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 the implant.
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 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 into each fracture fragment. Relative stability results from leaving plate holes empty over the fracture zone.
4 Plate fixation to proximal fragment topenlarge
As a first step, a guide wire for the dynamic screw is placed proximally.
Therefore, the aiming device is lined up parallel to the femoral neck in the axial view and, in the AP view, the guide wire should be aimed at the lower portion of the femoral head.
The wire is advanced to just short of the subchondral bone of the femoral head. Its position is checked fluoroscopically, and adjusted, if necessary.
After indirectly determining the screw length by using the measuring device over the protruding guide wire, drilling is performed over the guide wire with a triple reamer that has been set to the measured screw length.
Condylar screw insertion
The condylar screw is inserted to its final position over the guide wire. The T-handle is lined up parallel to the femoral shaft in order to ensure correct plate alignment.
Plate and screw combination
Next, the plate barrel is slid over the condylar screw shank.
Plate fixation with cortical screw
After checking the correct plate position, a cortical screw is inserted into the proximal plate hole, in order to secure the plate in the proximal fragment.
5 Plate fixation to distal fragment topenlarge
Insertion of first screw into distal fragment
With the help of two blunt Hohmann retractors placed ventrally and dorsally around the femoral shaft, the lateral position of the plate can be controlled.
If the reduction is found to be adequate, the first cortical screw in the distal fragment is inserted, without being fully tightened. This still allows for the plate position to be fine tuned.
Pearl: Final reduction
If the lateral position prior to the placement of the second screw is inadequate, the use of sterile bolsters can be helpful.
Insertion of second screw into distal fragment
The lateral plate position can be confirmed by palpation.
Once the most distal screw is inserted, the earlier screw is fully tightened.