title: In-plane three-step needle insertion technique for ultrasound-guided continuous femoral nerve block after total knee arthroplasty: a retrospective review of 488 cases.
abstract: BACKGROUND
  Continuous femoral nerve block (CFNB) improves postoperative analgesia after total knee arthroplasty (TKA). The aim of this study was to investigate the clinical efficacy and complications of our in-plane three-step needle insertion technique that was devised to reduce the risk of direct femoral nerve injury during CFNB in anesthetized patients.
  
  
  METHODS
  This retrospective study included 488 patients who had undergone TKA. Ultrasound (US)-guided CFNB was performed under general or spinal anesthesia using an in-plane, three-step needle insertion technique. The success rate and difficulties of catheter placement, clinical efficacy of analgesia, and complications were recorded.
  
  
  RESULTS
  Femoral catheters were placed with a 100% success rate. In 488 patients, real-time US imaging revealed easy separation of the fascia iliaca and the femoral nerve following injection of local anesthetic through a Tuohy needle. Verbal numerical rating scale pain scores (0-10) were 2.0 ± 1.2, 3.5 ± 1.9, 3.2 ± 1.7, 2.9 ± 1.3, and 2.5 ± 1.1 at 1, 6, 12, 24 and 48 h postoperatively. No femoral hematoma, femoral abscess, or neurologic complications, including paresthesia or neurologic deficits, were observed during the 8-week follow-up period.
  
  
  CONCLUSIONS
  This retrospective study suggests that an in-plane three-step needle insertion technique for CFNB may reduce the risk of femoral nerve injury in anesthetized patients.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hyeon Ju
authors.identifier: 0000-0003-3150-6840
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jung Sub
authors.initials: JS
authors.lastname: Soh
authors.affiliation: Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hyong Hwan
authors.initials: HH
authors.lastname: Lim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Bumjoon
authors.initials: B
authors.lastname: Joo
authors.affiliation: Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hae Ja
authors.initials: HJ
authors.lastname: Lim
keywords: Arthroplasty; Catheters; Femoral nerve; Knee; Ultrasonography