**5. Conclusions**

RNB reduced the occurrence of delirium in elderly patients with hip fracture and relieved acute pain after surgery without complications. Therefore, we recommend RNB as a standard procedure for elderly patients with hip fracture due to lower delirium incidence and more effective analgesia in the early postoperative period.

**Author Contributions:** Writing—original draft, formal analysis, visualization, E.J.L.; Investigation and resources, data curation, W.U.K.; Investigation and resources, H.K.; Validation, project administration, H.- J.K.; Methodology, supervision, H.-C.S.; Conceptualization, investigation and resources, writing—review and editing, J.W.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Technology Innovation Program (20000397, Development of Two Track Customized 3D Printing Implant Manufacturing and Commercializing Techniques for Complex Bone Fractures) funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea).

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board of ASAN MEDICAL CENTER (protocol no. 2019-0267; December, 2019).

**Informed Consent Statement:** Patient consent was waived owing to the retrospective nature of this study.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to conditions of the ethics committee of our university.

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**

