In the past, wedge fractures have usually been fixed rigidly. The underlying principle focused on mechanical issues, not on biology. Today, biology takes precedence and for this reason not all wedge fragments are incorporated rigidly into the fixation.Small wedge fragments that do not have a significant effect on stability should not be addressed (they will become incorporated into the fracture by indirect bone healing). Larger wedge fragments that contribute to the stability of the fixation, are fixed to one main fragment. Sometimes, fixation of the wedge to one main fragment helps reduction of the residual fracture.
If a lag screw is inserted separate from the plate, a 2.7 mm screw is often used, depending on the size of the bone, for biological reasons, and to reduce the risk of splitting the wedge.
If a lag screw is inserted through a 3.5 mm plate, a 3.5 mm screw should be used.
For proximal radial shaft fractures, the anterior approach (Henry) is most often used to minimize the risk of damage to the posterior interosseous nerve, which crosses the proximal radius within the supinator muscle.
In mid and distal radial shaft fractures, either the anterior approach (Henry) or posterolateral approach (Thompson) can be used, depending on surgeon’s preference.
If the wedge occupies less than 50% of the diameter of the bone, there is likely to be sufficient cortical contact between the two main fragments to allow primary fixation by axial compression.
Depending on the exact fracture configuration, there is a “grey zone” in which the area of contact between the two main fragments, the obliquity of the contact zone, the length of the wedge fragment, any fragmentation of the wedge and the quality of the bone will all be factors to be considered by the surgeon when deciding which technique to use.
Three options will be described:
Depending on the procedure chosen, the plate will be applied to either the anterior or posterior surface of the radius.
The plate should not be applied over the base of the wedge fragment as this would be likely to damage its soft-tissue attachments.
In the following example, we illustrate the plate applied to the posterior surface.
If unstable, temporary stabilization of the small wedge fragment onto one of the main fragments helps anatomical reduction. When performing this maneuver, pointed reduction forceps are preferred. In placing the forceps take care not to interfere with the planned plate position, or to damage the soft-tissue attachments of the wedge. If necessary, apply the forceps through a plate hole.
The holes of the plate are shaped like an angled cylinder. The spherical undersurface of the screw head slides down the inclined cylinder as the screw is tightened.
The horizontal movement of the head, as it impacts against the angled side of the hole, results in movement of the bone fragment relative to the plate, and leads to compression of the fracture.
After the plate has been contoured anatomically to the reduced bone surface, prebend it with the handheld bending pliers, or a pair of bending irons, as explained in the principles section.
A second screw is inserted eccentrically (yellow drill sleeve) into the opposite fragment.
Note: the arrow on the drill sleeve must point towards the fracture line.
By tightening the eccentrically-inserted screw, axial compression is achieved. Retain the pointed reduction forceps, while the axial compression is being applied.
For inserting screws into the limited contact dynamic compression plate (LC-DCP), the Universal Drill Guide can be used as well. When this drill guide is pressed into the plate hole, the screw position will be neutral (A). When it is held against the end of the plate hole, without exerting downward pressure, the screw position will be eccentric (B).
If possible, reduce the large wedge fragment(s) to one of the main fragments. The main fragment with the more oblique fracture line is often preferred. A smaller i.e. 2.7 mm or 2.0 mm lag screw may sometimes be appropriate, if the fragment(s) is small.Use of reduction forceps
Insert the sleeve of the 3.5 mm / 2.5 mm drill guide through the plate and into the gliding hole. Check that the anatomical reduction of the wedge fragment is maintained and use a 2.5 mm drill bit to drill a pilot hole just through the far cortex of the wedge.
Insert the lag screw through the plate and carefully tighten it, making sure that the wedge fragment stays reduced and is compressed.
Remove the pointed reduction forceps and use it to reduce the wedge to the other main fragment. Ensure that the plate is correctly aligned to the other main fragment and hold its position using a blunt reduction forceps.
Fix the plate to the bone using three 3.5 mm bicortical cortex screws in each main fragment. The first screw into the main fragment that is not attached by a lag screw is inserted eccentrically. As this load screw is tightened, take great care not to over-compress. The purpose of this axial compression is to close the fracture gap without producing excessive interfragmentary compression, for fear that the wedge fragment could be split.
All other screws are then inserted in neutral positions.
Reduce the large wedge fragment to one of the main fragments. The main fragment with the more oblique fracture line is often preferred.
Anatomical reduction of the wedge fragment is achieved by using a pointed reduction forceps. Often, twisting the forceps aids the reduction.
Insert the sleeve of the 2.7 mm / 2.0 mm drill guide into the gliding hole until in gentle contact with the opposite wedge cortex. Check that the anatomical reduction of the wedge is maintained and use a 2.0 mm drill bit to drill a pilot hole just through the far cortex of the wedge.
To spread the load of the screw head on the underlying cortex, the cortex is lightly countersunk, taking care not to overdeepen, which could weaken the cortex.
Insert the lag screw and carefully tighten it, making sure that the fracture stays reduced, and is compressed.
Check the completed osteosynthesis by image intensification. Make sure that the plate is at a proper location, the screws are of appropriate length and a desired reduction was achieved.
The elbow should be stabilized at the epicondyles and the forearm rotation should be checked between the radial and ulnar styloids.
Before starting the operation the uninjured side should be tested as a reference for the injured side.
After fixation, the distal radioulnar joint should be assessed for forearm rotation, as well as for stability. The forearm should be rotated completely to make certain there is no anatomical block.
The elbow is flexed 90° on the arm table and displacement in dorsal palmar direction is tested in a neutral rotation of the forearm with the wrist in neutral position.
This is repeated with the wrist in radial deviation, which stabilizes the DRUJ, if the ulnar collateral complex (TFCC) is not disrupted.
This is repeated with the wrist in full supination and full pronation.
In order to test the stability of the distal radioulnar joint, the ulna is compressed against the radius...
...while the forearm is passively put through full supination...
If there is a palpable “clunk”, then instability of the distal radioulnar joint should be considered. This would be an indication for internal fixation of an ulnar styloid fracture at its base. If the fracture is at the tip of the ulnar styloid consider TFCC stabilization.