The purpose of this study is to elucidate whether patients operated with high tibia open-wedge osteotomy for osteoarthritis of the knee can be treated more appropriately, so that both healing and rehabilitation are served optimally.

Axis corrective surgery of the knee is an attractive alternative to the knee prosthesis in young active patients with unilateral osteoarthritis of the knee. The purpose of this study is to elucidate whether patients operated with high tibia open-wedge osteotomy for osteoarthritis of the knee pain can be treated more appropriately, so that both healing and rehabilitation are served optimally.

Proximal open-wedge tibia osteotomy is an accepted treatment option for younger patients with unilateral osteoarthritis of knee. 70 such operations are performed in the investigators Orthopaedic Divisions each year. The surgery involves cutting through the upper end of the tibia and opens the bone using specialized instruments. The tibia is lengthened on the medial side with the purpose of correcting the mechanical axis of the knee joint. The surgery is associated with many pains in the early postoperative phase. Until now, pain treatment has been controlled with either epidural block, or regional block via femoral catheter. Both treatments may involve risks such as loss of strength and sensibility disturbance, which often prolongs the early recovery and mobilization. Moreover, pain treatment administered via femoral catheter is often not sufficient as a part of the area behind the knee joint is not covered.

With the advent of new pain therapies, particularly intra operative administration of local anaesthetics directly in the operating field and catheter administration for postoperative pain management, there is hope that those disadvantages are eliminated. By ensuring an effective pain treatment and the possibility of early mobilization only hours after completion of surgery, this will allow for better patient care in terms of reduced pain, shorter hospitalization and quicker rehabilitation.

New results show that the healing of bone opening is not compromised by rapid mobilization. The migration of bone parts around the opening is measured by roentgen stereometric analysis (RSA), with a precision of approximately 0.2 mm. This verifies stable healing of the bone opening.

Inclusion Criteria:

• Planned primary open-wedge high tibia osteotomy
• Patients (male/female) ≥ 18 år
• Patients giving written informed consent and authority.
• Patients receiving epidural anaesthesia

Exclusion Criteria:

• Patients with intolerance to trial medications
• Rejection of or contraindicated epidural anaesthesia
• Patients with rheumatoid arthritis.
• Patients with Body Mass Index (BMI) ≥ 35
• Patients that do not read or write Danish