Investigators hypothesise that for patients undergoing elective total hip replacements, a single injection Transmuscular Quadratus Lumborum (TQL) block, when compared to a single injection Fascia Iliaca Block (FIB), will provide better analgesia and less motor block in the initial 24 hour period.

Total hip replacement is a commonly performed surgical procedure with up to 4,500 procedures performed annually in Ireland and up to 400,000 per year in the United States. Most of the patients experience moderate to severe pain in the initial post-operative period. Multimodal analgesia with peripheral nerve blockade is recommended as the gold standard modality for management of lower limb joint replacements. The limitations with peripheral nerve block include duration of therapy with single shot injections and associated motor block which can delay rehabilitation.

Transmuscular Quadratus Lumborum injection has been described recently as an effective option for post-operative analgesia in patients undergoing total hip replacement. Single injection can provide analgesia for up to 24 hours. We aim to investigate if a TQL block when compared to FIB provides superior analgesia and less motor block in the acute post-operative period.

All patients scheduled for elective hip replacement surgery will be contacted prior to the surgery (at least 24 hours) over the telephone and information about the nature and purpose of the study will be provided to them by Anaesthesia personnel who are involved in the study. They will be directed to a dedicated page on our website to further inform themselves, if desired. Written informed consent will be obtained from all patients prior to participation in the study. Patients can remove their consent without question at any time during or after the study.

Patients will be randomised to either the TQL group (intervention group) or FIB group (conventional group) by computer generated random numbers and allocation will be enclosed in sealed envelopes. Due to the nature of the intervention, the Anaesthetist performing/supervising the block and patient receiving the block cannot be blinded. Outcome measurements will be recorded by study observers blinded to the group allocation.

On arrival to the Anaesthesia induction room baseline monitoring (non-invasive blood pressure, pulse oximetry and 3-lead ECG) and intravenous access will be established. Patients in both groups will be positioned sitting on a level trolley with feet resting on a foot rest. They will be given a pillow to hug and requested to maintain an arched back posture with an assistant holding the patient to aid positioning. No sedation will be given prior to or during administration of spinal anesthesia.

Spinal anaesthesia will be performed under strict aseptic precautions (Chlorhexidine 0.5% for skin decontamination with anaesthetist performing the procedure scrubbed wearing sterile gown, cap and sterile gloves). A 25G Whitacre needle will be used and 3.2ml 0.5% plain bupivacaine will be infiltrated into the intrathecal space.

Transmuscular Quadratus Lumborum Block (TQL):

Following the administration of spinal anaesthetic, the patient will be positioned laterally with the operating side as the non dependant side. Skin decontamination of the block site will be carried out with 2% Chlorhexidine (Chloraprep 3 ml applicator, CareFusion Corporation, San Diego, CA 92130,USA). Under strict aseptic precautions (cap, mask, sterile gloves, sterile probe cover and sterile ultrasound gel), a 100 mm (Stimuplex® Ultra 360® 22 gauge insulated echogenic needle with 30° bevel and extension set) needle will be used to perform TQL block. A curvilinear low frequency probe (2-5 MHz) will be placed above the iliac crest and the following structures will be identified i) Transverse process ii) Erector spinae muscle iii) Quadratus lumborum muscle iv) Psoas major muscle. The needle will be advanced by in-plane technique and local anaesthetic will be deposited between psoas major and quadratus lumborum muscles. 20 ml of 0.25% bupivacaine will be administered under ultrasound guidance following careful intermittent aspiration.

Fascia Iliaca Block (FIB):

Following the administration of spinal anaesthetic, the patient will be positioned supine. Skin decontamination of the block site will be carried out with 2% Chlorhexidine (Chloraprep 3 ml applicator, CareFusion Corporation, San Diego, CA 92130,USA). Under strict aseptic precautions (cap, mask, sterile gloves, sterile probe cover and sterile ultrasound gel), an 80 mm (Stimuplex® Ultra 360® 22 gauge insulated echogenic needle with 30° bevel and extension set) needle will be used to perform FIB. A linear high frequency probe (8-13 MHz) will be placed along the inguinal crease to identify the femoral artery, femoral nerve and Iliacus fascia. The needle will be advanced by in-plane technique and local anaesthetic will be deposited under the fascial iliaca. 20 ml of 0.25% bupivacaine will be administered under ultrasound guidance following careful intermittent aspiration.

All patients (unless contraindicated) will receive intra-operative intravenous medication as follows: paracetamol 1g, Parecoxib 40mg, tranexamic acid 1g and antibiotics as per local guidelines. Perioperative sedation will be left to the discretion of the anaesthetist. Following transfer to the recovery unit if patient reports pain score by numerical rating score (NRS) > 3, morphine 2 mg increments will be given intravenously by the recovery staff. This will be repeated every 5 minutes till the pain score is <4. In patients requiring more than 10 mg of morphine in the recovery, an Anaesthetist will be requested to review the patient. Post-operatively, in the absence of contraindications, all patients will be prescribed regular Paracetamol 1g every 6 hours and Celecoxib 200 mg every 12 hours. Anti-emetics (Ondansetron 4 mg every 8 hours and Cyclizine 50 mg every 8 hours) will be prescribed for all patients to be administered as required. All patients will receive morphine PCA in the post-operative period. All patients will be reviewed at 6 hours and 24 hours post peripheral nerve block insertion to assess their pain scores (NRS) and motor block.

Statistics:

A sample size of 46 patients (23 per group) is estimated based on 50% reduction in morphine consumption with power of 80% and alfa error of 0.05%. To allow for drop outs,investigators aim to recruit 50 patients in total.

Inclusion Criteria:

• Patients undergoing elective total hip replacements under spinal anaesthesia
• ASA 1-3
• Age > 18 yrs.
• Patient is able to provide written informed consent

Exclusion Criteria:

• Local infection
• Allergy to local anaesthetics
• Severe coagulopathy

Due to nature of intervention (one single injection vs a second single injection in different anatomical location) the participant and the care provider cannot be blinded.The investigator will use an already filled data collection sheet and enter randomised data into a master file. The data will be analysed by an individual blinded to the which group the participant was in.