Evaluation of the Role of Genicular Nerve Block When Combined With Adductor Canal Block for Pain Control Following Knee Arthroscopy

A. Preoperative settings:

All patients will be assessed preoperatively by careful history taking, full physical examination, and laboratory evaluation. An informed written consent will be taken from every patient just before the surgery.

Intraoperative and postoperative settings:

On arrival to the operating room, baseline parameters such as ECG, mean arterial blood pressure, heart rate, and oxygen saturation will be recorded. Intravenous line will be inserted, and IV Ringer's solution will be started, then induction of general anesthesia: Preoxygenation with 100% oxygen will be carried out for 2-3 minutes. Induction of anesthesia will be done using intravenous fentanyl 1-2 µg/kg and propofol 1-2 mg/kg. Endotracheal intubation will be facilitated with atracurium 0.4-0.5 mg/kg. Proper intubation will be confirmed by ETCO2 and bilateral auscultation of the chest. Anesthesia will be maintained with 60:40 oxygen mixed with air and isoflurane 1.2%. Lungs will be ventilated using volume-controlled ventilation with tidal volumes and respiratory rate adjusted to maintain end tidal CO2 at 35-40 MMGH.

After induction of general anesthesia and intubation:

Group A: • All patients will receive adductor canal block under complete aseptic conditions using a high-frequency ultrasound guidance (Sonosite turbo M, Bothell, Washington, USA ). while patient is laying supine lower limbs will slightly abducted at the hips and flexed at the knees , using linear ultrasound probe(2.5-7.5MHZ) on the anterior aspect of the patient's thigh, At the level of mid-thigh, by moving probe medially until the boat shaped Sartorius muscle is visualized , at which the adductor canal is identified beneath the sartorius muscle, a, 20ml bupivacaine (0.25%) will be injected in the canal after a careful negative aspiration. The spread of the drug lateral and around the femoral artery will be seen real time on ultrasound.

Group B: All patients will receive adductor canal block as described above under complete aseptic conditions then they will receive the genicular nerve block using a high-frequency ultrasound guidance (Sonosite turbo M, Bothell, Washington, USA ), genicular nerve block will be done at three locations, i.e., superomedial, superolateral, and inferomedial locations of the condyle-shaft junction, while patient is lying supine linear ultrasound probe(2.5-7.5MHZ) will be used to target the superomedial, superolateral, and inferomedial genicular nerves, 2ml bupivacaine (0.25%) will be injected in the 3 mentioned points after a careful negative aspiration.

Inclusion criteria

• Physical status: ASA 1 or 2 and candidates for knee arthroscopy.
• Age group: 18-50 years.
• No sex predilection.

Exclusion criteria

• Physical status: ASA III or above.
• Patients with a history of drug allergies to study drugs.
• Previous trauma or surgery to the leg.
• Opioids or alcohol abuse.
• Bleeding tendency.
• Dysesthesia, loss of sensation around the knee or medial aspect of the thigh.
• Inability to cooperate.