**1. Introduction**

Osteoporotic hip fracture is a major health problem because it is associated with high mortality, morbidity, and costs [1]. Although there are downward trends of mortality related to hip fracture, greater efforts are needed to achieve better outcomes [2]. The health status and health-related quality of life of elderly patients are seriously affected by the presence of hip fracture, and most patients cannot return to their performance status before injury [3].

Postoperative delirium is one of the most common complications in elderly patients with hip fracture and could result in cognitive impairment, short-term functional impairment, and increased mortality [4]. The known predisposing factors for delirium include advanced age, hip fracture surgery (in comparison to elective hip surgery), preoperative psychiatric illness, and preoperative cognitive impairment [5]. In addition, pain is a major risk factor for delirium; however, most elderly patients with hip fracture have a limited

**Citation:** Lim, E.J.; Koh, W.U.; Kim, H.; Kim, H.-J.; Shon, H.-C.; Kim, J.W. Regional Nerve Block Decreases the Incidence of Postoperative Delirium in Elderly Hip Fracture. *J. Clin. Med.* **2021**, *10*, 3586. https://doi.org/ 10.3390/jcm10163586

Academic Editor: Gianluca Testa

Received: 21 July 2021 Accepted: 12 August 2021 Published: 15 August 2021

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use of systemic opioid analgesics owing to side effects and their vulnerability in the drug metabolism process [6,7].

For this reason, comprehensive pain protocols have been suggested for elderly patients with hip fracture; these include evidence-based block use, timely repeated pain assessment, and multidisciplinary orthogeriatric care [8]. Regional nerve blocks (RNBs) have been proven to be effective in controlling pain in hip fractures, along with the advantages of few systemic effects [9]. Considering that pain control is essential for the reduction in delirium, we hypothesized that RNB use in hip fracture surgery would decrease postoperative pain and the incidence of delirium. This study aimed to evaluate the incidence of delirium according to RNB use in patients with hip fracture.
