The utilization of technology, including robotics and computer navigation, in total hip arthroplasty (THA) has been steadily increasing; however, conflicting data exists regarding its effect on short-term clinical and patient-reported outcomes. Therefore, this study sought to explore the association between different surgical technologies and postoperative outcomes following THA. We retrospectively reviewed 9892 primary THA cases performed by 62 surgeons from a single institution from September 2017 to November 2022. Three cohorts were created based on the utilization of technology: conventional (no technology), navigation, or robotics. Patient demographics, clinical outcomes, and patient-reported outcome measures were collected over the first 90 days following surgery. This data was compared using analysis of variance and multivariate logistic regressions. In total, 4275 conventional, 4510 navigation, and 1107 robotic cases were included in our analyses. The robotic cohort achieved a perfect Activity Measure for Post-Acute Care (AM-PAC) score earliest (0.1 days, P < .001). After adjusting for potential confounding variables, use of robotic assistance was associated with greater odds of achieving a perfect AM-PAC score on postoperative day 0 (odds ratio 1.6, P < .001) and greater odds of having length of stay shorter than 24 hours (odds ratio 2.3, P < .001) compared to no technology use in THA. Hip dysfunction and Osteoarthritis Outcome Score, Joint Replacement and Patient-Reported Outcomes Measurement Information System Pain Interference scores showed the greatest improvement in the robotic cohort at both 6 weeks and 3 months following surgery. The present study demonstrates favorable clinical and patient-reported outcomes in the first 90 days following surgery for patients undergoing robot-assisted THA compared to conventional and navigation-assisted THA.

The Coronal Plane Alignment of the Knee (CPAK) classification method describes knee phenotypes. The rise in robotic-assisted total knee arthroplasties (RA-TKA) has enabled surgeons to fine-tune bony cuts, minimizing soft tissue release while prioritizing balanced gaps rather than predetermined alignment targets, a technique known as functional alignment (FA). As a patient’s preoperative CPAK changes when using FA, our aim was to assess which preoperative CPAK phenotypes are maintained post-TKA and further define this change with a simplified classification. We retrospectively reviewed 1,028 primary RA-TKA cases performed using functional alignment (FA) technique from 2023 to 2024. Arithmetic hip-knee-ankle (aHKA) and joint line obliquity (JLO) angles were obtained using robotic software, with boundaries in accordance with CPAK. Demographics, CPAK phenotypes, and planned resections were collected and analyzed. Most cases were in CPAK 1 (34.1%), 2 (30.5%), or 3 (19.5%) preoperatively and 4 (30.2%) or 5 (51.2%) postoperatively. Postoperatively, 63.5 and 27.1% of cases retained their preoperative aHKA and JLO alignments, respectively. Of 427 cases that changed CPAK, most varus and neutral cases retained preoperative aHKA alignment, otherwise becoming neutral and varus respectively, while most valgus became neutral. Preoperative varus and valgus cases that retained aHKA had larger native deformities compared to those that became neutral. Most preoperative neutral JLO cases remained neutral, while a majority of apex distal cases became neutral. Cases that changed CPAK, compared to retained CPAK cases, were more neutral (aHKA) and apex distal preoperatively (P < 0.001). Based on results, we classified preoperative alignment according to final functional coronal alignment that would reflect tibia and aHKA angles and propose a new, simplified Functional Coronal Alignment (FCA) classification composing of four categories. This study highlighted the clinical usefulness of robotics for FA and described the FCA classification system to guide surgeons in optimizing kinematics using robotic assistance for FA.

Background Varying degrees of flexion contracture appear commonly in total knee arthroplasty (TKA) patients and can be corrected using increasing distal femoral bone resection. Robotic-assisted (RA) technology aims to avoid ligament release through optimized bony resections. This study evaluated the influence of preoperative flexion contracture on the magnitude of resections surgeons perform to balance knees in RA-TKA. Materials and methods We reviewed 789 primary RA-TKAs from 2023 to 2024 using cruciate-retaining (CR) implants. The cohort was divided by native flexion deformity into three groups: <0° flexion (“hyperextension”, n = 157), 0-9.9° flexion (“minimal contracture”, n = 457), and ≥ 10° flexion (“clinically important contracture”, n = 175). Mean preoperative flexion contracture was − 3.8, 4.1, and 13.5° for the hyperextension, minimal contracture, and clinically important contracture cohorts, respectively. Demographics, implants, and intraoperative data were collected and analyzed. The arithmetic hip-knee-ankle (aHKA) angle was used to determine native deformity groups for additional subanalyses. Results Significant differences were found between cohorts for mean distal femur and proximal tibia resections, with the clinically important contracture group having the largest resections. After accounting for implanted polyethylene thickness, differences in mean tibia resections were quite small, varying by 0.9 millimeters (mm) laterally and 0.7 mm medially. Similarly, the mean distal femoral resection varied by only 1.4 mm laterally and 0.7 mm medially between the hyperextension and clinically important contracture cohorts. Indeed, 85% of cases with clinically important contractures were managed with less than 2 mm of additional distal femoral resection compared to the minimal contracture cohort. Conclusion With robotic-assisted TKA, bone resections can be guided by collateral ligament tension in flexion and extension. Our data suggest that surgeons can follow this strategy and successfully address flexion contractures with very small increases in resection magnitudes, which may help to maintain the joint line.