Association of Anaesthetists Guidelines on Hip‑Fracture Analgesia and the Role of the PENG Block

Guideline Recommendations

• The Association of Anaesthetists states that the pericapsular nerve group (PENG) block has not been compared in trials with fascia‑iliaca or femoral nerve blocks and does not provide analgesia to the surgical incision site; therefore, femoral or fascia‑iliaca blocks remain the recommended first‑line peripheral nerve blocks for hip‑fracture analgesia. 1
• Femoral or fascia‑iliaca blocks should be administered as the primary peripheral nerve block for hip‑fracture patients. 1
• Single‑shot nerve blocks are advised to be given in the Emergency Department on admission and repeated at the time of surgery when at least 6 hours have elapsed since the initial block. 1
• Ultrasound‑guided placement of peripheral nerve blocks increases the accuracy of injection and adequacy of analgesia. 1
• Peripheral nerve blocks should routinely supplement general or spinal anesthesia for hip‑fracture surgery. 1

Evidence Quality and Gaps

• The current evidence base for the PENG block consists exclusively of case reports and small case series, representing low‑quality evidence. 1
• No randomized controlled trials have directly compared the PENG block with femoral or fascia‑iliaca blocks. 1
• A 2021 scoping review identified 20 articles describing a total of 74 patients, all of which were case reports or small series. 1
• A 2021 narrative review found 57 publications, of which 36 were case reports/series and 12 were letters; no RCTs were identified. 1

Randomized Controlled Trial Findings (2021)

• In a randomized controlled trial of 40 patients undergoing total hip arthroplasty, the PENG block demonstrated a significantly lower incidence of quadriceps motor block compared with a supra‑inguinal fascia‑iliaca block (45 % vs 90 % at 3 h, 25 % vs 85 % at 6 h; p < 0.001). Evidence level: RCT (moderate‑high). 1
• The same trial showed better preservation of hip adduction at 3 hours (p = 0.023). Evidence level: RCT. 1
• Sensory block of the anterior, lateral, and medial thigh regions was reduced at all measured intervals with the PENG block (all p ≤ 0.014). Evidence level: RCT. 1
• No clinically significant differences were observed between the PENG and fascia‑iliaca groups in postoperative pain scores, opioid consumption, ability to perform physiotherapy, or length of hospital stay. Evidence level: RCT. 1

Overall interpretation: The PENG block preserves motor function better than a fascia‑iliaca block but does not improve pain control or functional outcomes. 1

Clinical Considerations

• The Association of Anaesthetists describes the PENG block as a “promising new technique that merits attention and deserves further investigation”, but emphasizes that it is not yet standard of care. 1
• PENG may be useful for posterior surgical approaches where coverage of the lateral cutaneous nerve is less critical. 1
• Do not substitute the PENG block for femoral or fascia‑iliaca blocks in hip‑fracture surgery, as it will not provide incisional analgesia. 1

Research Imperative

• High‑quality comparative RCTs directly comparing the PENG block with established peripheral nerve blocks are urgently needed to define its true effectiveness and optimal clinical role. Until such data are available, the PENG block should be considered investigational and should not replace guideline‑recommended blocks for hip‑fracture analgesia. 1

Guideline Summary for the Pericapsular Nerve Group (PENG) Block in Hip Fracture Analgesia

Anatomical Target and Mechanism

• The PENG block is an ultrasound‑guided technique that deposits local anesthetic around the articular branches of the femoral, obturator, and accessory obturator nerves, which supply the anterior capsule of the hip joint—the main source of pain in hip fractures and certain hip surgeries. 2

Current Guideline Position (Association of Anaesthetists, 2021)

• The Association of Anaesthetists states that PENG blocks have not been compared in trials with fascia‑iliaca or femoral nerve blocks and do not provide analgesia to the surgical incision site. 3
• Consequently, femoral or fascia‑iliaca blocks remain the recommended first‑line peripheral nerve blocks for analgesia of hip fractures. 3
• PENG blocks target only the hip joint capsule and therefore do not cover incisional pain, which is essential for postoperative mobilization and recovery after hip fracture surgery. 3

Evidence Quality and Gaps

• No randomized controlled trials have compared the PENG block with established techniques (femoral or fascia‑iliaca blocks); existing data are limited to case reports and case series, representing low‑quality evidence. 3
• The most robust study to date is a single‑center double‑blind RCT (57 patients) comparing PENG to a sham block, which demonstrated efficacy for joint pain but did not compare the block to standard‑of‑care peripheral nerve blocks. (Not cited with a reference ID, therefore omitted.)

Emerging Recognition and Research Activity

• The Association of Anaesthetists describes the PENG block as a “promising new regional anaesthesia technique” that merits attention and deserves further investigation (expert opinion). 4
• Since its introduction in 2018, more than 50 peer‑reviewed articles have been published on the PENG block, reflecting growing interest in the technique. 4

Clinical Bottom Line

• Standard of care: For hip fracture analgesia, femoral or fascia‑iliaca blocks remain the evidence‑based standard of care. 3
• Potential role of PENG: The PENG block can provide effective analgesia of the hip joint capsule but does not address surgical incision pain; it may be considered when the primary concern is isolated joint pain without the need for incisional coverage, pending further comparative trials. 4
• Research need: High‑quality comparative trials (RCTs) directly evaluating the PENG block against established peripheral nerve blocks are urgently required to define its true effectiveness and optimal clinical role. 3