Use of a new off-the-shelf 3D-printed trabecular titanium acetabular cup in Chinese patients undergoing hip revision surgery: Short- to mid-term clinical and radiological outcomes

BACKGROUND: Revision total hip arthroplasty (THA) has been a challenge for surgeons. The purpose of this study was to explore the short-to mid-term clinical and radiological outcomes of Chinese patients who underwent revision THA using a new off-the-shelf three-dimensional (3D)-printed trabecular titanium (TT) acetabular cup by comparison with a conventional porous coated titanium acetabular cup, to provide a reference for the recommendation of this prostheses. METHODS: A retrospective analysis of 57 patients (57 hips) who received revision THA was performed from January 2016 to June 2019. A total of 23 patients received 3D-printed cups (observation group) and 34 patients received non-3D-printed cups (control group). Clinical scores including Visual Analogue Scale (VAS), Harris Hip Score (HHS) and Short Form 36 (SF-36), upward movement of the hip center of rotation(HCOR)and limb-length discrepancy (LLD), stabilization and bone ingrowth of cups were compared between two groups. The multivariate linear regression was used to determine the factors potentially influencing the HHS score. Postoperative complications in the two groups were also recorded. RESULTS: All 57 patients were routinely followed up. The average follow-up durations in the control and observation groups were 43.57 ± 13.68 (24–65) months and 41.82 ± 11.44 (24–64) months, respectively (p = 0.618). The postoperative clinical scores significantly improved in both groups compared to the preoperative scores (p < 0.001). The VAS score did not significantly differ between the groups at 3 (p = 0.946) or 12 (p = 0.681) months postoperatively, or at the last follow-up (p = 0.885). The HHS score did not significantly differ between the groups at 3 months (p = 0.378) postoperatively but differed at 12 months (p < 0.001) postoperatively and the last follow-up (p < 0.001). The SF-36 score did not significantly differ between the groups at 3 months (p = 0.289) postoperatively, but was significantly different at 12 months (p < 0.001) postoperatively and the last follow-up (p < 0.001). Compared with the control group, the postoperative recovery of HCOR and LLD was better in the observation group. All cups remained stable, with no loosening throughout the follow-up period. But the observation group had a significantly better rate of bone ingrowth compared to the control group (p = 0.037). Multivariate linear regression analysis showed that different cup types, upward movement of the HCOR, and LLD influenced the HHS score at the last follow-up (p < 0.001, p = 0.005, respectively). None of the patients exhibited severe postoperative complications. CONCLUSION: The new off-the-shelf 3D-printed TT acetabular cup demonstrated encouraging short-to mid-term clinical outcomes in Chinese patients. It can effectively relieve pain, improve hip function, provide satisfactory biological fixation and high survival rate. But further follow up is necessary to assess its long-term outcomes.