BLOCK AT A GLANCE
The hip (PENG) block consists of an infiltration of local anesthetic (LA) along the proximal insertion of the anterior hip capsule, deep to the iliopsoas muscle, to block the sensory branches supplying the hip joint. In addition to the infiltration, a lateral femoral cutaneous nerve (LFCN) block can be performed for hip surgery.
Indications: Analgesia after total hip arthroplasty or other hip surgeries resulting in moderate to severe postoperative pain and chronic hip pain
Goal: LA spread in the plane between the iliopsoas muscle and anterior capsule of the hip cranially to the acetabular rim
Local anesthetic volume: 10 to 12 mL
The pericapsular block of the hip aims to provide analgesia for hip procedures while preserving its motor function to allow for early postoperative ambulation. Fascia iliaca and femoral nerve blocks are the most commonly performed regional anesthesia techniques to treat acute hip pain. However, they result in motor weakness of the quadriceps muscle, limiting their utility in enhanced recovery protocols and potentially increasing the risk of falls. As a result of the search for alternative interventional analgesia modalities to provide a selective articular sensory block, several pericapsular infiltration techniques have been proposed. They all consist of an injection of a LA around the acetabulum in the plane between the iliopsoas muscle and the proximal insertion of the anterior hip capsule, but they differ in the transducer orientation, needle approach, and recommended volumes of LA. Thus, the optimal injection site with respect to the iliopsoas tendon (lateral, below, or medial) and the resulting implications of the injectate’s spread are not well-defined. Initial reports suggest that this block may be effective for analgesia after hip fractures and hip replacement surgeries.
Deep musculofascial planes may be difficult to visualize with ultrasound (US), often requiring low-frequency, curved transducers for adequate imaging. The location and extent of LA spread may be inconsistent when using low volumes or may reach motor branches of the femoral nerve when using large volumes.
The femoral nerve and artery may not be readily visible when using curvilinear transducers, increasing the risk of unintentional puncture. Likewise, the LFCN can be injured inadvertently due to its location in the superficial plane deep to the fascia lata and lateral to the transducer, close to needle entry. Additionally, when performing a hip block, needle insertion could be rather deep, or follow a long path, or both, possibly resulting in intra-abdominal (pelvis) and intra-articular needle placement.
The analgesic techniques for hip procedures target the nociceptive innervation, predominantly located in the anterior surface of the hip capsule, which is innervated by nerves of the lumbar plexus (Figure 23-1).