SLR - June 2016 - Todd Jaramillo

Continuous Popliteal Sciatic Nerve Block Versus Single Injection Nerve Block for Ankle Fracture Surgery: A Prospective Randomized Comparative Trial

Reference: Ding DY, Manoli A 3rd, Galos DK, Jain S, Tejwani NC. Continuous Popliteal Sciatic Nerve Block Versus Single Injection Nerve Block for Ankle Fracture Surgery: A Prospective Randomized Comparative Trial. J Orthop Trauma. 2015 Sep; 29(9): 393–98.

Scientific Literature Review

Reviewed By: Todd Jaramillo, DPM
Residency Program:  Wake Forest Baptist Health

Podiatric Relevance: Many methods of postoperative pain control exist. Each has its relative advantages and disadvantages. Peripheral nerve blocks provide intraoperative pain control along with postoperative pain control but can lead to “rebound phenomenon,” where patients feel a high level of pain within a day after surgery. With the large amount of ankle fractures being treated by foot and ankle surgeons, along with the side effects of oral opioid usage, a different method of pain control that can reduce postoperative pain and the required amount of oral opioids to control said pain would be of benefit. In this article, the authors hypothesize that a continuous infusion peripheral nerve block would be associated with decreased pain levels and decreased narcotic utilization in the early postoperative period for patients undergoing surgical management of ankle fractures. They also hypothesize that this type of block will prevent rebound pain.

Methods: Patients with unstable ankle fractures (AO/OTA type 44) who were undergoing open reduction and internal fixation were randomized to one of two anesthetic protocols. One group received general anesthesia/sedation with a single-shot peripheral nerve block (SSB group), and the other group received general anesthesia/sedation with a continuous peripheral nerve block (On Q group) using an On Q pump. The patients were blinded to the group to which they were randomized until the day after the surgery. The surgeon and anesthesiologist were blinded to the randomization until the day of surgery. Patients in both groups received an ultrasound-guided popliteal sciatic nerve block. An indwelling catheter was placed for those receiving a continuous infusion. If a medial incision was necessary for proper reduction, a saphenous nerve block was performed. The continuous infusion, which consisted of 0.2 percent ropivicaine at a rate of 8 mL/h, began in the postoperative care unit (PACU) and was self-discontinued 48 hours after surgery. All patients were treated for breakthrough pain in the PACU if needed. All patients were discharged to home with the same prescription and instructions for pain control. Patients were contacted eight, 12, 24, 48 and 72 hours after surgery to assess their numeric rating pain scale and amount of pain medication used. All patients were also assessed during routine postoperative follow-up visits at two, six and 12 weeks after surgery for pain, infection, satisfaction and residual neurologic symptoms.  

Results: A total of 44 patients were included in this study. The single shot group consisted of 21 patients, and the continuous infusion group consisted of 23 patients. None of the 44 patients had intraoperative complications. Twelve patients from the single shot group and 13 patients from the continuous infusion group required a medial incision for which a local saphenous nerve block was performed. Time to discharge from the PACU was longer for the On Q group. The mean VAS score at time of discharge was similar between groups. The average total amount of fentanyl given in the PACU was less in the On Q group, and there was no significant difference in the average amount of oral pain medication given before discharge. The On Q group had a lower mean numeric rating scale pain scores at all points, but the score was significant only at the 12-hour time point. On Q group patients took a mean of 14.9 pain pills vs. 20.0 in the SSB, which was a significant difference. At two and 12 weeks after surgery, the On Q group reported lower VAS pain scores, but at six weeks, the difference was not statistically significant. No differences were found between groups when reporting on neurologic symptoms or satisfaction rates at two, six and 12 weeks after surgery. In eight instances, the On Q pump may have been compromised. The patients with compromised pumps were still analyzed in their original groups on an intention-to-treat basis.

Conclusions: The results of this study show a significant decrease in rebound pain and the amount of postoperative narcotics used over a 72-hour period in the patients managed with continuous infusion nerve block anesthesia when treated operatively for an ankle fracture. There were no statistically significant differences in narcotic side effects between the two groups, but reduction of the amount of narcotics used has been shown to prevent complications such as nausea, vomiting, respiratory depression, ileus and narcotic-induced hypotension. To enhance postoperative pain control and reduce the amount of oral opioids needed by patients treated operatively for an ankle fracture, continuous infusion peripheral nerve blocks are an important part of perioperative pain control. Surgeons can have confidence that continuous infusion blocks will enhance pain control and reduce the required amount of oral opioids required to control pain in patients that fit the demographics of this article.

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