[A comparative study evaluating reconstructive accuracy and clinical result of robotic total hip arthroplasty via...

Objective: To investigate the differences in prosthesis implantation accuracy, biomechanical indicators, and 2-year postoperative clinical outcomes between robotic-assisted traditional posterior approach (RA-PLA) and robotic-assisted direct anterior approach (RA-DAA) in total hip arthroplasty (THA). Methods: This study is a prospective randomized controlled trial. Patients with unilateral femoral head ischemic necrosis or primary hip osteoarthritis who meet the inclusion and exclusion criteria and were admitted to the Department of Orthopedics,Xinqiao Hospital, Army Medical University from May to September 2022. Divided into RA-PLA group and RA-DAA group through central randomization. Use cumulative and fitting methods to analyze the learning curve of robotic surgery and eliminate cases before the inflection point of the learning curve. Compare the abduction angle and anteversion angle of acetabular cup implantation between two groups of patients, as well as the rate of falling into the safe zone, the difference in length between the two lower limbs, hip joint eccentricity, rotation center height, the complete accuracy of prosthesis planning (the number of cases in which acetabular cup prosthesis, femoral stem prosthesis specifications, and neck shaft angle were completely consistent with surgical planning during surgery/total cases×100%), patient reported outcome indicators (including Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC), and 12 item Short Form Health Survey (SF-12) score) and clinical outcomes. Data comparison was conducted using independent sample t-test, Wilcoxon rank sum test, chi square test, Fisher's exact probability method, or repeated measures analysis of variance. Results: A total of 98 patients were included in this study, with 48 in the RA-PLA group and 50 in the RA-DAA group. After excluding cases before the inflection point of the learning curve, 30 patients were included in each group. There was no statistically significant difference in baseline data between the two groups before surgery (all P>0.05). There was no significant difference in the values of the anterior tilt angle and abduction angle between the two groups of acetabular cups compared to preoperative planning (all P>0.05). The proportion of patients who fell into the Lewinnek and Callanan safe zones was 90.0% (27/30) and 96.7% (29/30), respectively (χ²=0.268, P=0.605). There was no significant difference in postoperative lower limb length, hip joint eccentricity, and rotation center height deviation and grading between the two groups (all P>0.05). The complete accuracy of prosthesis planning in the RA-DAA group was higher than that in the RA-PLA group (86.7% (26/30) compared to 63.3% (19/30),χ²=4.356,P=0.037).All patients were followed up for more than 2 years. In terms of postoperative HHS, WOMAC, and SF-12 score, there was no statistically significant difference in the inter group effect comparison (all P>0.05), but there was a significant statistical significance in the time effect (all P<0.05). There was no significant difference in the incidence of perioperative complications and adverse events between the RA-DAA group and the RA-PLA group (20.0% (6/30) vs. 13.3% (4/30),χ²=0.480,P=0.488). Conclusions: RA-DAA and RA-PLA techniques can achieve similar clinical efficacy after two years of surgery, and both can achieve similar reconstruction accuracy in terms of acetabular cup implantation angle, lower limb length, hip joint eccentricity, and rotation center height. The accuracy of prosthesis planning in RA-DAA is higher.