Reduction and fixation of the first metatarsal
Our preferred method of achieving fixation is as follows.
The 1st TMT is reduced under direct visualization and image intensification. Provisional fixation can be done with a pointed reduction (Weber) clamp and/ or K-wires placed from the base of the first metatarsal to the medial cuneiform. A “pocket hole” is made along the dorsal base of the first metatarsal. The pocket hole allows the screw head to engage the cortex without breaking the dorsal cortex, which would result in loss of fixation.
A 4.0/2.5 mm drill combination is used to place the lag screw from the dorsal base of the first metatarsal into the medial cuneiform. Usually for a 4.0 screw, a 2.5 mm drill can be used instead of a 2.9 mm drill as foot bones are soft and just a pilot hole is needed. The screw will hold better with the smaller pilot hole.
A second screw can be placed if desired from the dorsal medial cuneiform through the plantar base of the first metatarsal. However, it is sometimes difficult to insert the screw through the crowded area. A smaller-diameter screw may be easier to insert.