Novel use of motor-sparing genicular nerve blocks for knee injuries in the emergency department

Abstract

Knee injuries are quite prevalent in the Emergency Department (ED) and often present with severe pain, necessitating effective pain management strategies. Traditional pain management approaches, including opioid medications, may carry undesirable side effects and potential risks, leading to the growing interest in non-opioid alternatives. Nerve blocks have emerged as promising options for targeted pain relief in the ED. Motor-sparing nerve blocks have gained importance due to their ability to provide effective analgesia without compromising motor function [1].

The case series demonstrates the successful use of ultrasound-guided genicular nerve blocks(GNB) in the Emergency Department, providing targeted pain relief without compromising motor function. GNBs offer a valuable alternative to traditional nerve blocks(femoral, fascia iliaca, adductor canal) and opioid-based pain control strategies in the ED. As the evidence base grows, GNBs may become a more established component of ED pain management protocols, enhancing patient outcomes and safety in the management of acute knee injuries. The incorporation of ultrasound-guided motor-sparing nerve blocks in ED pain management protocols may hold great promise in optimising pain control and enhancing patient comfort.

Trial Registration: N/A.

1 Case 1

A 27-year-old presented to the ED with severe right knee pain after falling from his motorbike. He was unable to bear weight on the affected leg and described the pain as 9/10 on the numeric rating scale(NRS) despite taking 800 mg of ibuprofen and 1000 mg of Paracetamol. On examination, his right knee displayed mild effusion and tenderness to palpation over the proximal anterior tibia, lateral and medial joint line. Knee extension was limited due to pain, and the patient’s neurovascular status was intact.Radiographic imaging revealed an isolated fracture of the right lateral tibial plateau.

Given the patient’s unrelieved pain and request for non-opioid alternatives, informed consent was obtained for ultrasound-guided GNBs of the right knee. The skin was first anesthetized with 1% lidocaine at each site.

The patient was positioned supine with knees slightly flexed. A linear transducer probe was placed in the coronal orientation on the medial and lateral aspects of tibia and femur. The superior lateral genicular artery was identified at the junction of the lateral femoral epicondyle and the femoral diaphysis ( Fig. 1 ). The superior medial genicular artery was identified at the junction of the medial femoral diaphysis and epiphysis ( Fig. 2 ). The inferior medial genicular artery was identified at the junction of the medial tibial epicondyle and the tibial diaphysis ( Fig. 3 ).