





























The evoluTion of The AdducTor cAnAl 
Block: The emerging Technique for 
moTor-SpAring AnAlgeSiA To The knee

Jonathan P. Kline, CRNA, M.S.N.A.

Keywords

adductor canal, ultrasound, saphenous nerve block

AbstrAct 
This article summarizes current relevant data regarding the 

adductor canal block. It provides readers with background infor-
mation of this emerging technique, including history, review of 
literature, relevant anatomy, and the technique itself.

IntroductIon

The adductor canal block has recently gained attention from 
anesthesia and orthopedic communities. The desire to produce 
analgesia without the loss of motor control to the thigh seems 
to be beneficial. Benefits of this technique may include shorter 
hospital stays, earlier and more efficient rehabilitation, and pain 
control. Additionally, patients will retain the ability to report 
pain in neighboring distributions that can be involved when 
attempting to block the femoral nerve at the inguinal crease. This 
technique also embraces the emerging regional philosophy of 
selectivity or blocking only the area involved in the surgery. This 
article will review this novel technique. Review of the literature 
was performed using keywords adductor canal block and saphe-
nous nerve block. Articles less than 5 years old were included, 
with the exception of one article which added historical context.

AEJ



HIstory  
One of the earliest works leading to the development of the 

adductor canal block was done by van der Wal and associates in 
Canada.1 In their 1993 article, they established the block’s clin-
ical viability utilizing cadavers. They described what they referred 
to as a “subsartorial approach” to the saphenous nerve blockade. 
Their intent was to describe an alternative to a traditional land-
mark approach to the saphenous nerve block, primarily for foot 
and ankle procedures. This established a foundation for clini-
cians to incorporate a regional blockade of the saphenous nerve 
to provide analgesia for surgical knee procedures.

revIew of LIterAture

Horn and colleagues made a significant step forward in 2009 
in the report titled “Anatomic Basis to the Ultrasound-Guided 
Approach to the Saphenous Nerve Blockade.”2 It is arguably 
the earliest work establishing the sonographic description of the 
block. In this article, the technique describes the close proximity 
under ultrasound of the saphenous nerve to the descending genic-
ular artery. They showed this technique on cadavers in 2009.

Manickam and colleagues 3 were the first to link the tech-
nique of saphenous nerve blockade in the adductor canal for the 
purposes of knee joint analgesia. This publication described the 
blockade of the saphenous nerve in the adductor canal, bringing 
together the components in use today. These components are 
the placement of the probe at the mid-thigh, the ultrasound 
short-axis view description of the femoral artery and vein (as 
opposed to the descending genicular artery), the short-axis view 
of the sartorius, adductor longus, and magnus muscles, and 
the vastus medialis muscle. These findings were well-timed as 
Sharma et al 4 drew the first association between femoral nerve 
blocks, commonly used for knee analgesia for knee surgery, and 
increased fall risk. This was the beginning of the push to establish 
a new technique that would spare the motor strength of the thigh 
muscles and find suitable alternatives to the femoral block which 
would reduce the risk of falls.



In 2011, Lund and colleagues 5 applied the concept of 
performing the adductor canal block for the purposes of anal-
gesia after major knee surgery. The investigators introduced the 
first peri-neural catheters to the field of adductor canal mediated 
analgesia and established that 30 ml of local anesthetic would 
effectively fill the adductor canal. The same year, Saranteas et al 6 
investigated the efficacy of needle placement under ultrasound 
into the adductor canal, between the sartorius muscle and the 
femoral artery. This work demonstrated the saphenous nerve 
location between the femoral artery and sartorius muscle. Of 
particular clinical significance was the conclusion that the saphe-
nous nerve exits the adductor canal in over 80% of the popu-
lation studied. Also in 2011, Karpoor and associates 7 spared 
the undesired muscle weakness of the femoral nerve block and 
implemented a saphenous nerve block in the adductor canal as 
an effective alternative approach. They demonstrated that in over 
70% of the studied cadavers, the distal portion of the femoral 
nerve entered the vastus medialis muscle proximal to the location 
of the region which contains the saphenous nerve in a location 
anterior to the femoral artery. This portion of the femoral nerve 
innervates motor control of the vastus medialis muscle.7 This 
article added further information to the relatively elusive saphe-
nous nerve location.

In 2012, Jaeger et al 8 conducted a proof-of-concept study 
which demonstrated a reduction in opioid requirement after 
total knee arthroplasty for study patients that received the block. 
Additionally in 2012, Jenstrup and colleagues 9 sought to estab-
lish a reduction of pain during a 45-degree flexion after knee 
surgery, reduce morphine consumption, and formally link muscle 
strength preservation by means of early ambulation. They were 
successful in all aspects, the most notable of which was the pain 
reduction at the 2 and 24 hour marks. 

Henningsen and some of the original Lund study investigators 
sought to show the incidence of saphenous nerve injury with the 

AEJ



ultrasound-guided adductor canal block in 2013. They demon-
strated that no patients suffered saphenous nerve injury from 
the ultrasonography (USG) technique and over 80% of patients 
had successful blocks.10 This study highlighted two important 
aspects of the technique; it established the technique’s safety and 
demonstrated that even under controlled conditions, it is not 
100% effective. These results are consistent with other regional 
techniques investigation findings. In 2013, Mudumbai et al 11 
again investigated continuous peri-neural catheters to the USG 
adductor canal block. Their results showed that compared with 
the same technique at the femoral nerve, patients ambulated 
farther distances postoperatively on days one and two. Their 
findings additionally indicated analgesia was similar between 
groups that received either a femoral block or an adductor canal 
block. Evolving the adductor canal block further as a means of 
preserving thigh muscle strength, Jaeger and colleagues 12 again 
studied the effects of the block strictly compared to femoral 
nerve blocks. They showed, albeit on a small study population, 
that, in healthy volunteers, strength was preserved to nearly a 
state prior to having no block at all. This study suggests that the 
adductor canal block does allow for thigh muscle strength preser-
vation and may therefore reduce fall risks for patients following 
knee surgery.

In similar research, Kwofie et al 13 enrolled slightly more volun-
teers, again studying the effect of the adductor canal block on 
quadriceps muscle strength and demonstrated similar results as 
the Jaeger study on strength preservation. Also in 2013, a head-
to-head, retrospective study comparing the analgesic/ambulatory 
effects of the adductor canal block to femoral nerve block was 
published by Perlas et al 14 The authors quantitatively suggested 
that despite the femoral nerve block showing better analgesia, 
the strength loss in the quadriceps muscle was approximately 
50%. They also demonstrated that an adductor canal block, 
plus local infiltration following surgery, was associated with 
earlier ambulation and strength preservation. In 2013, Hanson 



et al 16 illustrated that the adductor canal block with ropivic-
aine was superior in reducing equivalent resting pain scores than 
the same block with saline in patients post-arthroscopic medial 
meniscectomy.

Investigating the adductor canal block in other surgical proce-
dures, Espelund et al 17 evaluated the efficacy of the block on 
patients post anterior cruciate ligament reconstruction in 2013. 
The study results failed to show any benefit of the block over 
intravenous (IV) non-steroidal anti-inflammatory medicines. 
This important study poses a question regarding the effect of the 
saphenous nerve innervation to this area of knee.

Another important factor which may affect block outcome is 
the block technique itself. Previous studies show that the saphe-
nous nerve is located on the medial side of the distal femoral 
artery. However, in the Espelund study, the adductor canal block 
technique was approached from the lateral side of the artery. 
This approach required the local anesthetic to bathe the nerve 
from the infiltration entirely and negates the nerve’s natural posi-
tion. Additionally, all study blocks were performed after surgery.

Several researchers have demonstrated that regional anes-
thesia can inhibit the inflammatory cascade in a variety of loca-
tions.18,19,20,21,22 Findings suggest that regional techniques of 
any kind may lower pain scores more effectively when done 
pre-procedurally. 

In 2013, Andersen et al 23 studied the effects of an ultrasound-
guided continuous peri-neural catheter technique on patients’ 
pain scores after total knee arthroplasty. The authors concluded 
that pain scores were significantly reduced in the group that 
received ropivicaine through the adductor canal catheter versus 
saline. An interesting caveat, all patients in the study received 
a spinal anesthetic as the primary route of anesthesia, and 
all catheters were placed postoperatively. This study design 

AEJ



demonstrated two key outcomes: a reduction or elimination of 
the inflammatory response by implementing a regional tech-
nique prior to the generation of surgical pain and a postopera-
tive catheter placement potentially improving block safety and 
efficacy. Reduction in inflammatory response effect has been 
demonstrated in a number of different techniques whose validity 
will likely have a dramatic impact on the field of regional anes-
thesia. Considerations for regional blockades utilizing catheter 
technique are that preoperative placement of catheters can be 
displaced by surgical manipulation or tourniquet compression to 
the thigh may result in catheter injury to underlying structures.

reLevAnt bLocK AnAtomy

The relevant anatomy for the adductor canal block focuses on 
the specific target of the saphenous nerve. The femoral nerve 
originates from the L-2 to L-4 spinal nerves. These L-2 through 
L-4 nerves join together as a structure known as the lumbar 
plexus. This plexus passes through the psoas compartment made 
of the psoas muscle posteriorly and the quadratus lumborum 
anteriorly. The femoral nerve emerges from under the inguinal 
canal and bifurcates into two smaller peripheral nerves in the 
anterior thigh.24 Near the location of the superior third of the 
thigh, the femoral nerve continues its path deep into the leg to 
innervate the rectus femoris, vastus lateralis, vastus medialis, 
vastus intermedius, and sartorius. This group is primarily respon-
sible for extending the lower leg and lifting the thigh forward 
and transferring weight during ambulation. The femoral nerve 
also sends off a pure sensory nerve called the saphenous nerve 
in the anterior thigh. The saphenous nerve separates from the 
femoral nerve and continues its path toward the knee accompa-
nying the femoral artery and vein. This trio travels through the 
adductor canal. This canal is made up of the sartorius muscle 
superficially, and the vastus intermedius muscle as the deep 
component. The side wall completing a triangle is the adductor 
longus (see Figure 1). Within these three structures, a tunnel or 
canal is formed, allowing for passage of the saphenous nerve 



and the distal femoral artery and vein. The saphenous nerve is 
responsible for the sensory innervation of the anterior knee. It 
sends a sensory branch inferiorly to the region under the patella 
called the infrapatellar nerve. With this information, it seems 
logical that by blocking only the saphenous nerve, it is possible 
to cause analgesia to the anterior knee while preserving the ante-
rior thigh motor control.

tecHnIque

There are a few techniques described for blocking the saphe-
nous nerve selectively. Advancing a needle blindly into the 
adductor canal was the first landmark-based technique, using the 
middle third of the inner thigh as the starting point. Today, with 
the advances of ultrasound guidance, this is not recommended. 
The adductor canal’s relevant structures can be easily viewed 
with ultrasound. 

      video: Adductor canal ultrasound 

Begin by slightly externally rotating the thigh. Select a linear 
probe, and set the depth to around 4 cm. Begin the scan by 
placing the probe in the midpoint of the patella and inguinal 
crease, on the medial side of the thigh. The probe should be posi-
tioned to allow for a short-axis view of the distal femoral artery. 
If in doubt of the artery’s identity, track the femoral artery path 
starting at the inguinal crease as in a femoral block or femoral 
vessel cannulation. Once satisfied with the artery’s identity, place 
the adductor canal in view, with distal femoral artery in short-
axis visible. The Doppler modes can be used to confirm the struc-
tures’ pulsatile flow. The sartorius and adductor longus should be 
easily visible (see Figure 1).

Prep the needle insertion region with the institution’s antiseptic 
solution. For awake patients, advance a small gauge needle in 
plane through the projected needle path and deposit a fast-acting 
local anesthetic solution such as lidocaine or mepivacaine. Once 
the needle path has been localized, advance a long blunt block 

AEJ



needle under the artery. It is unlikely that the saphenous nerve 
will be visible but tilting the probe about 20-30 degrees away 
from the head can help. Once the needle has arrived deep to the 
artery, aspirate and begin to deposit the local anesthetic block 
solution. Redirect the needle in plane as necessary to fill the 
adductor canal. This volume will vary depending on a variety of 
factors, but one study showed that 30ml can fill the canal.5

figure 1. The relevant Structures Within the Adductor canal

summAry

The adductor canal block is in its infancy compared to other 
well-established regional techniques. In 2013, the greatest 
number of research articles on various aspects of the block was 
published. Unlike other traditional techniques that seek to cause 
a sensory as well as a motor blockade, the adductor canal block 
attempts to spare the motor block of the neighboring distribu-
tions in an attempt to offer selective analgesia and strength pres-
ervation. A frequently asked question is “Can the nerve stimu-
lator be used as a secondary identifier for the saphenous nerve, 
either in combination or solo for saphenous nerve localization?” 
The answer seems to be that it can. 

Although the saphenous nerve is a purely sensory nerve, the 
nerve stimulator is not without merit. However, sensory nerves 
do not elicit a motor twitch, so how then can this be explained? 
This is because although they have a higher rheobase† and 

† In this text, the rheobase is a physics term that describes the lowest electrical 
intensity required to elicit a nerve impulse.

26



chronaxie‡, they will elicit an appreciable response in awake 
patients. Clinical electrical current settings for traditional motor 
twitch elicitation are between 0.2-1.0 mA. This avoids unde-
sired sensory responses traditionally associated with stimulator 
settings above 1.0. These increased current settings above 1.0 mA 
produce sensory pulsations. These can be useful for sensory nerve 
localization.25 It should be noted that as current settings exceed 
1.0 mA, there is an increased likelihood that the patient will 
complain of painful nerve pulsations. Consequently, combining 
the nerve stimulator with ultrasound for nerve identity seems 
of some use, although not one study included in this article 
employed this technique. 

The majority of the recent studies2-5, 17 are optimistic that this 
relatively novel technique shows promise to accomplish the goal 
of knee analgesia and thigh strength preservation. Although it is 
too early to be certain of its success, many of the various aspects 
regarding this technique have been cursorily reviewed. The 
research currently available is overwhelmingly positive, with only 
one reviewed study which did not demonstrate adductor canal 
block benefit over IV medications following knee arthroscopy. 
Current understanding regarding the evolution of the adductor 
canal block, while limited, shows promise for this emerging tech-
nique to potentially address the issue of surgical knee pain anal-
gesia and preservation of upper leg motor strength.

AutHor Info

Jonathan P. Kline, CRNA, M.S.N.A.
Director of Education
Twin Oaks Anesthesia Services, LLC
26714 Winged Elm Drive,Wesley Chapel, Florida 33544
813-857-5559 / nerveblocker@gmail.com

‡ In this text, the chronaxie is a physics term describing the time needed that, 
doubling the rheobase, will elicit the same impulse.

26

AEJ



references 
1 van der Wal M, Lang SA, Yip RW. Transsartorial 

approach for saphenous nerve block. Can J Anaesth. 
1993;40(6):542-546.

2 Horn J, Pitsch T, Salinas F, et al. Anatomic basis to the 
ultrasound-guided approach for saphenous nerve blockade. 
Reg Anesth Pain Med. 2009;34(5):486-489.

3 Manickam B, Perlas A, Duggan E, et al. Feasibility and 
efficacy of ultrasound-guided block of the saphenous 
nerve in the adductor canal. Reg Anesth Pain Med. 
2009;34(6):578-580.

4 Sharma S, Iorio R, Specht L, et al. Complications of femo-
ral nerve block for total knee arthroplasty. Clin Orthop 
Relat Res. 2010;468(1):135-140. Published online August 
13, 2009. doi: PMCID: PMC2795813.

5 Lund J, Jenstrup T, Jaeger P, et al. Continuous adductor-
canal-blockade for adjuvant post-operative analgesia after 
major knee surgery: preliminary results. Acta Anaesthesiol 
Scand. 2011;55:14–19.

6 Saranteas T, Anagnostis G, Paraskeuopoulos T, et al. 
Anatomy and clinical implications of the ultrasound-guided 
subsartorial saphenous nerve block. Reg Anesth Pain Med. 
2011;36(4):399-402.

7 Karpoor R, Adhikary D, Siefring C, et al. The saphenous 
nerve and its relationship to the nerve to the vastus media-
lis in and around the adductor canal: an anatomical study. 
Acta Anaesthesiol Scand. 2012;56(3):365-367.

8 Jaeger P, Grevstad M, Henningsen B, et al. Effect of adduc-
tor-canal-blockade on established, severe post-operative 
pain after total knee arthroplasty: a randomized study. 
Acta Anaesthesiol Scand. 2012;56(8):1013-1019.

9 Jenstrup MT, Jaeger P, Lund J, et al. Effects of adductor-
canal-blockade on pain and ambulation after total knee 
arthroplasty: a randomized study. Acta Anaesthesiol Scand. 
2012;56(3):357-64.



10 Henningsen MH, Jaeger P, Hilsted KL, et al. Prevalence 
of saphenous nerve injury after adductor-canal-block-
ade in patients receiving total knee arthroplasty. Acta 
Anaesthesiol Scand. 2013;57(1):112-117.

11 Mudumbai SC, Kim TE, Howard SK, et al. Continuous 
adductor canal blocks are superior to continuous femoral 
nerve blocks in promoting early ambulation after TKA. 
Clin Orthop Relat Res. 2013. Published Online July 2013. 
http://www.clinorthop.org/Journals/Online_First.html. Last 
accessed Nov 2013

12 Jaeger P, Neilsen Z, Henningsen MH, et al. Adductor 
canal block versus femoral nerve block and quadriceps 
strength: a randomized, double-blind, placebo-controlled, 
crossover study in healthy volunteers. Anesthesiology. 
2013;118(2):409-415.

13 Kwofie M, Shastri U, Gadsden J, et al. The effects of 
ultrasound-guided adductor canal block versus femoral 
nerve block on quadriceps strength and fall risk: a blinded, 
randomized trial of volunteers. Reg Anesth Pain Med. 
2013;38(4):321-325.

14 Perlas A, Kirkham K, Billing R, et al. The impact of anal-
gesic modality on early ambulation following total knee 
arthroplasty. Reg Anesth Pain Med. 2013;38(4):334-339.

15 Ilfield B, Hadzic A. Walking the tightrope after knee 
surgery: optimizing postoperative analgesia while 
minimizing quadriceps weakness. Anesthesiology. 
2013;118(2):248-250.

16 Hanson N, Derby R, Auyong DB, et al. Ultrasound-guided 
adductor canal block for arthroscopic medial meniscec-
tomy: a randomized, double-blind trial. Can J Anaesth. 
2013;60(9):874-880.

17 Espelund M, Fomsgaard J, Haraszuk J, et al. Analgesic 
efficacy of ultrasound-guided adductor canal blockade 
after arthroscopic anterior cruciate ligament reconstruc-
tion: a randomised controlled trial. Eur J Anaesthesiol. 
2013;30(7):422-428.

AEJ



18 Beilin B, Bessler H, Mayburd E, et al. Effects of preemptive 
analgesia on pain and cytokine production in the postop-
erative period. Anesthesiology. 2003;98:151-155.

19 Freise H, Daudel F, Grosserichter C, et al. Thoracic 
epidural anesthesia reverses sepsis-induced hepatic hyper-
perfusion and reduces leukocyte adhesion in septic rats. 
Crit Care. 2009;13:R116.

20 Le Bars D, Adam F. Nociceptors and mediators in 
acute inflammatory pain. Ann Fr Anesth Reanim. 
2002;21:315-335.

21 Sheeran P, Hall GM. Cytokines in anaesthesia. Br J 
Anaesth. 1997;78:201-219.

22 Watkins LR, Maier SF, Goehler LE. Immune activation: 
the role of pro-inflammatory cytokines in inflamma-
tion, illness responses and pathological pain states. Pain. 
1995;63:289-302.

23 Andersen H, Gyrn J, Moller L, et al. Continuous saphe-
nous nerve block as supplement to single-dose local 
infiltration analgesia for postoperative pain manage-
ment after total knee arthroplasty. Reg Anesth Pain Med. 
2013;38(2):106-111.

24 Hadzic, A. Chapter 35. In: Texbook of Regional 
Anesthesia and Acute Pain Management. New York, NY: 
McGraw Hill;2007:500.

25 Hadzic, A. Chaper 5. In: Texbook of Regional Anesthesia 
and Acute Pain Management. New York, NY: McGraw 
Hill;2007:94-98.

26 Hadzic, A. Chapter 5. In: Texbook of Regional Anesthesia 
and Acute Pain Management. New York, NY: McGraw 
Hill;2007:94-95.


