1 Preliminary remarks topenlarge
Beware! Some of these fractures may be unstable, eg, fractures with a large lesser trochanteric fragment.
The definitive decision for the treatment of this fracture will be made after positioning of the patient and reduction of the fracture. Since emergency department x-rays are often of suboptimal quality, verification of the preoperative diagnosis using image intensification is necessary.
The lesser trochanter is the key in the decision making as to the choice of the appropriate fixation device.
A2.1 fractures are three-part fractures. The third part is the lesser trochanter.
Some surgeons consider this fracture to be a stable trochanteric fracture and feel that it can be treated with closed reduction and an extramedullary sliding screw system for internal fixation. If in doubt about the number of parts and stability, resort to a different fixation (eg, DHS with a trochanteric stabilization plate (TSP), or intramedullary fixation).
There are many different designs of extramedullary sliding devices for the fixation of these fractures available. The general concept of their application is shown on the next pages with the AO dynamic hip screw (DHS) which is currently the gold standard.
2 Closed reduction topenlarge
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. In case the closed reduction should fail, open reduction will be necessary. If an unsatisfactory reduction is achieved (eg, large and displaced lesser trochanter) use an intramedullary fixation device.
3 Guide wire insertion topenlarge
Technique of insertion
The approach is between the vastus lateralis and the septum. The first step is to position a guide wire on the neck and hammer it into the head. With the C-arm positioned to show the neck axis slide the guide wire along the neck parallel to its axis and gently tap it into the head. With the C-arm in the AP make sure that it subtends the CCD angle (collum-center-diaphysis angle, ie, angle subtended between the femoral neck and shaft axes). This will help you with the insertion of the guide wire for the DHS screw.
Application of the aiming device
Choose the correct aiming device according to the CCD angle of the neck. Check its position in the AP with the image intensifier.
Insertion of guide wire for the screw
Insert the guide wire through the aiming device and advance it into the subchondral bone of the head, stopping 10 mm short of the joint.
Position it so that in the AP it is in the caudal half of the neck, and in the axial view in the center of the neck.
4 Screw insertion topenlarge
Determination of the length of the DHS screw
Determine the length of the DHS screw with help of the measuring device. Select a screw which is 10 mm shorter than the measured length.
Adjust the cannulated triple reamer to the chosen length of the screw.
Drill a hole for the screw and the plate sleeve.
The correct screw is mounted on the handle and inserted over the guide wire. By turning the handle it is advanced into the bone. Do not push forcefully or you may distract the fracture.
In young patients with hard bone, it is best to use the tap to precut the thread for the screw. Otherwise the screw may not advance, and you may actually displace the fracture by twisting the proximal fragment as you attempt to insert the screw.
When the screw has reached its final position (checked with the image intensifier: 10 mm short of the subchondral bone in the AP and lateral), the T-handle of the insertion piece should be parallel to the long axis of the bone to ensure the correct position of the plate.
5 Plate fixation topenlarge
Fixation of the DHS plate
Generally, a four-hole DHS plate with the preoperatively determined CCD
angle will be chosen.
Fixation of the plate
Fix the plate to the femoral shaft with an appropriate number and size of plate holding cortical screws.