Minimally Invasive Operative Treatment of Proximal Fifth Metatarsal Fractures



Minimally Invasive Operative Treatment of Proximal Fifth Metatarsal Fractures


Kathryn L. Williams

Robert B. Anderson





PATIENT POSITIONING

Surgery is performed as an outpatient and can be done with either a regional or general anesthetic. An Esmarch bandage placed at the midcalf level suffices as a tourniquet. General anesthesia is used if the surgeon desires a thigh tourniquet or bone marrow aspirate/graft from the iliac crest. The patient is positioned on a standard operating room table in the supine position. A radiolucent table may be used but is not necessary. The patient is positioned at the distal end of the table and a bump
is placed under the ipsilateral hip in order to internally rotate the operative extremity. The patient’s entire body is moved as far to the operative side of the table as safely possible so that the starting point can be accessed without obstruction. The ipsilateral knee must be able to be flexed in order to place the foot plantigrade on the edge of the fluoroscopy unit or the operating room table. A mini C-arm is essential and the physician should confirm that true oblique, AP, and lateral views of the fifth metatarsal can be obtained before prepping and draping the extremity.






Figure 28-1. The three anatomic zones of the proximal fifth metatarsal.

If general anesthesia is used, a nonsterile tourniquet may be placed high on the thigh of the operative leg. As mentioned previously, a sterile Esmarch tourniquet may be applied either with general anesthesia or with an ankle/popliteal block and sedation. This latter method is our preference for most patients. The foot is prepped to the level of the midtibia or knee and draped using an extremity drape. The iliac crest is also prepped and draped if bone marrow aspirate or autologous bone graft is to be harvested. The surgeon stands on the injured side of the patient to access the lateral foot and the assistant or scrub tech stands at the foot of the bed. The mini C-arm is positioned on the injured side and brought in at an approximately 45-degree angle to allow for access to all three views of the foot (Fig. 28-4).






Figure 28-2. Illustration of the vascular supply to the proximal fifth metatarsal demonstrating the avascular (watershed) zone in the metaphyseal-diaphyseal region.


SURGICAL APPROACH

The base of the fifth metatarsal is palpated and drawn out with a surgical marker on the lateral foot for anatomic reference. In order to estimate the axial alignment, a Kirschner wire can be laid over the top of the fifth metatarsal and fluoroscopic images taken in the oblique plane. Using a surgical pen, a line can drawn on the skin along the wire proximal to the base. The axial alignment can also be visualized with fluoroscopy and the guidewire inserted in line with the fifth metatarsal shaft. A 1- to 2-cm longitudinal incision is made in line with the metatarsal approximately 2 cm from the base (Fig. 28-5A, B). Blunt dissection is done to protect terminal branches of the sural nerve, and should be protected during drilling and screw insertion to prevent injury and the potential for a painful neuroma. The peroneus brevis tendon may be encountered but usually lies superior to the insertion site of the screw. The soft tissues are carefully and bluntly spread in line with the incision down to the level of the bone to allow for insertion of the guidewire.







Figure 28-3. A, B: Oblique and lateral radiographs of a type II nonunion of the fifth metatarsal base.


REDUCTION TECHNIQUES AND FIXATION

A formal reduction is not usually needed as the correct placement of the Kirschner wire, tap and partially threaded screw allows for indirect reduction of the fracture. However, there is a definite order of steps that must be carried out to achieve appropriate placement of the screw and fracture alignment.






Figure 28-4. Patient positioned before draping.

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Jan 24, 2021 | Posted by in ORTHOPEDIC | Comments Off on Minimally Invasive Operative Treatment of Proximal Fifth Metatarsal Fractures
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