Postoperative urinary retention induced hyponatremic seizure following total knee arthroplasty with an enhanced recovery after surgery protocol: a case report and literature review

Abstract

Background: Although the enhanced recovery after surgery (ERAS) protocol in total knee arthroplasty (TKA) aimed at facilitating overall outcomes and reducing complication rates, the incidence of postoperative urinary retention (POUR) is still of concern. Case presentation: A 70-year-old woman underwent TKA with an ERAS protocol for severe osteoarthritis of right knee. She developed generalized tonic-clonic seizure on post-operative day 1. The occurrence of altered consciousness initiated further investigation, revealing hyponatremia of 117 mEq/L and significant urinary retention. Following urinary catheterization, during which 1350 mL of urine was immediately drained and an additional 2550 mL over the next 8 hours, her sodium level improved to 130 mEq/L under regular saline solution supply, accompanied by a marked improvement in consciousness. Subsequently, she was discharged with a normal sodium level and complete recovery of the conscious level. The prompt resolution of neurological symptoms highlights the correlation between hyponatremia-induced seizures and POUR. Conclusions: Hyponatremic seizure related to POUR after TKA with an ERAS protocol represents an uncommon yet potentially lethal complication. This case emphasized the importance of recognizing and addressing hyponatremic seizure as well as considering POUR as a potential cause despite the implementation of ERAS protocol. Urinary catheterization and early removal are suggested in elderly patients scheduled for TKA under spinal anesthesia.