PENG block after hip arthroplasty: possible motor preservation without consistent analgesic superiority

Polish version: Blok PENG po endoprotezoplastyce biodra — możliwa ochrona siły bez stałej przewagi przeciwbólowej

A systematic review of 10 randomized trials presents a nuanced view of the pericapsular nerve group (PENG) block after total hip arthroplasty (THA). It may preserve quadriceps function better than some blocks, but does not consistently outperform other modern analgesic strategies. Its additional benefit alongside effective peri-articular infiltration may be small.

Why this study matters

PENG targets articular branches of the femoral and accessory obturator nerves while aiming to spare the main femoral nerve trunk and quadriceps strength. That goal matters in early mobilisation after THA. However, the literature is heterogeneous. Bravo and colleagues restricted their review to prospectively registered randomized trials without discrepancies between the registered protocol and publication, excluding many nominally randomized studies for methodological reasons.

Review methods

The review concerned adults undergoing THA. MEDLINE, EMBASE, CINAHL and Google Scholar were searched from inception to May 2026. Of 468 initially identified publications, 44 randomized trials underwent full-text assessment; 34 were excluded mainly because of inadequate prospective registration or discrepancies between registered and reported outcomes. Ten RCTs were included.

Comparators included intrathecal morphine, infra- and suprainguinal fascia iliaca blocks, quadratus lumborum block, L4 erector spinae plane block and peri-articular local anaesthetic infiltration. Outcomes included static and dynamic pain, opioid consumption, quadriceps weakness and function.

Main results

• PENG provided analgesia noninferior to 100 µg intrathecal morphine and better than infrainguinal fascia iliaca block.
• Analgesia and opioid requirements were similar to suprainguinal fascia iliaca, anterior quadratus lumborum and L4 erector spinae blocks, with possible advantages in early muscle strength.
• In one comparison with suprainguinal fascia iliaca block (SIFIB), quadriceps motor block occurred in 45% after PENG versus 90% after SIFIB at 3 hours, and 25% versus 85% at 6 hours.
• Effective peri-articular infiltration produced less movement pain during the first 6 hours and less resting pain during the first 48 hours than PENG.
• Adding PENG to a comprehensive peri-articular infiltration regimen provided little additional benefit.

Clinical interpretation for an orthopaedic surgeon

PENG is an option whose value depends on the overall analgesic pathway and mobilisation goals. Preserving quadriceps function may be particularly useful for very early mobilisation, but a well-designed multimodal regimen can provide similar or better analgesia without routinely adding another block.

The term “motor-sparing” does not mean that motor weakness is eliminated. Local anaesthetic may spread to the femoral nerve, and injectate volume matters. These considerations are relevant when physiotherapy begins soon after surgery.

Limitations

• Only 10 RCTs were included, with varying drugs, volumes, block techniques and background analgesia.
• Diverse comparators prevent a single effect estimate applicable to every ERAS protocol.
• Excluding 34 trials for methodological problems strengthened the selected evidence but reduced its volume.
• The review itself was registered in INPLASY only after completion, which the authors acknowledged as a limitation.
• Preserving muscle strength is most consequential where very early mobilisation is actually planned.

Implications for practice

The useful question is what PENG adds to a particular analgesic regimen. With effective peri-articular infiltration and multimodal treatment already in place, its incremental value may be limited. It remains a reasonable option when quadriceps preservation is a priority.

The review does not justify abandoning PENG or establish one universally optimal strategy after THA. Results cannot automatically be transferred between centres using different surgical approaches, infiltration regimens or mobilisation schedules.

References

Bravo D, Arancibia H, Manzanilla M, Jara Á, Pirotesak S, Aliste J, Tran DQ. Pericapsular nerve group block for total hip arthroplasty: A systematic review. J Int Med Res. 2026;54(8):3000605261476867. Published online 25 August 2026. DOI: 10.1177/03000605261476867. PubMed · Full text in PubMed Central.

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Content prepared by: Tomasz Poboży - orthopaedic surgeon.