The purpose of this study is to determine whether Minimal Invasive Surgery results in less postoperative pain and better mobilization than conventional technique in Unicompartmental Knee Arthroplasty, provided that both groups receive Local Infiltration Analgesia.

Postoperative pain is often moderate to severe following unicompartmental knee arthroplasty. In order to reduce postoperative pain and improve mobilization the minimal invasive technique was developed. After a 8-10 cm skin incision, a medial parapatellar capsule incision in made. The rectus tendon or the vastus medialis are not incised and the patella is not everted.

In recent years The Local Infiltration Analgesia (LIA) technique has been developed to reduce postoperative pain. With this LIA-technique, a long-acting local anesthetic (ropivacaine), a nonsteroidal anti-inflammatory drug (ketorolac), and epinephrine are infiltrated intraoperatively and via an intraarticular catheter postoperatively.

The aim of this study is to investigate if Minimal Invasive Surgery results in less postoperative pain and better mobilization than conventional technique in Unicompartmental Knee Arthroplasty, provided that both groups receive Local Infiltration Analgesia.

Inclusion Criteria:

• Patients scheduled for unicompartmental knee arthroplasty
• Aged 20-80 yrs
• ASA physical status I-III and mobility indicating normal postoperative mobilization

Exclusion Criteria:

• Known allergy or intolerance to local anesthetics, ASA or NSAID
• Serious liver-, heart- or renal decease
• Rheumatoid arthritis
• Chronic pain or bleeding disorder