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UC Irvine
Clinical Practice and Cases in Emergency Medicine
Title
Analgesia in the Emergency Department for Lower Legand Knee Injuries: A Case Report
Permalink
https://escholarship.org/uc/item/7j79g812
Journal
Clinical Practice and Cases in Emergency Medicine, 0(0)
Authors
Shalaby, Michael
Lee, Yonghoon
McShannic, Joseph
et al.
Publication Date
2025-01-16
DOI
10.5811/cpcem.7201
Copyright Information
This work is made available under the terms of a Creative Commons Attribution License,
available at https://creativecommons.org/licenses/by/4.0/
Peer reviewed
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University of California
Article in Press 1 Clinical Practice and Cases in Emergency Medicine
Michael Shalaby, MD*†
Yonhoon Lee, MD†
Joseph McShannic, MD†
Michael Rosselli, MD†
Section Editor: Austin Smith, MD
Submission history: Submitted January 14, 2024; Revision received September 4, 2024; Accepted September 10, 2024
Electronically published January 16, 2025
Full text available through open access at http://escholarship.org/uc/uciem_cpcem
DOI: 10.5811/cpcem.7201
Introduction: Lower extremity injuries are commonly evaluated and treated in the emergency
department (ED). Pain management for these injuries often consists of acetaminophen, non-
steroidal anti-inammatories, and opioids. Despite this treatment regimen, adequate analgesia is not
always achieved.
Case Report: A 38-year-old man presented to the ED with a non-displaced tibia-bula fracture. The
patient did not attain analgesia with intravenous medications but did get complete anesthesia of his
lower leg with a combination saphenous and popliteal sciatic nerve block.
Conclusion: Emergency physicians possess the skill set required to eectively perform a saphenous
and popliteal sciatic nerve block and should consider adding this procedure to their armamentarium
of pain management techniques in treating injuries distal to the knee. [Clin Pract Cases Emerg Med.
XXXX;X(X):X–X.]
Keywords: saphenous; adductor canal; popliteal sciatic; regional anesthesia; lower limb; fracture.
Lower extremity (LE) injuries account for nearly 15%
of emergency department (ED) visits yearly, with trauma to
the knee and distal comprising an overwhelming majority
(greater than 75%).1 Lower extremity injuries are painful,
particularly fracture-dislocations.2 Analgesia for LE injuries
is highly variable in time to administration, dosing, and
adequacy. For example, patients with LE injuries tend to wait
longer than average for analgesics (especially ambulatory
patients).3 Moreover, even when treated with opioids, most
patients with serious LE injuries do not attain adequate pain
control in the ED.4 Opioids also lead to complications such as
nausea, vomiting, hypotension, and respiratory depression.5
Elderly patients with LE injuries are especially susceptible to
increased mortality and morbidity,6 perhaps partly due to the
administration of opioids.
Lower extremity limb injuries requiring inpatient
hospitalization can lead to signicant nancial, psychosocial,
Herbert Wertheim College of Medicine at Florida International University, Department
of Emergency Medicine, Miami Beach, Florida
Mount Sinai Medical Center Miami Beach, Department of Emergency Medicine,
Miami Beach, Florida
*
†
and quality-of-life burdens for patients, which extend far
beyond the hospital stay.7 Herein we present the case of a
patient with a combined tibia-bula fracture with intractable
pain despite signicant amounts of opiate analgesics, but who
achieved complete anesthesia with saphenous and popliteal
sciatic nerve blocks.
A 38-year-old male presented via emergency medical
services (EMS) after sustaining a right lower leg injury
from falling o a skateboard. The lower leg had no visible
deformity, but the patient was in severe pain, which he
described as the worst of his life. He had received 10
milligrams (mg) of intramuscular morphine by EMS
without improvement. Given his signicant pain level, upon
arrival to the ED he was given 1 mg of intravenous (IV)
hydromorphone, which was repeated 15 minutes later with
minimal improvement. The patient subsequently received two
Clinical Practice and Cases in Emergency Medicine 2 Articles in Press
Analgesia for Lower Leg and Knee Shalaby et al.
CPC-EM Capsule
What do we already know about this clinical
entity?
Saphenous and sciatic nerve blocks have been
well documented for use in emergency medicine.
What makes this presentation of disease
reportable?
Used together as a form of dense anesthesia, these
nerve blocks proved eective for rapid pain relief in
a patient with a non-displaced tibia-bula fracture.
What is the major learning point?
Saphenous and sciatic nerve blocks are relatively
straightforward to perform and eective for pain
control.
How might this improve emergency medicine
practice?
Lower extremity injuries are painful. These nerve
blocks can provide emergency physicians with the
tools to alleviate pain from any injury distal to
and including the knee.
separate doses of 0.1 mg per kilogram of IV ketamine, after
which his pain was minimally relieved. A radiograph was
performed and showed a tibia-bula fracture. The patient had
soft LE compartments, full sensation, and 2+ dorsalis pedis
and posterior tibial pulses, so there was no concern for acute
compartment syndrome.
After minimal relief with opioids and ketamine, the patient
consented to an adductor canal and a popliteal sciatic block. The
adductor canal block was performed with 15 milliliters (mL)
bupivacaine 0.5% without epinephrine, and the popliteal sciatic
block was performed with 10 mL bupivacaine 0.5% without
epinephrine. Within 10 minutes, the patient noted complete
resolution of his pain and ironically opted to leave against
medical advice instead of being admitted for future pain control
and operative planning. On follow-up with the patient one week
later, he noted that the anesthetic lasted about 14 hours and that
he had presented to another hospital two days later where he
underwent successful and uncomplicated open reduction and
internal xation of his injury.
The saphenous nerve is the largest cutaneous branch
of the femoral nerve,8 consisting of purely sensory neurons
without a motor component.9 The saphenous nerve provides
sensation to the patella, the medial femoral and tibial
condyles, and the medial malleolus (Figure). The saphenous
nerve courses immediately lateral to the femoral artery in
the distal thigh between the adductor longus and vastus
medialis muscles, a potential space known as the “adductor
canal.” Thus, the saphenous nerve block is synonymous with
the “adductor canal block.” Although the saphenous nerve
is dicult to visualize directly on point-of-care ultrasound
(POCUS), it can be presumed to course immediately
anterolateral to the femoral artery in the middle to medial
lower third of the thigh. This view is already familiar to most
emergency physicians who perform POCUS for deep vein
thrombosis of the LE. Most commonly, the adductor canal can
be visualized anywhere from the middle anterior to the lower
medial third of the thigh based on patient anatomy.
The sciatic nerve has a unique architecture. It is
comprised of the tibial nerve and the common peroneal nerve,
each with its own epineurium, surrounded by a paraneural
sheath.10 These two nerves diverge from each other in the
popliteal fossa, where the popliteal sciatic nerve block is
performed. The sciatic nerve provides sensory innervation
to the rest of the lower leg not covered by the saphenous
Figure. Tissue and osseous sensory distributions of saphenous and
popliteal sciatic nerves. Red color: sensory distribution of popliteal
sciatic nerve. Green color: sensory distribution of saphenous nerve.
Image courtesy of Anthony Casazza.
Image 1. Transverse ultrasound view for popliteal sciatic nerve block.
BF, biceps femoris muscle; PV, popliteal vein; PA, popliteal artery.
Blue arrow: sciatic nerve.
Articles in Press 3 Clinical Practice and Cases in Emergency Medicine
Shalaby et al. Analgesia for Lower Leg and Knee
For physicians performing a popliteal sciatic block, we
recommend rst blocking the saphenous if the patient is already
supine, and then allowing the patient to turn to lateral decubitus
with the aected leg up (Image 4). Patients do not have to be
prone, which may be dicult with LE injuries. Given its depth
in most patients, the popliteal sciatic nerve block should also be
performed with a spinal needle in a lateral-to-medial trajectory.
The sciatic nerve is usually visualized immediately supercial
to or adjacent to the popliteal vein (Image 1). The most crucial
aspect of the popliteal sciatic block is to instill anesthetic within
the surrounding paraneural sheath, which provides denser
and faster blockade.10, 11 As with the saphenous nerve block,
bupivacaine and ropivacaine impart longer lasting anesthesia
compared to lidocaine. While it is common for physicians to
block immediately at the bifurcation of the common peroneal
and tibial nerves, blocking proximally to the bifurcation has been
nerve, including the lateral calf and the entire foot (Figure).
Unlike the saphenous nerve, the sciatic nerve also has a motor
component, which imparts function to all the muscles of the
lower leg and the foot. The popliteal, or “distal,” sciatic nerve
can be visualized in the popliteal fossa, usually supercial to
the popliteal vein (Image 1). The paraneural sheath, which
surrounds the sciatic nerve, is visible as a hyperechoic fascial
layer separating the nerve from the surrounding musculature.
Physicians may also be familiar with POCUS of the sciatic
nerve since it is the same view for the popliteal vein
component of the deep vein thrombosis exam.
To perform the saphenous nerve block, the patient should
be supine (Image 2). The femoral artery should be visualized
within the middle of the screen, with the adductor canal
lateral to it (Image 3). From anterolateral to posteromedial,
a spinal needle is advanced in-plane to the transducer. To
ensure that no anesthetic is wasted, the physician should
rst hydrodissect the adductor canal with normal saline to
Image 2. Patient positioning for an adductor canal (saphenous
nerve) block. The needle’s trajectory is lateral to medial.
Image 3. Ultrasound view for saphenous nerve block.
FA, femoral artery. White arrow: adductor canal. Blue arrow:
anatomic location of saphenous nerve.
visualize the “unzipping” of the fascial plane prior to instilling
anesthetic. The procedure may be performed with a variety of
anesthetics depending on treatment goals: bupivacaine 0.5%
and ropivacaine 0.5% provide anesthesia on the order of hours
to days, while anesthesia from lidocaine 1% usually lasts less
than three hours.
Image 4. Patient positioning for a distal sciatic nerve block. The
needle’s trajectory is lateral to medial.
successfully described.12 Blockade proximally may be technically
easier and equally eective since it allows for a larger target than
at the exact point of bifurcation. Physicians must provide crutches
to any ambulatory patient receiving a popliteal sciatic block since
the block will result in lower leg paralysis.
Emergency physicians regularly treat patients with LE
limb injuries. Frequent opioid analgesic administration for such
patients carries high complication rates and does not guarantee
adequate analgesia. Lower extremity injuries impose signicant
costs in both hospital charges and days lost of production, as
well as psychosocial burdens.7 The saphenous nerve block
combined with the popliteal sciatic block is a powerful tool for
physicians to treat and eliminate any pain from the knee down.
Both blocks boast relatively straightforward sonoanatomy, with
which physicians who are procient with POCUS may already
be familiar. Furthermore, while each block carries intrinsic risks
such as nerve damage, vascular puncture, and local anesthetic
systemic toxicity (as with all methods of regional anesthesia),
these techniques are relatively safe given the lack of risky
anatomic structures nearby, such as the lungs or carotid arteries
with brachial plexus blocks.
In our experience, both the saphenous nerve block and the
popliteal sciatic block are relatively quick procedures that can be
Clinical Practice and Cases in Emergency Medicine 4 Articles in Press
Analgesia for Lower Leg and Knee Shalaby et al.
performed within a few minutes each. Additionally, if long-acting
anesthetics such as bupivacaine or ropivacaine are employed for
blockade, patients can experience hours to days of anesthesia.
Thus, regional anesthesia in general can reduce patients’ use
of opioids. Moreover, time- and labor-intensive procedural
sedation and anesthesia, which carries risks of respiratory
depression, hypotension, and vomiting, can be avoided for
LE fractures requiring reduction.13 Lastly, the use of regional
anesthesia for patients with LE injuries and exam ndings
concerning for compartment syndrome (such as signicant
edema, tenderness, altered sensation, coolness to touch, or
pulselessness) is controversial. While the American Society
of Regional Anesthesia does not oppose the use of regional
anesthesia in suspected compartment syndrome, citing that
compartment pressure measurement is the most accurate method
for determining the need for emergent fasciotomy,14 emergency
physicians should consult with their surgical team before
performing regional anesthesia, as this may disguise worsening
compartment syndrome and the need for emergent fasciotomy.
Lower extremity limb injuries are common and can be
quite painful. The combined saphenous nerve block and
popliteal sciatic blocks can provide dense anesthesia to the
lower extremity from the knee down. Emergency physicians
who are familiar with in-plane needle-guided procedures (such
as ultrasound-guided peripheral IV lines) possess the skill set
required to eectively perform a saphenous and popliteal sciatic
nerve block and should consider adding this procedure to their
multimodal approach to analgesia for injuries distal to the knee.
The authors attest that their institution requires neither Institutional
Review Board approval, nor patient consent for publication of this
case report. Documentation on le.
Address for Correspondence: Michael Shalaby, MD, Mount
Sanai Medical Center, Department of Emergency Medicine,
4300 Alton Road, Miami Beach, Florida 33140. Email:
michael.shalaby@msmc.com.
Conicts of Interest: By the CPC-EM article submission agreement,
all authors are required to disclose all aliations, funding sources
and nancial or management relationships that could be perceived
as potential sources of bias. The authors disclosed none.
Copyright: © 2025 Shalaby et al. This is an open access article
distributed in accordance with the terms of the Creative Commons
Attribution (CC BY 4.0) License. See: http://creativecommons.org/
licenses/by/4.0/
REFERENCES
1. Lambers K, Ootes D, Ring D. Incidence of patients with lower
extremity injuries presenting to US emergency departments by
anatomic region, disease category, and age. Clin Orthop Relat
Res. 2012;470(1):284-90.
2. Clapp ADM, Thull-Freedman J, Mitra T, et al. Patient-reported pain
outcomes for children attending an emergency department with
limb injury. Pediatr Emerg Care. 2020;36(6):277-82.
3. Abbuhl FB and Reed DB. Time to analgesia for patients with
painful extremity injuries transported to the emergency department
by ambulance. Prehosp Emerg Care. 2003;7(4):445-7.
4. Neighbor ML, Honner S, Kohn MA. Factors aecting emergency
department opioid administration to severely injured patients.
Acad Emerg Med. 2004;11(12):1290-6.
5. Ramadan M, Alnashri Y, Ilyas A, et al. Assessment of opioid
administration patterns following lower extremity fracture among
opioid-naïve inpatients: retrospective multicenter cohort study. Ann
Saudi Med. 2022;42(6):366-76.
6. Sharfman ZT, Parsikia A, Rocker TN, et al. Increased morbidity
and mortality in elderly patients with lower extremity trauma and
associated injuries: s review of 420,066 patients from the National
Trauma Database. Injury. 2021;52(4):757-66.
7. Dischinger PC, Read KM, Kufera JA, et al. Consequences and
costs of lower extremity injuries. Annu Proc Assoc Adv Automot
Med. 2004;48:339-53.
8. Sebastian MP, Bykar H, Sell A. Saphenous nerve and IPACK
block. Reg Anesth Pain Med. 2019:rapm-2019-100750.
9. Rasouli MR and Viscusi ER. Adductor canal block for knee
surgeries: an emerging analgesic technique. Arch Bone Jt Surg.
2017;5(3):131-2.
10. Karmakar MK, Reina MA, Sivakumar RK, et al. Ultrasound-guided
subparaneural popliteal sciatic nerve block: there is more to it than
meets the eyes. Reg Anesth Pain Med. 2021;46(3):268-75.
11. Perlas A, Wong P, Abdallah F, et al. Ultrasound-guided popliteal
block through a common paraneural sheath versus conventional
injection: a prospective, randomized, double-blind study. Reg
Anesth Pain Med. 2013;38(3):218-25.
12. Tran DQH, González AP, Bernucci F, et al. A randomized
comparison between bifurcation and prebifurcation subparaneural
popliteal sciatic nerve blocks. Anesth Analg. 2013;116(5):1170-5.
13. Shalaby M, Smith M, Tran L, et al. Utility of supraclavicular
brachial plexus block for anterior shoulder dislocation: could it be
useful? West J Emerg Med. 2023;24(4):793-7.
14. Lam D, Pierson D, Salaria O, et al. Pain control with regional
anesthesia in patients at risk of acute compartment syndrome:
review of the literature and editorial view. J Pain Res.
2023;16:635-48.
