- Nailing approach
Make a longitudinal skin incision from lower pole patella to the tibial tuberosity. The incision is centered over the patellar ligament.
Relationship to patellar ligament
The patellar ligament can either be split in the middle, or retracted after dividing the fascia on either the medial or lateral side. The entry site should be centered over the tibial medullary canal.
Mobilizing the fat pad
Identify the anterior edge of the tibial plateau and release the retro-patellar fat pad from the tibia.
Move it posteriorly without opening the knee joint.
Determination of the entry point
The nail entry point, on the lateral view, varies depending on nail design.
The recommendations for the selected nail must therefore be carefully considered. The more proximal the entry point, the less likely it is to create a large anterior tibial defect from reaming.
The nail must clear the patella, but not penetrate the posterior tibial cortex. It is first aimed slightly posteriorly, but then redirected along the medullary canal.
Entry point location
The entry point is on the anterior edge of the tibial plateau, missing the menisci, and centered over the medullary canal on the AP view.
Entry site fluoroscopy
The entry site is just medial to the lateral tibial spine on the AP fluoroscopic view.
Opening the cortex
Different instruments are available for opening the cortex. A cannulated drill or cannulated cutting instrument can be inserted over a guide wire or pin. Alternatively, a curved entry site awl may be used, according to the surgeon’s preference. Initial placement of a guide pin allows radiographic confirmation before entering the bone.
Insertion of centering pin
(For cannulated cutter) Insert a 4 mm centering pin (Steinmann pin). Pass the pin distally, angled 15° in the sagittal plane to the axis of the tibial shaft, into the proximal aspect of the medullary canal. In the coronal plane, the pin is inserted in line with the axis of the tibia shaft.
Verify placement under image intensification in both planes.
Opening the medullary canal with a cutter
Insert a cannulated cutter over the centering pin. Manually advance the cutter rotating it to remove a core of cancellous bone until the canal is entered. Use the protection sleeve in order to prevent damage of the patellar tendon.
Alternative: Opening the medullary canal with an awl
Press the sharp tip of the awl into the cortex at the entry site, aim posteriorly, and advance it, turning the awl back and forth. Stay posterior to the anterior cortex, and in the midline aiming down the medullary canal on the AP view. Gradually rotate the awl to align it with the center of the canal on the lateral view.
The shaft of the awl should finish parallel to the anterior cortex of the tibia.
Protect the patellar tendon with a retractor.