Ipsilateral neck and shaft fractures are high energy traumas that occur in about 1-6% of cases. These injuries are rare, but important. Neck fractures may be missed in about 20-30% of cases. Most of the associated neck fractures are classified as vertical Pauwel III; basicervical and nondisplaced.
An x-ray diagnosis is difficult due to the inability to take a good quality image because the fracture is not displaced. Also, because the hip is externally rotated from the fractured femur, it is hiding the fracture of the neck. CT scan thin cuts may detect the neck fracture prior to surgery. An x-ray should be obtained of the hip before, during, and after the fixation of the fracture of the femur’s shaft. The fracture is usually occult and it can be discovered at the time of surgery or after fixation.
Risk factors include an acetabular fracture and patellar fracture. The hip should also be checked for a fracture as comminuted midshaft fractures, fracture secondary to axial loading is another risk. Because of the potential complication of AVN and nonunion, femoral neck fractures are given priority in treatment.
Options of Treatment
Femoral neck fractures must have an anatomic reduction, open or closed, and a stable fixation. One or two devices may be used; however, two different devices are typically used. An open reduction of the hip can be done by the Watson Jones approach or by the limited Smith Petersen approach. Timing of discovery of the femoral neck fracture may decide the available options for treatment.
If a patient complains of hip pain after IM rodding of the femur, the physician should obtain hip x-rays to rule out a hip fracture. Postoperative 15 degrees of internal rotation of the hip before walking, the patient may discover the fracture. If a fracture is discovered and the patient already has an IM rod for the fractured femur, reduce the neck and put screws anterior to the rod. If the neck is not displaced, the physician can use a Cephalomedullary nail.
Although, this technique is unpredictable and rarely used as the fracture may displace. The use of IM nailing for both fractures may lead to malreduction of one of the fractures. The femoral neck may displace and go into varus. The fixation may fail and nonunion may occur. If a neck fracture is displaced, the fracture must be reduced anatomically and fixed with screws or compression hip screws. The surgeon will want to focus on the neck in order to gain anatomic reduction. The femur shaft can be fixed with a retrograde nail or with a plate. There is a lesser chance of an incident of avascular necrosis in this type of neck fracture than in isolated neck fractures due to dissipation of the force of the shaft of the femur (5% AVN). In general, the surgeon will want to fix the neck fracture first, and use a different device for the femur fracture.
