1 Preliminary remarks topenlarge
Fracture assessment and decision making
B type injuries are partial articular fractures. In B1.1 fractures, the articular fracture is in a sagittal plane.
B1.1 fractures involve the radial styloid, and can occur as a result of either avulsion injuries, associated with intercarpal ligament injuries, or compression injuries of the scaphoid facet of the distal radius.
B1.1 fractures may also involve rotation of the radial styloid and/or compression of the articular surface. CT scans in axial and coronal projections are advisable for preoperative assessment and planning.
An L-shaped locking plate may be used. Care needs to be taken to ensure the plate can achieve adequate fixation of the radial styloid fragment.
Plates with variable angle screw options may be useful in this situation.
Choice of approach
If dealing with a rotated avulsion fracture without associated ligament injury, this can be approached through a palmar incision.
If there is a compression fracture with impaction of the articular surface, and/or a scapholunate ligament disruption, it is better to use a dorsoradial approach.
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 topenlarge
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 (see A1.1). 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).
3 Reduction and provisional fixation topenlarge
If necessary, use a periosteal elevator to disimpact and derotate the radial styloid fragment.
Provisional K-wire fixation
Insert a K-wire through the tip of the radial styloid to hold the fragment provisionally.
Confirm using image intensification.
4 Plate fixation topenlarge
Apply the plate to the bone. The distal end of the plate should end at the anatomic watershed zone of the distal radius.
Insert a screw through the oblong plate hole. Measure for length and choose a screw that will just engage the dorsal cortex.
Before fully tightening it, check the plate position using intraoperative imaging, adjusting the position of the plate as necessary.
Insertion of distal screws
Insert at least two locking head screws into the radial styloid fragment.
Care must be taken to contour the very radial part of the plate so that it does not protrude and irritate the flexor tendon of the thumb.
Confirm plate and screw position using image intensification
Confirm the distal position of the plate and screws using an image intensifier, with the beam angled 20° from the true lateral. This projection will profile the radial articular surface and visualize any encroachment of a screw into the joint.
Additional proximal screw
Insert a final standard screw through the proximal part of the plate.
5 Assessment of Distal Radioulnar Joint (DRUJ) top
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.