The best approach to balancing analgesia, opioid use and passive range of motion after total knee arthroplasty (TKA) is to block multiple nerves rather than any single nerve, according to a sophisticated network meta-analysis. This approach proved better than periarticular local anesthetic infiltration and epidural analgesia.
“Based on available evidence, we found that combinations of multiple nerve blocks—especially combining a femoral nerve block (FNB) with a sciatic nerve block (SNB)—perform better than other modalities for superior analgesia, less opioid consumption and larger range of motion in the first 72 hours after surgery,” said lead author Abdullah Terkawi, MD, an anesthesia resident at the University of Virginia School of Medicine, in Charlottesville. “In other words, two nerve blocks are better than one, and one nerve block is better than none.”
However, epidural analgesia, which is often considered a standard pain management modality after TKA, “appears inferior to multiple peripheral nerve blocks and even selective femoral nerve blocks in most outcomes,” Dr. Terkawi said.
Differing Approaches Spark Study
The network meta-analysis (NMA) of 170 published trials, consisting of 12,530 patients and 17 treatment options, has been published in Anesthesiology(2017;126:923-937).
Dr. Terkawi was inspired to undertake the evaluation because he noticed how pain management after TKA differs markedly across institutions. “I also recognized how strongly various anesthesiologists believed that their choice was optimal—often in the absence of evidence,” he said.
Because there are more than 10 different analgesic strategies for TKA, “it would be prohibitively expensive and impractical to conduct a randomized controlled trial (RCT) simultaneously comparing them all,” Dr. Terkawi said.
Instead, Dr. Terkawi believes that analgesia for TKA would be a great topic for an NMA. “This is a relatively new methodology that extends the concept of the traditional meta-analysis to produce pairwise comparisons and relative treatment effects across a range of interventions, through both direct and indirect comparisons,” he said.
Moreover, an NMA allows comparisons among treatment modalities that have never been directly compared. “You end up with a relative ranking of all modalities, while properly accounting for correlations in effect size from multiarm trials,” Dr. Terkawi said. “For example, if one RCT demonstrates that treatment A is superior to B, and a second RCT provides evidence that treatment C is superior to A, then by ‘networking’ the two we have evidence that treatment C is superior to B, even though these two interventions were not directly compared.”
The authors defined the optimal modality as best balancing low pain scores, low opioid consumption and a large knee range of motion. “Each of these primary outcomes was measured at multiple time points during the first 72 hours after surgery,” Dr. Terkawi said.
Afterward, the authors ranked each treatment modality for each outcome, using the surface under the cumulative ranking curve values and rankograms to present the hierarchy of interventions for each outcome.
Patient-controlled analgesia and systemic opioids alone were found to be inferior to virtually every other approach. “Thus, I would strongly encourage anesthesiologists to provide their patients with whatever possible adjuvant pain management modalities might be available,” Dr. Terkawi said. “If nerve blocks are unavailable for some reason, the surgeon should at least provide periarticular local anesthetic infiltration.”
Two surprising findings of the NMA were that liposomal bupivacaine (Exparel, Pacira Pharmaceuticals), a relatively new product, did not appear to be superior to traditional periarticular infiltration during the initial 72 hours; and auricular acupuncture (at the sympathetic, Shen Men, stomach and occipital points) effectively prevented postoperative nausea and vomiting, although for pain management it was worse than all peripheral nerve blocks, periarticular infiltration and epidurals.
“Clinicians should consider published evidence, not just their own practice and experience,” Dr. Terkawi said. In addition, “good analgesia improves the quality of recovery and speeds recovery of joint function.”
The NMA found an adductor canal block to have similar efficacy to a FNB alone for pain control and opioid consumption.
The incidence of falls, however, was rarely reported, “either because it is rare or because most of the studies restricted their follow-up to the first 24 hours,” Dr. Terkawi said.
A fall was most reported with placebo (3%), followed by combined FNB/SNB infusion (2.28%) and FNB alone (0.18%). “Therefore, it seems that single-injection femoral nerve block does not necessarily increase the risk of falls, as previously thought,” Dr. Terkawi said.
The authors concluded that the best modality for a given outcome was not necessarily the best treatment option for other outcomes. “Consequently, focusing on one outcome can easily lead to selection of a modality that performs poorly for other important outcomes,” Dr. Terkawi said.
More comprehensive tools that wisely combine multiple outcomes may be better end points for future studies, according to Dr. Terkawi.
“Although functional outcomes were suboptimally studied, the combination of a femoral nerve block and a sciatic nerve block was judged to be the overall best approach,” he said.