Soft-tissue integrity is an important pre-requisite for open reduction and plate fixation of metatarsal neck fractures. If soft-tissue conditions do not allow for open reduction and plate fixation, percutaneous pinning should be considered as an alternative either as a temporary or definitive form of fixation.
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.
3. Patient preparation and approach
This procedure is normally performed with the patient in a supine position.
One or multiple subcapital metatarsal fractures or dislocations can best be approached through appropriately placed dorsal incision(s) (see Dorsal intermetatarsal approach).
Manual traction through the toe is generally sufficient to correct length and rotational alignment of the distal segment.
The reduction is held with pointed forceps, applied perpendicular to the fracture plane. Temporary K-wires may also be used. Protect the metatarsal head from damage when applying the clamp. Intraoperative x-rays may help to confirm appropriate alignment.
Screw purchase in the metatarsal head can be tenuous. For this reason, a plate with a larger distal buttress surface like the L- or the T-plate is usually used for improved fixation. Fixation in the distal fragment can also be improved by the use of locking screws which provide angular stability.
Consider fixation of a simple fracture with a lag screw. If the fracture is transverse use the L- or the T-plate as a compression plate.
Screw length Make sure that the screws are not so long that they protrude below the plantar bone surface or articular cartilage.
Temporary fixation If the fracture is multifragmentary maintain your reduction with temporary K-wire fixation.
Plate application Secure permanent fixation with the L- or T-plate which will be used then in a bridging mode.
Alternative: K-wire fixation
For simple fractures, manual reduction and percutaneous fixation with K-wires may also be considered. The K-wire is inserted percutaneously into the distal phalanx across the DIP and PIP joints, along the central axis of the toe.
The head is manually reduced and the K-wire is advanced across the MTP joint into the metatarsal shaft. The K-wire can either exit the metatarsal shaft or enter the proximal cuneiform.
Alternatively, the corresponding toes may be elevated and the K-wire may be inserted plantar to the toe, up the central axis of the fractured metatarsal.
A sterile dressing is applied and the patient is immobilized in a boot or in a below-knee cast. If the state of the soft tissues is precarious, a padded bandage should be applied initially, and the limb should be maintained elevated until the swelling has subsided and healing of the soft tissues without further problems can be anticipated. The foot is then immobilized either in a boot or in a below-knee cast. The advantage of the boot is that it can be easily removed for inspection of the wound and for regular exercises and mobilization of the joints.
Weight bearing is delayed until such time as the wound is healed. The sutures are removed 2 weeks postoperatively and graduated weight bearing is started. The degree of loading of the extremity is determined by the severity of the injury and the stability of the fixation achieved. Early loading is important but not at the expense of loss of fixation. Intermittent elevation of the foot and extremity should be continued until such time as the swelling has subsided.
For percutaneous K-wire fixation
Weight bearing in a heel-wedge shoe is permitted. The K-wires are removed in the clinic at six weeks, at which point a flat postoperative or hard-sole shoe is permitted as tolerated.
X-rays are taken at 6 weeks postoperatively to assess union and the integrity of the fixation. The resumption of the use of normal footwear is guided by the clinical signs and x-ray evidence of union.