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.
Minimally displaced fractures may be treated nonoperatively, non-weight bearing in a short leg cast for at least six weeks. Before discontinuing immobilization there has to be evidence of union.
A transverse fracture, if displaced, requires an open reduction and internal fixation. Any malreduction will have a deleterious effect on the medial arch of the foot and foot mechanics.
2. Patient preparation and approaches
This procedure is normally performed with the patient in a supine position.
For ORIF of isolated fractures of the first metatarsal, a medial approach is recommended. If more than one metatarsal is fractured, then utilize a dorsal approach.
3. ORIF of oblique fractures
If one is dealing with an oblique fracture, once exposed and reduced, it is maintained with pointed reduction clamps.
Forceps are applied perpendicular to the fracture for oblique fractures.
A single lag screw is not enough to immobilize the first metatarsal. Once fixed with a lag screw the fixation is protected with a medial neutralization plate.
For a long oblique or spiral fracture, additional lag screws can be inserted perpendicular to the fracture plane.
4. ORIF of transverse fractures
Transverse fractures are unstable, particularly if associated with fractures of the adjacent MTs. For these reasons ORIF is recommended.
Reduction is obtained by manipulating the fracture fragments with pointed reduction forceps, paying careful attention to rotation of the distal fragment.
Rotation can be assessed with intraoperative fluoroscopy or radiographs or plantar flexion of the great toe at the MTPJ and IPJ.
In softer bone reduction is maintained with provisional K-wire fixation. K-wire fixation of the first metatarsal may be difficult if the bone is thick and hard.
Selection of hardware
A transverse fracture requires axial compression in order to obtain optimal stability. If a locking plate does not provide option for achieving axial compression it should be used with caution.
Use a miniplate. If not available, a 1/3rd tubular plate may be used or more complex plates which can be found in a foot set.
For more proximal or distal transverse fractures, the specialized broader plates allow a minimum of two screw fixation on either side of the fracture site. Examples of this plate include 2.7 mm hind-, midfoot plates.
2.4/2.7 mm variable angle X-locking or T-plates may be useful in softer metaphyseal bone.
Mesh plates may be useful in highly comminuted fractures and when the quality of bone is poor.
Bone graft for bony deficits may be obtained from the calcaneus or distal tibia.
A transverse fracture of a short tubular bone should be fixed under axial compression. Once the fragments are aligned fix the plate to the medial side of the proximal fragment with one screw.
Check the reduction of the fracture and the alignment of the plate. If satisfactory proceed now to insert eccentrically a screw through the first hole of the plate distal to the fracture.
Once the screw is seated, the fracture will have been compressed. Insert now the remaining screws. There should be at least two screws on each side of the fracture.
Weight bearing as tolerated in a flat, rigid sole shoe for 6 weeks or until clinical and radiographic signs of healing are noted.