1 Principles topenlarge
Internal fixation of ulnar shaft fractures restores the length of the ulna and congruency of the distal radioulnar joint (DRUJ). Oblique and spiral fractures may be fixed with a lag screw and a protection plate. If the distal ulnar fragment is short, a locking plate, or mini condylar plate may be used.
In transverse ulnar fractures (“defense fractures”) a pre-contoured compression plate is used.
These fractures are not usually associated with DRUJ injuries, but it is good practice to assess the joint after fixation in all cases.
2 Reduction and preliminary fixation with lag screws topenlarge
Anatomical reduction is achieved using a pointed reduction forceps.
Insertion of a lag screw
After anatomical reduction, the fracture is fixed with one or two interfragmentary lag screws, depending on the length of the fracture zone.
3 Insertion of a protection plate topenlarge
If available, a low profile plate should be used, as soft tissue irritation is a common postoperative problem.
The plate is applied without axial compression, to protect the lag screw fixation. At least 2 screws must gain a hold in the distal fragment.
In osteoporotic bone, the use of locking screws improves the purchase.
If the distal fragment is very short, a condylar or a T-plate with two locking screws may give more secure fixation.
4 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.
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.