One-Year Patient Outcomes for Robotic-Arm-Assisted versus Manual Total Knee Arthroplasty.

Although there are many studies on the alignment advantages when using the robotic arm-assisted (RAA) system for total knee arthroplasty (TKA), there have been questions regarding patient-reported outcomes. Therefore, the purpose of this study was to use this index to compare: (1) total, (2) physical function, and (3) pain scores for manual versus RAA patients. We compared 53 consecutive RAA to 53 consecutive manual TKAs. No differences in preoperative scores were found between the cohorts. Patients were administered a modified Western Ontario and McMaster Universities Osteoarthritis Index satisfaction survey preoperatively and at 1-year postoperatively. The results were broken down to: (1) total, (2) physical function, and (3) pain scores. Univariate analysis with independent samples t-tests was used to compare 1-year postoperative scores. Multivariate models with stepwise backward linear regression were utilized to evaluate the associations between scores and surgical technique, age, sex, as well as body mass index (BMI). Statistical analyses were performed with a p < 0.05 to determine significance. The RAA cohort had significantly improved mean total (6 ± 6 vs. 9 ± 8 points, p = 0.03) and physical function scores (4 ± 4 vs. 6 ± 5 points, p = 0.02) when compared with the manual cohort. The mean pain score for the RAA cohort (2 ± 3 points [range, 0-14 points]) was also lower than that for the manual cohort (3 ± 4 points [range, 0-11 points]) (p = 0.06). On backward linear regression analyses, RAA was found to be significantly associated with more improved total (ß coefficient [ß] -0.208, standard error [SE] 1.401, p < 0.05), function (ß = 0.216, SE = 0.829, p < 0.05), and pain scores (ß -0.181, SE = 0.623, p = 0.063). The RAA technique was found to have the strongest association with improved scores when compared with age, gender, and BMI. This study suggests that RAA patients may have short-term improvements at minimum 1-year postoperatively. However, longer term follow-up with greater sample sizes is needed to further validate these results.

Robotic-Assisted Total Knee Arthroplasty in the Presence of Extra-Articular Deformity.

INTRODUCTION: Tibial or femoral extra-articular deformities complicate the goal achieving optimal mechanical axis alignment for successful total knee arthroplasty (TKA) outcomes. In the presence of these extra-articular deformities, standard operative techniques and instruments may not be reliable. Robotic-arm assisted technology was developed to help achieve a well-aligned and balanced knee in a variety of clinical scenarios. Although prior case series have reported on the use of robotic-arm assisted devices for cases with severe angular deformity, there is a lack of data concerning the use of the robotic device for patients with other potentially complex surgical factors. Therefore, the purpose of this series was to present cases in which the robotic-arm assisted TKA application was used in the setting of extra-articular deformities to educate the surgeon community on this potentially useful method to address these complex cases. MATERIALS AND METHODS: Three cases of patients who underwent robotic-arm assisted TKA in the setting of preoperative extra-articular deformities were identified. These included one with femoral and tibial fracture malunion, another with a proximal tibial fracture nonunion, and another with a healed tibial plateau fracture. Patient clinical histories, intraoperative surgical techniques, and postoperative outcomes were obtained. Specific focus was placed on the surgical management of the patient's pre-existing deformity. RESULTS: These three case reports are discussed in detail, with emphasis on preoperative planning and intraoperative techniques. The robotic software was able to appropriately consider the extra-articular deformity in the preoperative and real-time updated intraoperative plans. Doing so, the surgeon was able to achieve balanced and aligned TKA in each case. All three patients underwent robotic-assisted total knee arthroplasty with no intraoperative or postoperative complications. For all patients, their anteroposterior and lateral radiographs demonstrated well fixed and aligned femoral and tibial components with no signs of loosening or osteolysis. On physical exam, all patients had excellent range-of-motion with mean flexion of 122° (range: 120 to 125° of flexion) at final follow up. DISCUSSION: The decision on how to best approach TKA in patients with extra-articular deformity should be based on an extensive patient history, physical examination, and thorough evaluation of the magnitude and proximity of the deformity to the knee joint. Utilizing preoperative CT-scans with a 3D plan for robotic-arm assisted surgery allowed for appropriate assessment of the deformity preoperatively and execution of a plan for a balanced and aligned total knee arthroplasty. We have demonstrated excellent results utilizing robotic-arm assisted TKA in these complex cases.

Does the Robotic Arm and Preoperative CT Planning Help with 3D Intraoperative Total Knee Arthroplasty Planning?

Although several studies highlight the advantages of robotic arm-assisted total knee arthroplasty (RA-TKA), few investigate its intraoperative outcome. Therefore, the purpose of this study was to analyze the RA-TKA's ability to assist with intraoperative correction of: (1) flexion and (2) extension gaps, as well as its ability to (3) accurately predict implant sizes. Additionally, in this RA-TKA cohort, length of stay, complications, and readmissions were assessed. A total of 335 patients who underwent RA-TKA were included. The robotic software virtually measured the intraoperative prebone cut extension and flexion gaps. Differences in medial versus lateral prebone cut extension and flexion gaps were calculated. A total of 155 patients (46%) had an extension gap difference of between -2 and 2 mm (mean, -0.3 mm), while 119 patients (36%) had a flexion gap difference of between -2 and 2 mm (mean, -0.6 mm). Postbone cut differences in medial versus lateral flexion and extension gaps were measured. Balanced knees were considered to have a medial and lateral flexion gap difference within 2 mm. The robot-predicted implant size was also compared with the final implant size. Additionally, lengths of stay, complications, and readmissions were assessed. All patients achieved a postbone cut extension gap difference between -1 and 1 mm (mean, -0.1 mm). A total of 332 patients (99%) achieved a postbone cut flexion gap difference of between -2 and 2 mm (mean, 0 mm). For 98% of prostheses, the robotic software predicted within 1 implant size the actual tibial or femoral implant size used.The mean length of stay was found to be 2 days. No patients suffered from superficial skin infection, pin site infections or fractures, soft tissue damage, and no robotic cases were converted to manual TKA due to intraoperative complications. A total of 8 patients (2.2%) were readmitted; however, none were directly related to robotic use. The robotic software and use of a preoperative computed tomography (CT) substantially helped with intraoperative planning and accurate prediction of implant sizes. Therefore, based on the results of this study, the RA-TKA device does, in fact, provide considerable intraoperative assistance.

Difficult Cases in Robotic Arm-Assisted Total Knee Arthroplasty: A Case Series.

Sagittal deformity of the knee is commonly corrected to neutral biomechanical axis (±3 degrees) during total knee arthroplasty (TKA), which is a widely accepted goal. Recent advances in surgical technology have made it possible to accurately plan and fulfill these goals. One of these is robotic-assisted TKA, which has been noted to help increase accuracy and precision of restoring a neutral mechanical axis. While there are data confirming the ability of robotic devices to better correct knee alignment than the manual technique, there is a lack of data concerning the use of the robotic devices in more complex cases, such as those in patients with severe varus or valgus deformity, as well as in flexion contractures. Therefore, the purpose of this case study is to present three cases in which the robotic-assisted TKA device was used to correct a severe varus and severe valgus deformities. Based on this case series, it should be noted that the robotic device can also help correct severe varus/valgus deformities and flexion contractures.