In patients undergoing arthroscopic hip surgery, the addition of a preoperative fascia iliaca compartment block to intra-articular local anesthetic injection showed no improvement in postoperative analgesia and resulted in leg weakness, compared with placebo.
According to the researchers, these results contradict earlier reports and suggest that the fascia iliaca compartment block fails to change a patient’s pain experience due to incomplete coverage of the surgical field.
“We see pain relief achieved with this block performed postoperatively,” said Matthias Behrends, MD, associate professor of anesthesiology at UCSF School of Medicine, in San Francisco. “We thought the fascia iliaca block would solve the problem of pain control after arthroscopy while limiting the leg weakness experienced with the femoral nerve block. However, the block did not improve pain, and it reduced quadriceps strength, increasing patient risk for falls.”
As Dr. Behrends reported, there’s been a dramatic increase in the number of arthroscopic hip surgeries to address pathologies of the hip joint. Despite the minimally invasive approach, patients undergoing these procedures experience significant postoperative pain. Furthermore, in a recently published study, use of a femoral nerve block with 0.5% bupivacaine caused increased quadriceps weakness, which may have contributed to an increased number of subsequent falls (Am J Sports Med 2015;43:2680-2687).
“Recent studies have dealt with regional anesthesia techniques, but the overall level of evidence for these nerve blocks is extremely low,” Dr. Behrends said. “Whether peripheral nerve blocks can improve postoperative analgesia after hip arthroscopies is still a matter of debate. We also wanted to know whether a fascia iliaca compartment block, with its use of more dilute local anesthetic and an injection outside of the femoral sheath, could reduce the unwanted effects on quadriceps strength.”
Postoperative Pain Control Unchanged
Dr. Behrends and his colleagues enrolled 80 ambulatory surgery patients (ASA physical status class I-II) undergoing a hip arthroscopy for femoroacetabular impingement in a randomized, double-blind trial. The researchers compared preoperative fascia iliaca compartment block with 40 mL of 0.2% ropivacaine versus sham block with 40 mL of 0.9% saline. In addition, all patients received an intra-articular injection of 10 mL of 0.25% ropivacaine at the end of the surgical procedure.
The investigators assessed pain scores up to 24 hours after surgery and opioid requirements at several time points throughout the perioperative period. Quadriceps strength was measured via maximum voluntary isometric contractions with a stationary dynamometer three times: before fascia iliaca or sham blockade was performed, approximately 30 minutes after block completion and before patient discharge.
As Dr. Behrends reported at the 2017 annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstracts 3849 and 3907), 78 patients completed the pain control portion of the study on the day of surgery; four patients were lost to 24-hour follow-up.
Pain scores and opioid requirements were similar between groups in the PACU, said Dr. Behrends, as was the time required to meet the discharge criteria. Once discharged home, patients in both groups experienced a similar degree of pain and need for opioid analgesia in the first 24 hours after surgery.
According to Dr. Behrends, patient selection may have influenced these unexpected results.
In addition, said Dr. Behrends, the placebo effect may have played a role.
“Inserting a needle into the groin definitely impresses patients,” he said. “They tend to get better once an invasive procedure has been performed.”
Reduced Leg Strength and Increased Falls Risk
A total of 40 patients completed all three sets of measurements of quadriceps strength, and a clear difference emerged between groups, Dr. Behrends reported. Patients receiving the sham block experienced a 40% reduction in leg strength from baseline, whereas patients receiving the fascia iliaca compartment block had nearly 90% reduction in leg strength from baseline. Block performance with benzodiazepine sedation and surgery had little effect on leg strength of the nonsurgical leg, the authors noted.
“After discharge, average strength went from 170 N to 100 N in the sham group but from 160 N to 18 N in the fascia iliaca group, which was really a profound reduction of length strength,” Dr. Behrends said. “This is not what we were anticipating, given the lower concentration of local anesthetic injected outside of the femoral sheath. Nonetheless, quadriceps strength was dramatically reduced.”
According to Dr. Behrends, this reduction in leg strength also may have caused an increased number of falls. In the fascia iliaca block group, four patients reported falls compared with only one in the sham group.
“The study was underpowered to detect significance for this outcome, but this block may potentially put patients at risk of injury,” Dr. Behrends said. “I don’t know if I’ve convinced you at this point, but considering its questionable efficacy in reducing postoperative pain following hip arthroscopy, the routine use of fascia iliaca block is not recommended in this patient population.”
Robert S. Weller, MD, section head of anesthesia and the acute pain service at Wake Forest Baptist Health, in Winston-Salem, N.C., noted the trade-offs between pain relief and adequate postoperative ambulation.
“At our institution, we used to do a combined psoas–sciatic block in patients undergoing total hip arthroplasty,” Dr. Weller said. “It was fantastic for pain relief when compared to patients not receiving the block, but it obviously wasn’t good for ambulation. At that time, patients were all staying overnight, so none were discharged home, but it’s a challenging population.”