1 Principles topenlarge
Important module-wide statement
Where appropriate, a “generic” fracture zone will be illustrated and not necessarily the specific fracture morphology under consideration. Where the fracture morphology determines the fixation technique, the specific morphology will be shown.
Bridge plating uses the plate as an extramedullary splint, fixed to the two
main fragments, leaving the intermediate fracture zone untouched. Anatomical
reduction of intermediate fragments is not necessary. Furthermore, their direct
manipulation would risk disturbing their blood supply. If the soft tissue
attachments are preserved, and the fragments are relatively well aligned,
healing is enhanced.
Alignment of the main shaft fragments can be achieved indirectly with the
use of traction and the support of indirect reduction tools, or indirectly via
Mechanical stability, provided by the bridging plate, is adequate for gentle
functional rehabilitation and results in satisfactory indirect healing (callus
formation). Occasionally, a larger wedge fragment needs to be approximated to
the main fragments with a lag screw.
Note: choice of implants
Implants that can be considered for this technique include the DCS, proximal femoral locking plate and the 95° angled blade plate.
The use of a 95° angled blade plate is possible but technically very demanding. It should therefore only be considered for acute fractures if no other implant is available. It is a valuable technique for nonunions and corrective osteotomies.
It is important to restore axial alignment, length, and rotation.
Reduction can be performed with a single reduction tool (eg, large distractor) or by combining several steps (for example fracture table +/- external fixator, +/- reduction via the implant, etc.) to achieve the final reduction.
The preferred method depends on the fracture and soft-tissue injury patterns, the chosen fixation device, and the experience and skills of the surgeon.
If a large fragment has separated from the fracture and impaled the adjacent muscle, direct reduction may be required through a separate limited approach.
2 Preliminary reduction topenlarge
Subtrochanteric fractures present a particular problem in terms of fracture reduction and alignment. Due to the strong pull of the iliopsoas muscle, the proximal fragment is flexed and externally rotated and therefore difficult to control.
Preliminary reduction should be undertaken before the plate is applied. Once the plate is attached to the proximal fragment the definitive reduction with respect to length, rotation and axis can then be achieved.
The iliopsoas muscle flexes and externally rotates the proximal fragment.
Use of reduction clamps
Reduction clamps are often required to achieve proper alignment. Pointed reduction forceps may be used, but may not provide enough force.
Use of large distractor
After the placement of two pins - one in the greater trochanter and the second one in the shaft - the large distractor is attached.
Attention has to be paid so that the pins do not conflict with the later plate position.
The preliminary reduction is held by tightening the clamps of the large distractor.
Please refer to an AO-video for the application of the large distractor.
3 Preoperative planning topenlarge
Plate length and number of screws
Depending on the extent of the zone of fracture comminution and the underlying bone stock (osteoporosis), the appropriate plate length is chosen. Sufficient bicortical screws (a minimum of three up to six) should be inserted in each fracture fragment. The relative stability results from leaving plate holes empty over the fracture zone.
4 Plate fixation to proximal fragment topenlarge
Guide wire insertion and verification of trajectories
The proximal femoral plate is anatomically shaped to match the profile of the upper femur. First, the plate is adjusted optimally to fit the proximal fragment. Through the two attached wire guides, the proximal 2.5 mm guide wires are inserted into the proximal fragment.
The positions of the guide wires are verified under image intensification in both planes (AP and lateral).
Screw length measurement
The correct screw lengths are determined by measuring the remaining guide wire length, using the dedicated measuring device.
Proximal 7.3 mm screw insertion
Cannulated 7.3 mm screws (locking or non-locking) are inserted over the guide wires into the proximal fragment.
5 Plate fixation to distal fragment topenlarge
Verification of reduction
Under image intensifier control, the preliminary reduction is again checked in respect to axial alignment and length and, to a degree the rotation (in more complex fractures the clinical judgment of the rotation becomes more important while the radiological findings in that respect is challenging to interpret).
The illustration shows the fracture incompletely reduced.
Insertion of first screw into distal fragment
Two blunt Hohmann retractors placed ventrally and dorsally around the femoral shaft can help to control the lateral position of the plate.
If the overall reduction is found to be satisfactor the first cortical non-locking screw in the distal fragment is inserted. This screw helps to reduce the bone to the anatomically shaped implant. Nevertheless, this screw should not fully be tightened, still allowing fine tuning of the plate position on the lateral surface of the femur.
Insertion of second screw into distal fragment
Once the most distal screw has been inserted, the first screw is now fully tightened.
Pearl: final reduction
In case the lateral position, prior to the placement of the second screw, is not correct the use of sterile bolsters is helpful.
Pearl: osteoporotic bone
In case of osteoporotic bone the usage of locking screws is advantageous.
6 Additional screw placement topenlarge
In accordance with preoperative planning, additional screws are inserted into the proximal and distal main fragments.