Proximal femoral nail
The proximal femoral nail (PFN) is an osteosynthetic implant designed to treat proximal femoral fractures in the trochanter area with a closed intramedullary fixation method.
Similar to the gamma nail the proximal femoral nail (PFN) consists of a funnel-shaped intramedullary nail with slight bending to reflect proximal femoral diaphyseal trochanteric morphology. But different to the gamma nail the proximal femoral nail features two proximal openings, a larger one further distally for a large femoral neck lag screw and a smaller one immediately above for a smaller anti-rotation screw/pin. There a small holes at the distal end of the nail for locking screws .
The proximal femoral nail (PFN) comes also in different lengths with a version reaching caudally up to the distal femoral metaphysis. Longer nails are designed to treat low and extended subtrochanteric or combined trochanteric and femoral shaft fractures. There are different versions for different CCD angles available.
It can be combined with a wire cerclage with an open reduction for additional stability in complicated subtrochanteric fractures .
Terminology
A proximal femoral nail antirotation (PFNA) is a similar implant except that it comes with a helical blade rather than a femoral neck screw and anti-rotation pin .
History and etymology
The proximal femoral nail (PFN) was introduced for the treatment of proximal femoral fractures in 1997 .
Indications
Main indications of the proximal femoral nail are the treatment of peritrochanteric, intertrochanteric and subtrochanteric fractures with the fracture type AO/OTA 31-A1 31-A2 and 31-A3 .
Other indications include pathological fractures and extended subtrochanteric fractures especially in case of the long version.
Contraindications
Contraindications of proximal femoral nail fixation are medial femoral neck fractures.
Procedure
The surgical technique comprises several steps including the following :
determination of nail length, diameter as well as angle and anteversion of lag screw insertion
- exact anatomic closed reduction on the traction table
- the positioning of guide wires
- opening of the insertion point at the top of the greater trochanter
- insertion of the proximal femoral nail
- drilling of the holes for antirotation pin/screw and lag screw
- insertion of the antirotation pin/screw
- insertion of the femoral neck lag screw
- distal locking
Complications
Complications of gamma nail fixation include the following :
- hematoma formation
- secondary displacement
- infection
- fracture non-union
- periprosthetic fracture
- malposition e.g. cut out
- loosening
- osteonecrosis of the hip
- hardware failure (rare)
general complications associated with proximal femoral surgery:
- cardiovascular complications
- pneumonia
- pulmonary edema
- pulmonary embolism
Radiographic features
Implant position, fragment position and fracture healing can be evaluated with an anteroposterior view and a lateral view of the hip. The position of the femoral neck screw should be ideally in an inferior position from the AP view and centered position from the lateral view. The antirotation screw should be positioned above in a centered slightly superior position. The femoral neck screw tip should be at least 1-2 mm from the joint space and the tip of the antirotation pin should have considerably more distance.
Radiological report
The radiological report should include a description of the following features:
- implant malposition e.g. cut out of the femoral neck screw or the antirotation pin/screw through the femoral head
- fragment displacement
- implant loosening
- signs of fracture healing
- hardware failure
Outcomes
The use of a proximal femoral nail is associated with a lower blood loss than the use of gamma nails and dynamic hip screws.
Early postoperative outcome and weight-bearing and length of postoperative hospital stay are similar to other methods .
Like with other similar methods fracture healing occurs usually within 12 weeks.
Advantages
A proximal femoral nail features the following benefits :
intraoperative blood loss is low compared to other methods (e.g. dynamic hip screw and gamma nail)
no reaming of the femoral canal is required
additional rotational and angular stability due to the antirotation pin/screw
Disadvantages
Disadvantages of the proximal femoral nail versus other methods are lateral protrusion of the proximal screws .
