Objective: To determine the incidence of and risk factors for peripheral nerve block-related complications after orthopedic surgery at a single-tertiary hospital.

Materials and Methods: The prospective observational study included 500 patients scheduled to undergo orthopedic surgery with peripheral nerve block [PNB] guided by ultrasound, nerve stimulation, paresthesia elicitation, or landmark during the period October 2015 to September 2017
study period. Tntra-operative complications related to PNB (e.g., pneumothorax, local anesthetic systemic toxicity) were recorded. All patients were assessed for nerve block resolution within 48 h and followed to evaluate for postoperative neurological symptoms [PONS] at postoperative day [POD]
3, 4, 5, 10 and 6 weeks after surgery. Tf already discharged, they were followed-up by phone. Those with remaining PONS were continually evaluated at 6 months postoperatively. The incidence of and risk factors for PONS were analyzed.

Results: The incidence of PONS at POD 3 was 2.2% (95% confidence interval [CT] 1.2 to 3.9), at POD 4 was 1.6% (95% CT 0.8 to 3.1), at POD 5 was 1.4% (95% CT 0.7 to 2.9), at POD 10 was 1.2% (95% CT 0.6 to 2.6), and at 6 weeks postoperatively was 0.8% (95% CT 0.3 to 2.0). Only two patients with open reduction internal fixation [ORTF] of distal humerus fracture had persistent PONS lasting longer than 6
months (p<0.001). Male gender (adjusted odds ratio [AOR] 4.92, 95% CT 1.26 to 19.29; p = 0.022), body mass index [BMT] >30 kg/m2 (AOR 4.35, 95% CT 1.18 to 16.03; p = 0.027), and 0.5% bupivacaine (AOR 3.95, 95% CT 1.11 to 14.03; p = 0.034) were significantly risk factors for PONS. Neither pneumothorax nor local anesthetic systemic toxicity was occurred.

Conclusion: The incidence of PNB-related complications is low. Risk factors for PONS after PNB are male gender, BMT
>30 kg/m2, and 0.5% bupivacaine.

Keywords: Tncidence, Risk factors, Peripheral nerve block, Postoperative neurological symptoms, Orthopedic surgery