The treatment of an acute metatarsal fracture depends heavily on the extent of the fracture and the involvement of surrounding structures. In the following, the therapy is presented in relation to the above-mentioned classification of the fracture.
The conservative therapy
The treatment of a metatarsal fracture can be done in a conservative or surgical way. The treatment of a metatarsal fracture depends on which of the five metatarsals is broken, how the fracture has developed and how severe the fracture is. For example, the metatarsals II, III, IV are usually treated conservatively in the case of a shaft fracture.
If the bones involved in the fracture are displaced relative to each other or diverge, the fracture is a “complicated fracture” (also known as a “dislocated fracture”) and usually requires surgical treatment, as the bone parts are returned to their healthy position (=reposition) and must be fixed there (see surgical procedures). However, if the fracture is uncomplicated, it can be treated conservatively. In the case of a fatigue fracture (for example: a fracture that occurs when the bone has been permanently overloaded), conservative treatment methods are usually used.
These are usually as follows: First, the injured foot is placed in a plaster cast or special shoe for six to eight weeks, which should have a hard sole. This involves immobilising the joints. Later, a hard boot is sufficient for stabilization.
In case of slight fractures, a bandage with tape may be sufficient. In addition, the foot should be relieved and only be loaded if necessary in a pain-adapted manner. The patient can be given crutches to relieve the strain.
Since the foot is usually swollen after a fracture, additional measures are taken to reduce the swelling. These include cooling and elevating the affected foot. Lymph drainage can also be applied.
After three months at the latest, the fracture should have healed. Sport and other major strains should be avoided until this period. Physiotherapy can be done afterwards or even during the healing process to prevent the muscles from weakening or shortening.
So-called magnetic field or ultrasound therapies can be carried out for fractures that heal poorly; however, these are not usually covered by the statutory health insurance. This is often not sufficient on its own to stabilize a metatarsal fracture. This involves the insertion of screws into the bone in question in order to attach, for example, brittle bone fragments to the adjacent bone.
These are 2 wires that are knotted together to hold two bone fragments together. This is necessary when different muscles attach to these bone fragments and pull the affected bone apart, making healing impossible. The Kirschner wires are very similar to nails.
However, they are thinner, somewhat mobile and have no thread. They are used to stabilize unstable fractures. In addition, the insertion of Kirschner wires in metatarsal fractures is very gentle on the tissue.
This is a temporary treatment of the metatarsal fracture until the soft tissue involved has calmed down and surgical treatment can follow. It is a fixation by means of a frame from the outside. This is intended to hold the fracture in the desired position, but is not stable in movement.
If necessary, closed fractures are brought back into normal position (reduced). If the closed fracture is unstable, the metatarsal fracture is fixed with so-called Kirschner wires. This is possible percutaneously and does not require open surgery.
However, fractures that cannot be reduced from the outside must be brought into a normal position and possibly fixed surgically. In the case of open fractures, the fracture should be reduced and fixed in the same way as in closed fractures. However, antibiotic prophylaxis is very important to avoid infections caused by the open metatarsal fracture.
Since the soft tissue is severely affected in open fractures, only an initial reduction and antibiotic treatment should be performed. Once the soft tissue involved has been calmed, the final therapy follows. This usually consists of reduction and fixation using an external fixator (fixation from the outside) or Kirschner wires.Soft tissue involvement can be a clinical emergency if it is a compartment syndrome.
This must be excluded or treated within 6 hours by intracompartmental pressure measurement to avoid permanent nerve damage. In case of doubt, all nine compartments should be relieved via one medial (from the inside of the foot) and two dorsal (from behind) incisions. In almost all cases, the Kirschner wires are removed 6 weeks postoperatively, but they can also be left in the bone.
If a single metatarsal bone is broken, fixation is often not necessary, since the fracture is usually stable. If compartment syndrome is ruled out, the metatarsal fracture is reduced if necessary and can then be treated conventionally with a tape bandage or an individually adapted insole. The duration of this therapy is usually 6 weeks.
An increasing pain-dependent load, especially over the heel, is possible. An exception to this is a fracture of the 1st metatarsal bone. In this case, the therapy consists of a lower leg plaster cast with an adapted insole for about 3 to 4 weeks.
This is followed by a slow transition to full weight bearing until the 6th to 8th week. If two or more adjacent metatarsal bones are broken, this is a serial fracture. These are partially unstable and must then be reduced and fixed as described above.
Here too, loading is pain-dependent and slow. The Kirschner wires are removed about 6 weeks postoperatively. Luxation fractures are reduced and fixed with Kirschner wires if necessary.
Once the soft tissues have been calmed, stable osteosynthesis is often necessary. This is done with plates or screws and thus stabilizes the bone permanently. The final osteosynthesis is followed by at least 6 weeks of treatment with a lower leg plaster cast.
The load is applied slowly, pain-adapted and via the heel. The metatarsal fracture as a base fracture is usually a luxation fracture and is treated as such until proof of the opposite is provided. Stable fractures are reduced, unstable ones are reduced and fixed.
Treatment is carried out as described above using a lower leg cast and slow loading. Shaft fractures are also usually not dislocated. They are also reduced and fixed if necessary.
If the metatarsal fracture is a comminuted fracture, they are often fixed to adjacent metatarsals using Kirschner wires. Subcapital fractures are usually dislocated and unstable, i.e. they do not remain in the desired position after reduction. Therefore, fixation with axially inserted Kirschner wires is necessary.
These are either removed after 4 to 6 weeks, or completely sunk into the bone and can remain there for life. Further therapy is carried out as above by means of a plaster cast and a slow increase in load. Smaller fractures within the joint space are treated with a roof tile bandage.
Here the adjacent toe is included to ensure stability. This form of bandage is called buddy taping. If the fractured fragment is too large, instability may result.
In such a case, osteosynthesis using Kirschner wires or screws is indicated. This is followed by a plaster cast and immobility for about 6 weeks.
