Genicular Nerve Block for Total Knee Arthroplasty

A Comparison of Analgesic Efficacy of Ultrasound-guided Genicular Nerve Block Versus Saline Injection for Total Knee Replacement: a Prospective, Randomized Controlled Trial

This study seeks to examine the analgesic efficacy of genicular nerve blocks for pain after total knee replacement.

Part of the way in which pain is controlled during total knee replacement surgery is through a nerve block. The investigators have developed an effective protocol for pain control after knee replacement, but know that many patients still experience pain around the knee after knee replacement. There are nerves around the knee that carry pain impulses from behind the knee. The investigators believe that placing numbing medicine around these nerves can help with pain in front of the knee after surgery, in addition to the standard nerve block placed for knee replacement surgery. This may result in taking less pain medication by mouth,and having less pain with movement. For this study, before the operation, either a placebo solution or the local anesthetic bupivacaine (a numbing solution) will be placed at three sites around the knee where these nerves reside. The investigators will evaluate how participants feel in recovery after surgery, during the stay in the hospital, and call at home one week after surgery. Knowing if numbing these nerves helps with pain after surgery will help us further refine our postoperative care plan for patients.

The ultrasound-guided genicular nerve block will be performed at the site of the superior lateral, the superior medial, and the inferior medial genicular nerves. Color Doppler will be used to identify the arterial structures which serve as landmarks for the corresponding nerves. After skin local anesthetic infiltration, a 10 cm 21G insulated block needle will be inserted and aligned with the ultrasound scanning plane. Once satisfactory position of the needle is confirmed, 5mL of a solution containing 15 ml 0.25% bupivacaine with 2mg dexamethasone or 5mL saline will be slowly injected. Spread of local anesthetic will be documented adjacent to the target nerve. This procedure will be performed at the site of the three genicular nerves described.

The ultrasound-guided genicular nerve block will be performed at the site of the superior lateral, the superior medial, and the inferior medial genicular nerves. Color Doppler will be used to identify the arterial structures which serve as landmarks for the corresponding nerves. After skin local anesthetic infiltration, a 10 cm 21G insulated block needle will be inserted and aligned with the ultrasound scanning plane (in-plane approach). Once satisfactory position of the needle time is confirmed, 5mL of a saline will be slowly injected. Spread of local anesthetic will be documented adjacent to the target nerve. This procedure will be performed at the site of the three genicular nerves described.

The ultrasound-guided genicular nerve block will be performed at the site of the superior lateral, the superior medial, and the inferior medial genicular nerves. Color Doppler will be used to identify the arterial structures which serve as landmarks for the corresponding nerves. After skin local anesthetic infiltration, a 10 cm 21G insulated block needle will be inserted and aligned with the ultrasound scanning plane. Once satisfactory position of the needle is confirmed, 5mL of a solution containing 15 ml of 0.25% bupivacaine with 2mg dexamethasone or 5mL saline will be slowly injected. Spread of local anesthetic will be documented adjacent to the target nerve. This procedure will be performed at the site of the three genicular nerves described.

The Numerical Rating Scale (NRS) is an 11-point numeric rating scale, with 0 representing "no pain" and 10 "unbearable pain." This scale demonstrates reliability and validity and is widely used to assess acute pain after surgery.

The Numerical Rating Scale (NRS) is an 11-point numeric rating scale, with 0 representing "no pain" and 10 "unbearable pain." This scale demonstrates reliability and validity and is widely used to assess acute pain after surgery.

Self-reported (by telephone questionnaire) opioid consumption in oral morphine equivalents on postoperative day 7

The Numerical Rating Scale (NRS) is an 11-point numeric rating scale, with 0 representing "no pain" and 10 "unbearable pain." This scale demonstrates reliability and validity and is widely used to assess acute pain after surgery.

The patient will be questioned by a member of the research team about how many times they were awoken by pain overnight.

Patient reported satisfaction with his/her pain control at 24 h on a scale of 0-10 (0=completely dissatisfied, 10=completely satisfied)

Patient reported satisfaction with his/her pain control on postoperative day 7 on a scale of 0-10 (0=completely dissatisfied, 10=completely satisfied)

This standardized test measures the time it takes for the participant to walk 20 meters at their usual walking pace. The 20-meter walk test is a physical function measure commonly used in clinical research studies and rehabilitation clinics to measure gait speed and monitor changes in patients' physical function over time.

Inclusion Criteria: Subjects scheduled for primary elective total knee arthroplasty American Society of Anesthesiologists Physical Status I-III BMI 18-40 kg/m2 Exclusion Criteria: Inability to cooperate with protocol Inability to understand or speak English Allergy to ropivacaine, bupivacaine or other local anesthetic Contraindication to peripheral nerve block (e.g. local infection, neurologic deficit or disorder, previous trauma or surgery to ipsilateral knee, etc.) Revision knee surgery Chronic opioid consumption (daily morphine equivalent of >30 mg for at least four weeks prior to surgery) History of chronic pain History of psychiatric disorder History of diabetes mellitus

Rambhia M, Chen A, Kumar AH, Bullock WM, Bolognesi M, Gadsden J. Ultrasound-guided genicular nerve blocks following total knee arthroplasty: a randomized, double-blind, placebo-controlled trial. Reg Anesth Pain Med. 2021 Oct;46(10):862-866. doi: 10.1136/rapm-2021-102667. Epub 2021 Jul 14.