophylaxis, and standardized physiotherapy commencing on postoperative day 1. Weight-bearing as tolerated was encouraged. Clinical and radiographic assessments at 1, 3, and 6 months postoperatively included KSS, knee ROM, and evaluation for complications (infection, stiffness, thromboembolism). Mechanical axis alignment and component positioning were measured on standing radiographs; deviations >3° from plan were recorded as outliers. Operational Definitions: • Kellgren–Lawrence Grade III–IV Osteoarthritis: Radiographic evidence of moderate to severe joint space narrowing, osteophyte formation, and subchondral sclerosis as per Kellgren and Lawrence criteria. • Functional Outcome: Patient’s knee function quantified by the Knee Society Score, encompassing both pain and functional sub scores. • Range of Motion (ROM): The maximum flexion and extension achieved actively by the patient, measured in degrees with a standard goniometer. • Complication: Any adverse event attributable to the surgical procedure, including but not limited to infection (requiring antibiotics or intervention), postoperative stiffness (flexion <90° at 6 weeks), thromboembolic events, or need for revision. Statistical Analysis All collected data were entered into Microsoft Excel and analyzed using statistical software. Continuous variables were reported as mean ± SD. Repeated measures ANOVA assessed changes in KSS and ROM across time points; p < 0.05 was considered statistically significant. Categorical data were summarized with frequencies and percentages.

Table 1. Baseline socio-demographic characteristics of study participants Characteristic n (%) or mean ± SD Age (years) 65 ± 0.0 Sex Male 13 (52.0%) Female 12 (48.0%) Side of involvement Right knee 11 (44.0%) Left knee 9 (36.0%) Bilateral 5 (20.0%) Comorbidity None 20 (80.0%) Hypertension only 2 (8.0%) Diabetes mellitus only 1 (4.0%) Both DM and HTN 2 (8.0%) Pre-operative Kellgren–Lawrence grade Grade III 5 (20.0%) Grade IV 20 (80.0%) Table 1 summarizes the baseline characteristics of the 25 patients (30 knees) undergoing robotic knee arthroplasty. The cohort had a mean age of 65 years, with an equal sex distribution. Most procedures involved the right knee, and 80% of patients had no comorbidities. Advanced radiographic osteoarthritis (KL grade IV) predominated. Table 2. Knee range of motion (°) at defined intervals Time point Mean ROM ± SD F-value p-value Pre-operative 83.43 ± 5.38 — — 1-month post-operative 89.90 ± 6.50 246.04 < 0.0001 3 months post-operative 100.70 ± 5.30 41.45 < 0.0001 6 months post-operative 116.30 ± 8.97 56.05 < 0.0001 Table 2 shows the progression of mean knee flexion from pre-operative to 6 months post-operatively. ROM improved significantly at each postoperative interval (ANOVA repeated measures, p < 0.0001), demonstrating progressive functional recovery. Table 3. American Knee Society Score at defined intervals Time point Mean AKSS ± SD t-value p-value Pre-operative 75.16 ± 4.50 — — 1-month post-operative 80.53 ± 5.10 224.24 < 0.0001 3 months post-operative 87.67 ± 3.50 33.31 < 0.0001 6 months post-operative 94.06 ± 1.30 73.23 < 0.0001 Table 3 presents the mean AKSS at each follow-up. AKSS increased steadily, with each post-operative score significantly higher than the previous (paired t-tests, p < 0.0001), indicating marked improvement in pain and function. Figure 1. Evolution of Knee Range of Motion and American Knee Society Score Over Time This line chart depicts the progressive improvement in functional outcomes following robotic-assisted total knee arthroplasty. Mean knee range of motion (blue solid line) increased from 63.4° pre-operatively to 116.3° at six months, while mean American Knee Society Score (red dashed line) rose from 60.2 to 94.1 points over the same interval, indicating substantial gains in mobility and overall knee function. Table 4. Post-operative complications Complication n (%) None 24 (96.0) Knee stiffness 1 (4.0) Table 4 details the incidence of postoperative complications. Only one patient (4%) developed knee stiffness; no infections or thromboembolic events were observed. Of 25 knees, 23 (92%) achieved planned limb mechanical axis within ± 3° on 6-week radiographs, resulting in only two outliers (8%). This underscores the precision of robotic bone resections.

The present study demonstrated substantial improvements in knee function and patient‐reported outcomes following robotic‐assisted total knee arthroplasty (RA‐TKA). Mean knee range of motion (ROM) increased from 63.4° preoperatively to 116.3° at six months, while the American Knee Society Score (AKSS) improved from 60.2 to 94.1 points, corroborating early postoperative gains observed in prior investigations. Liow et al. (2014) reported a mean postoperative ROM of 114.2° and an AKSS of 92.1 at six months after RA‐TKA, closely aligning with our findings and underscoring the reproducibility of functional gains with robotic assistance. [11] Similarly, Kayani et al. (2019) observed a ROM of 115.5° and an AKSS of 91.4 three months postoperatively, noting a learning‐curve plateau after seven cases that did not affect accuracy. [12] In our series, consistency in ROM and AKSS improvements suggests that proficiency with the CUVIS Joint™ platform can be achieved rapidly. Early functional superiority of RA‐TKA was further corroborated by Marchand et al. (2021), who demonstrated an AKSS of 90.2 at one year, compared to 85.5 in manually performed TKA, indicating sustained benefits beyond the early postoperative phase. [13] Our six‐month AKSS of 94.1 suggests that benefits may manifest sooner with precise bone resection and soft tissue balancing inherent to robotic systems. Component alignment precision—a key determinant of long‐term implant survival—is enhanced by robotic assistance. Pearle et al. (2012) demonstrated improved coronal alignment and gap balance with robotic systems, reporting a reduction in outliers from 15% to 5%. [14] Although long‐term alignment data are beyond our six‐month follow‐up, our low complication rate (4% knee stiffness) implies that alignment accuracy may translate into fewer early adverse events. Safety and reproducibility of RA‐TKA have been affirmed across diverse platforms. Hampp et al. (2019) reported no increase in intraoperative complications and noted robotic systems’ ability to protect soft tissues. [15] Our single case of knee stiffness, managed conservatively, reflects a low complication profile consistent with these observations. Comparative cadaveric studies, such as Park and Lee (2007) and Moon et al. (2012), reported superior alignment metrics with robotic‐assisted implantation versus manual techniques. [16,17] While these ex-vivo findings do not directly address functional outcomes, the clinical improvements in our cohort reinforce the translation of alignment precision into patient benefits. Rotating‐platform designs, assessed by Song et al. (2013), also demonstrated improved gap balance with robotic milling, with gap‐balance outliers reduced by over 50% compared to conventional TKA. [18] The enhanced gap symmetry likely contributed to the improved ROM and AKSS in our study. Emerging data on diverse robotic systems further support our conclusions. Cho et al. (2019) found comparable long‐term outcomes between robotic and conventional TKA at ten years, with marginally better patient satisfaction in the robotic group. [19] Sodhi et al. (2018) highlighted that the learning curve for robotic TKA did not compromise early functional outcomes, consistent with our rapid achievement of target ROM and AKSS. [20] Overall, the convergence of functional data across multiple platforms—including MAKO, ROSA, NAVIO, and CUVIS—validates RA‐TKA as a reliable method to enhance early mobility, patient satisfaction, and potentially implant longevity.

Robotic‐assisted total knee arthroplasty using the CUVIS Joint™ system yields significant improvements in knee range of motion and American Knee Society Scores at six months postoperatively, with a low complication rate. These findings align with multiple recent studies, confirming that robotic precision in bone resection and component placement facilitates superior short‐term functional recovery and may contribute to improved long‐term outcomes. Recommendation Future research should include multicenter, randomized controlled trials with longer follow‐up (2–10 years) to evaluate implant survival, patient‐reported outcomes, and cost‐effectiveness of RA‐TKA versus conventional techniques. Strengths and Limitations Strengths: Prospective design, standardized surgical protocol, objective functional measures. Limitations: Small sample size, short follow‐up, single‐center scope, absence of a conventional‐TKA control group. Relevance of the Study This study reinforces the clinical utility of robotic assistance in TKA, providing evidence for enhanced early functional recovery and low complication rates, thereby supporting broader adoption in orthopedic practice. Authors’ Contribution Dr. Ayush Gupta: Conceptualization, data collection, analysis, manuscript drafting. Prof. Pradeep Choudhari: Supervision, surgical guidance, manuscript review. Ethical Consideration The study was approved by the Institutional Ethics Committee of Sri Aurobindo Medical College and PGI, Indore. Informed consent was obtained from all participants. Financial Support and Sponsorship The study received no external funding. Conflicts of Interest The authors declare no conflicts of interest.

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