Total knee arthroplasty or replacement (TKA), a commonly performed surgery for osteoarthritis of the knee, is a painful procedure and requires a multimodal analgesic approach. A method for analgesia is local infiltration analgesia (LIA), where a mixture of drugs is injected around the knee joint.

Adductor canal block (ACB) is an alternative regional anaesthesia technique which has been shown to result in minimal thigh weakness.

The investigators aim to study if the analgesia provided by ACB is superior to LIA while preserving quadriceps strength.

Inclusion Criteria:

• Patients scheduled for primary TKA under single shot spinal anaesthesia, between ages 45-85 years old, American Society of Anesthesiologists (ASA) physical status 1 to 3 and BMI 18-35 kg/m2

Exclusion Criteria:

• Patients unable to give consent, inability to communicate/ cooperate, patients with regular consumption of strong opioids (morphine, oxycodone) or steroids, allergy to local anaesthetics or any drugs included in the study, patients with lower limb surgery in the preceding year, patients with pre-existing neurological deficits and patients who have contraindications for spinal anaesthesia.