Kneecap (Patellar) Instability: Tibial Tubercle Osteotomy Animation

Kneecap (Patellar) Instability: Tibial Tubercle Osteotomy Animation

This animation demonstrates a tibial tubercle osteotomy for the treatment of kneecap instability. The kneecap, or patella, sits within a groove in the thigh bone, or femur. It is connected to the quadriceps tendon from above and the patellar tendon from below. Additionally, it is stabilized by many ligaments, including the medial patellofemoral ligament, or MPFL.

Kneecap instability results when the kneecap does not properly stay within the groove when the knee is moved. In some cases, this can cause the kneecap to dislocate. For some patients, poor knee alignment can cause recurrent kneecap dislocations. A tibial tubercle osteotomy is a surgery that aims to address the knee alignment problem by shifting the attachment of the patellar tendon on the shinbone so that the kneecap is better aligned within the groove.

Here we see a left knee. As we get closer to the shinbone, we can see where the patellar tendon attaches to a bump called the tibial tubercle. To begin the surgery, an incision is made through the skin, and a guide is placed over the patellar tendon and tibial tubercle. A guidewire is drilled, and the guide is removed.

Next, a cutting guide is placed over the guidewire and screwed tightly to secure it. A flat metal instrument is placed behind the shinbone to protect the soft tissue. Then, pins are inserted through the cutting guide into the shinbone to secure it in place. Part of the guide is unscrewed from the guidewire, and the guide and guidewire are both removed. Another part of the guide is used to mark out where the bone cut will be made.

A final pin is placed in the middle of the cutting guide to secure its position. The ends of the pins are snapped off to create more space for a saw. Next, the saw is passed through the slots in the cutting guide, making a bone cut through the shinbone while leaving portions of bone attached at the top and the bottom. The middle pin is removed, and the cutting guide is removed.

A bone chisel, called an osteotome, is used to complete the top portion of the bone cut. The tissue protector is removed. While the bottom portion of the bone cut stays connected to the shinbone, the tubercle is moved toward the inner side of the shinbone to better align the kneecap within the groove.

The tubercle is pinned in this position with guidewires. A drill is passed over the guidewire to make room for a screw, which is then inserted to hold the new position of the tubercle in the shinbone. This is repeated for the second guidewire, and the guidewires are removed. The tibial tubercle will heal in its new position. The skin incision will be closed, and the procedure is complete.