Patellar (knee cap) realignment procedures are used to treat instability problems at the knee cap joint. Patients with instability of the knee cap suffer from dislocations or feelings of their knee cap slipping. Many times, patients with instability of the knee cap have problems with the alignment of the knee cap (see figures 1 and 2). Some people are born with abnormal alignment of the knee cap and it becomes bothersome after an injury. Other people are born with normal alignment, but develop problems after an injury to their knee cap.
The goal of patellar realignment surgery is to bring the knee cap back into a normal alignment. There are several different surgeries that can be done to realign the knee cap. Your surgeon will make the determination of which procedure is right for you on a case-by-case basis.
All patellar realignment surgeries begin with an arthroscopy (scope). This procedure is used to examine the knee joint and look for damage to the cartilage surfaces of the bones. The trauma from a patella dislocation can cause damage to the cartilage. If necessary, these injuries are treated at this time.
Types of patellar realignment surgeries
Following the scope, the surgeon will begin with the procedure to re-center the patella. Basically, the realignment surgeries can be divided into two types. The first type of surgery, called a proximal repair, involves repairing the soft tissue near the knee cap. The second type of surgery involves moving the insertion of the patellar tendon to the tibia (shin bone) and is called a Trillat procedure. The goal of both of these surgeries is to bring the knee cap to a centered position.
The proximal repair requires the surgeon to make a small (about 2-3 inches long) incision on each side of the knee cap. The knee cap is stabilized by soft tissue called the retinaculum. After a patella dislocation, the retinaculum on the inner side of the knee is torn or stretched. Also, the retinaculum on the outer side of the knee shortens when the knee cap is not in a centered position. The proximal repair procedure tightens the retinaculum on the inner side of the knee and loosens the retinaculum on the outer side of the knee. This brings the patella back to a centered position.
The Trillat procedure (the second type of surgery) requires one incision on the upper part of the tibia (shin bone). This is the area where the patellar tendon inserts into the tibia. This area of bone is slightly elevated from the rest of the tibia and is called the tibial tubercle. The Trillat procedure involves removing the tibial tubercle from its original position and moving it slightly. This new position re-centers the knee cap.
A plate and screws are used to keep the tibial tubercle in this new position.