Forefoot, Sesamoid, and Turf Toe Injuries



Forefoot, Sesamoid, and Turf Toe Injuries


Ariel Palanca, MD

Christopher E. Gross, MD


Dr. Palanca or an immediate family member serves as a paid consultant to or is an employee of Medline Unite, Inc. and Stryker. Dr. Gross or an immediate family member has received research or institutional support from Wright Medical Technology, Inc.


This chapter is adapted from Hunt KJ: Forefoot, Sesamoid, and Turf Toe Injuries in Chou LB, ed: Orthopaedic Knowledge Update: Foot and Ankle 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2014, pp 343-354.





Introduction

The foot is a complex and durable biomechanical structure composed of 28 bones and their articulations. The foot is of integral importance to gait, and fractures of the foot can have a substantial effect on normal function. Forefoot injury is particularly likely to cause long-term pain and disability after trauma.1 A study from a level I trauma center found that 15% of patients involved in a motor vehicle collision had trauma to the foot and ankle, and these injuries often were severe.2 Recent advances may improve the success and efficiency of treatment techniques and implants designed to restore function to patients with traumatic foot injury.


Evaluation of Forefoot Injuries

Given the complexity of the foot and the diversity of injuries, making the correct diagnosis depends on understanding the mechanism and location of the patient’s injury. The location, magnitude, and duration of the symptoms must be determined. The patient may be able to point to a particular location of pain. A thorough history of any previous injury, surgical intervention, or underlying disease that could affect the feet is useful, especially if the patient has a history of diabetes, venous insufficiency, congenital or acquired deformity, or uses assistive devices. It is important to have a good understanding of the patient’s functional demands, work and recreational activities, and needs during and after injury treatment.

Comparing the injured foot with the uninjured foot allows detection of any deviation from the patient’s normal state. Inspection and palpation aid in locating the injured foot structures and ruling out involvement of other, uninjured structures. The associated joints should be assessed for active and passive ranges of motion. Resistive testing of the associated muscles ensures that the tendons are intact and the muscles are functional. The entire foot and ankle should be assessed for stability and alignment, particularly in comparison with the contralateral extremity. Documentation of neurovascular status should include assessment of pulses, capillary refill to the toes, reflexes, motor function of all muscle groups in the foot and leg, and all five major sensory nerves using light touch (with a paper clip or a 5.07 monofilament). In an acute injury, any suspicion of excessive or worsening pain, swelling, numbness and tingling, or coolness in the foot requires immediate reassessment of neurovascular status and possibly measurement of foot compartment pressure. Foot compartment syndrome may require decompression to mitigate complications.

Radiographs are imperative to assess for fractures and foot alignment. Three views of the foot typically are needed, and they should be weight bearing if tolerated by the patient. Additional views, including sesamoid views, are obtained as indicated. If the patient is unable to bear weight, a simulated weight-bearing view can be obtained with the patient seated or supine. High-quality radiographs are important to the diagnosis and treatment decision making; any low-quality radiographs should be retaken. Proper training of technical personnel can help improve the quality of radiographs.



Treatment of Forefoot Fractures and Turf Toe Injuries

Most, but not all, fractures of the forefoot can be successfully treated without surgery. Standard trauma principles include anatomic reduction of the fracture and any involved joints, with sufficiently rigid internal or external fixation. It is important to evaluate the associated soft tissues to avoid incisions in areas at high risk for skin necrosis, dehiscence, or other complications. A surgical procedure should be delayed until resolution of the soft-tissue injury is sufficient to minimize the risk of complications.


Metatarsal Fractures

Metatarsal fractures are relatively common. Each of the five metatarsals functions in a different manner, and optimal fracture healing requires a different approach to the treatment of each metatarsal. With the exception of the proximal fifth metatarsal, only limited published studies are available on the indications for treating metatarsal fractures and the long-term results. Most metatarsal fractures are effectively treated without surgery. Surgical treatment typically is indicated for severe displacement, multiple fractures, intra-articular injury, an open wound, compartment syndrome, displaced fracture fragments creating risk to the skin, significant sagittal displacement in any ray, or significant transverse displacement in the first or fifth metatarsal. It is considerably less problematic to initially reduce and stabilize a fracture than to do so after malunion, nonunion, or after a skin complication has developed. This can be accomplished with percutaneous pinning, external fixation, and/or open reduction and internal fixation.


First Metatarsal Fractures

The first metatarsal is wider, shorter, and stronger than the lesser metatarsals. It is more mobile because the ligaments and articulation at its base allow more motion. Unlike the lesser metatarsals, the first metatarsal does not have a stout transverse intermetatarsal ligament distally between the adjacent second metatarsal neck. The first metatarsal bears almost half of the body’s weight through the forefoot.3 Displacement of the first metatarsal head in any direction disturbs the tripod-like weight-bearing complex of the anterior portion of the foot and impairs forefoot function. Because even a small malalignment can affect the distribution of weight during ambulation, it is important to tolerate almost no displacement in the coronal or sagittal plane. The primary goal of treatment of a fracture of the first metatarsal is to maintain the normal distribution of weight under all of the metatarsal heads.





Middle Metatarsal Fractures

Fracture of a middle (second, third, or fourth) metatarsal is common. The injury can occur in isolation or with other injuries from vehicular or other high-energy trauma. Often a middle metatarsal fracture has a direct mechanism such as a crush injury, a puncture wound, or axial loading of a plantarflexed foot. Heightened suspicion is necessary to identify the fracture in a patient with multiple injuries and to evaluate for open fracture, which is most common with a crush injury. A metatarsal fracture is classified by its location as a neck, shaft, or base fracture.


Metatarsal Neck Fractures

A metatarsal neck fracture is inherently less stable than a shaft or base fracture. Often, more than one metatarsal is affected, further decreasing fracture stability and the ability to maintain adequate alignment by closed means. In particular, sagittal plane deformity can lead to painful plantar callosities and dorsal exostosis and corns.5 A nondisplaced or minimally displaced fracture can be treated with a hard-soled shoe with weight bearing as tolerated. A more displaced fracture initially should be treated with closed reduction under sedation, using finger traps and direct manipulation with pressure over the metatarsal heads. An unstable fracture or a fracture with persistent sagittal plane deformity should be treated with closed reduction and retrograde pinning with Kirschner wires (from the plantar surface), open reduction and antegrade-retrograde pinning, or internal fixation with a small-caliber plate (if the head fragment is sufficiently large). A longitudinal skin incision that allows simultaneous access to adjacent metatarsals is used.6 As an alternative, fixation after closed reduction can be done by driving Kirschner wires from the intact fifth metatarsal neck into the adjacent fractured middle metatarsal necks.7


Metatarsal Shaft Fractures

As with a metatarsal neck fracture, a minimally displaced or nondisplaced metatarsal shaft fracture can be treated with a hard-soled shoe and weight bearing as tolerated. Moderate frontal plane deformity does not typically lead to functional complications, but sagittal plane deformity is more problematic. A malunited fracture with significant sagittal plane deformity can lead to painful plantar callosities and dorsal exostoses and corns. The typical apex dorsal deformity in a shaft fracture results from plantar flexion of the distal fragment produced by the strong flexor tendons. In general, the more distal the fracture, the greater the apex dorsal deformity is, and the higher probability is that open reduction will be required.8 As for every foot injury, the radiographic evaluation should include AP, lateral, and oblique views. Oblique views are particularly useful because the metatarsals are seen as superimposed on the lateral view.






FIGURE 1 A, AP radiograph showing an open, displaced third metatarsal shaft fracture. B, Oblique radiograph showing the same third metatarsal shaft fracture treated using an intramedullary Kirschner wire.

Most diaphyseal fractures can be treated nonsurgically. The surgical indications generally are limited to metatarsal shortening, significant displacement or angulation, and multiple displaced metatarsal fractures. The methods of fixation include intramedullary Kirschner wires, small plates and screws, and external fixation. Kirschner wires are suitable for most fracture patterns except comminuted length-unstable fractures, for which plates and screws may be more appropriate (Figure 1). Kirschner wires and external fixation are particularly useful for fractures with significant soft-tissue injury.

After surgery, a well-padded short leg splint should be applied, and the patient should not bear weight for 1 to 2 weeks, until acute swelling resolves. A walking short leg cast then can be applied if plantar pins are present. If no pins are present, the patient can gradually begin to use a CAM walker boot. After the initial 1 to 2 weeks, the patient is allowed to bear weight only through the heel. Pins are removed at the 4- to 6-week mark, based on evidence of fracture healing. In general, a relatively young patient will have radiographic healing earlier than an older patient.


Metatarsal Base Fractures

A metatarsal base fracture inherently is more stable than a shaft or neck fracture because of the shorter lever arm of the deforming flexor forces and the surrounding interosseous ligaments and capsular attachments.5 Most base
fractures are treated by closed means with a hard-soled shoe and weight bearing as tolerated. Care should be taken to rule out a Lisfranc variant injury before proceeding with closed treatment. Weight-bearing radiographs, if possible, or cross-sectional advanced imaging (MRI and/or CT) should be obtained to rule out such an injury (Figure 2). Open reduction and fixation should be considered if there is significant displacement, an open injury, or an unstable pattern (Figure 3). Fixation can be achieved with plates, screws, or percutaneous Kirschner wires. Plates spanning the tarsometatarsal (TMT) joints can be considered. Primary fusion may be desirable for a comminuted intra-articular injury.






FIGURE 2 Axial CT showing fractures of the third and fourth metatarsal bases and the medial cuneiform.


Fifth Metatarsal Fractures

Fifth metatarsal fractures account for approximately one quarter of all metatarsal injuries.9 Fractures of the fifth metatarsal differ from those of the other lesser metatarsals in several respects. The fifth metatarsal is the only one with extrinsic tendon attachments; both the peroneus brevis and the peroneus tertius insert at the base of the fifth metatarsal. The fifth metatarsal has very little soft-tissue coverage on the lateral and plantar foot. There is a very strong ligamentous attachment to the plantar aponeurosis. The proximal fifth metatarsal has a vascular watershed area that creates a biomechanical and biologic environment in which fractures are common, often are difficult to treat, and can have problematic healing.10

A fifth metatarsal fracture can be classified as a proximal (base) fracture or a diaphyseal fracture. Each of these types has a unique etiology, treatment, and prognosis.11 The management of a diaphyseal fracture is similar for all metatarsals. Most can be treated nonsurgically; however, stress fractures of the diaphysis have a tendency to prolonged union and refracture, particularly in obese patients, or in the setting of a large fourth-fifth inter-metatarsal angle (IMA4-5).12 The surgical indications generally are limited to shortening, malangulation, significant displacement, and multiple metatarsal fracture.

The proximal half of the fifth metatarsal often is classified into three distinct fracture zones. Zone I includes the styloid process; zone II, the metadiaphyseal region; and zone III, the proximal diaphyseal region. Zones I, II, and III are subject to, respectively, an avulsion fracture (Figure 4), a Jones fracture (Figure 5), and (usually) a stress fracture.


Avulsion Fractures

Almost all fifth metatarsal fractures are avulsion fractures at the base.13 This injury is believed to occur secondary to the forces exerted on the base by the strong attachment of the peroneus brevis and the lateral plantar aponeurosis. The plantar aponeurosis probably has a key role; these fractures are rarely displaced, and some fibers of the peroneus brevis remain intact.14 The mechanism of injury usually is an acute inversion moment, as occurs when stepping off a curb. Many patients describe hearing a popping sound and have acute swelling, ecchymosis, and difficulty in ambulation. The location of tenderness and swelling determines whether a foot or ankle radiograph should be obtained to look for a fifth metatarsal avulsion fracture or another injury that can occur with the same mechanism, such as a fracture on the anterior process of the calcaneus or distal fibula.

Fifth metatarsal avulsion fractures typically are successfully treated without surgery. Patients can be made weight-bearing as tolerated in a cast or boot, or even a well-cushioned shoe with a stiff sole, for 4 to 8 weeks.15 The progression of treatment often is based on clinical symptoms; radiographs are not correlated with outcome, and radiographic healing can be prolonged or not occur. Most of these injuries clinically heal within 6 to 8 weeks. Painful nonunions are uncommon and are treated by excision of the fragment and repair of the peroneus brevis or, for larger fragments, by fixation and grafting. Primary internal fixation is typically reserved for fractures that include a large fragment entering the metatarsal-cuboid joint with more than 2 mm of
displacement. Fixation usually is with a narrow tension band wire or a small-caliber lag screw. A recent study demonstrated that primary operative fixation may lead to lower rates of malunion and earlier return to weight bearing and work, though patient outcome scores were not significantly improved at 1 year postoperative compared with patients managed nonsurgically.16






FIGURE 3 A, AP radiograph showing an unstable fracture pattern involving displaced fractures of the medial cuneiform and the third and fourth metatarsal bases. Postoperative (B) AP and (C) lateral radiographs showing reduction and plate fixation of all fractures.






FIGURE 4 AP (A) and oblique (B) radiographs showing an avulsion fracture of the base of the fifth metatarsal.

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Feb 27, 2020 | Posted by in ORTHOPEDIC | Comments Off on Forefoot, Sesamoid, and Turf Toe Injuries
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