1 General considerations topenlarge
Proper alignment of the metatarsal heads is a critical goal in restoring the pathomechanics of the forefoot. On the AP view, a normal curved “cascade” (Lelièvre’s parabola) appearance, symmetric with the other foot, is mandatory. See illustration. This ensures that the normal length of the metatarsal is restored.
It is also critical to restore the metatarsals in their axial or horizontal plane so that in the axial or tread view all the metatarsal heads are on the same level.
Any malalignment particularly flexion will recreate focally high pressure during the stance phase and toe-off and will result in pain and subsequent callus formation.
Note that for the first ray, it is the sesamoids rather than the first metatarsal head, that bear weight, and therefore one must look at the sesamoid level in establishing the alignment in the axial or horizontal plane of the first metatarsal.
Usually if the first MT head is broken, the foot has sustained significant trauma. Most of these fractures are displaced. But minimally displaced fractures with the hallux in good alignment may be treated nonoperatively with buddy taping and a rigid sole shoe.
Displaced fractures may be associated with first MTP joint dislocation. Reduction of the articular surface and alignment of the first MTP joint and its associated soft tissues are important in treating this injury.
Look for damage to the plantar plate by assessing sesamoid position on an AP radiograph. Check whether they are spread apart or not. If the volar plate was avulsed, it may interpose itself into the metatarsophalangeal joint and block reduction.
2 Closed reduction and K-wire fixation topenlarge
Closed manual reduction and percutaneous pinning may be attempted. However, as this is an intraarticular fracture anatomic reduction of the metatarsal head is preferred.
Once alignment of the fragments is obtained, a 1.6 mm K-wire may be placed percutaneously through each fracture fragment, perpendicular to the fracture lines, exiting the MT shaft proximal to the fracture site.
Reduction is confirmed with intraoperative fluoroscopy or radiographs.
3 Open reduction internal fixation topenlarge
If the fracture cannot be reduced with manual traction, carry out an open reduction through a medial approach to the hallux. The fracture fragments may have to be disimpacted and reduced with a Freer elevator.
Maintain the reduction with pointed reduction forceps and secure provision fixation with K-wire fixation.
A 2.0 mm or 2.4 mm lag screw may be placed into one of the fracture fragments perpendicular to the plane of the fracture.
The remaining stabilized fracture fragments are similarly treated with lag screws.
For fractures on the lateral aspect of the head, the lag screws may be placed percutaneously.
A second or third lag screw may be placed for long oblique fractures. If one is dealing with osteoporotic bone, then a washer under the head of the screw is useful to prevent the head from sinking.
Final fixation with two small lag screws securing the intraarticular fracture.