PFNA Enhancements

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PFNA Enhancements

Fig 1 New PFNA blade design.

Fig 2 Compression instrument.

Fig 3 End caps with T40 recess and StarDrive T40 for new end caps.

Fig 4 Aiming arm.

Fig 5 Insertion handle.

Fig 6 Guide-wire aiming device.

Introduction

The PFNA in its short and long version is indicated for pertrochanteric fractures, intertrochanteric fractures, and high subtrochanteric fractures. In addition the long version is indicated for low and extended subtrochanteric fractures, ipsilateral trochanteric fractures, segmental fractures of the femur, and pathological fractures. Several components of the PFNA system have been improved to enable intraoperative compression, and facilitate insertion and cleaning.

Blade

The design has been changed to allow intraoperative compression and to improve the strength of the blade also with respect to implant removal. The current insertion/extraction instrument can be used with the new blade and vice versa because the interface is exactly the same. The new blade can be used with the existing stainless steel insertion handle, or with the existing radiolucent insertion handle. The blade comes in lengths of 75130 mm in 5 mm increments and is available in titanium and stainless steel. New blade lengths of 75, 125, and 130 mm offer more options to better fit the patients anatomy.

The compression instrument is screwed into the blade through the protection sleeve. Then the buttress nut is turned counterclockwise to move the protection sleeve backwards until it pushes towards the compression instrument. Under image intensifier control, the buttress nut is turned counterclockwise achieving intraoperative compression and closing the fracture gap.

End caps and screwdriver StarDrive

The end caps, available with extensions of 0, 5, 10, or 15 mm in titanium and stainless steel now have a StarDrive T40 recess and are intended for use with a new screwdriver. This new T40 screwdriver has a ball tip which allows angulation of the instrument in relation to the nail/end cap. This facilitates insertion of the end cap over guide wire with hook and is an advantage compared to the current straight T40 screwdriver.

Aiming arm

The new aiming arm is made of PEEK carbon fiber which is easier to clean. It can be used for locking of standard and short nails which reduces the number of instruments needed. The self-holding feature of the protection sleeve makes the handling easier. The new aiming arm is compatible with the existing and new insertion handles.

Insertion handle

Compared to the existing radiolucent handle the new design is slimmer, allowing smaller incisions and therefore reducing potential interference with the pelvis and soft tissues. The handle is radiolucent which provides for good visibility on x-rays. The integrated positioning aids lateral-orientation-facilitated guide-wire positioning and insertion. The new insertion handle is compatible with the existing instruments and implants.

Guide-wire aiming device

This new device facilitates guide-wire positioning and insertion. It is attached to the aiming arm using the connecting screw for PFNA. The C-arm is rotated in AP view until any two orientation lines are symmetrical to the protection sleeve. The midline in between these two orientation lines predicts the location of the guide wire and PFNA blade. The insertion depth of the nail is adapted until the midline is centered in the femoral head. The C-arm may be readjusted to make sure that two lines are symmetrical to the sleeve. The guide-wire aiming device can be attached to the existing aiming arms and also to the new aiming arms.

Locking screw for distal locking

Locking screws for distal locking are now available: either 5.0 mm locking screw, self-tapping in lengths of 28100 mm, or 5.0 mm locking screw with StarDrive recess in lengths of 26100 mm.

Clinical Cases
Disclaimer

a Clinical picture of the whole aiming and insertion construct.

b After closed and minimally invasive open reduction with a Hohmann retractor pushing on the anterior aspect of the femoral neck for better axial alignment, the guide-wire aiming device has been mounted to the aiming arm and helps to identify the optimal position of the guide wire in the femoral head.

c The K-wire runs parallel to the chosen line of the aiming device. In AP projection the tip of the blade should be positioned in the center of the femoral head.

d In AP projection the tip of the blade should be positioned in the center of the femoral head, in lateral projection the blade should run parallel to and in middle of the neck and also end dead center of the femoral head. The distance of the tip of the blade to the joint should be approximately 10 mm. No predrilling is recommended in osteoporotic bone.

Compression feature used intraoperatively.

Case provided by Michael Blauth, Innsbruck, Austria

Fig 1 Preoperative x-ray.

Fig 2a-b Intraoperative compression images.

Fig 3a-b Immediately postoperative AP and lateral images.

Fig 4a-b Postoperative AP and lateral x-rays.

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