1 Preliminary remarks top
Choice of fixation method
Displaced transcervical and subcapital fractures are unstable. Their prognosis is by and large the same and they will be discussed as one group for the purpose of manner of reduction and choice of fixation, should internal fixation be chosen as the method of treatment.
They can be stabilized with either cannulated screws or DHS. At this point we do not have sufficient evidence-based information to point to one or the other method as superior. If the surgeon feels that optimal stability is required, he should choose a sliding hip screw (DHS) type of implant for fixation.
If added rotational stability is desired in addition to the DHS, a cannulated screw is inserted above and parallel in both planes to the DHS. It must be parallel in order not to block the sliding property of the DHS implant.
Principles of reconstruction
Use two or three 7.0 mm or 7.3 mm cancellous screws. Make sure they are parallel and that the thread is in the head fragment and does not cross the fracture line.
The inferior screw should rest on the calcar. A washer may be used to stop the screw head from penetrating the bone of the greater trochanter.
These screws can be inserted open or percutaneously through stab incisions.
AO teaching video: The 7.3mm Cannulated Screw: Femoral Neck Fracture
2 Reduction topenlarge
Always start with an attempt at closed reduction. If a satisfactory
reduction is achieved, proceed with fixation as described below.
The patient is positioned supine on the fracture table. The ipsilateral arm is elevated in a sling, and the contralateral uninjured leg is placed on a leg holder.
Reduction is usually achieved by first pulling in the direction of the long axis of the leg in order to distract the fragments and regain length.
Next comes internal rotation.
The reduction must be checked in both the AP and lateral with an image intensifier.
If closed reduction fails, carry out a limited open reduction.
If closed reduction fails, an open reduction must be carried out. The
reduction of the neck fracture is carried out under direct vision.
Once the capsule is opened up while applying traction the head is manipulated with hooks or K-wires, inserted to act as joy sticks until an anatomical reduction is achieved.
3 Fixation top
The screws must be parallel. The guide wires may be inserted freehand under x-ray control to ensure they are parallel, or an aiming device may be used if available.
If using an aiming device with a central hole, it may be best to start by placing a wire in the center of the neck and head. The three wires for screws may then be placed through the aiming device in a triangle around the central wire, with one wire below and two above the central wire.
Alternatively, the first wire may be placed along the inferior border of the neck, with the two superior wires then being placed parallel to the first wire.
Determine screw length
Determine the length of the screws with the aid of the measuring device.
Choose the length of the drill and screws 5 mm shorter than the length of the guide wires.
Insertion of the cannulated screws
Drill over the wires with a 3.6 mm cannulated drill bit. Then insert three 7.0 mm or 7.3 mm cannulated cancellous screws over the wires.
In younger patients with dense cancellous bone, the cannulated tap may be necessary to precut the thread.
A washer may be used to avoid penetration of the screw head through the thin cortex.