In adult patients undergoing internal fixation of a fracture of the femur, anterior 3-in-1 femoral block and posterior lumbar plexus block have been found to provide comparable analgesia in a recent clinical study.
Although the anterior approach resulted in a higher percentage of incomplete blockade, pain scores and opioid requirements did not differ significantly from the posterior approach.
“Irrespective of the fact that there was significantly more obturator sparing, patients who had the anterior approach still had comparable analgesia to patients who had the posterior approach,” said Jane Nithya Tolson, MD, in the Department of Anesthesiology and Critical Care, Jawaharlal Institute of Postgraduate Medical Education & Research, in Pondicherry, India. “Therefore, the most important nerves that need to be blocked for patients undergoing internal fixation of femur fracture surgery are the femoral and lateral cutaneous nerves. Blocking the lumbar plexus by the anterior approach is a viable analgesic option to explore in this patient population.”
Although the lumbar plexus block is commonly used in patients undergoing hip and knee arthroplasties, as Dr. Tolson noted at the 2016 annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 2811), its effectiveness in surgeries involving fixation of femoral fractures has not been well documented in the literature.
“It’s known that the posterior approach more consistently blocks all three nerves that we would want to block in order to provide perioperative analgesia for these patients,” Dr. Tolson said, “but it also requires specific positioning of the patient who may not be able to sit or lie laterally.”
Block Effectiveness, Opioid Use
Dr. Tolson and her colleagues randomly assigned 44 patients with American Society of Anesthesiologists (ASA) physical status I and II who were undergoing intramedullary fixation of femoral fracture to one of two groups: For the anterior approach, Winnie’s technique (Anesth Analg 1973;2:989-996) was applied, and for the posterior approach, Capedevila’s technique (Anesth Analg 2002;94:1606-1613) was used.
After measuring the visual analog scale (VAS) score at baseline, the attending anesthesiologist performed the blocks under peripheral nerve stimulator guidance, and a styleted catheter was threaded following a bolus of 30 mL of 0.25% bupivacaine.
VAS score and nerve blockade were assessed at 30 minutes of block performance. All patients then were given general anesthesia.
Continuous infusion of 0.25% bupivacaine (6 mL per hour) was given up to 48 hours, and pain scores and nerve blockade were assessed at six, 24 and 48 hours after block initiation.
“As expected, there was a considerable decrease in VAS scores following blocks,” said Dr. Tolson, who noted that scores did not differ significantly at any time point between the groups. “Fentanyl requirement and PCA [patient-controlled analgesia] morphine were also comparable between groups and did not differ significantly.”
The median intraoperative fentanyl requirement was 30 mcg in the anterior block group and 20 mcg in the posterior block group (P=0.1568). PCA morphine consumed postoperatively in the first 24 hours was 8.8 and 6.9 mg, respectively (P=0.0540).
Although obturator nerve blockade was significantly less in the anterior group (66.6%) than in the posterior group (94.7%), the authors noted a slight increase when compared with previous studies (J Int Med Res 2002;30:161-167; Can J Anaesth 2004;51:45-51).
“On motor assessment, we saw that obturator is significantly spared in the anterior approach,” Dr. Tolson said, “but previous studies have shown a 47% obturator blockade. I know it’s a small increase, but our study demonstrated a 66.6% blockade. We believe that increase is attributable to the use of styleted catheters.”
“In addition,” she said, “these blocks were performed under nerve stimulator guidance and may be improved in the future with ultrasound. … I think with imaging, we can place the catheter more accurately and safely with the anterior approach.”
Moderator James C. Eisenach, MD, president and CEO of Foundation for Anesthesia Education and Research (FAER), in Schaumburg, Ill., suggested that following up with patients one to two months after surgery may provide additional meaningful data.
“Dr. Mark Newman from Penn [in Philadelphia] is doing a very large trial looking at spinal anesthesia versus general anesthesia, and an important patient-centered outcome measure that he’s using is the ability to walk 10 meters 60 days after surgery. If people are unable to walk that far after surgery, they’re likely to die in the coming year and are likely to be in an assisted-living situation,” Dr. Eisenach said.
“[Dr. Newman’s] preliminary data, at least with spinal versus general anesthesia, suggest that there might be a fairly large effect on this outcome. I think that other forms of regional anesthesia would be interesting to examine in this area,” Dr. Eisenach concluded.