K-wires can be applied to many different fracture patterns. Considerations include fracture obliquity, comminution, and soft tissue status.
As K-wires cannot compress the fracture, the fracture needs to be reduced before K-wire insertion. This is particularly true for articular fractures.
The preferred K-wire configuration would be extra-articular to prevent damage to the articular surface. Axially inserted wires that break may be challenging to retrieve.
Threaded K-wires are generally not preferred as they are more challenging to extract and potentially maintain fracture gaps.
It is not as critical to have an anatomic reduction for the phalanges of the lesser toes.
The goal of an intramedullary wire would be to secure the fracture site in a soft-tissue-friendly manner while maintaining alignment.
K-wires should be sized appropriately to the bone. Typically wires thicker than 2.0 mm are not needed. The surgeon should be careful to cool the K-wire during insertion to reduce the risk of thermal necrosis.
Toe fractures versus long bone fractures
Toe fractures are different from long bone fractures.
The bones are very small
Fracture gaps are small
Fixation devices don't need to counter large forces
Thus, following the AO principles is less critical than for long bones, and often isolated screws or K-wires alone will work satisfactorily.
Restoration of length, rotation, and angulation are important for cosmesis.
The hallux is particularly critical due to its importance for walking.
Timing of surgery
The timing of surgery is influenced by the soft tissue injury and the patient's physiologic status.
Dislocation or injuries associated with the skin at risk requires immediate intervention regardless of the amount of soft tissue swelling.
If possible, swelling should be significantly decreased before surgery, which can take up to two weeks in some instances.
Open fractures should be promptly irrigated and debrided, and treated with antibiotics. Definitive fracture fixation may not be possible during this setting.
Forefoot fractures do not contribute to physiologic instability. If there is no soft tissue at risk, urgent intervention is not required.
2. K-wire pattern applicable for all fractures
Although it is not desirable to cross the articular surface with wires, it is usually the only configuration possible.
Axially inserted K-wires are used similar to an intramedullary nail.
Typically, the insertion starts at the tip of the toe and continues across the fracture site. Depending on the location of the fracture, wire insertion just to the base of the injured phalanx may be sufficient.
However, the K-wire may also be inserted to cross the MTP joint.
Consider inserting the K-wires outside the skin incision to prevent contamination.
4. Reduction and preliminary fixation
Throughout this treatment option, illustrations of a generic fracture pattern are shown in four different ways:
Fracture reduced and fixed provisionally
Fracture fixed definitively
Grasp the digit's terminus and use a combination of axial and angular traction to exaggerate the deformity.
Realign the toe and release the traction.
A sturdy cylindrical object at the fracture's apex can be used as a fulcrum to facilitate reduction.
If closed reduction is not successful, open reduction may be required.
In the rare case indirect reduction is not successful, a direct reduction may be performed.
Restore anatomical axial rotation, length, and angulation using one or more of the techniques below.
A small, pointed reduction forceps can be used for larger fragments. Be careful not to apply excessive force as this can lead to fragmentation. If possible, apply the reduction clamp so that the forces created by the clamp are at right angles to the fracture line. This clamp placement helps in reducing the fracture and in applying compression.
A periosteal elevator can be used as a lever to reduce the fracture.
Use image intensification to confirm the reduction in all three planes.
5. K-wire fixation
Marking K-wire track
To avoid unnecessary radiation from image intensification, mark the K-wire's planned track with a skin marker on the distal phalanx in both the AP and the lateral aspects.
K-wire insertion into the distal phalanx
A 16 gauge hypodermic needle or a drill guide can be used to prevent the K-wire from slipping during insertion. Either instrument facilitates K-wire insertion along the longitudinal axis of the phalanx.
Optional reduction and fixation technique: Use K-wire as a joystick
Advance the K-wire up to the fracture line but not across it. Use the K-wire as a joystick to reduce the fracture.
Once satisfactory reduction is achieved, the wire can be advanced across the fracture plane and into the phalanx base.
In open fractures, another option is to introduce a double-ended K-wire in a retrograde fashion with the inside-out technique.
Flex the distal fragment to gain an optimal view of the fracture surface. Insert the K-wire through a drill guide and advance it along the medullary canal and through the distal tip of the tuft, piercing the soft tissues until it exits the skin.
Leaving the drill guide in place for soft-tissue protection, pull on the K-wire's distal end until it is flush with the fracture surface.
Use the K-wire as a joystick to reduce the fracture, and advance it through the fracture up to the base of the fractured phalanx.
Proximal or comminuted fractures
In proximal or multifragmentary fractures, advance the K-wire across the joint and into the phalanx base (or metatarsal) proximal to the injured phalanx.
Cut the K-wire
Cut the K-wire so that it protrudes through the skin, about 1 cm from the tip of the toe.
With the wire placed in a finished position, clamp the portion of the wire nearest the skin with a Kocher.
Using a sucker tip that goes over the tip of the K-wire, the K-wire is bent 170°.
Leaving the K-wire to protrude through the skin in this way has the advantage of its being easy to remove. The disadvantages are patient discomfort and the risk of pin-track infection.
An appropriate well-padded dressing should be applied to protect the surgical incision.
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 be encouraged to begin early weight-bearing as permitted by the stability of the fracture. In general, patients can be weight-bearing as tolerated.
A stiff-soled shoe can be used to protect the surgical site.
Patients must exercise their ankle and subtalar joints to prevent stiffness (eg, by stretching their Achilles).
X-ray the toe at six weeks to confirm satisfactory union and remove K-wires if present. Once the fracture is united, the orthosis may be gradually discontinued.