[Application of robot-assisted posterolateral approach in complex primary total hip arthroplasty]

Objective: To analyze the short-and medium-term clinical outcomes of Mako robotic-assisted posterior-lateral approach in complex primary total hip arthroplasty (THA). Methods: A retrospective case series analysis was conducted on 29 patients with complex hip conditions who underwent Mako robotic-assisted posterior-lateral approach at Department of Orthopaedics, the Second Affiliated Hospital of Zhejiang University School of Medicine from November 2020 to December 2024. The patient cohort included 14 cases of developmental dysplasia of the hip, 8 cases of ankylosed hip, 3 cases of traumatic hip arthritis, 3 cases of sequelae of purulent hip arthritis, and 1 case of synovial chondromatosis. There were 12 males and 17 females, with an age of (62.3±9.4) years (range:44 to 79 years). Surgical time, intraoperative blood loss, vascular and nerve injury, postoperative infection, and other complications were recorded. Preoperative and postoperative lower limb length discrepancy, combined offset difference (ΔCO), acetabular abduction angle, and acetabular anteversion angle were measured. The Harris hip score was recorded at regular follow-ups. Data comparison was conducted using the paired sample t-test. Results: All patients successfully underwent surgery with the Mako robotic system. The surgical time was (107.6±41.5) minutes (range:50 to 235 minutes), and the intraoperative blood loss was (165.5±147.7) ml (range:50 to 800 ml). All patients were followed up for a duration of (27.3±16.7) months (range:3 to 51 months). The planned intraoperative acetabular cup abduction angle was 40.1°±1.6° (range: 36° to 45°), and the measured postoperative acetabular cup abduction angle was 40.2°±3.5° (range: 33° to 54°), with no significant difference (t=0.231,P=0.819). The planned intraoperative acetabular cup anteversion angle was 19.1°±3.9° (range: 15° to 25°), and the measured postoperative acetabular cup anteversion angle was 18.5°±3.4° (range: 10° to 26°), with no significant difference (t=1.792,P=0.084). The difference in length of both lower limbs was (-17.6±15.0) mm (range:-50 to 10 mm) before operation and (-1.5±16.0) mm (range:-33 to 53 mm) after operation (t=6.282,P<0.01)(positive values indicate that the surgical side is longer than the contralateral side). The ΔCO was (4.1±12.0) mm (range:-18 to 30 mm) before operation and (-2.2±13.3) mm (range:-44 to 17 mm) after operation, with statistically significant difference (t=2.635,P=0.014). One patient experienced vascular injury with embolism postoperatively, while no other complications were observed in the remaining patients. No loosening, dislocation, or fracture of the prosthesis was noted during the follow-up period. The Harris function score was improved from (47.1±8.3) points(range:15 to 62 points) preoperatively to (73.0±5.5) points(range:57 to 83 points) at the three-month postoperative follow-up (t=22.630,P<0.01). Conclusion: The use of Mako robotic assistance in complex total hip arthroplasty can enhance the accuracy of prosthesis placement, minimize lower limb length discrepancy, and improve hip joint function.