How to perform a patellar fracture fixation with tension band

K-Wire Placement

The goal of the K-wire placement is to secure and maintain the correct alignment of the fractured bone fragments, providing a foundation for the subsequent placement of the cerclage wire. The K-wires should be positioned in a way that ensures stability, without being too close to the cortices or joint line.

There are various methods for inserting K-wires into the patella. Here, two K-wires are drilled in a proximal-to-distal direction across the fracture line.

1. Position the K-wire approximately 5 mm from the anterior cortex of the patella. The lateral K-wire should be placed longitudinally slightly lateral from the midline and the medial K-wire slightly medial from the midline.

2. Insert the K-wire through the quadriceps tendon and into the surface of the patella.

3. Drill the K-wire through the patella. Avoid damaging the skin on the distal side.

4. Drill a second K-wire parallel to the first one. Leave approximately 1 cm between the two K-wires to provide stability.

5. Using fluoroscopy, check for proper alignment and reduction of the fracture and verify the correct alignment of the joint line. Assess the symmetry and placement of the K-wires, confirming they are not too close to the cortices or joint line.

Cerclage Wire Placement

The goal is to stabilize the fracture and minimize displacement. This is achieved by placing a cerclage wire in a figure-of-eight configuration beneath the K-wires and as close to the patellar bone surface as possible, providing direct support to the bone structure.

1. Use a needle to create a horizontal path for the cerclage wire on the proximal aspect of the patella. The tip of the needle can be used to palpate the patellar cortex, aiming to position it as close as possible to the patellar surface.
   
   Ensure that the needle is placed beneath the K-wires.
   
   

2. Pass the cerclage wire through the needle while simultaneously pulling out the needle.

3. Cross the wire ends in the middle to form a figure-of-eight configuration.

4. Repeat the insertion of the wire distally, again close to the patellar surface and below the K-wires.

5. Connect the wire ends to complete the figure-eight configuration. Leave sufficient wire length to form the loop on the opposite side.

6. Gradually tighten these loops, alternating between the two sides to ensure balanced compression. The loops should be tightened in opposite directions—one clockwise and the other counterclockwise—for optimal stability.

7. Using fluoroscopy, assess the tension band wiring from AP and lateral views. Ensure the reduction remains satisfactory and the cerclage wire is correctly positioned under the K-wires. The wire should be close to the bone surface. Adjust the wire's tension if necessary.

Finalizing the Fixation

Fixation is secured by creating hooks on the ends of the K-wires. These hooks hold both the K-wires and the cerclage wire in place. The aim is to get the K-wire hooks around the tension band wire to prevent it from slipping from the patellar surface.

1. Bend the proximal ends of the K-wires 180 degrees with pliers to form a hook and cut the excess part.
   
   The hook is turned posteriorly, so make sure that the hook is small enough so that it stays inside the patella when fixed in place.
   
   

2. Make small incisions on the quadriceps tendon for the K-wire hooks.

3. Rotate the hooks 180 degrees and tap the hooks into the patella through the small incisions.

4. Cut the excess parts of the K-wires distally. Cut them close to the patellar tendon so that distal ends do not poke the skin after closure. A subtle bending of the distal ends of the K-wires can be used to prevent inadvertent retraction of the K-wires. However, excessive bending makes it difficult to remove the K-wires later if needed.

5. Bend the ends of the twisted cerclage wires into the soft tissue to prevent soft tissue irritation. If necessary, cut any excessive wire.

6. Assess the fixation with fluoroscopy. The bent K-wires should go around the cerclage wire and the wire should run on the patellar surface, or as close as possible.

7. Lastly, examine the stability of the fixation. Flex the knee and check that the fracture line is flush, and no separation is detected.

Closure

1. Use size 2 absorbable sutures to repair the torn capsule, ensuring a watertight joint capsule.

2. The subcutaneous layer is closed using absorbable size 0 sutures on the deeper layer and size 2-0 sutures on the superficial layer. Either interrupted or continuous sutures can be used.

3. The skin is closed using single or continuous sutures or with staples.