Stefano Marco Paolo Rossi

Background: Robotic-assisted technologies and evolving implant designs have been introduced in unicompartmental knee arthroplasty (UKA) to improve the accuracy and reproducibility of component positioning. However, the relative contribution of robotic assistance compared with conventional instrumentation to radiographic outcomes in experienced, high-volume centers remains unclear. Methods: This retrospective comparative study included 96 consecutive medial UKAs performed at a single high-volume institution. Patients were stratified into three groups: Journey I UKA implanted with NAVIO imageless robotic assistance ( n = 38), Journey II Uni UKA implanted using conventional instrumentation ( n = 27), and Journey II UK UKA implanted with CORI imageless robotic assistance ( n = 31). Standardized standing long-leg weight-bearing radiographs were obtained preoperatively and postoperatively. Radiographic evaluation included hip–knee–ankle (HKA) angle, femoral component coronal angle (FCCA), tibial component coronal angle (TCCA), and sagittal alignment parameters. Tibial coronal alignment was interpreted according to the Cartier metaphyseal alignment philosophy. Intergroup comparisons were performed using appropriate statistical tests. Results: Baseline demographic characteristics and preoperative radiographic parameters were comparable among the three groups (all p > 0.05). Postoperative mean HKA was 177.1° ± 2.1° in the Journey I NAVIO group, 177.3° ± 2.5° in the Journey II Uni conventional group, and 177.7° ± 2.2° in the Journey II UK CORI group, with no statistically significant differences ( p = 0.56). Femoral and tibial component coronal alignment, including TCCA, showed no significant intergroup differences. All cases across the three cohorts were within predefined safe zones for HKA, FCCA, and TCCA. Sagittal alignment parameters were also comparable between groups. Conclusion: In a high-volume center adopting a consistent alignment philosophy, medial UKA achieves equivalent and highly accurate radiographic outcomes regardless of robotic assistance or conventional instrumentation.

Background: Restoration of native distal femoral sagittal morphology is increasingly recognized as an important goal in total knee arthroplasty (TKA). Alterations in anterior femoral offset (AFO), posterior femoral offset (PFO), and anteroposterior (AP) femoral size may affect knee biomechanics and patellofemoral function. This study evaluated whether imageless robotic-assisted TKA performed using a functional alignment (FA) philosophy resulted in statistically significant preoperative-to-postoperative differences in distal femoral sagittal morphology and coronal alignment. Methods: A retrospective analysis of a prospectively collected database included 250 consecutive primary TKAs performed with the imageless ROSA Knee System (Zimmer Biomet) using a tibia-first FA workflow. Preoperative and postoperative radiographic measurements included mechanical hip–knee–ankle angle (mHKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), AP femoral size, AFO, and PFO. Paired comparisons were performed using appropriate statistical tests. Results: While no statistically significant differences were observed between preoperative and postoperative mean values for overall mechanical alignment (mHKA) (177.1 ± 7.7° vs. 177.3 ± 3.2°, p = 0.11), secondary coronal parameters demonstrated statistically significant controlled adjustments reflecting the patient’s individualized functional alignment. No significant differences were observed in sagittal morphology: AP femoral size (70.7 ± 6.3 vs. 71.0 ± 6.2 mm, p = 0.31), AFO (10.7 ± 5.9 vs. 10.8 ± 5.8 mm, p = 0.70), and PFO (34.1 ± 7.6 vs. 34.5 ± 7.2 mm, p = 0.24). Conclusions: Imageless robotic-assisted TKA performed with an FA philosophy and a tibia-first workflow demonstrated minimal mean preoperative-to-postoperative changes in distal femoral sagittal parameters at the cohort level. While overall mean mechanical alignment remained unchanged, secondary coronal parameters showed controlled, statistically significant adjustments, reflecting the implementation of an individualized three-dimensional alignment strategy. These findings support robotic FA as a patient-specific three-dimensional alignment strategy. Further prospective studies are needed to determine whether these radiographic results translate into improved clinical outcomes.

Learning curves for robotic total knee arthroplasty (TKA) have been widely described during the initial adoption of robotic technology. However, it remains unclear whether robotic surgical proficiency is platform-specific or transferable between systems based on different modelling paradigms. The purpose of this study was to evaluate whether an experienced robotic surgeon demonstrates a measurable learning curve when transitioning from imageless to CT-based robotic TKA. A senior surgeon with experience exceeding 1000 robotic knee arthroplasties performed using imagel-ess platforms transitioned to a CT-based robotic TKA system. The first 25 consecutive CT-based robotic TKAs were prospectively analysed. Operative time and postoperative radiographic alignment (HKA, LDFA, MPTA, tibial slope) were assessed. Learning curve dynamics were evaluated using cumulative sum (CUSUM) and segmented regression analyses. Radiographic outliers were defined as deviations greater than 2° from the planned target. Operative time decreased from 65 min in the first case to a steady-state mean of 55 ± 3 min (95% CI 53.8-56.2) by case 3, corresponding to a 15.4% reduction. Continuous CUSUM demonstrated an inflection point at case 2, confirmed by segmented regression (p < 0.05). Mean postoperative alignment was 0.7° ± 1.2° for HKA, 88.5° ± 1.1° for LDFA, 87.8° ± 1.2° for MPTA, and 4.8° ± 0.7° for tibial slope. No radiographic outliers (> 2°) were observed after case 2. In an experienced robotic surgeon, transition from imageless to CT-based robotic TKA was not associated with a clinically relevant learning curve. Operative efficiency stabilised rapidly and radiographic alignment accuracy was maintained from the earliest procedures. These findings suggest that robotic TKA proficiency may be transferable across platforms, although confirmation through multicentre comparative studies remains necessary. Level IV.

Robotic-assisted total knee arthroplasty (TKA) significantly enhances surgical precision and alignment accuracy. While traditional robotic systems rely on preoperative imaging, imageless technology has emerged as a viable alternative, leading to a reduction in costs, radiation exposure, and logistical challenges. This narrative review aims to evaluate the efficacy and reliability of imageless robotic-assisted TKA, specifically assessing its accuracy in component positioning, functional outcomes, and potential advantages over image-based systems. A review of current literature was conducted, comparing imageless robotic TKA with both manual and image-based techniques. The key parameters analyzed include alignment precision, joint line restoration, patient-reported outcomes, and complication rates. Notably, imageless robotic-assisted TKA demonstrated alignment accuracy and functional outcomes comparable to those of image-based systems, while providing enhancements in workflow efficiency and the elimination of radiation exposure. Although a moderate learning curve was observed, no significant differences in patient satisfaction or clinical performance were recorded. Overall, imageless robotic-assisted TKA represents a safe and effective alternative to image-based systems, achieving comparable surgical precision with additional economic and practical benefits. Further research is required to confirm long-term outcomes and to optimize intraoperative guidance strategies.

Background: Dislocation of a total hip arthroplasty (THA) is a highly disabling complication following the implantation of primary and revision hip arthroplasties, as well as a prevalent reason for subsequent revisions. This study is designed to evaluate the survival rate, functional outcomes, and the reasons for further revision due to implant failure of Constrained Acetabular Liners (CALs). Methods: 56 patients underwent hip revision surgery using a Constrained Acetabular Liner between June 2018 and December 2022 were retrospectively evaluated. Inclusion criteria consisted of age > 18 years, follow-up of at least 12 months, prior total hip arthroplasty or bipolar hemiarthroplasty, a history of recurrent implant dislocation, or, alternatively, the presence of a high risk of implant instability in hip revisions due to mechanical conditions. Results: The average age at the time of surgery was 72.4 years (SD 12.4). 55.6% of implants were performed for recurrent dislocation of THA, 8.9% for recurrent dislocation of bipolar hemiarthroplasty, 13.3% for aseptic loosening revisions, 4.4% for adverse reactions to metal debris revision procedures, and 17.8% for two-stage revision for periprosthetic joint infection. The average follow-up at the final evaluation was 32 months (SD 12.3). The survivorship of the implant was 88.9% at final follow-up. At the final follow-up: average HHS 77.4 ± 13.2; average WOMAC 31.4 ± 13.4; average OHS 32.1 ± 6.9; and average FJS-12 69.5 ± 19.6., and 65% showed excellent or good outcomes (HHS > 80). Conclusions: The CALs assessed in this study have shown satisfactory functional outcomes, even when compared with other anti-dislocation systems available on the market. Both cemented and uncemented solutions have shown a good survival rate in the mid-term. However, their use should be reserved for selected cases.

Total knee arthroplasty (TKA) remains a cornerstone of orthopedic surgery, with optimal coronal alignment playing a pivotal role in determining both clinical outcomes and implant longevity. Traditionally, mechanical alignment has been regarded as the gold standard. However, the emergence of alternative philosophies—such as kinematic alignment and hybrid techniques—has shifted the focus toward individualized approaches. Recent advancements in robotic and computer-assisted systems have significantly enhanced the precision of implant positioning, allowing surgeons to better replicate native knee biomechanics and improve patient satisfaction. This narrative review examines current alignment philosophies in TKA, including mechanical, kinematic, and hybrid methods. It analyzes each technique’s principles, functionalities, benefits, and limitations while highlighting ongoing debates regarding their clinical application. Special attention is given to the role of technology in enabling more accurate, patient-specific surgical execution. Despite promising developments, challenges remain in standardizing these techniques and validating their long-term efficacy. To ensure a comprehensive evaluation relevant literature was reviewed, focusing on studies that explore alignment strategies, biomechanical outcomes, and the integration of technology in TKA. This review aims to synthesize current evidence, identify gaps in knowledge, and outline directions for future research needed to optimize alignment strategies in modern knee arthroplasty.

Introduction: Total hip arthroplasty (THA) is a widely performed procedure presenting substantial functional improvement in patients with hip joint pathology. Cementless acetabular components have well renowned popularity for their potential for long-term durability and bone preservation. Among these implants, trabecular metal technology (TMT), particularly using tantalum, has been introduced to enhance biological fixation and implant longevity. Methods: This retrospective study analyzed 3464 primary THAs performed using tantalum TMT acetabular cups between 2012 and 2022 at a single high-volume arthroplasty center. Patients included were adults undergoing THA for osteoarthritis, hip dysplasia, post-traumatic arthritis, or avascular necrosis, with a minimum follow-up of 24 months. Clinical outcomes were evaluated using the Harris Hip Score (HHS), and implant survivorship was assessed via Kaplan–Meier analysis. Results: The mean follow-up was 7.03 years (± 2.58). The mean HHS improved significantly from 46.7 (± 7.2) preoperatively to 91.07 (± 7.8) at final follow-up. The implant survivorship free from any reoperation was 97.78%, while survivorship free from aseptic loosening was 99.89%. Radiographically, mean cup inclination was 41.3° (± 5.9), with signs of potential aseptic loosening in only four cases (0.11%). Complications included 46 infections managed with DAIR/DAPRI and 30 implant-related revisions, primarily due to dislocation or mechanical failure. Conclusion: Tantalum acetabular components demonstrate excellent mid-term clinical and radiographic performance in a broad patient population, suggesting their utility in both high-demand and compromised bone quality cases. Continued follow-up is necessary to confirm long-term implant survivorship.