Screw length measurement in distal femoral articular block
Use the measuring device indirectly to measure the lengths of the screws
using the previously inserted guide wires.
Although screws may be inserted in any order, it is usual to start with the
central 7.3 mm screw. Advance the guide wire until it reaches the medial cortex
of the femoral condyle. Measure for screw length using the measuring device.
For proper screw length measurement, the measuring device must contact the end
of the threaded wire guide. This will place the tip of the screw at the tip of
the guide wire.
Pearl: self-drilling/self-tapping screws
The self-drilling, self-tapping flutes of the 7.3 mm and 5.0 mm screws make
predrilling and pretapping unnecessary in most cases. In dense bone, the
lateral cortex can be predrilled, if necessary.
- Use the 5.0 mm drill bit for 7.3 mm screws.
- Use the 4.3 mm drill bit for 5.0 mm screws.