Postoperative pain and mobility outcomes after primary hip and knee arthroplasty. A comparison of intravenous morphine with local wound infiltration.

INTERVENTION: Trade Name: Levobupivacaine Product Name: Levobupivacaine Pharmaceutical Form: Injection* Trade Name: Morphine Sulphate Product Name: Morphine Sulphate Pharmaceutical Form: Injection* CONDITION: Osteoarthritis of the hip and knee joints INCLUSION CRITERIA: Inclusion criteria will be: Age (18‐85) Males and females American Association of Anesthesiologists (ASA)class I‐III. Patients requiring primary hip/knee arthroplasty Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range PRIMARY OUTCOME: Main Objective: The principal research question is whether infiltration of the surgical wound site with a long acting local anaesthetic (levobupivacaine) will provide a superior quality of postoperative pain relief compared to traditional methods such as intravenous morphine. Primary end point(s): Following informed and written consent, 200 patients (ASA grades I‐III) presenting for primary hip and knee arthroplasty will be studied. Patients will be randomly allocated to two groups A (n=100) and B (n=100). All patients will receive a standardised anaesthetic protocol comprising intrathecal isobaric bupivacaine 0.5% (0.1‐0.2 mg/kg), intravenous propofol or midazolam to allow sedation to an appropriate depth, granisetron (1mg) and supplemental oxygen (4 l/min). After surgery all patients will be prescribed a patient controlled analgesia system. (Morphine [1mg/ml], bolus of 1 mg and a lockout time of 5 minutes). Patients in group A will act as controls and will receive no local infiltration of levobupivacaine. Patients in group B will receive local infiltration to the operative site (before wound closure)of levobupivacaine with adrenaline in 100 ml of saline giving a final concentration of 0.2% levobupivacaine in 1:200,000 adrenaline per ml. The morphine consumption in milligrams, pain scores (by a visual analogue scale [VAS]) and the mobility scores for each patient will be assessed in the postoperative period.Postoperative mobilisation will follow a set protocol supervised by a core team of experienced orthopaedic physiotherapists who will be blinded to the type of pain used (Group A or B). The mobility tests performed will comprise; 1)the level of assistance required for transfer from the supine to the sitting position and from the sitting position to the standing position and for mobilisation with a walking aid, 2)a timed 10 metre walk to assess walking velocity, and 3)a timed stair‐climbing test. Data collection will commence on an hourly basis immediately after surgery and will continue for 48 hours at which time the study period will end. Secondary Objective: The secondary research objectives are: 1)does local infiltration of the wound with levobupivacaine result in earlier mobilisation after hip and knee arthroplasty and 2)does this contribute to a reduced incidence of nausea and vomiting and 3) an ultimately shorter hospital stay?