Application of Intraoperative Individualized Cup Combination-Cup-on-Cup Technique in Severe Acetabular Defects

This study aimed to investigate the application of the cup-on-cup technique in revision total hip arthroplasty (THA) and report clinical and radiographic outcomes from a series of case follow-ups. Retrospective analysis of 10 patients who underwent acetabular prosthesis revision with cup-on-cup technique. According to the Paprosky classification of acetabular bone defects, there were 2 cases of type II C, 3 cases of type III A, and 5 cases of type III B. The average follow-up was 54.8 ± 5.1 months, and the Harris score of the hip joint increased from 37.0 ± 9.9 preoperatively to 80.5 ± 3.1 postoperatively at the final follow-up (p < 0.001). Comparing the surgical side's hip center of rotation (COR) to the contralateral side, the preoperative average upward displacement was 33.8 ± 15.0 mm, while the postoperative average upward displacement was 0.2 ± 3.3 mm (p < 0.001). Similarly, the preoperative average inward displacement was 9.1 ± 5.1 mm, while the postoperative average outward displacement was 1.8 ± 1.6 mm (p < 0.001). There was no significant difference (p = 0.71) between the average density values of the contralateral and surgical sides at the final follow-up, which were 127.4 ± 13.7 and 125.0 ± 14.8, respectively. During the follow-up period, all patients achieved satisfactory radiographic outcomes, and no prosthetic loosening was observed. The cup-on-cup technique can reconstruct acetabular bone defects and restore hip COR in revision THA, with favorable clinical and radiographic outcomes.