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Aims: Dislocation is a major cause of early failure after THA and is highly influenced by surgical approach and component positioning. Robotic-arm assisted arthroplasty has been developed in an attempt to improve component positioning and reduce postoperative complications.The purpose of this study was to compare the rate of dislocation after robotic total hip arthroplasty through 3 different surgical approaches., Materials and Methods: All patients who had undergone robotic arm-assisted THA at 3 centres between 2014 and 2019 were reviewed. After applying exclusion criteria, 1059 patients were included in the study. An anterior approach was used in 323 patients, a lateral approach in 394 and a posterior approach in 342 patients.Episodes of dislocation were recorded after 6 months follow-up. Stem anteversion, cup anteversion, cup inclination and combined anteversion were collected using the integrated navigation system.Cumulative incidence (CI), incidence rate (IR) and risk ratio (RR) were calculated with a confidence interval of 95%., Results: 3 cases of dislocation (2 posterior approach, 1 anterior approach) were recorded, with a dislocation rate of 0.28% and an IR of 0.14%.The rate of placement of the cup in the Lewinnek safe zone was 82.2% for the posterior approach, 82.0% for the lateral approach and 95.4% for the anterior approach.The rate of placement in the combined version safe zone was 98.0% for the posterior approach, 73.0% for the lateral approach and 47.1% for the anterior approach.The incidence rate of dislocation was 0.30% for the anterior approach, 0.34% for the posterior approach and 0% for the lateral approach., Conclusions: The robotic arm-assisted technique is associated with a low risk of dislocation. The combined version technique appears to be a reliable way to reduce the risk of dislocation through the posterolateral approach but does not appear to be essential when using the lateral and anterior approaches.

Total Hip Arthroplasty (THA) has been defined the surgical procedure of the century considering its outcome and cost-benefit ratio (1). Both standard and robotic assisted procedures are increasing, thus, comparison between standard and robotic surgery become useful to understand the cost-benefit of the latter. The prerequisites of the robotic assisted arthroplasty are precision, accuracy, limitation of errors and safety but, on the other hand, its cost is the main drawback. The primary endpoint of our research was to evaluate differences in terms of blood transfusion rates between standard manual and robotic arm assisted THA. All the robotic procedures have been managed using semi active Robotic Arm interactive orthopaedic System (RIO® MAKO Stryker surgical corporation) in a group of patients who underwent primary uncemented total hip arthroplasty (THA) for osteoarthritis or avascular necrosis. Secondary endpoints were the evaluation of length of hospital stay (LOS), age category, gender and the impact of the learning curve on surgical time in the robotic surgery sample. Our retrospective cohort study was conducted between July 2014 and December 2018. Data have been collected from the Tuscany regional hospital discharge register, extracting the relative Hospital Discharge Forms (SDO). During the period of the study, 1537 patients underwent uncemented total hip arthroplasty for osteoarthritis or avascular necrosis. The sample was divided in two subgroups: 1142 patients (74.3%) operated on with standard manual technique and 395 patients (25.7%) operated on with Mako- Stryker Robotic System. In the descriptive analysis, the average values of age and days of hospitalization with 95% CI were calculated. Mean significance was assessed by the T student test. The association between surgical modality and gender was assessed with the chi-square test. The multivariate logistic regression model was used to evaluate the risk of transfusion (outcome variable), between conventional and robotic surgical techniques. The significance threshold was set up at p <0.05. During the period of the study we observed a decrease in standard surgery and an increase in robotic surgery; an increasing number of women per year underwent total uncemented total hip arthroplasty. We found a statistical significance in favor of robotic procedures in terms of transfusion percentage (OR 6.10, 95% CI 2.96-12.59, p<0,001), highlighting the greatest risk in women (OR 1.90, 95%CI 1.30-2.78, p=0.001 ), length of hospital stay (Mr=4.24, SD=2.04, 95% CI 4.04-4.44) (Ms=8.04, SD=2.84, 95%CI 7.88-8.21), (p<0.01). Operative time in the robotic sample decreased substantially with the rise of surgical experience (106.75±13.4 mins in 2014; 82.79±15.95 mins in 2018) (p<0.01). Since the Robotic procedure is a technologically demanding process, an adequate surgical learning curve is mandatory. Our paper, comparing conventional vs robotic assisted THA, showed in favor of the robotic one, a statistically significant reduction of number of transfusions (p<0.001) and length of hospital stay (p<0.01)., (Copyright 2020 Biolife Sas. www.biolifesas.org.)

Background: Combined anteversion in total hip arthroplasty influences both dislocation risk and range of motion. One of its components, stem version (SV), could be dictated by many factors, from native femoral anatomy to stem geometry and surgeon's choice. In the present multicenter study, robotic technology was used to assess the influence of native femoral version on final SV and combined anteversion using a straight, uncemented stem., Methods: Three hundred sixty-two patients undergoing total hip arthroplasty were enrolled from 3 different orthopedic centers from 2012 and 2016. All patients underwent computed tomography planning with measurement of femoral neck version (FNV) and intraoperative measurement of stem version (SV), acetabular component version (AV), and combined version (CV) with robotic instrumentation., Results: Mean FNV was 5.0° ± 9.6°, and SV was 6.4° ± 9.7°. The average difference between FNV and SV was 1.6° ± 9.8°. A moderate correlation was found between FNV and SV (R = 0.48, P < .001). SV was between 5° and 20° in 174 patients (48%). Mean CV was 28.2° ± 7.9°. A strong correlation was found between SV and CV (R = 0.89, P < .001). A significant difference in SV was found between the 3 centers (P < .001). CV was <25° in 109 patients (30.1%). Relative risk of CV < 25° was 8.6 times greater with SV < 5° (P < .001)., Conclusion: With the use of an uncemented, single-wedge, straight stem, SV is highly variable. Despite being moderately correlated with native FNV, SV can be partially influenced by the surgeon. A low SV could be hardly corrected, bringing high risk of low CV., (Copyright © 2018 Elsevier Inc. All rights reserved.)