To investigate the application strategy of robot-assisted navigation technology in anterior approach total hip arthroplasty (THA) for severe hip dislocations and to evaluate its clinical safety and effectiveness.

Eighteen patients with severe hip dislocations (Crowe type IV), including three males and 15 females, age range was 23 to 72 years, were enrolled in the department of sports medcine and adult reconstruction, Nanjing Drum Tower Hospital from October 2022 to October 2023. The patients with joint infection on the involved side and those who were intolerant to surgery were excluded. Before surgery, the MAKO robot was used to plan the acetabular position, prosthesis type and size, and implantation angle. The prosthesis type and size were also planned based on the morphology of the proximal femur. The anterior approach was used to expose the hip in the supine position, with the acetabular cup prepared and installed under robotic arm assistance, while manual reaming and femoral prosthesis installation were performed. Data were collected on preoperative and postoperative (three and six months, one year) Harris hip function scores and evaluated by repeated measurement of variance analysis. The data of operative duration, leg length discrepancy, acetabular cup anteversion and abduction angles, preoperative and postoperative hematocrit and hemoglobin levels were analyzed by paired t test; postoperative complications were recorded.

The average operative duration was (162.5±36.3) min. Hemoglobin levels decreased from (126.2±12.9) g/L to (109.0±10.9) g/L after surgery, and hematocrit decreased from (41.2±12.0) % to (33.1±3.1) %, with statistically significant differences (t=5.241, 2.791, both P<0.01). Leg length discrepancy was corrected from an average of (35.4±20.4) mm preoperatively to (9.6±6.2) mm postoperatively. Postoperative measurements showed an average acetabular cup anteversion angle of (19.6±4.1)°, which was larger than the preoperative plan of (14.4±1.6)°, and an average abduction angle of (40.3±5.1)°, which was smaller than the preoperative plan of (43.8±2.6)°, with statistically significant differences (t=5.130, 4.940, 2.591, all P<0.05). There was no statistically significant difference in the eccentricity before and after surgery (t=0.897, P=0.130). The preoperative planning for femoral stem and acetabular cup sizes matched the intraoperative use with 100% consistency. The Harris hip function score increased from an average of (58.2±10.8) preoperatively to (79.9±15.9) at six months postoperatively and (89.5±8.3) at one year postoperatively, indicating significant improvement in hip function. Two patients (11.1%) experienced proximal femoral fractures, and two patients (11.1%) had postoperative prosthesis dislocations. One case of postoperative femoral nerve palsy was treated with hip flexion fixation combined with neurotrophic therapy. The symptoms were relieved three months after the operation. After open reduction and fixation with braces, no recurrences occurred. No patients experienced complications such as wound infection or poor wound healing.

Preoperative robotic planning aids in personalized prosthesis selection for severe hip dislocations, ensuring precise installation. The anterior approach helps release the tensor fascia lata for limb length correction. However, hip deformities and muscle atrophy may delay recovery and increase dislocation risks, necessitating detailed perioperative soft tissue management beyond robotic capabilities.