1 Principles topenlarge
Note on illustrations
Throughout this treatment option illustrations of generic fracture patterns are shown, as four different types:
A) Unreduced fracture
B) Reduced fracture
C) Fracture reduced and fixed provisionally
D) Fracture fixed definitively
Bridge plating uses the plate as an extramedullary splint, fixed to the two main fragments, while the intermediate fracture zone is left untouched. Anatomic reduction of the shaft fragments is not essential but should be attempted. Furthermore, direct manipulation risks disturbing their blood supply. If the soft-tissue attachments are preserved, and the fragments are relatively well aligned, healing is predictable.
Alignment of the main shaft fragments can usually be achieved indirectly using traction and soft-tissue tension.
Mechanical stability, provided by the bridging plate, is adequate for indirect healing (callus formation).
Shaft fractures with more proximal extension
If a fracture extends more proximally, particularly if it involves the greater tuberosity, a PHILOS plate may be selected. This is inserted through a transdeltoid lateral approach proximally, with the plate applied to the lateral aspect of the humerus.
Bridge plate insertion through MIO approach
The minimally invasive (MIO) approach accesses the humerus anteriorly through two small incisions, made proximally and distally. The soft tissues over the fracture site are not affected. The plate is inserted through an extraperiosteal tunnel usually coming from distally. Occasionally the plate may be inserted from proximal to distal, particularly if a PHILOS plate has been selected. This should be checked with image intensification.
In the following procedure the insertion from distally is illustrated.
2 Choice of implant topenlarge
Either a standard plate or a plate with locking head screws (LCP) can be used as a neutralization device. In poor quality bone the use of an LCP is recommended.
As bridge plating should span a long section of the bone, the length of the implant has to be chosen accordingly. It should be long enough to allow sufficient hold in the proximal and distal segments, generally a minimum of three bicortical screws in each. Typically, a ten or twelve-hole 3.5 mm LCP is sufficient. It is also possible to use a long PHILOS plate, placed laterally (see MIO transdeltoid lateral approach).
Longer plates are normally twisted to form a helix, so that the proximal end is applied to the lateral humerus while the distal end lies on the anterior surface.
3 Plate position topenlarge
For minimally invasive osteosynthesis (MIO) the anterior surface is preferred. A major advantage is that this avoids detachment of the deltoid muscle and further bending or twisting of the plate is not necessary.
An anterior plate may be less well suited for the very distal humeral shaft.
4 Reduction top
It is important to restore axial alignment and rotation. A little shortening of 1 or 2 cm can be accepted in the humerus, and in complex multifragmentary fractures may improve bone contact.
Manual reduction - limb realignment
Begin the reduction with traction on the distal humerus restoring bone length, tension in the soft tissues, realignment of the axis, and rotation.
Reduction by external fixator or distractor
Particularly with comminuted fractures, use of an external fixator, or distractor, can provide alignment and stability for bridge plating without disturbing the soft tissues at the fracture site.
Insert proximal and distal pins outside the planned plate location. Take care not to injure the radial nerve. If in any doubt use incisions wide enough to allow palpation or direct visualization of the radial nerve.
Complete reduction may require additional correction of angulation or rotation. Folded linen bolsters under the fracture often help.
5 Percutaneous plate insertion topenlarge
Preparing extraperiosteal tunnel
Use a dedicated soft-tissue retractor or periosteal elevator to prepare the extraperiosteal tunnel. Insert the device from distally and slide it cranially with close contact to the bone, until the cranial incision is reached.
Pearl: If no tunneling periosteal elevator is available, the tunnel may be created directly with the plate, using two drill sleeves acting as a handle.
Slide the plate along the bone through the prepared extraperiosteal tunnel, and deep to the overlying soft tissues. Stay anterior on the humerus to avoid the radial nerve.
Confirm plate position using image intensification.
Pearl: Attach drill guides in the two most distal locking holes and use these as a handle to maneuver the plate.
6 Plate fixation topenlarge
Preliminary proximal fixation
When the plate fits satisfactorily against the proximal segment, attach it provisionally in the third hole from proximal with a single bicortical screw. Alternatively, a push-pull reduction device may be used in the second hole.
Confirm reduction and plate position with image intensification. Remember to check external appearance for alignment, particularly rotation especially in multifragmentary fractures.
Preliminary distal fixation
After confirming the appropriate reduction and plate position fix the plate to the bone in the third hole from distal with a second bicortical screw.
Again, confirm reduction and plate position with image intensification. Remember to check external appearance for alignment, particularly rotation.
If needed adjust reduction of the main segments.
If reduction and plate position are satisfactory, insert the remaining proximal and distal screws. Using locking screws, two screws in each end may be sufficient.
Confirm the reduction, plate position, and screw length under image intensification.
For further screw fixation, stab incisions may be used.
To avoid damage to the axillary nerve they must not be placed proximal to the 7 cm blue line.
7 Final radiological assessment top
Check for proper reduction and implant positions with image intensification in AP and lateral views.
Confirm also a proper rotational alignment of the humerus.