Study of Transdermal Fentanyl Patch to Treat Postoperative Pain in Total Knee Arthroplasty

Transdermal Fentanyl Patch for Postoperative Analgesia in Total Knee Arthroplasty

The purpose of this study is to determine whether transdermal fentanyl patch

Total knee arthroplasty (TKA) has severe postoperative pain that prevents mobilization of patient. The best standard analgesia regimen is patient-control analgesia (PCA) which requires a PCA pump that is expensive.

Transdermal fentanyl patch (TFP)(50 mcg/hr) can release fentanyl into blood circulation at rate 50 mcg/hr for three days. It has slow onset of about 12-14 hours, so it's used to treat chronic pain, not popular for a cure of pain. If the investigators apply TFP at appropriate times, i.e. 12-14 hours before surgery, it may be used to treat acute postoperative pain.

If it can give good analgesia for TKA, it can replace PCA. The benefit is that it is much cheaper and more convenient.

Inclusion Criteria:

• Patients who were scheduled for TKA gave informed consent for inclusion

Exclusion Criteria:

• ASA class 3-4
• Known allergy to any of the drugs to be used, eg. TFPs ,MO
• History of substance or alcohol abuse, and tolerance or dependence on opioids
• Can not use PCA
• Contraindication for spinal anesthesia