1 Preliminary remarks topenlarge
In general, extramedullary and intramedullary fixation devices are available for the treatment of unstable fractures of the proximal femur. Currently, there is insufficient evidence to say which is best.
Fixation with a cephalomedullary device allows immediate full weight bearing postoperatively. However, it is more difficult than extramedullary fixation and more intraoperative problems may arise. Immediate weight bearing is a must for the elderly. This justifies the preference for intramedullary devices. The Proximal Femoral Nail Antirotation (PFNA) device is a short intramedullary nail which uses a spiral blade device to obtain fixation in the femoral head, rather than a conventional screw. The operative technique for other cephalomedullary devices is similar, but for details see the manufacturer’s guides.
An A2 fracture without a distal extension or without another fracture distally can be treated successfully with a short IM nail. Preoperatively check the degree of the anterior bow of the femur on an x-ray of the uninjured extremity. If the tip of the nail comes to lie at the apex of the anterior bow, use a long nail or choose a plate.
We shall demonstrate now the steps for the insertion of a short proximal femoral intramedullary nail (PFNA) .
Depending on the implant used, the most appropriate CCD angle has to be determined preoperatively.
Take an AP x-ray of the uninjured leg. Using the preoperative planning template, measure the CCD angle of the uninjured leg (center-collum diaphysis angle, ie, angle subtended between the femoral neck and shaft axes). In most cases an implant with a CCD angle of 130° angle will be appropriate.
Determine nail diameter
Determine the intramedullary diameter by placing the radiographic ruler over the AP x-ray of the fractured femur. This will determine which nail to use. It has to correspond to the intramedullary diameter of the femur.
2 Positioning and reduction topenlarge
Helpful instruments for reducing proximal femoral fractures include Schanz screws and T-handle, ball-tipped pusher, and larger pointed reduction forceps. All can be used percutaneously.
The patient is positioned supine on the fracture table. The ipsilateral arm is elevated in a sling while the uninjured leg is placed on a leg holder. It is important to ensure that the ipsilateral hip is in an adducted position. To accomplish this, push the torso 10º to 15º to the contralateral side.
To reduce the fracture, first apply traction in the direction of the length of the extremity. This will distract the fragments and restore length.
The second step is internal rotation. Check each step with the image intensifier.
Excessive traction, in an attempt to reduce the fracture, can lead to pelvic rotation around the perineal post of the fracture table. When the pelvis rotates, as illustrated, it produces relative abduction of the hip, thus interfering with access to the proximal femoral nail entry site.
Placing both legs in traction prevents pelvic rotation.
The injured hip is slightly flexed and adducted to allow nail entrance. The hip on the uninjured side is extended and abducted to allow lateral imaging. (The two legs are positioned like open scissors.)
The C-arm is placed beside the uninjured hip. It is helpful to use slightly oblique lateral views to avoid superimposition of instrumentation, or of the patient’s opposite leg.
3 Positioning of a guide wire topenlarge
Determination of the entry point
The short nails are slightly curved anteriorly to correspond to the anterior bow of the femur and have a slight lateral deviation of the proximal part in the AP plane to correspond to the shape of the greater trochanter. The entry point is usually on the lateral aspect of the greater trochanter.
Make your skin incision in line with the femoral shaft axis and about 5 cm proximal to the tip of the trochanter.
Take the guide wire for the short nail and insert it just lateral to the tip of the greater trochanter and in line with the middle of the femoral neck, and slightly lateral to a line corresponding to the anatomical axis of the shaft.
As the lateral deviation of different implants vary, the exact entry point changes accordingly.
Check guide wire position
Insert the guide wire into the femoral shaft and check its position using the image intensifier. Ideally, the guide wire’s position in the femoral shaft should be central and deviate slightly proximally according to the degree of the lateral bend of the implant in the AP plane. In the axial view it must be in line with the middle of the femoral neck.
4 Reaming and nail insertion topenlarge
Opening of the femur
Insert the protection sleeve with its trocar over the guide wire and push it through the soft tissues until it abuts against the greater trochanter. Then withdraw the trocar and insert an appropriate drill bit over the guide wire. Ream out the trochanteric area. Ream by hand in the elderly to avoid damage to the fragile trochanteric shell. In young patients, use power. Remove the guide wire after reaming.
Only in exceptional cases, where the medullary canal is smaller than the chosen nail, it will be necessary to overream the femoral shaft so that its diameter is 1 mm greater than that of the chosen nail.
Pearl: Maintaining reduction during reaming
If the fracture passes through the nail entry site, a medially directed force applied to the lateral trochanteric region helps prevent drills or reamers from displacing the greater trochanteric segment(s) laterally. This allows reaming of a channel for the nail, so that its insertion does not distract the fracture.
Achieve a neck-shaft axis > 130°
Avoiding varus deformity is important to improve fixation, and to preserve functionally important anatomy. Begin by choosing a nail with a neck-shaft angle of at least 130°.
Tips to correct varus:
- Advance nail
- Increase traction
- Remove guide wire from the femoral head and abduct extremity (this will require modifying its entrance channel).
In most patients the nail, mounted on the insertion device, can be inserted manually.
Use the image intensifier as a help and insert the nail to such a depth that it will allow the blade to be placed through the middle of the femoral neck.
There are many devices now available with various proximal locking options. Refer to the manufacturer’s guides for technical details.
5 Insertion of blade topenlarge
Positioning of the guide wire
Mount the aiming arm for the blade onto the insertion device. Make a small skin incision at the appropriate place. Insert the drill sleeve assembly through the aiming device and advance it through the soft tissues to the lateral cortex.
The ideal position of the guide wire in the AP plane is in line with the axis of the neck and slightly in the lower half. In the lateral view it must be in line with the axis of the neck.
The guide wire is inserted subchondrally into the femoral head. Its tip should end 5 mm proximal of the joint.
Measuring length of blade
Because the tip of the guide wire was inserted into the subchondral bone, take a blade which is 10-15 mm shorter than the measurement. This will ensure that the tip of the blade will be 10 mm from the joint.
Drilling hole for blade
If you are using the PFNA, insert the 11.0 drill bit over the guide wire and open the lateral cortex to 11 mm. In a young patient, drill the neck with the 11.0 mm reamer to make room for the helical blade. In the elderly, stop once you have opened the lateral cortex. The neck has so little bone that it is best to insert the helical blade by hand over the guide wire without reaming the bone. This prevents unnecessary destruction of the remaining bone stock.
Insertion of blade
Insert the blade over the guide wire to the stop.
Check under image intensification that the blade protrudes slightly over the lateral cortex.
The blade has to be locked, and locking has to be verified intraoperatively. The blade is locked if all gaps are closed. If it cannot be locked, it has to be replaced.
6 Distal locking topenlarge
Drilling hole for distal locking
Make a stab incision and insert the drill bit using a protection sleeve through the selected locking hole. Drill both cortices.
Insertion of locking bolt
For 31-A2 fractures static locking is sufficient. This should be inserted according to the producer’s instructions.
Insertion of end cap
Use of an end cap might be considered, according to producer's instructions.
However, as nearly none of the implants will be removed, this step is generally
The final position of the nail is checked in two planes.