- Discussion:
- radial styloid frxs most commonly occur from tension forces sustained during ulnar deviation and supination of the wrist;
- strong radiocarpal ligament, particularly radioscaphocapitate ligament, avulse radial styloid from metaphysis of the radius;
- ligamentous attachments maintains alignment radial styloid to carpus, but styloid may be markedly displaced from the rest of radius;
- brachioradialis & extrinsic wrist & finger flexors & extensors exert powerful displacing force on carpus/radial styloid complex;
- frx of styloid are frequently accompanied by dislocations of lunate;
- Associated Injuries:
- Scapholunate Dissociation
- Transstyloid Perilunar Dislocation
- Dorsal Barton's
- Radiographs:
- while styloid is best visualized radiographically in partially pronated view, identification of scapholunatae diastasis requires supinated view;
- evaluation of radial styloid frxs should always include supinated view so that SLD can be ruled out; (see x-ray findings)
- Surgical Fixation: (see percutaneous fixation)
- fixation of radial styloid begins at tip, which is best approached via small incision along margin of 1st dorsal compartment (APL, EPB);
- although K wire or cannulated lag screw fixation can be achieved percutaneously, it is advisable to make small incision;
- remember that the the radial styloid lies slightly volar to the mid axis of the radius, and therefore the wire should be directed slightly dorsally as well as ulnarly and proximally;
- reduction is secured w/ either K wire or lag screw;
- 3 indications formal ORIF; (See: ORIF of Distal Radius Frx:)
- rotational displacement in axial or coronal plane may prove difficult to overcome, or hematomas may interfere w/ reduction;
- interposed tissue (FCR, or rarely wrist extensors);
- metaphyseal defect after reduction which requires bone grafting; use of either a small drill guide or tissue protector to protect dorsal sensory radial nerve;
- evaluation of reduction:
- articular reduction is best evaluated by radiocarpal arthrotomy between second & fourth dorsal compartments, just distal to Lister's tubercle;
- when bone grafting is necessary, placement is usually required in thearea between the first and second dorsal compartments;
- K wire fixation devices should pass perpendicular to the fracture site, enter the tip of the radial styloid, and exit proximal to distal RU joint;
- stabilization of styloid w/ K wires alone is hazardous, becuase medial, single cortex fixation is often insufficient to prevent redisplacement;
- as an alternative, two cancellous screws (4.0 mm cancellous) or 3.5 mm cortex screws or 3.5 mm cannulated screws;
- butress plate is more reliable (2.7 mm condylar plate)