Pericapsular Nerve Group (PENG) Block

The PENG block is a recently described block which supposedly provides superior dynamic pain relief following fracture neck of femur without causing motor weakness due to femoral nerve blockade.

Level of difficulty: Basic

Anatomy:

Anterior hip capsule contributes to dynamic pain following fracture neck of femur. The anterior hip capsuleis richly innervated by branches from the femoral nerve (FN), obturator nerve (ON) and accessory obturator nerve (AON). The FN, AON gives high and low articular branches. The articular branches from FN enter the hip joint at the L4-L5 level. The high articular branches of FN and AON are consistently found between the anterior inferior iliac spine (AIIS) and iliopubic eminence in the superior pubic ramus. These branches are not consistently blocked by fascia iliaca or 3 in 1 block.

Surface anatomy:

Anterior superior iliac spine, anterior inferior iliac spine, pubic symphysis, femoral artery

Indications:

  • Analgesia for preoperative and perioperative management of fracture neck of femur
  • Possibly can be used for postoperative analgesia following total hip arthroplasty

Nerves blocked: high articular branches of FN and AON

Positioning: supine, hip extended

Scanning technique: 2-5MHz, low frequency, curvilinear probe is placed in the transverse plane, medial to the AIIS, the medial end of the probe is rotated counter clockwise approximately 45° to align to the superior pubic ramus.

Structures to identify:

AIIS, superior pubic ramus, iliopubic eminence, iliacus muscle, psoas tendon, femoral artery, pectineus.

Block performance:

  • Position/Ergonomics: patient supine, operator on the ipsilateral side to be blocked, machine in front of operator
  • Probe: 2-5MHz C60 curvilinear probe or 6-13MHz high frequency linear probe if patient very thin.
  • Settings: MSK, General
  • Depth: 4-6cms
  • Needle size:80mm B-bevel nerve block needle
  • Needling technique: Transverse inplane lateral to medial approach
  • Optimal needle tip position: needle place in the fascial plane between psoas tendon and pubic ramus.
  • Drug choice: 0.25% Bupivacaine or 0.375% Ropivacaine with 1:200,000-400,000 Adrenaline
  • Volume: 20mls
  • Testing block success: pain scores at rest and on dynamic movement of hip (straight leg raise to 15°), assessment of quadriceps strength.
  • Pearls
    • Block onset time is around 30 minutes, sufficient time needs to elapse before block testing.
    • Block useful for preoperative phase, as its another low skill block with minimal vasculature could be used in the emergency department and by non-anaesthetists.
    • Obturator or Fascia iliaca block may need to be added for extensive analgesia for peri-operative phase, further comparative trial sare warranted.
  • Side effects
  • Complications
    • Vascular puncture
    • Femoral nerve damage
    • LAST

Contraindications:

  • Patient refusal
  • Allergy/Anaphylaxis to LA
  • Significant Coagulopathy

References:

Girón-Arango LPeng PWHChin KJBrull RPerlas A. Pericapsular Nerve Group (PENG) Block for Hip Fracture. Reg Anesth Pain Med. 2018 Nov;43(8):859-863.