Defining the Optimal Location to Place an Adductor Canal Block

Defining the Optimal Location to Place Local Anesthetic for an Adductor Canal Block for Pediatric Knee Arthroscopy Patients

The aim of the current project is to address a gap in the existing literature related to optimal placement of local anesthetic for an adductor canal (AC) block. The current study seeks to examine whether placement of the local anesthetic in the AC for knee surgery is more effective at reducing post-operative pain following arthroscopic knee surgery compared to a control. Specifically, if the anesthetic is more beneficial than the control group, the research will determine which location is optimal by comparing groups that receive anesthetic in the midpoint of the thigh, the proximal end of the thigh, or the distal end of the thigh.

Although there has been an abundance of literature highlighting the efficacy of using regional blocks to decrease post-operative pain, the exact location of placement of local anesthetic for anesthetizing the nerves in the AC is unknown for optimal pain relief in patients undergoing knee surgery. The saphenous nerve consistently lies in the AC at various points of local anesthetic deposit, however there are many other nerves that lie in the canal that may branch off proximally or distally from the AC that are important to target in achieving optimal pain relief for patients undergoing knee arthroscopy.1-3 The AC is bounded in a triangular shape by the vastus medialis anterolaterally, the sartorius medially, and the adductor longus/adductor magnus posteriorly. The canal contains the deep femoral artery and the deep femoral vein. The saphenous nerve consistently lies within this canal, a significant sensory contributor to the knee.1-3 Other branches of the femoral nerve can also be found in the AC. The nerve to the vastus medialis (NVM) and the posterior branches of the obtruator nerve (PON) can also be found, although inconsistently, in the AC at various locations.4,5 These nerves are thought to innervate the knee as well and contribute to pain when missed during this block. The course of these nerves is unknown. While some surmise that the NVM branches proximally and the PON branches distally, there is no consensus on this. Currently, an AC block is most often placed in the mid-thigh as measured by visual observation. The investigators seek to investigate where along the tract of the AC would be optimal to place local anesthetic to optimize analgesia on all nerves that innervate the knee without having motor loss as would occur with a femoral nerve block

Saline will be placed in syringe instead of ropivicaine 0.2% and the nerve block will be placed in the adductor canal at the desired location by the anesthesiologist

An adductor canal block will be placed with local anesthetic in the proximal 1/3 of the operative leg

An adductor canal nerve block will be placed in a patient undergoing a knee arthroscopy in 1 of 3 locations with local anesthetic or placebo (without location definition or local anesthetic) to assess optimal placement of local anesthetic, pain management and anxiety scores post operatively.

Patient self-reported pain intensity following the procedure. The scale ranges from 0-10 (0 = no pain; 10 = extreme). Collected at two points: pre-and-post procedure.

Patient self-reported anxiety levels will be measured on a thermometer-style graphic, where the bottom (near the base) represents low anxiety and the top represents high levels of anxiety.

Parent self-reported anxiety levels will be measured on a thermometer-style graphic, where the bottom (near the base) represents low anxiety and the top represents high levels of anxiety

Patients will report sensation on their knee postoperatively by reponding if they can (yes) or cannot (no) feel a pinprick and piece of ice.

The amount of narcotic pain medication that the patients utilize after their discharge will be documented as morphine milligram equivalents (e.g., MME).

Inclusion Criteria: Patient is 7 to ≤ 17 years of age Patient at St. Christopher's Hospital for Children Receiving a knee arthroscopy procedure English speaking Exclusion Criteria: Patient is less than 7 years of age or over 17 years of age Patient has cognitive impairments Patient had previous operations on the same lower extremity as the current knee arthroscopy Patient has a positive B-HCG (identified through urine or blood test) Patient does not speak English

Wong WY, Bjorn S, Strid JM, Borglum J, Bendtsen TF. Defining the Location of the Adductor Canal Using Ultrasound. Reg Anesth Pain Med. 2017 Mar/Apr;42(2):241-245. doi: 10.1097/AAP.0000000000000539.

Bendtsen T.F., Lopez A.M., Clark T.B. (2018). Ultrasound-Guided Saphenous (Subsartorius/Adductor Canal) Nerve Block. NYSORA Continuing Medical Education. Retrieved from https://www.nysora.com/ultrasound-guided-saphenous-subsartoriusadductor-canal-nerve-block

Burckett-St Laurant D, Peng P, Giron Arango L, Niazi AU, Chan VW, Agur A, Perlas A. The Nerves of the Adductor Canal and the Innervation of the Knee: An Anatomic Study. Reg Anesth Pain Med. 2016 May-Jun;41(3):321-7. doi: 10.1097/AAP.0000000000000389.

Quemby D. & McEwen A. (2014). Ultrasound Guided Adductor Canal Block (Saphenous Nerve Block). Anesthesia Tutorial of the Week. Retrieved from https://www.aagbi.org/sites/default/files/301%20Ultrasound%20Guided%20Adductor%20Canal%20(Saphenous%20Nerve)%20Block.pdf

Runge C, Moriggl B, Borglum J, Bendtsen TF. The Spread of Ultrasound-Guided Injectate From the Adductor Canal to the Genicular Branch of the Posterior Obturator Nerve and the Popliteal Plexus: A Cadaveric Study. Reg Anesth Pain Med. 2017 Nov/Dec;42(6):725-730. doi: 10.1097/AAP.0000000000000675.

Ersig AL, Kleiber C, McCarthy AM, Hanrahan K. Validation of a clinically useful measure of children's state anxiety before medical procedures. J Spec Pediatr Nurs. 2013 Oct;18(4):311-9. doi: 10.1111/jspn.12042. Epub 2013 Jun 25.