1 Preliminary remarks topenlarge
Ulnar styloid fractures can extend from the very distal tip to fractures at the base of the styloid, and may or may not be associated with instability of the distal radioulnar joint.
They may also be associated with injury to the triangular fibrocartilaginous complex (TFCC).
In the rare cases with significant instability, fixation of an ulnar styloid fragment should be considered. This may be with a tension band wire, or if the ulnar styloid fragment is sufficiently large, screw fixation may be an option. In practice, an ulnar styloid fracture would normally be fixed with a 2.0 or 2.4 mm screw.
Cannulated / conventional lag screw
If a small enough cannulated screw is available, this may be chosen. Otherwise, a conventional lag screw may be used.
2 Assessment of Distal Radioulnar Joint (DRUJ) top
Before starting the operation, the uninjured side should be tested as a reference for the injured side.
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.
3 Direct reduction topenlarge
Irrigate and clean the fracture site of hematoma.
The fragment is reduced by direct manipulation, aided using a small pointed reduction clamp. It is important to recognize that the ulnar styloid is occasionally more palmar than it would appear in a radiograph.
Reduction with stay suture
A strong stay suture can be inserted around the tip of the styloid, analogous to the application of a tension band suture.
By pulling proximally on this suture, the ulnar styloid is reduced.
Alternatively, the fracture may be reduced using a dental pick.
The ulnar styloid must not be overreduced, to avoid overtension of the TFCC, which may cause restriction of forearm rotation.
4 Reattachment of the ulnar styloid topenlarge
Reattachment of the ulnar styloid
While reduction is maintained by pulling on the suture, or by pressure with the dental pick, the styloid is fixed with an appropriate sized screw introduced from the tip of the styloid into the lateral cortex of the ulnar shaft.
The ulnar styloid needs to be overdrilled for the screw to have a lag effect.
Fixation - Assessment of DRUJ
Stable reattachment of the ulnar styloid with correct tension of the TFCC should be achieved with this single screw.
The stability of the radioulnar joint is tested after insertion of the screw. The suture can now be withdrawn.
The illustrated case was associated with a large soft-tissue defect. Microvascular clips, seen on the x-ray, were used in the free tissue transfer covering the defect.