1 General considerations top
The objective of compression plating is to produce absolute fracture stability, prohibiting interfragmentary motion.
Compression plating is mainly useful in two-part fracture patterns, where the bone fragments can be compressed. In wedge fractures, where there are large enough fragments, one or two lag screws should be used to add additional stability of the fracture, either through or outside the plate.
The plate length has to be chosen long enough, so that on both sides of the fracture six cortices will be involved.
Dynamic compression principle
Compression of the fracture is usually obtained by eccentric screw placement at one or more of the dynamic compression plate holes. These holes are shaped like an inclined and transverse cylinder. The screw head slides down the inclined cylinder as it is tightened, forcing the plate to move along the bone, thereby compressing the fracture.
Before dynamic compression can be applied, the intact wedge has to be fixed to one of the main fragments with a lag screw. Thus an axilla is created which allows compression by eccentric screw insertion.
Compression with ATD
In wedge fractures, the articulated tension device (ATD) is more often used to gain length than for compression because of the limited compressibility of these fractures. If a push-pull screw is used the same hole could be used to place the tensioning device.
If too much tension is applied and/or the plate has not been prebent, there is a risk of axial deformity.
2 Plate preparation topenlarge
Overbending the plate
The plate should be overbent at the fracture site approximately 1-2 mm to ensure compressioin of the side opposite the plate.
Twisting the plate
The anteromedial surface of the tibial shaft twists internally approximately 20° as it approaches the medial malleolus.
The first step of plate contouring is to twist the plate so it matches the tibial surface upon which it will lie.
If the plate is bent before it is twisted, the process of twisting will alter the bend that has been created.
Matching the curvature
Depending upon the plate location, more or less bending of the plate will be required to match the contour of the intact (or reduced) bone. Much of the medial tibial shaft is quite straight, so that little bending is required. However, the distal medial surface has a significant concavity, with a typical radius of curvature of 20 cm as illustrated.
Such a 20 cm radius can be drawn on a sterile drape and used as a template for plates to be used in this location.
Bending the plate
The plate can be bent with bending irons alone, but it is preferable to bend with a bending press, because the press gives more control.
In either case, the bending is done in small steps to produce a smooth contour. Contouring only takes place over the distal 10-12 cm of the plate. When finished, the plate should match the 20 cm radius of curvature.
3 Reduction and fixation topenlarge
Application of the plate
After contouring, the plate is fixed with two screws to the distal main fragment.
Reduction with the plate
If necessary, the ATD is applied proximally and the fracture is distracted. Gently reduce the wedge fragment with a small hook.
Depending on the fracture configuration, insert one lag screw through or outside the plate. With this lag screw, the wedge fragment is fixed to the distal main fragment.
If the ATD has preliminarily been used for reduction, compression can now be applied by converting the ATD from distractor to compressor. After compression of the fracture, insert a screw excentrically next to the fracture into the proximal main fragment.
After reduction without ATD, compression is achieved by inserting a screw in maximally eccentric position (drilling without protection sleeve).
The tension device must be applied in such a way that the spike of the mobile fragment is pressed into the axilla formed by the plate and the other fragments to which it has been fixed.
The remaining screws are then inserted. Screws closest to the fracture site are placed first.