Postoperative Analgesia in Patients Undergoing Hip and Knee Replacement Surgery - a Study Comparing Ultrasound-guided Nerve Blocks With Intraoperative Local Anesthetic Infiltration or Opioids

400 patients with osteoarthritis of the knee (200) or hip (200) necessitating total hip- or knee replacement are entered into the study. All patients are given a standard protocol of analgesics pre- and postoperatively. Patients are receiving general- or spinal anaesthesia during the surgery. General anaesthesia is conducted using Remifentanil 50ug/ml and Propofol 20 mg/ml utilizing a TCI protocol. The airway is managed by LMA or endotracheal tube. Spinal anaesthesia is conducted using isobaric Bupivacaine (hip) and hyperbaric bupivacaine (knee). Decision regarding type of anaesthesia is following guidelines of our department taking contraindications and patients preference into account.

Patients randomized to the block-group undergoing hip replacement surgery with posterior approach are given och combination of PENG block and Iliohypogastric block using Ropivacain 5 mg/ml with a total dose of 200 mg along with clonidine in a total dose of 75 micrograms. Patients undergoing hip replacement with lateral approach are given a combination of PENG block and LFCN block using Ropivacain 5 mg/ml with a total dose of 125 mg along with clonidine in a total dose of 56,25 micrograms. Patients randomized to the standard pain management strategy undergoing hip replacement surgery are given a combination of opioids, paracetamol and Cox-II inhibitors.

Patients randomized to the block-group undergoing knee replacement surgery are given a combination of iPACK-, genicular-, AFCN-, adductor canal and vastus intermedius block using Ropivacain 5 mg/ml with a total dose of 225 mg along with clonidine in a total dose of 75 micrograms. Patients randomized to the standard pain management strategy undergoing knee replacement surgery are given a perioperative periarticular LIA using Ropivacaine 300 mg along with 0,5 mg of adrenaline.

The randomization is executed on the day before surgery by opening of a closed numbered envelope giving information if the specific patient should have a block (intervention) or not (control). There are 200 prepared envelopes for the hip replacements and 200 for the knee replacements, with 100 blocks and 100 no blocks for each type. The envelopes are prepared by block randomization performed by computer software. Nurses and physiotherapists who evaluate postoperative pain are blinded from the intervention. The physician compiling the data from the study is also blinded to the intervention.

Preoperatively, information is collected regarding doses of analgesics and pain in everyday life is evaluated using the NRS scale. Preoperative pain is evaluated at rest and during mobilization.