Continuous femoral nerve block after total knee arthroplasty?

Acta Anaesthesiol Scand. 2009 Aug;53(7):914-20. doi: 10.1111/j.1399-6576.2009.01965.x. Epub 2009 Apr 15.


Background: A continuous femoral nerve block is frequently used as an adjunct therapy after total knee arthroplasty (TKA). However, there is still debate on its benefits.

Methods: In this prospective, randomized study, patients received a basic analgesic regimen of paracetamol and dicloflenac for the first 48 h postoperatively. In addition, the study group received a continuous femoral nerve block. A morphine patient-controlled analgesia pump was also available as a rescue analgesic to all the patients. Patients' numeric rating scores for pain, the amount of morphine consumed and its side effects during the first 48 h were recorded. Knee flexion angles achieved during the first week were registered. Three months postoperatively, patients completed Western Ontario and McMaster Universities Osteoarthritis Index and Knee Society Score.

Results: The study group (n=27) had less pain (P=0.0016) during the first 48 h, was more satisfied with the analgesia (P<0.001) and used less morphine (P=0.007) compared with the control group (n=26). Fewer patients were nauseated, vomited or were drowsy in the study group (P=0.001). Also, the study group achieved better knee flexion in the first 6 days after surgery (P=0.001), with more patients reaching 90 degrees flexion than the control group. However, after 3 months, there were no significant functional differences between the groups.

Conclusion: A continuous femoral nerve block leads to better analgesia, less morphine consumption and less morphine-related side effects after TKA. Early functional recovery is improved, resulting in more patients reaching 90 degrees knee flexion after 6 days. However, after 3 months, no significant functional benefits were found.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Analgesics, Opioid / administration & dosage
  • Analgesics, Opioid / therapeutic use
  • Anesthesia, Spinal
  • Arthroplasty, Replacement, Knee*
  • Double-Blind Method
  • Female
  • Femoral Nerve*
  • Humans
  • Knee / anatomy & histology
  • Knee / physiology
  • Male
  • Morphine / administration & dosage
  • Morphine / therapeutic use
  • Nerve Block*
  • Pain Measurement
  • Pain, Postoperative / drug therapy*
  • Prospective Studies
  • Treatment Outcome


  • Analgesics, Opioid
  • Morphine