Tibial osteotomy is a surgical procedure designed to restore function to a knee with osteoarthritis due to malalignment of the joint. The goal of tibial osteotomy is to shift the patient's body weight off the damaged area and onto the other side of the knee where the cartilage is still healthy. This is achieved by removing a wedge of the tibia from underneath the healthy side of the knee. This allows the tibia and femur to bend away from the damaged cartilage.
Prior to surgery x-ray and CT scans are carried out in order to measure the degree of correction and the size of the wedge which will be needed to be removed during surgery.
In theatre a general anaesthetic is administered and antibiotics given intravenously to prevent infection. A tourniquet is placed around the thigh to stop blood flow and to allow the best visualisation of the operative site.
A 15-20cm incision is made on the outside of the knee and the soft tissues are retracted away from the bone, exposing the tibia where the osteotomy will be performed. At this point, usually the joint between the fibula and the tibia is exposed and divided to avoid pain from here once the osteotomy has been performed. Retractors are placed carefully around the front and back of the tibia protecting important soft tissues from damage from the instruments (eg: patellar tendon, major blood vessels and nerves to the leg which are located just behind the tibia).
X-ray is used to ensure correct placement of the osteotomy. The wedge of bone is cut and the osteotomy is slowly closed and compressed with a plate and screws used to hold the osteotomy rigidly.
There are two methods to performing a tibial osteotomy: closing wedge osteotomy and opening wedge osteotomy:
Closing wedge osteotomy involves removing a wedge of bone usually just below the joint in the upper part of the tibia. For patients with arthritis affecting the medial compartment (varus knees) the bone wedge is taken from the outer part of the tibia. Once the wedge of bone is removed the two bone ends are then put together and held with either a metal plate or pins. This has the effect of shifting your body weight from the inner part of the knee to the non-affected lateral compartment.
Opening wedge osteotomy in this technique the surgeon cuts through the tibia on the medial (inner) side and opens a wedge, sometimes by adding a piece of bone graft from the pelvic area to hold the wedge open. In order to stabilise this a plate is inserted once again. This operation is also commonly performed in the upper part of the tibia just below the knee joint.
A final check with x-ray confirms the position and correction of the osteotomy. The wound is then closed and the patient is returned to the ward.
The surgery typically takes between 60 and 90 minutes.