Fifth Metatarsal Fracture Treated with Intramedullary Screw Fixation

Figure 16.1

Three non-weight bearing images of the foot initial images, and images 2 days later

Treatment and Timing of Surgery

While most literature focuses on fractures of the fifth metatarsal in the athlete, this case reviews other scenarios where fixation may be beneficial to promote healing. Current recommendations are for surgical fixation in patients who are actively engaged in high level athletics so as to enable a faster return to training [1, 2]. In the remainder of the population, there is controversy over whether surgical fixation is necessary or whether fractures can best be managed non-weight bearing in a cast. Nonunion rates in patients treated nonoperatively have been reported in a wide range, but average in the area of 15–20%, compared to 5% in operative fixation [1, 3]. Some evidence indicates that hindfoot varus may be a predisposing factor to Jones fracture s and nonunions [3].

In this patient we discussed operative and nonoperative treatment, and began with a trial to see if he would be able to maintain non-weight bearing. Unfortunately, due to his size he was unable to adequately maintain non-weight bearing, and the decision was made to proceed with fixation. This was deemed the best chance of healing since, in this scenario, his mechanism was consistent with a stress fracture and we were unable to remove the inciting stresses.

Surgical Tact

Position

The patient can be positioned supine or side lying with the affected side up. The author’s preference is for side lying as it places the surgeon in a more advantageous position to place the guidewire. In the lateral position you are able to advance the guidewire without needing assistance to support or hold the leg; this is especially helpful if operating alone. The nonoperative leg is positioned anteriorly, and the surgical leg is positioned on a stack of towels or blankets to make a supportive working surface. A large or small C-Arm can be used to image the foot, but it is this surgeon’s preference to use the large C-Arm to prevent moving the foot while trying to obtain the starting point (Fig. 16.2).

Figure 16.2

Setup with the patient sidelying. AP and lateral imaging can be done with very little manipulation of the leg

Approach

Fluoroscopy is used to identify the level of the incision by obtaining a lateral X-ray and placing the incision in line with the canal of the fifth metatarsal (Fig. 16.3). The incision is approximately 2 cm in length starting 1–2 cm proximal to the base of the fifth metatarsal. Once through the skin, careful dissection down to the base of the metatarsal is performed to be sure that crossing branches of the sural or superficial peroneal nerve are not injured. In addition, this allows spreading and protection of the peroneal tendons. Throughout the case, tissue protectors should be used to protect these structures during drilling and tapping.

Figure 16.3

Lateral Images to help determine level of incision

Reduction and Fixation

Much like all other intramedullary devices, the critical step of the procedure is getting the appropriate starting point. In the fifth metatarsal this is frequently described as the “high and inside” position (Fig. 16.4) [4]. On AP, lateral, and oblique images there needs to be a straight line down the center of the canal with the guidewire. Using fluoroscopy, the guidewire is carefully advanced to a central place within the canal. The shape of the fifth metatarsal is generally over 4 mm in diameter with a slight curve in the distal half of the bone. This prevents placing the guidewire along the length of the intramedullary canal. It is important not to over-advance the guidewire, tap or drill, and perforate distal cortex creating a distal stress riser.