• Anesthesia, Local
• Pain Management
• Lower Extremity

We are honored to receive a nice compliment from Dr Pascarella and colleagues, a prestigious research group.1 I would like to comment on two issues raised by them.

The pericapsular nerve group (PENG) block was first published in this journal in late 2018. The latest PROSPECT guideline on hip fracture analgesia published in 2024 listed PENG block as ‘not recommended’.2 We respect the conclusion but are not discouraged by this. In their search methodology, they included randomized controlled trials (RCTs) published between April 4, 2005 and May 12, 2021. By May 2021, there was only a handful of controlled trials on the PENG block. However, the randomized trials on the PENG block increase exponentially as evident in our article which include RCTs up to February 2024.3 We are delighted to see the mounting evidence to support the efficacy of the PENG block with 7 randomized trials on hip fracture and 13 on hip arthroplasty.

We also echo the concern of Dr Pascraella’s group on the importance of evaluation of the spread. In performing a fascial plane block where the plane is between a bone and muscle (eg, PENG block, erector spinae plane block), the provider should pay attention to make sure that the needle ‘pierces’ through the epimysium of the muscle.4 Because the muscle epimysium cannot be indented for the needle to go through, one of the mistakes that the provider may commit is to accept the spread of injectate deep to the epimysium, simulating a muscle lift (figure 1).5 Therefore, a recent article was published to highlight some of the tips and pearls to perform the PENG block properly.4

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Figure 1

Upper two panels for the spread pattern of injectate following the erector spinae plane (ESP)—left: schematic diagram and sonogram of a proper needle location in the ESP ready for injection; middle: intramuscular spread of injectate deep to the epimysium simulating the lift of muscle; right: proper spread of injectate with lifting of muscle. Pericapsular nerve group (PENG) block in the lower two panels with the schematic diagram on top of the corresponding sonogram. Lower two panels for the spread pattern of injectate following the PENG block—left: schematic diagram and sonogram of the PENG block ready for injection; middle: intramuscular spread of injectate deep to the epimysium simulating the lift of muscle (please note that the epimysium is still close to the ilium block without any lifting); right: proper spread of injectate with lifting of muscle. Picture produced by Dr Vicente Roques-Escolar with permission from IMEDAR.com.

In conclusion, the evidence supporting the analgesia efficacy of the PENG block is mounting. We are confident that the PENG will receive appropriate recognition in the next international guidelines. Practitioners performing the PENG block are encouraged to make sure the occurrence of a proper psoas lift, which is an important part of the technique.