[The application and effect of bispherical augment in acetabular defects reconstruction]

Objective: To evaluate the clinical effect of bispherical augment in acetabular defects reconstruction in hip revision. Methods: This is a retrospective case series study. A retrospective analysis of 119 patients (124 hips) patients who underwent hip revision surgery and reconstructed with bispherical augment for acetabular bone defects from January 2019 to December 2023 was performed. There were 57 males (58 hips) and 62 females (66 hips), aged (65.0±11.8) years (range:40 to 102 years). The body mass index was (23.9±3.5) kg/m² (range:16.1 to 32.2 kg/m²). Acetabular bone defects were typed as follows: 2 hips in Paprosky type ⅡA, 29 hips in type ⅡB, 34 hips in type ⅡC, 31 hips in type ⅢA, and 28 hips in type ⅢB, of which 9 patients (9 hips) were combined with pelvic discontinuity. Differences in Harris hip score (HHS) and lower limb discrepancy (LLD) were compared between preoperatively and final follow-up. The height of the hip center of rotation and the horizontal distance from the center of rotation to the teardrop were measured by radiographs before and after surgery, and prothesis stability and the occurrence of postoperative complications were evaluated. Data were compared using the paired sample t test. Results: All patients successfully completed the operation. The operation time was (167.0±53.4) minutes (range:90 to 380 minutes) and the intraoperative bleeding was (345.3±124.2) ml (range:100 to 1 200 ml). The height of the hip center of rotation decreased from (39.7±13.0) mm preoperatively to (21.8±7.1) mm postoperatively and the horizontal distance from the center of rotation to the teardrop increased from (34.0±10.1) mm preoperatively to (38.5±5.9) mm postoperatively, and the differences were statistically significant (t=15.859, P<0.01; t=5.266,P<0.01). All the patients were followed up for (26.1±15.4) months (range:6 to 60 months). At the last follow-up, HHS improved from (35.2±10.0) points preoperatively to (85.5±9.5) points, and the difference was statistically significant (t=50.723,P<0.01). LLD decreased from (2.1±1.1) cm preoperatively to (0.5±0.5) cm, and the difference was statistically significant (t=13.767, P<0.01). All acetabular components were stable and free of displacement on imaging during follow-up. Three patients suffered dislocation and received closed reduction, all prosthesis were in good position during follow-up. No dislocation, loosening, fracture, recurrence of infection and vascular nerve injury occurred in other patients. Conclusion: Bispherical augment can effectively reconstruct acetabular bone defects, restore the hip center of rotation, and improve hip joint function scores at short and mid-term follow-up.