Analgesic Benefits of Genicular Nerve Blocks of the Posterior Knee for Patients Undergoing ACL Reconstruction

Northwestern University

Status and phase: Terminated; Phase 4

Conditions: Rupture of Anterior Cruciate Ligament

Treatments: Drug: Preservative free normal saline; Drug: Bupivacaine

Study type: Interventional

Funder types: Other

Identifiers

NCT02008617

STU00085894

Details and patient eligibility

About

Outpatients scheduled to have ACL surgery typically receive a femoral nerve block to provide analgesia for the front of the knee. Postoperatively, these patients will often report pain in the back of the knee. Local anesthetic infiltration of the posterior aspect of the knee results in blockade of the genicular nerves of the posterior knee. These nerves originate off of the tibial and common peroneal nerves and their blockade will result in improved posterior knee pain relief and may decrease narcotic consumption compared to patients who receive the same infiltration with normal saline.

Full description

Femoral nerve blocks are commonly used to provide postoperative analgesia for ACL surgery. The limitation of these blocks is the incomplete analgesia they provide of the knee joint subjecting the patient to posterior knee pain. As a result, some of these patients receive rescue sciatic blocks in the postoperative care unit to cover posterior knee pain. The sciatic block provides excellent analgesia for the posterior knee; however its blockade invariably affects other territories of the sciatic nerve such as the lower leg and foot. For ACL surgery, the loss of sensation and/or motor strength to this area is unnecessary and may make ambulation more difficult. The ability to ambulate with minimal assistance may be more important for a patient undergoing an outpatient surgery when compared to an inpatient surgery.

At the posterior knee, the sciatic nerve branches off into the tibial and common peroneal nerves which give rise to sensory fibers that innervate the posterior knee. We propose targeting these terminal fibers in the popliteal fossa by infiltrating local anesthetic between the distal femoral shaft and popliteal artery thereby providing posterior knee analgesia without affecting the lower leg.This application of this block has not been studied in patients having ACL surgery. A single interim analysis is scheduled after the data for 50 cases are available.

Enrollment: 18 patients

Sex: All

Ages: 18 to 70 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. patients who are presenting for ACL reconstruction
2. candidates for peripheral nerve blocks patients
3. ASA 1-3

Exclusion criteria

1. Patient refusal
2. ASA Classification of 4 or higher
3. Pre-existing neuropathy in the femoral or sciatic distribution
4. Coagulopathy
5. Infection at the site
6. Non-English speaking or non-reading patients
7. Chronic opioid use (>3months)
8. Pregnancy
9. Any other contra-indication to regional anesthesia
10. Failed femoral nerve block
11. Sciatic nerve block placed due to severe pain not managed by intravenous and oral agents.

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Quadruple Blind

---

18 participants in 2 patient groups

Study Drug

Active Comparator group

Description:

Ultrasound guided posterior genicular nerve infiltration with 30mL of Bupivicaine 0.20% with epinephrine 1:300,000 (Study Drug)

Treatment:

Drug: Bupivacaine

Preservative free normal saline

Sham Comparator group

Description:

Ultrasound guided posterior genicular nerve infiltration posterior knee with 30mL of preservative free normal saline

Treatment:

Drug: Preservative free normal saline