Open Reduction and Internal Fixation of Proximal Fifth Metatarsal Fractures

Mark E. Easley, MD

Jeannie Huh, MD

Dr. Easley or an immediate family member has received royalties from Exactech, Inc.; is a member of a speakers’ bureau or has made paid presentations on behalf of Exactech, Inc.; serves as a paid consultant to or is an employee of Exactech, Inc. and Medartis; serves as an unpaid consultant to Mirus; has received research or institutional support from Acumed, LLC, Medartis, and Trimed; and serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot & Ankle Society. Dr. Huh or an immediate family member serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons and the American Orthopaedic Foot & Ankle Society.

PATIENT SELECTION

Contraindications

Contraindications to ORIF include skin compromise or active infection of the surgical foot, particularly the lateral midfoot; vascular insufficiency; an immunocompromised patient (on immunosuppressive medications that may lead to delayed healing); neuropathy; and a patient with varus heel and a tendency for lateral foot overload.⁶ In the last situation, ORIF should not be performed in isolation but should be considered with concomitant correction of hindfoot malalignment, either with surgical realignment or with orthoses.

FIGURE 1 Illustrations depict the classification of fifth metatarsal base fractures. A, Zones of the base of the fifth metatarsal. B, Designation of fracture types in the proximal fifth metatarsal.

Specific correction of hindfoot alignment depends on the etiology of hindfoot varus, including the following in isolation or in combination: calcaneal malunion, distal tibial malunion, peroneal tendon insufficiency, chronic lateral ankle instability, forefoot-driven hindfoot varus (rigidly plantarflexed first ray), and cavus foot with or without neuromuscular imbalance. With a hindfoot that can easily be positioned in physiologic valgus, an orthosis may suffice.

PREOPERATIVE IMAGING

Plain radiographs, including AP, oblique, and lateral views of the proximal fifth metatarsal fracture, are sufficient (Figure 2). CT or MRI is rarely, if ever, indicated.

FIGURE 2 Non-weight-bearing AP (A), oblique (B), and lateral (C) radiographs of the foot of a 22-year-old college athlete with a Zone II base of the fifth metatarsal fracture (Jones fracture). Note that the subtle fracture, most readily seen on the oblique view, extends into the articulation between the fourth and fifth metatarsal bases, thus designating this fracture as a Zone II injury.

PROCEDURE

Room Setup/Patient Positioning

The patient is positioned supine, with a bolster under the ipsilateral hip, to provide improved access to the lateral foot (Figure 3, A). The surgical foot should be on edge of the operating table, directly where the surgeon is positioned.

There should be ample clearance for the fluoroscopy unit to be placed immediately adjacent to the operating table and surgical foot. The fluoroscopy unit must have a sterile cover so that it can serve as an extension of the table for portions of the procedure (Figure 3, B).

FIGURE 3 Intraoperative photographs show patient positioning for open reduction and internal fixation of a proximal fifth metatarsal fracture. A, The patient is positioned on the edge of the operating table with support under the ipsilateral hip and lower leg. This position allows satisfactory access to the base of the fifth metatarsal. B, The fluoroscopy unit may easily be positioned adjacent to the table so that it can serve as a lateral extension to the operating table, to support the surgical foot during the fluoroscopic portions of the procedure.

A tourniquet may be used to avoid bleeding that may obscure structures at risk at the surgical site. A calf or ankle tourniquet is typically adequate. A calf tourniquet is placed distal to the fibular head to avoid untoward pressure on the common peroneal nerve.

Special Instruments/Equipment/Implants

The following equipment should be on hand for this procedure:

Fluoroscopy unit
Cannulated drill system
Graduated taps
Solid screws (generally stronger than cannulated screws, and our preference)⁷^,⁸^,⁹^,¹⁰
Dedicated intramedullary screw instrumentation and implant sets. These are commercially available and obviate the need to collect equipment from multiple sets.
Low-profile, precontoured fifth metatarsal fracture hook plates are now available and helpful to have as a backup or as an alternative fixation option when intramedullary screw fixation is inadequate.

Surgical Technique

Intramedullary screw fixation is the most widely used technique for the surgical management of proximal fifth metatarsal fractures. Alternatively, low-profile, precontoured fifth metatarsal fracture hook plates may be useful in cases of comminution, poor bone quality, loss of cortical integrity, and revision for nonunion or failed screw fixation¹¹ (Figure 4, A through C).

Intramedullary Screw Fixation of Proximal Fifth Metatarsal Fractures

Approach

The surgical approach is similar to intramedullary fixation of a long bone. A longitudinal incision is made on the lateral foot, approximately 1 cm proximal to the base of the fifth metatarsal (Figure 5). The goal is to achieve the “high and inside” starting position for the guide pin and screw on the fifth metatarsal base (Figure 6). This position facilitates directing the screw in line with the metatarsal shaft. High and inside implies superior and medial on the proximal end of the metatarsal to optimally direct the screw along the longitudinal axis of the fifth metatarsal.² A recent cadaveric study has challenged the high and inside starting position, and instead, recommends a central start point at the base of the fifth metatarsal, based on a retrograde assessment of the ideal starting point.¹² In either case, if the starting point is too plantar or too lateral, the screw cannot be directed properly.

FIGURE 4 AP (A), oblique (B), and lateral (C) foot radiographs of a 20-year-old college athlete with a proximal fifth metatarsal (Jones) fracture nonunion after intramedullary screw fixation.

The structures at risk are shown in Figure 7. The sural nerve courses directly at the incision site for this procedure.¹³ The peroneus brevis inserts on the dorsal base of the fifth metatarsal, and the peroneus longus courses lateral to and then plantar to the cuboid, immediately proximal to the fifth metatarsal base. The sural nerve and peroneus brevis are typically retracted dorsally, while the peroneus longus is typically retracted plantarward.

With the structures at risk protected, the high and inside position should be easily accessible with the cannulated drill’s guide pin. A drill guide should be used with the guide pin, drill, and tap to further protect the structures at risk for injury.

Guide Pin Positioning and Drilling

The guide pin for the cannulated drill must be directed into the center of the intramedullary canal of the fifth metatarsal, and its position must be confirmed in three
planes (AP, oblique, and lateral). Two of three views may suggest an ideal position for the guide pin while the third does not; thus, it is necessary to confirm proper guide pin position in all three planes.²

FIGURE 5 Intraoperative photograph shows surgical approach for open reduction and internal fixation of a proximal fifth metatarsal fracture. An incision is made approximately 1 to 2 cm proximal to the fifth metatarsal base, in line with the fifth metatarsal shaft. The assistant retracts the peroneus brevis tendon and sural nerve dorsally and the peroneus longus tendon plantarward, while the surgeon uses a protective sleeve for guide pin, drill, and tap.

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