A comparison of the need for opiate pain relief medication after elective hip replacement surgery between patients given Local Anaesthetic Infiltration to the new joint and then an infusion of either local anaesthetic or placebo around the new joint

INTERVENTION: The total duration of treatment is 48 hours from the time of surgery and the total duration of time in the study is for 6‐12 weeks from time of discharge. 1. Attendance at pre‐assessment clinic (no additional visit to a patient not in the study), study information given to potential trial participants. 2. Admission to orthopaedic unit and written consent obtained 3. Administration of standard anaesthetic technique (spinal +/‐ sedation or light general anaesthetic) as for non‐trial patients 4. Standard hip replacement performed as for non‐trial patients 5. Study intervention performed; local anaesthetic mixture infiltration (ropivacaine 300mg, ketorolac 30mg and adrenaline 0.5mg) and insertion of pain pump device 6. Treatment group receive a 48h infusion of 0.25% bupivicaine via the pain pump device into the tissues surrounding the new joint. Placebo group receive an infusion over 48h of 0.9% saline in the same way. 7. Patient care in recovery area as for non‐trial patients 8. Assessment of pain using standardised pain scoring technique 9. Physiotherapy session and routine observations and ward care including analgesia and antiemetics if needed as for non‐trial patients 10. Routine blood test on morning after surgery as for non‐trial patients 11. Removal of pain pump device at 48h 12. Routine follow up clinic appointment as for non‐trial patients CONDITION: Primary hip arthroplasty ; Musculoskeletal Diseases ; Primary hip arthroplasty PRIMARY OUTCOME: A 30% reduction in the number of patients requiring opiate analgesia in the 48 hours post‐operative period in the treatment group compared to the placebo group. ; 1. Pain is measured using a 10‐point Visual Analogue Score (VAS); 2. The case report file for each study participant includes data collection on pain scores, opiate and other analgesia requirements and anti‐emetic use. SECONDARY OUTCOME: 1. Pain scores postoperatively as measured using a 100mm Visual Analogue Score (VAS); 2. Time to first mobilisation in hours; 3. Time to independent mobilisation in hours; 4. Time to fulfill discharge criteria in days; 5. Time to hospital discharge in days; 6. Urinary retention post operatively indicated by requirement for urinary catheter; 7. Deep vein thrombosis (DVT) / pulmonary embolism (PE) rate at up to outpatient follow up (6‐12 weeks post operation); 8. Side effects and general medical complications INCLUSION CRITERIA: 1. All patients fit to undergo elective primary hip replacement at Chapel Allerton Hospital 2. Patients who are able to give informed consent 3. American Society of Anesthesiologists (ASA) 1‐3