Medial genicular neurovascular anatomy and its role in precision of ultrasound-guided nerve blockade in end-stage knee osteoarthritis.

BACKGROUND

Ultrasound identification of genicular nerves to perform their blockade can be challenging due to high anatomical variability. Initial identification of the easier to visualize genicular artery could allow for further identification of the genicular nerve, permitting precise ultrasound-guided nerve blockades.

MATERIALS AND

METHODS

Three subsequent patients with the end-stage medial knee osteoarthritis (OA) with history of non-successful intraarticular treatment were included. The procedure assumed an ultrasound-guided blockade of the superior and inferior medial genicular nerves using 7 mL solution of lidocaine 8.33 mg/mL and betamethasone 1.17 mg/mL. Firstly, the superomedial genicular artery was visualized near the femoral medial metaphysis. Then, 3.5 mL of solution was injected in the plane between the deep fascia of the vastus medialis and the femur using 21G 50 mm needle. The same procedure was repeated at the distal part of the knee using the medial condyle of the tibia and inferomedial genicular artery as landmarks.

RESULTS

In all cases, initial visualization of the genicular artery allowed for further identification of the genicular nerve adjacent to it. The procedure led to significant reduction of pain and improvement of the quality of life, with 50-80% of pain reduction at 6 weeks follow-up.

CONCLUSIONS

Despite the high variability of the course of genicular nerves, the ultrasound guidance of perineural blockades facilitates a highly reliable and consistent measure to provide symptomatic relief in patients with knee OA. Genicular arteries are easier to visualize than adjacent genicular nerves, helping in effective identification of anatomical variations.