Monday, December 16, 2013

Pain Medicine News - Study Suggests Four Days of Nerve Block No Better Than One Day, After Knee Replacement

Pain Medicine News - Study Suggests Four Days of Nerve Block No Better Than One Day, After Knee Replacement

ISSUE: JUNE 2011 | VOLUME: 9:06

Study Suggests Four Days of Nerve Block No Better Than One Day, After Knee Replacement

by Rosemary Frei, MSc

Patients who have four days of a continuous femoral nerve block (cFNB) after total knee arthroplasty (TKA) do not receive additional benefits compared with those who get one day of cFNB, according to a one-year follow-up study (Reg Anesth Pain Med 2011;36:116-120).
Previously, the authors reached different conclusions—they demonstrated that extending a cFNB from one to four days after TKA provided clear benefits during the infusion, but not after the catheter was removed (Anesth Analg 2009;108:1688-1694). However, they also noted limitations in their ability to generalize these results.
To validate their conclusions, the investigators performed a similar study using a multicenter format, many health care providers and patients on general orthopedic wards. The current study was conducted at five different centers across the United States between April 2007 and August 2009. Subjects undergoing TKA received a single injection of cFNB with ropivacaine 0.2% after surgery up until the next morning. By morning, patients were randomized to continue either perineural ropivacaine (n=28) or normal saline (n=26). Patients, investigators and statisticians were blinded to treatment group.
On postoperative day 4, patients were discharged with a portable infusion pump and catheters were removed. Investigators evaluated pain, stiffness and physical functional disability using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) preoperatively and at seven days, as well as one, two, three, six and 12 months after surgery. Patients were included if they were evaluated for at least four of the six follow-up time points.
The two treatment groups had similar WOMAC scores for the mean area-under-the-curve calculations (P=0.32) and at all individual time points (P>0.05).
The authors concluded that there was “no evidence that extending an overnight cFNB to four days improves (or worsens) subsequent pain, stiffness or physical function after TKA in patients of multiple centers convalescing on general orthopedic wards.”
J.C. Gerancher, MD, professor of anesthesiology and section head, Regional Anesthesia and Acute Pain Management, Wake Forest University Baptist Health, Winston-Salem, N.C., who was not involved in the study, was intrigued by the study findings.
“Our practice is to use femoral catheters for two days after total knee replacement,” he said. “What this study does is give credence to the idea of shortening our duration of infusion and possibly opting for overnight infusions in select patients in the future.”

Patients who received cFNB with ropivacaine 0.2% for one day or four days experienced similar pain, stiffness and functional disability seven days to one year following surgery.

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