These are partial articular injuries involving the ulnar column of the distal radius, so affect both the radiocarpal and distal radioulnar joints. The fixation needs to resist the shearing forces to which the fragment is subjected.
An isolated fracture of the lunate facet of the distal radius results from a direct axial impaction by the carpal lunate.
CT scans are strongly recommended to define this unusual articular injury better.
Provisional reduction in displaced fractures
Reduction is achieved by applying longitudinal traction either manually or using Chinese finger traps.
The reduction is maintained by a temporary splint.
If definitive surgery is planned, but cannot be performed within a reasonable time scale, a temporary external fixator may be helpful.
2. Associated injuries
Median nerve compression
If there is dense sensory loss, or other signs of median nerve compression, the median nerve should be decompressed.
Associated carpal injuries
These injuries may be associated with shearing injuries of the articular cartilage, scaphoid fracture and rupture of the scapholunate ligament (SL). Every patient should be assessed for this injury. If present, see carpal bones of the Hand module.
These injuries may be accompanied by avulsion of the ulnar styloid and/or disruption of the DRUJ. If there is gross instability after the fixation of the radial fracture, it is recommended that the styloid and/or the triangular fibrocartilaginous disc (TFC) is reattached. This is not common in simple fractures, but may occur with some high energy injuries.
The uninjured side should be tested as a reference for the injured side.
It may not be possible to assess DRUJ stability until the fracture has been stabilized (as described below).
If necessary, use a periosteal elevator to disimpact and elevate the dorsoulnar fragment.
Provisional K-wire fixation
Insert a K-wire to hold the fragment provisionally. Confirm reduction using image intensification.
If in doubt about congruity of the articular surface under image intensification it is mandatory to open the joint (dorsal capsulotomy).
5. Plate positioning and contouring
Many plates are available for this fracture, some with locking screws. The most recently designed plates have variable angle locking screws.
Because of the shape of the dorsal distal metaphysis, the plate may need to be adapted to fit the bone surface and the proximal limb may require some torsional adaptation.
An appropriately sized L-plate is chosen, preferably one with locking holes distally.
If the plate being used has fixed angle locking screws, there is a risk that the screws may penetrate the joint. To prevent this, the distal limb of the plate must be bent to ensure the screws are parallel to the joint surface.
To avoid this problem, the use of variable angle plate is recommended.
Pitfall: Screw hole distortion
Avoid contouring the plate through the locking holes, otherwise the locking head screw might not fit any more.
The plate should be applied as distal and as ulnarward as possible onto the dorsoulnar column of the distal radius.
6. Plate fixation
Insert a screw through the oblong plate hole, using a screw long enough to engage the opposite cortex. Do not fully tighten the screw yet.
Confirm the reduction and plate position using image intensification. If necessary, adjust the plate position until it is as distal and as ulnar as possible. Now tighten the screw.
Insert proximal screw
A screw is inserted through the most proximal plate hole.
Insert distal screw
Insert a distal screw.
Confirm screw position
Confirm using image intensification that the distal screw has not penetrated the articular surface. To have a view in line with the articular surface, the beam should be angled 20º from the true lateral.
Depending on the fragment size, an additional distal variable angle locking screw may be inserted.
7. Assessment of Distal Radioulnar Joint (DRUJ)
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.
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.
Immediately postoperatively, the patient should be encouraged to elevate the limb and mobilize the digits, elbow and shoulder.
Some surgeons may prefer to immobilize the wrist for 7-10 days before starting active wrist and forearm motion. In those patients, the wrist will remain in the dressing applied at the time of surgery.
Wrist and forearm motion can be initiated when the patient is comfortable and there is no need for immobilization of the wrist after suture removal.
Resisted exercises can be started about 6 weeks after surgery depending on the radiographic appearance.
If necessary, functional exercises can be under the supervision of a hand therapist.
See patient 7-10 days after surgery for a wound check and suture removal. X-rays are taken to check the reduction.
Implant removal is purely elective but may be needed in cases of soft-tissue irritation, especially tendon irritation to prevent late rupture. This is particularly a problem with dorsal or radial plates. These plates should be removed between nine and twelve months.