Fractures of the femoral neck (31-B)

Authors

Reinhard Hoffmann, Norbert P Haas

Surgical treatment

X-rays in two planes must be obtained in all cases. Retroversion of the head and posterior comminution can easily be evaluated by a cross-table lateral view. Nondisplaced or valgus impacted subcapital fractures (31–B1), also known as abduction fracture, may be stable enough for nonoperative treatment. The stability of the fracture should be checked under image intensification and regularly monitored. As secondary displacement does occur, especially in the presence of even slight retroversion of the femoral head (which increases the risk of AVN), internal fixation is strongly recommended for most of these fractures, particularly in younger individuals and active elderly patients. Percutaneous fixation with cannulated screws adequately prevents secondary displacement of these impacted fractures.

  • In unstable and displaced fractures of the femoral neck the choice of treatment mainly depends on the general and biological conditions of the patient.

A reasonable treatment algorithm should address the age and the level of activity, the bone density, additional diseases, the estimated life expectancy, and the compliance of the patient [12]. Internal fixation is the treatment of choice for patients with high functional demands and good bone stock. Patients who are less than 65 years old and do not have a chronic illness should have urgent open reduction and internal fixation. In patients over 75 years of age, prosthetic replacement is recommended. In those who have low functional demands, chronic illness or severe osteoporosis, or who are noncompliant, hemi or total hip  arthroplasty is preferred. Patients of any age with severe chronic illness or a limited life expectancy should be managed with a prosthesis. When there is a life expectancy of less than one year a unipolar prosthesis can be used.

  • In general, the biological rather than the chronological age should determine the management.

There is no strong evidence in favor of either internal fixation or arthroplasty with regard to mortality. However, the literature does suggest a higher rate of reoperations in those who had internal fixation compared with those with arthroplasty [14–16]. When prosthetic replacement is indicated, it can be done within the first 24 hours after stabilizing the patient’s general condition to reduce postoperative morbidity. The same principles apply for polytrauma patients, where fixation of a displaced femoral neck fracture must have high priority in the management protocol. Closed reduction can usually be obtained with gentle traction and internal rotation under anesthesia and with x-ray control. The Leadbetter maneuver can also be used. The leg is abducted with lateral traction and external rotation. The leg is then gently returned to the neutral position and internally rotated. Traction is then reduced to allow impaction of the fragments. In cases that do not reduce easily, repeated and vigorous attempts must be avoided and open reduction is indicated. With the patient in the supine position, an anterolateral approach to the hip is chosen and an anterior capsulotomy is performed.

 

Open reduction of a displaced subcapital fracture. Anatomical reduction is essential in young patients but can be difficult to achieve. A bone hook is used to disimpact the fragments and two K-wires in the femoral head serve as joysticks to control rotation.

The femoral head, which is usually displaced posteriorly and inferiorly, is carefully disimpacted by additional abduction of the leg or by lateral traction with a bone hook. It may be helpful to place two temporary 2.0 mm K-wires into the femoral head fragment. They act as joysticks and aid reduction, as rotational deformity can be difficult to correct and control. Reduction is then secured with one or two 2.0 mm K-wires. In young patients, the surgeon aims for anatomical alignment of the fragments; in elderly patients with osteoporosis, however, the fractures may be impacted in a slight valgus position. Correct reduction is verified with the image intensifier in two planes.

The crucial element for the choice of fracture fixation and implant is the quality of bone. Any fixation method used in osteoporotic fractures should be safe and easy to apply. With regard to complications and outcome, the DHS has proved to be superior to fixation by screws alone or by angled blade plates [17].

a Displaced femoral neck fracture (31-B2.2).

b The fragments have been reduced and impacted with slight overcorrection into valgus and without retroversion. Fixation with the DHS 135° and 2-hole side plate. Alternatively, a 4-hole plate could have been used. An additional cancellous bone screw was inserted in parallel to prevent rotation of the head fragment. The thread of this screw should engage fully in the head fragment. As some impaction of the fracture may occur during weight bearing, some backing out of the screws is possible.

c The same fracture can also be treated with an angled blade plate 130° with one or two screws. An additional cancellous bone screw may be inserted to increase the initial stability of the fixation, to close the fracture gap, and to put it under compression intraoperatively. The blade of the plate should be inserted into the lower half of the head.

To achieve rotational stability and good buttressing at the fracture site, an additional screw cranial to the DHS should be inserted, especially in case of marked posterior fragmentation. An angled blade plate 130° may also be used, but the technique is more demanding because good fragment contact has to be obtained and fracture distraction must be avoided especially in young patients with dense cancellous bone. With good bone quality, two, preferably three, 7.0 or 7.3 mm cannulated cancellous bone screws can be used to achieve compression of fragments.

A similar fracture as in Fig 6.6.1-10, treated with three large 7.0 or 7.3 mm cancellous bone screws. The screws should run parallel and peripherally in the neck and the inferior screw should abut on the inferior cortex of the femoral neck (calcar). The threads of all screws must engage completely in the head fragment. Cannulated screws facilitate correct placement and may even be inserted percutaneously if closed reduction can be obtained.

These screws should be inserted parallel to each other with the help of the aiming device to allow for gliding and secondary impaction of the fracture. The screws should run peripherally in the neck. Care must be taken that the threads of all three screws are positioned well within the head fragment and do not cross the fracture line, as only then compression can be achieved. The screws must be tightened carefully and repeatedly during the procedure.

Technique for the insertion of 7.3 mm cannulated screws for a subcapital fracture. The guide is used to ensure that the screws are parallel.

If a fracture table is used, traction must be released. This procedure can also be performed percutaneously through stab incisions. AP, lateral, and 45° oblique views must be taken with the image intensifi er to ensure the screws do not penetrate the hip joint. In the rare instance of a vertical shear fracture that may be difficult to reduce, a valgus osteotomy and fixation with a 120° angled blade plate may be considered.

In the presence of a vertical fracture plane, the shearing forces can be transformed into compressive forces by performing an intertrochanteric valgus osteotomy of some 30–40˚ and fixation with the  120˚ double angled blade plate. This is technically demanding and careful preoperative planning is essential.

For patients with limited life expectancy, in debilitated patients or those with minimum activity, the use of a unipolar prosthesis is recommended. For very active patients with preexisting osteoarthritis a total hip replacement is more appropriate [16].

In elderly patients with displaced femoral neck fractures and limited life expectancy, a femoral head prosthesis, or a total hip prosthesis are preferred treatment options.

Bibliography

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