The study aims to compare two different kinds of pain treatment after total knee replacement (operation with artificial knee joint): 1) a large local injection in and around the knee, supplemented with injection the day after, or 2) the department's conventional pain treatment consisting of continuous nerve block in the groin.

Postoperative pain after total knee arthroplasty is moderate to severe and can be difficult to treat. The current use of femoral nerve block by ropivacain pump for 48 hours provides considerable analgesia, but patients often experience slight motor block, inhibiting rehabilitation, and pain in the posterior part of the knee, innervated by the sciatic nerve. This study compares femoral nerve block to a new technique, where ropivacaine, ketorolac and adrenalin is used to infiltrate the tissue in and around the knee joint during surgery, and is injected by an intraarticular catheter at 10 pm on the day of surgery and again at 10 am the day after. Data of pain scores, analgesia consumption, adverse effects and mobilisation is collected for the first four postoperative days.

Inclusion Criteria:

• patients planned for primary total knee arthroplasty due to primary arthrosis

Exclusion Criteria:

• Patients unable to provide informed consent
• patients with contraindications for spinal anesthesia
• patients with known hypersensitivity towards the used drugs
• patients with severe chronic neurogenic pain or sensitivity disorders in the leg to be operated
• patients who have undergone major bone surgery in the knee to be operated