1 Principles topenlarge
Lag screw through protection plate
Simple oblique or spiral fractures (A1, A2) or wedge fractures with spiral or bending wedges (B1, B2) can be reduced and fixed with lag screws. An additional protection plate is always needed and ideally the lag screw is inserted through the plate.
This procedure can only be carried out in an open one.
Lag screw outside the plate
The position of the lag screw depends on the fracture pattern. Occasionally, it is placed outside the plate.
It is crucial to use a plate that is long enough so that at least three bicortical screws can be inserted into each main fragment.
Pitfall: risk of displaced fracture
Separate lag screw fixation may be tenuous. The fracture should be handled with great caution during plate application. It is important to contour the plate to fit the bone precisely so that tightening the plate screws does not displace the fracture and might pull out the lag screw.
2 Reduction and contouring of the plate topenlarge
After reduction of the main fragments using pointed forceps, precise contouring of the plate must be undertaken.
3 Lag screw fixation topenlarge
The lag screw is inserted perpendicular to the fracture plane, through the appropriate plate hole.
At this stage, careful handling is mandatory to avoid any stress on the lag screw!
4 Fixation of the protection plate topenlarge
Insertion of bicortical screws
The plate should be fixed to each main fragment with a minimum of three bicortical screws.
Alternative: lag screw outside plate
Illustration shows the completed osteosynthesis with the lag screw inserted outside the plate.