Midfoot Injuries



Midfoot Injuries


Joseph T. O’Neil, MD

Steven M. Raikin, MD

David I. Pedowitz, MS, MD


Dr. Raikin or an immediate family member has received research or institutional support from Zimmer. Dr. Pedowitz or an immediate family member has received royalties from Integra and Zimmer; is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex, Inc., Integra life sciences, and Zimmer; serves as a paid consultant to or is an employee of Arthrex, Inc., Integra, MiRus, and Zimmer; and has received research or institutional support from Integra life sciences. Neither Dr. O’Neil nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.





Introduction

The area of midfoot injury extends from the naviculocuneiform joints proximally to the tarsometatarsal (TMT) joints distally. Midfoot injury encompasses a wide spectrum of pathology from a subtle sprain incurred on an athletic field to a massive crush injury after a motor vehicle crash. Some patients are young but skeletally mature; others are of advanced age and often have poor bone quality. Keeping these distinctions in mind is vital when making clinical decisions regarding these complex injuries.


Navicular Fractures

Although navicular fractures are not common, they are particularly important to understand. The navicular articulates with four bones in the foot, serves as the major attachment site for the posterior tibial tendon, and is responsible for significant hindfoot motion. The navicular is named for its boat-like shape, which is concave from medial to lateral as well as dorsal to plantar at the talonavicular joint, and convex at the naviculocuneiform joints. The navicular represents a transition zone from the mobile talonavicular joint, which allows the entire foot to pivot on the talus, to the stiff naviculocuneiform joints. Navicular fractures range from simple dorsal and medial avulsion fractures to stress fractures and complex body fractures. Any of these fractures, if missed, can lead to significant morbidity in the midfoot.


Avulsion Fractures

Dorsal capsular avulsion fracture, the most common type of navicular fracture, often is caused by an acute plantar flexion injury or ankle sprain. Typically, trauma to a portion of the strong dorsal talonavicular ligament causes avulsion of a small piece of the bone. This fracture is relatively benign and can be treated with immobilization in a walking boot for 6 to 8 weeks or until the patient is asymptomatic (Figure 1). Traditionally, treatment with a short period of immobilization has been recommended as leading to minimal disability, with fragment excision recommended if pain persists after immobilization.1 A second recommendation is for a short period of immobilization with avoidance of weight-bearing, in the presence of significant soft-tissue swelling and ecchymosis, to give the associated ligamentous injury ample time to heal.2 If the avulsed fragment is a significant portion of the articular surface of the navicular, open reduction and internal fixation (ORIF) is indicated to minimize the risk of posttraumatic arthritis and the likelihood of subsequent midtarsal subluxation. Unfortunately, no clear criteria define the percentage of dorsal navicular involvement, indicating that surgical intervention is necessary.

Avulsion fracture of the navicular tuberosity is the result of forceful eversion of the midfoot. Eversion tensions
the posterior tibial tendon insertion, the tibionavicular ligament (the most anterior portion of the deltoid ligament), and the plantar calcaneonavicular (spring) ligament. Because of the broad insertion of the posterior tibial tendon throughout the plantar aspect of the midfoot, usually the tendon is not completely pulled off, and significant tuberosity displacement is rare. These fractures typically cause pain and ecchymosis medially and are easily seen on routine foot radiographs. Immobilization in a walking boot is used for 4 to 6 weeks. If a symptomatic nonunion develops, excision (a Kidner-type procedure) may be undertaken rather than internal fixation. Some experts recommend internal fixation for a fracture displaced more than 5 mm because of the risk of nonunion.2






FIGURE 1 Lateral radiograph showing a dorsal navicular avulsion fracture.






FIGURE 2 Schematic showing the three types of navicular fractures. A, Type I is best seen in a lateral view. The fracture line is in the coronal plane, there is no midfoot instability, and dorsal displacement is variable. B, Type II is best seen in an AP or oblique view. The fracture line is in the dorsolateral to plantarmedial plane, with medial displacement from the posterior tibial tendon. C, Type III is best seen in an AP view and is characterized by midbody comminution and valgus foot angulation as can be seen by comparing the medial column with its normal alignment demonstrated by the dashed line. (Reproduced from Ficke JR: Fractures and dislocation of the midfoot, in Pinzur MS, ed: Orthopaedic Knowledge Update: Foot and Ankle 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2008, pp 107-114.)

An acute fracture should be distinguished from a type II accessory navicular. The accessory bone and the corresponding medial navicular body have more rounded edges than the fracture. These entities typically are treated in a similar fashion but are largely based on the severity of the patient’s symptoms.


Navicular Body Fractures

Fractures of the navicular body are uncommon because of the stability imparted by the position of the navicular between numerous bones. Such a fracture often is caused by a high-energy mechanism, as in a fall from a height or an axial load. The classification is based on fracture morphology: a type I fracture is in the coronal plane and has no malalignment of the midfoot; a type II fracture, the most common type, has a dorsolateral to plantarmedial fracture line with the lateral fragment displaced dorsally; and a type III fracture is comminuted centrally or laterally within the navicular body (Figure 2). The foot collapses into abduction through the comminution. Many researchers suggest that displaced, comminuted fractures
(all type II and III fractures) and larger fracture fragments benefit from internal fixation. As in all foot and ankle trauma, the integrity and suitability of the soft tissues for surgical intervention must be respected, and for this reason, the surgery may need to be delayed 1 to 2 weeks. Temporary spanning external fixation may be necessary if there is gross instability. CT is particularly useful during surgical planning to fully appreciate the anatomy of the fracture fragments, especially in the presence of additional transverse tarsal and tarsometatarsal injuries.

Surgical treatment is done through a dorsal approach between the course of the anterior and posterior tibial tendons to facilitate visualization and evaluation. The saphenous vein and nerve must be avoided during the superficial dissection. Because the lateral aspect of the navicular is challenging to fully appreciate, usually it is beneficial to place the incision just over the anterior tibial tendon rather than more medially and closer to the posterior tibial tendon. With this exposure, surgical windows on either side of the tibialis anterior allow one to see both the medial and lateral navicular fully. One must, however, be careful to elevate the neuromuscular bundle, which lies lateral to the tibialis anterior and medial to the extensor hallucis longus tendon.

Simple fractures are fixed with lag screws. Screws may be placed medial to lateral or lateral to medial, depending on which placement will provide better fixation. If there is significant comminution, locked or mini-fragment plating of the navicular itself or temporary bridge plating of the medial column may be necessary.3,4,5 Manipulation of fracture fragments may require the use of a small external fixator or Kirschner wire distractor, which eliminates the deforming forces on the navicular and improve visualization.

Late osteonecrosis may occur following these injuries and, in advanced stages, may lead to medial column collapse. Symptoms of posttraumatic arthrosis of the talonavicular joint can be treated with shoe wear modification, a stiff custom insert, or a rigid or rocker-bottom soled shoe. Some patients require delayed talonavicular, naviculocuneiform, or talonaviculocuneiform (medial column) arthrodesis.


Stress Fractures

The navicular bone historically was believed to be particularly susceptible to stress fracture because of the relative avascular zone in the central third of the bone. Recent arterial anatomic studies suggest that biomechanical and other clinical factors play a more significant role in the development of stress fractures than previously believed.6 With explosive activity, this area undergoes considerable compression, which can cause stress responses including bone bruise, stress reaction, stress fracture, and complete fracture of the navicular. The diagnosis often is delayed because the symptoms are vague in location, insidious, and sometimes similar to those of a sprain. The fracture may be evaluated only after weeks or months of continued activity. Patients have poorly localized pain in the midfoot and usually are unable to perform the hop test, which requires jumping up and down on the involved forefoot. Radiographs of the foot should be carefully scrutinized for evidence of a fracture. Often the radiographs are normal, however, and a high index of suspicion and MRI confirmation are required. MRI is preferable to CT because CT can only document fractures with cortical disruption, which often does not occur until the later stages of a stress fracture which is evolving into a complete fracture.

The treatment ranges from avoidance of weight-bearing to early surgical intervention. The results of any treatment involving partial weight-bearing appear to be inferior to those of complete avoidance of weight-bearing or early surgical treatment, and therefore partial weight-bearing should be discouraged. Although surgery may be the preferred initial treatment for a competitive athlete, avoidance of weight-bearing and early surgical treatment appear to have similar results in the general population.7,8


Cuboid and Cuneiform Fractures


Cuboid Fractures

Through its articulation with the fourth and fifth metatarsal bases and the anterior process of the calcaneus, the cuboid forms an intercalary link from the lateral forefoot to the hindfoot. Like in the hand, the medial column is relatively rigid. Conversely, the lateral column of the foot is quite mobile to accommodate ground reactive forces and the geometry of uneven surfaces. Fractures of the cuboid are believed to be rare because its bony surroundings offer some protection. Patients report lateral foot pain and difficulty in weight-bearing. Lateral and plantar midfoot and hindfoot ecchymosis is common. Plain radiographs often are sufficient, but CT or MRI is recommended for surgical planning or evaluation to detect additional midfoot pathology.

Avulsion fractures and compression fractures are the two primary types of cuboid fractures. Avulsion fractures, which are more common, can occur even with mild to moderate foot and ankle sprains. These are capsular avulsions, and they can be treated nonsurgically with modified weight-bearing in a fracture boot, as symptoms allow. Minimally displaced or nondisplaced cuboid fractures also can be treated nonsurgically and may benefit from a 4- to 6-week period of non-weight-bearing.







FIGURE 3 Oblique radiograph of the foot showing lateral dislocation of the fifth tarsometatarsal joint with a compression fracture of the cuboid.

Although displaced fractures only rarely require surgical intervention, often they accompany more severe bony and soft-tissue midfoot Lisfranc injuries. Displaced fractures result from a direct crush or from an axial load in plantar flexion accompanied by eversion. In the second scenario, a so-called nutcracker fracture is produced when the cuboid is caught between the fourth and fifth metatarsal bases and the anterior process of the calcaneus, and it is cracked like a nut.9 In these compression injuries, the lateral column is crushed and becomes shorter because it is no longer held out to length (Figure 3). These fractures carry a significant risk of collapse and painful malunion, and therefore surgery to restore length and intra-articular anatomy is believed to be beneficial.10 No recommendations, however, have been published as to the amount of lateral column shortening required to warrant urgent internal or external fixation.11

The surgical options range from bone grafting with definitive internal fixation to temporary bridge plating or external fixation. Arthrodesis rarely is required but may be necessary if articular surfaces cannot be reconstructed. Although large studies of surgical treatment of compression injuries with lengthy follow-up are lacking, the importance of timely surgical intervention was underscored by midterm results, suggesting that persistent symptoms often are caused by associated midfoot injuries.12


Cuneiform Fractures

The cuneiforms are a relatively stable complex of bones between the navicular and the medial three metatarsal bases. The strong intertarsal ligaments allow the cuneiforms only a small amount of motion. Accordingly, displaced fractures are rare and suggest the presence of a more sinister midfoot injury elsewhere. The mechanism usually is direct trauma, and patients have pain over the central to medial midfoot. Plain radiographs should be obtained, but MRI or CT often is needed to evaluate subtle fracture patterns because there is bony overlap on plain radiographs. A nondisplaced fracture is treated with a walking boot and modified weight-bearing, as symptoms allow. A displaced fracture occasionally requires internal fixation and, when associated with a tarsometatarsal injury, is amenable to primary arthrodesis (PA).


Tarsometatarsal Fractures

Tarsometatarsal injury can be ligamentous, bony, or both. Jacques Lisfranc de St. Martin in 1815 described a fracture dislocation at the TMT joints that occurred when a soldier caught his foot in a stirrup while dismounting his horse. Such injuries often were treated by amputation, and there is little similarity between classic descriptions and current understanding. Nonetheless, the TMT joints often are called Lisfranc joints, and the terms tarsometatarsal injury and Lisfranc injury are used interchangeably.


Anatomy

The tarsometatarsal complex spans parts of the transverse and longitudinal arches of the foot and is stabilized by strong plantar ligaments and weaker dorsal ligaments. In the coronal plane, intrinsic stability is provided by the unique position of the second metatarsal base, which is recessed proximally between the medial and lateral cuneiforms. In the axial plane, the unique wedge shape of the bases of the metatarsals and their corresponding cuneiforms provide a bony congruity that maintains the transverse arch and confers tremendous stability.

The ligaments stabilizing the TMT joints are dorsal, plantar, and interosseous. The interosseous ligaments are the strongest; they extend between each of the lateral four metatarsal bases but are conspicuously absent between the first and second metatarsals. The first ray is connected to the second tarsometatarsal complex by the Lisfranc ligament, which extends from the medial cuneiform to the medial base of the second and third metatarsals, the plantar portion of which is the strongest and most important for midfoot stability.13

Little motion occurs at these articulations, but the bones of the TMT joints provide sturdy attachment sites for the anterior and posterior tibial tendons. The dorsal
neurovascular bundle, containing the dorsalis pedis artery and vein and the deep peroneal nerve, runs dorsally over the second TMT joint, just lateral to the extensor hallucis longus tendon.

Feb 27, 2020 | Posted by in ORTHOPEDIC | Comments Off on Midfoot Injuries
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