Pain control after ACL reconstruction: comparing two nerve block techniques

Brief name: IPACK block plus local infiltration analgesia for postoperative analgesia following hamstring tendon anterior cruciate ligament reconstruction. Description of intervention(s): Participants allocated to the intervention group will receive an ultrasound-guided IPACK (Infiltration between the Popliteal Artery and Capsule of the Knee) block administered by a consultant anaesthetist experienced in ultrasound-guided regional anaesthesia. Timing: Single administration intraoperatively, immediately following induction of general anaesthesia and prior to surgical incision. Technique and dose: Under ultrasound guidance, a 20-gauge needle is inserted into the interspace between the popliteal artery and posterior capsule of the knee. Following negative aspiration, 20 mL of bupivacaine 0.25% is injected incrementally. Single dose; not repeated. Co-intervention (standardised for both groups): All participants additionally receive local infiltration analgesia (LIA) — bupivacaine 0.5% 20 mL infiltrated into peri-articular tissues at surgical completion prior to wound closure, plus ketorolac 30 mg intravenously intraoperatively. Standardised background analgesia (both groups): General anaesthesia, paracetamol 1 g four times daily (regular), oxycodone 5–10 mg orally every 4 hours as required, and intraoperative fentanyl titrated to haemodynamic response. Adherence: All blocks are performed to a standardised protocol by consultant anaesthetists trained in ultrasound-guided regional anaesthesia. Anaesthetic records are reviewed post-procedure to confirm adherence to technique and dosing.