Genicular Nerve Block for Total Knee Arthroplasty

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.

• 15mL 0.25% bupivacaine (Drug): Patients will be randomly assigned to either a genicular nerve block with bupivacaine or saline
• Genicular nerve block (Procedure): 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.
• Saline (Drug): Patients will be randomly assigned to either a genicular nerve block with bupivacaine or saline

Primary outcomes

• Opioid Consumption at 24 Hours Post-op [24 hours after operation]: Opioid consumption documented in medical recorded will be converted to oral morphine equivalents.

Secondary outcomes

• Worst Pain Rating Score (NRS-11) at Rest on Postoperative Day 1 [Postoperative Day 1]: 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.
• Worst Pain Rating Score (NRS-11) With Movement on Postoperative Day 1 [Postoperative day 1]: 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.
• Total Opioid Consumption Through 48 Hours [48 hours]: Total of all opioids consumed converted to oral morphine equivalents.
• Opioid Consumption on Postoperative Day 7 [Postoperative day 7]: Self-reported (by telephone questionnaire) opioid consumption in oral morphine equivalents on postoperative day 7
• Worst Pain Rating Score (NRS-11) on Postoperative Day 7 [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.
• Sleep Quality Measured by Number of Times Awakened by Pain During the First Postoperative Night [Postoperative day 1]: The patient will be questioned by a member of the research team about how many times they were awoken by pain overnight.
• Patient Satisfaction With Pain Control at 24 h [24 hours]: Patient reported satisfaction with his/her pain control at 24 h on a scale of 0-10 (0=completely dissatisfied, 10=completely satisfied)
• Patient Satisfaction With Pain Control on Postoperative Day 7 [Postoperative day 7]: Patient reported satisfaction with his/her pain control on postoperative day 7 on a scale of 0-10 (0=completely dissatisfied, 10=completely satisfied)
• 20 Meter Walk Test Time Performed on Postoperative Day 1 [On postoperative day 1]: 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.

Sex: All, ages: 18 Years to 85 Years

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

Participant flow

Outcome results

• Opioid Consumption at 24 Hours Post-op (Primary), Mean, milligrams of oral morphine equivalents: Genicular Nerve Block With Bupivacaine and Dexamethasone 22.9 +/- 19.8; Genicular Nerve Block With Saline 58.1 +/- 34.8
• Worst Pain Rating Score (NRS-11) at Rest on Postoperative Day 1 (Secondary), Mean, score on a scale: Genicular Nerve Block With Bupivacaine and Dexamethasone 2.7 +/- 1.9; Genicular Nerve Block With Saline 3.5 +/- 1.6
• Worst Pain Rating Score (NRS-11) With Movement on Postoperative Day 1 (Secondary), Mean, score on a scale: Genicular Nerve Block With Bupivacaine and Dexamethasone 4.9 +/- 2.4; Genicular Nerve Block With Saline 6.3 +/- 1.9
• Total Opioid Consumption Through 48 Hours (Secondary), Mean, milligrams of oral morphine equivalents: Genicular Nerve Block With Bupivacaine and Dexamethasone 50.3 +/- 39.8; Genicular Nerve Block With Saline 97.6 +/- 56.2
• Opioid Consumption on Postoperative Day 7 (Secondary), Mean, milligrams of oral morphine equivalents: Genicular Nerve Block With Bupivacaine and Dexamethasone 10.4 +/- 13.7; Genicular Nerve Block With Saline 22.6 +/- 24.2
• Worst Pain Rating Score (NRS-11) on Postoperative Day 7 (Secondary), Mean, score on a scale: Genicular Nerve Block With Bupivacaine and Dexamethasone 4.4 +/- 2.0; Genicular Nerve Block With Saline 5.0 +/- 2.2
• Sleep Quality Measured by Number of Times Awakened by Pain During the First Postoperative Night (Secondary), Median, number of times awoken by pain: Genicular Nerve Block With Bupivacaine and Dexamethasone 0 (0 to 3); Genicular Nerve Block With Saline 1 (0 to 4)
• Patient Satisfaction With Pain Control at 24 h (Secondary), Mean, score on a scale: Genicular Nerve Block With Bupivacaine and Dexamethasone 9.1 +/- 0.9; Genicular Nerve Block With Saline 8.6 +/- 1.1
• Patient Satisfaction With Pain Control on Postoperative Day 7 (Secondary), Mean, score on a scale: Genicular Nerve Block With Bupivacaine and Dexamethasone 8.8 +/- 1.6; Genicular Nerve Block With Saline 8.9 +/- 1.2
• 20 Meter Walk Test Time Performed on Postoperative Day 1 (Secondary), Mean, seconds: Genicular Nerve Block With Bupivacaine and Dexamethasone 74.2 +/- 40.8; Genicular Nerve Block With Saline 80.2 +/- 43.6

Adverse events

Time frame: 7 days

• Results publication: 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. PMID 34261807

• Study Protocol and Statistical Analysis Plan (PDF, 2018-12-03)

• Jeffrey Gadsden, MD, Principal investigator, Duke University