Lag-screw fixation

Partial articular fractures require anatomical reduction and may be fixed with lag screws if the size of the fragment allows.

The joint may collapse if there is impaction or comminution while the lag screw is tightened. In this case, plate fixation should be considered for chondral support.

Percutaneous reduction and fixation may be performed.

The advantages are:

• Shorter operation time
• Less soft-tissue damage
• Faster mobilization

This treatment option needs some skills and experience and special reduction forceps to avoid impingement of swollen soft tissue (atraumatic technique).

These reduction forceps allow to hold the reduction at the planned screw placement, and drilling and screw insertion. There is no need for additional K-wire fixation or reduction forceps placement.

If a percutaneous reduction is not achievable, the treatment can be changed to open surgery.

For this procedure, a dorsal approach to the CMC joint or a dorsal approach to the 5th CMC joint can be used.

Alternatively, the proximal end of the following approaches can be used:

• Dorsal approach to the metacarpals
• Radial approach to the 2nd metacarpal
• Dorsoulnar approach to the 5th metacarpal base

Reduce the fracture indirectly by manual traction.

Special reduction forceps designed for percutaneous fixation may be used to hold the reduction.

For more accurate reduction, use small pointed reduction forceps gently to manipulate the fracture. Application of excessive force can result in fragmentation.

Confirm reduction with an image intensifier.

Preliminarily fix the fragments by inserting a K-wire. Be careful to place it so it will not conflict with later screw placement.

Each lag screw must be inserted perpendicularly to the fracture plane.

Do not insert screws too close to the fracture apex or the subchondral bone. A minimal distance from the fracture line, equal to the screw head diameter, must be observed.

The screw length needs to be adequate for the screw to penetrate and purchase in the opposite (trans) cortex.

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.

Insert the screw closest to the articular surface first.

• Cortical lag-screw insertion

Alternate tightening of the two lag screws helps to avoid tilting the fragment and applies even compression forces across the fracture surface.

Confirm anatomical reduction and fixation with an image intensifier.