Screw fixation
1. Introduction
Screw fixation
These fractures can usually be treated with retrograde screw fixation.
In severely impacted fractures, bone graft harvested from the distal radius may be necessary.
Fracture configuration
The degree of displacement and the number of fragments may be difficult to judge on standard x-rays. CT scans can be helpful in these situations.
2. Approaches
For this procedure, a dorsal approach to the CMC joint can be used.
Alternatively, the proximal end of the following approaches can be used:
3. Reduction
Reduction tools
Manipulate the articular fragments with a dental pick, small K-wires, or a small periosteal elevator.
Small K-wires can also be used for preliminary fixation. Depending on fracture configuration, pointed forceps may be useful for reduction.
Confirming anatomical reduction
Check anatomical reduction of the joint surface under direct view.
4. Screw fixation
Screw size selection
The exact size of the diameter of the screws used will be determined by the fragment size and the fracture configuration.
The various gliding and thread hole drill sizes for different screws are illustrated here.
Screw insertion
Insert lag screws in a retrograde manner, avoiding compromise of the joint.
Drill very carefully not to perforate the articular cartilage. If necessary, drilling is performed under image intensification. Drill at low speed and without exerting pressure.
As the screws do not engage the opposite cortex, they are inserted as position screws, ie, they are threaded in both fragments.
If the fragments extend to the metaphyseal region, bicortical lag screws can be used.
Carefully insert the screw without displacing the reduced fragments. Confirm correct screw insertion with an image intensifier.
Insert additional screws in a similar manner.
5. Final assessment
Confirm correct rotational alignment by clinical examination.
Image intensification may be used to confirm anatomical reduction and correct placement of implants in two views.
