Lag screw and neutralization plate

The first metatarsal has the largest diameter of all the metatarsal bones, and as such, a wedge fracture can be treated with lag screws and a neutralization plate.

Proper alignment of the metatarsal heads is a critical goal in restoring the forefoot mechanics.

A normal curved “cascade” (Lelièvre’s parabola) appearance, which is symmetric with the other foot, is mandatory on the AP view. See illustration. This symmetry 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 all the metatarsal heads are on the same level in the axial view.

Any malalignment, particularly flexion, will recreate focally high pressure during the stance phase and toe-off, resulting in pain and subsequent callus formation.

The sesamoids, rather than the first metatarsal head, bear weight in the first row. Therefore, one must look at the sesamoid level in establishing the alignment in the axial or horizontal plane of the first metatarsal.

Any malreduction of the first metatarsal will have a deleterious effect on the medial arch of the foot and foot mechanics.

The timing of surgery is influenced by the soft tissue injury and the patient's physiologic status.

This procedure is typically performed with the patient placed supine with the knee flexed at 90°.

For this procedure, the following approaches may be used:

• Dorsal approach to the 1st metatarsal
• Medial approach to the 1st metatarsal

Identify the end segment with the more oblique fracture line and use pointed reduction forceps to reduce the wedge to that end segment.

Fix the wedge with a lag screw.

• Insertion of a lag screw in cortical bone

The fracture is now simplified to an A-type pattern (simple fracture).

Reduce the remaining fracture and temporarily fix it using reduction forceps.

Insert a lag screw for final fixation.

Typically a 5–6 hole plate is used.

The plate should be placed medially or dorsally in the mid-axis of the first metatarsal.

The plate is contoured to fit the surface of the bone perfectly.

Secure the plate using screws inserted in neutral mode.

An appropriate well-padded dressing should be applied to protect the surgical incision. Compression will help control swelling.

If present, the skin-pin interface should be similarly well-padded but with dressings that can be readily removed to inspect for pin site infection.

Immediate postoperative treatment is rest, ice, and elevation.

The patient should restrict weight-bearing for six weeks until signs of radiographic healing are present. After this, patients can be weight-bearing as tolerated.

Patients must exercise their ankle and subtalar joints out of the orthosis to prevent stiffness (eg, by stretching their Achilles).

X-ray the metatarsals at six weeks to confirm satisfactory union and remove K-wires if present. Once the fracture is united, the orthosis may be gradually discontinued.

A gastrocnemius release may need to be performed in cases with postoperative gastrocnemius contracture. This occurs more typically in the mid- and hindfoot.

If the gastrocnemius muscle has been released, a splint or cam walker can be used to protect the surgical site.