Retrograde nailing approach to the femoral shaft

Outcomes for retrograde nails are very similar to outcomes for antegrade nails. But, retrograde nails may be advantageous for distal third fractures.

Care should be taken with the approach for retrograde nailing as several anatomical structures are at risk. The most important potential hazard is damage to the anterior cruciate ligament. In addition, cartilage from the weight bearing zone may be damaged if a non-anatomic approach is selected. A non-anatomic approach can also lead to a failure to reduce the fracture properly, resulting in a varus/valgus malposition of the distal main fragment. Lastly, plunging out the back of the knee is always a major risk of this procedure because of the neurovascular structures.

The anatomical landmark is the Blumensaat’s line (solid orange line) – this corresponds to the roof of the intercondylar notch.

Illustration showing the retrograde nailing approach to the femoral shaft, highlighting risks to anatomical structures, including the anterior cruciate ligament, cartilage, and neurovascular structures. The Blumensaat’s line (solid orange line) is marked as the anatomical landmark.

A 2 cm skin incision is made longitudinally just distal to the inferior patellar pole, over the midline of the patellar tendon.

Illustration showing a 2 cm longitudinal skin incision just distal to the inferior patellar pole, over the midline of the patellar tendon.

Clinical image of the skin incision.

Clinical image showing the skin incision for a retrograde nailing approach to the femoral shaft.

The medial parapatellar soft tissues are spread longitudinally with scissors. The patellar tendon is gently retracted laterally to allow for guide wire insertion.

The approach may alternatively involve splitting of the patellar tendon.

Illustration showing medial parapatellar soft tissues spread with scissors, patellar tendon retracted laterally for guide wire insertion, with an alternative approach involving splitting the patellar tendon.

It is very important to perform every step of the process of locating the entry point under image intensifier guidance.

On the AP view, the guide wire should be centered exactly in the middle of the intercondylar notch.
On the lateral view it should be located in the extension of Blumensaat’s line.
The entry point of the nail is in line with the axis of the medullary canal, just below the crest of the intercondylar notch.

The correct position is therefore located anterior and lateral to the proximal attachment of the posterior cruciate ligament.

Illustration showing steps for locating the entry point under image intensifier guidance, with guide wire centered in the intercondylar notch on AP view, aligned with Blumensaat’s line on lateral view, and nail entry point just below the crest of the intercondylar notch.

Care must be taken not to establish the entry point posterior to the Blumensaat’s line, to prevent damage to the anterior cruciate ligament upon reaming.

The x-ray shows the desired 30° flexion of the knee joint. With less flexion the tibial plateau hinders the guide wire insertion. With more flexion the articular surface is in danger and the patella is in the way.

Once the correct entry point is determined, a guide wire is inserted 3–4 cm.

Illustration showing the importance of not establishing the entry point posterior to Blumensaat’s line, with an x-ray of the knee joint in 30° flexion, and guide wire insertion 3-4 cm once the correct entry point is determined.

To open the medullary canal, the protection sleeve and drill sleeve are pushed over the guide wire into the notch, and the medullary canal is opened to a depth of approximately 30 mm using the cannulated drill bit.