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Regional Anesthesia: Hip, Groin, Buttocks

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Authors

Neha Raukar, MD MS

Kristi Colbenson, MD

Summary

  • In the emergency department, there has been significant literature published about the utilization of nerve blocks to provide anesthesia for hip fractures. This pathology is commonly encountered in the elderly for which systemic pain control can be difficult, especially when trying to limit the use of opiates, which are associated with increased adverse events such as delirium, when used in the elderly.  There are a variety of methods to achieve this, outlined below.
  • A dorsal penile block can provide pain control for the penis such as for paraphimosis or entrapped skin.
Link to Discussion of General Block Principles/Materials/Anesthetics & More

Anatomy

Link to Detailed Discussion of Lower Extremity Anatomy
Hip
  • The hip area is innervated by branches of the lumbar plexus. The dermatomal supply of the hip joint is typically from spinal nerve roots L4 to S2, while the bony structures of the hip joint are supplied from spinal nerve roots L3 to S1.
  • The hip joint itself is innervated by the femoral nerve, obturator nerve, nerve to the quadratus femoris, superior gluteal nerve, and sciatic nerve.

Innervation of the hip joint. [1]Image from Sensory Innervation of the Hip Joint and Referred Pain: A Systematic Review of the Literature. L:aumonerie et al. Pain Medicine, Vol 22, Issue 5, May 2021, … Continue reading

Distribution of sensory nerves [2]Image from Sensory Innervation of the Hip Joint and Referred Pain: A Systematic Review of the Literature. L:aumonerie et al. Pain Medicine, Vol 22, Issue 5, May 2021, … Continue reading

Penis
  • The innervation to the penis arises from the sacral nerve roots (S2-S4) via the pudendal nerve, which divides in the pudendal canal terminating in branches to the dorsal penis. The dorsal penile nerves lie just deep to the deep fascia (Buck’s fascia) and adjacent to the dorsal vessels. Blocking this nerve can provide anesthesia prior to reduction of a paraphimosis. 
  • Local anesthetic with epinephrine should never be used in penile blocks in the emergency department as this has been shown to lead to ischemia.

Innervation of the penis [3]Image from Weech D, Ameer MA, Ashurst JV. Anatomy, Abdomen and Pelvis, Penis Dorsal Nerve. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 … Continue reading

Cross-sectional anatomy of the penis [4]Image from Weech D, Ameer MA, Ashurst JV. Anatomy, Abdomen and Pelvis, Penis Dorsal Nerve. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. … Continue reading

Hip Blocks

Femoral Nerve Block

Overview
  • A femoral nerve block is a safe and widely practiced regional nerve block used to provide analgesia in patients with a hip fracture. [5] Mittal R, Vermani E. Femoral nerve blocks in fractures of femur: Variation in the current UK practice and a review of the literature. Emerg Med J. 2014;31(2):143-147. doi:10.1136/emermed-2012-201546
  •  The femoral nerve branches off of the lumbar plexus and courses along the psoas muscle, before passing beneath the inguinal ligament lateral to the femoral artery within the femoral triangle. A successful femoral nerve block will provide anesthesia to the anterior thigh (femoral nerve) as well as the medial lower leg (through the saphenous nerve).
  • This block only provides analgesia 50% of the time to the medial thigh (through the obturator nerve) [6]Kaloul I, Guay J, Cote C, Fallaha M. The posterior lumbar plexus (psoas compartment) block and the three-in-one femoral nerve block provide similar postoperative analgesia after total knee … Continue reading. 
  • Using ultrasound for femoral nerve blocks has been shown to improve onset of analgesia, lower required anesthetic dose, and decrease risk of vascular puncture or intraneural injection. [7] Mittal R, Vermani E. Femoral nerve blocks in fractures of femur: Variation in the current UK practice and a review of the literature. Emerg Med J. 2014;31(2):143-147. doi:10.1136/emermed-2012-201546
  • Specific considerations for contraindications for this block include:
    • Ipsilateral fractures that place the patient at high risk for compartment syndrome, such as tibial plateau fractures. 
    • Previous ilioinguinal surgery (femoral vascular graft, kidney transplantation)
    • Large inguinal lymph nodes or tumor
Ultrasound Anatomy
  • Identify the femoral triangle bordered by the femoral artery medially, the iliacus muscle posteriorly (with the fascia iliaca overlying anteriorly). The sartorius will be seen laterally.  
  • The nerve is oval or triangular shaped and is hyperechoic. 
  • While the depth varies, it is typically 2-6 cm beneath the skin surface.

US Anatomy – Identify the femoral triangle with femoral vasculature medially, the iliacus muscle posteriorly, and the sartorious laterally

Approach
  • Advance the needle from the lateral edge of the probe, directed medially, and aim for the space behind the nerve. 
  • If the nerve is not visualized, aim for the deep border of the triangle. 
  • You may feel a “pop” as the needle pierces the fascia iliaca.
  • When the needle tip is properly positioned, aspirate and then to confirm placement, infiltrate the area with 1-2 ml of local anesthetic as you hydrodissect the nerve. 
    • Troubleshoot – if the anesthetic only travels superiorly and does not layer out, the needle is likely superficial to the fascia lata and should be advanced
  • After needle placement is confirmed, 10-20ml of local anesthetic is injected. This volume of fluid will make the nerve “float” off of the iliopsoas. The patient should experience pain relief within 10-20 minutes. You may have to use 2 syringes 10ml each and switch out the syringe depending on your supplies and level of assistance.

Image or video of femoral nerve block

Fascia Iliaca Block

Overview
  • The fascia iliaca compartment block (FICB) is similar to the femoral nerve block, but uses a larger volume of anesthetic that is placed within the iliac fascia and allowed to diffuse to its target femoral nerve. The fascia iliaca is a layer of fascia that connects the internal oblique and sartorius muscles and overlies the muscle body of the iliacus.
  • Placement in the fascia itself allows the anesthetic to diffuse to the lateral femoral cutaneous nerve (lateral thigh), obturator nerve and femoral nerve. [8] Murgatroyd H, Forero M, Chin KJ. The efficacy of ultrasound-guided fascia iliaca block in hip surgery: a question of technique? Reg Anesth Pain Med. 2013;38(5):459-460.  
  • An additional benefit of the FICB is the needle can remain distant from the femoral neurovascular bundle, theoretically making this a safer block and easier to learn for the beginner
  • Specific considerations for contraindications for this block include:
    • Ipsilateral fractures that place the patient at high risk for compartment syndrome, such as tibial plateau fractures. 
    • Previous ilioinguinal surgery (femoral vascular graft, kidney transplantation)
    • Large inguinal lymph nodes or tumor
Ultrasound Anatomy
  • Identify the femoral triangle bordered by the femoral artery medially, the iliacus muscle posteriorly (with the fascia iliaca overlying anteriorly). The sartorius will be seen laterally.  
  • The nerve is oval or triangular shaped and is hyperechoic. 
  • While the depth varies, it is typically 2-6 cm beneath the skin surface.

US Anatomy – Identify the femoral triangle with femoral vasculature medially, the iliacus muscle posteriorly, and the sartorious laterally. The fascia iliaca is the fascial layer superior to the iliacus.

Approach
  • After locating the femoral vessels, slide the ultrasound probe laterally until the iliacus and sartorius muscles, and the interposed fascia iliaca is visualized. You can often visualize the femoral nerve on the medial side simultaneously.
  • The tip of the needle is pierced through the fascia iliaca, and rests just at the edge of the iliacus muscle. 
  • If the needle is in the correct position, injecting a small amount of anesthetic, 1-2ml, will hydrodissect the fascia off of the iliacus muscle. 
  • Once appropriate positioning is confirmed, 40ml of combined anesthetic and normal saline can be injected. 
    • One person can inject into tubing so another person can properly position the probe and needle.
  • Anesthesia will occur within 40-60min.

Image or video of fascia iliaca block

PEricapsular Nerve Group (PENG) Block

Overview
  • The PENG block is a new block targeting the sensory innervation of the hip, and is an option for hip and pelvic fractures
  • The block targets terminal sensory nerves only, allowing a motor-sparing effect and early mobilization compared to femoral nerve and fascia iliaca blocks. 
  • The block has only been described only in case series for the emergency department [9]Luftig J, Dreyfuss A, Mantuani D, Howell K, White A, Nagdev A. A new frontier in pelvic fracture pain control in the ED: Successful use of the pericapsular nerve group (PENG) block. Am J Emerg Med. … Continue reading [10]Rocha-Romero A, Arias-Mejia K, Salas-Ruiz A, Peng PWH. Pericapsular nerve group (PENG) block for hip fracture in the emergency department: a case series. Anaesth Rep. 2021;9(1):97-100. … Continue reading ,  but limited trials from the anesthesia literature suggests it provides better pain control and increased mobilization compared to femoral nerve and fascia iliaca blocks [11]Mosaffa F, Taheri M, Manafi Rasi A, Samadpour H, Memary E, Mirkheshti A. Comparison of pericapsular nerve group (PENG) block with fascia iliaca compartment block (FICB) for pain control in hip … Continue reading [12]Lin DY, Morrison C, Brown B, et al. Pericapsular nerve group (PENG) block provides improved shortterm analgesia compared with the femoral nerve block in hip fracture surgery: a single-center … Continue reading
  • This block, however, does not guarantee relief of extracapsular fractures, such as intertrochanteric fractures, and runs the risk of introducing infection into the joint so must be done under sterile conditions. 
Ultrasound Anatomy
  • With the patient in the supine position, the ultrasound probe is placed on a transverse plane over the anterior superior iliac spine (ASIS).
  • Once the ASIS is identified, the transducer is aligned with the pubic ramus and rotated counterclockwise at approximately 45 degrees, parallel to the inguinal crease. The transducer is then slid medially along this axis until the anterior inferior iliac spine (AIIS), iliopubic eminence (IPE), and the psoas tendon is clearly identified, serving as anatomic landmarks.

Patient and US positioning – place the US transducer on a transverse plane over the ASIS. 

Patient and US positioning – Rotate the transducer counterclockwise, parallel to the inguinal crease and slide medially until the AIIS comes into view

Approach
  • This block involves depositing 15-20ml of a long-lasting local anesthetic (i.e. 5 % ropivacaine) between the psoas tendon and the pubic ramus to block the nerves themselves.
  • Sliding the probe distally, or gently tilting the caudal will expose the head of the femur. Returning to the initial starting position, a standard 20-22 gauge 100mm needle is inserted in-plane, from lateral to medial, in the plane between the psoas tendon and the pubic ramus. 15-20ml of a long-lasting local anesthetic ((i.e. 5 % ropivacaine), is then deposited in this plane lifting the psoas tendon. Care should be taken to avoid puncturing the psoas tendon.

US image or video of PENG block

Penile Blocks

Dorsal Penile Block

Overview
  • Dorsal penile blocks are historically performed blind, but with the addition of ultrasound, the anesthetic can be deposited at the target with greater confidence
Ultrasound Anatomy/Procedure
  • Place the linear transducer transverse across the dorsal aspect at the base of the penis
  • The dorsal penile nerves can be identified just deep to the Buck fascia
  • Also identify the corpora cavernosa, to avoid
  • Insert the needle (27g) on either side through Buck’s fascia and inject the local anesthetic

US image or video of dorsal penile block

Pearls & Pitfalls

  • Consent should include the potential for vascular injury and muscular weakness. Specifically, note that quadricep strength and diffuse leg weakness are possible if the sciatic nerve is inadvertently anesthetized.

References[+]