Midfoot Injuries in Athletes: Fundamentals of Examination and Treatment
Article Outline
- Abstract
- Lisfranc Injuries/TMT Injuries
- Navicular Injuries
- Cuboid Stress Fracture
- C–C Joint Sprains
- Conclusions
- References
- Copyright
Anatomically, the midfoot acts as a solid construct connecting the hindfoot to the forefoot. Injury patterns to this structure occurring during athletics are characterized by relatively low-velocity loading mechanisms. “Midfoot injuries” in athletes are common and can be difficult to diagnose. They require a high level of clinical suspicion when evaluating an injured athlete's foot. Accurate diagnosis relies on a thorough physical examination and appropriate imaging studies. Plain foot x-rays are the primary imaging modality. These x-rays should be taken with the patient weight bearing whenever possible to allow alignment of the foot to be assessed and to help identify subtle instabilities. Occasionally, a magnetic resonance imaging, bone scan, or computed tomography is required to give more information on the nature of the injury. Treatment for many of these injuries is conservative. However, surgical intervention is sometimes required for unstable or significantly displaced injuries. Return to play can be prolonged, and several months of healing time is not uncommon.
Keywords: midfoot injuries, sports medicine, midfoot operative techniques
When dealing with athletes, an injured “midfoot” usually is assumed to be damage to the tarsometatarsal (TMT) joint—-also known as the Lisfranc joint. However, the area designated as the “midfoot” is much more complex. The “midfoot” region of the foot comprises 5 bones (3 cuneiforms, navicular, and cuboid) tethered together by a complex mesh of strong dorsal and even stronger plantar ligaments. It is bound proximally by the transverse tarsal joint (Chopart's joint) and distally by the Lisfranc joint. The midfoot itself functions as a solid unit with little inherent motion.1 The midfoot has several important biomechanical functions that includes (1) connecting the hindfoot to the forefoot; (2) acting to dissipate repetitive loading to the foot during midstance through its relationship with Chopart's joint; (3) providing for a stable arch when standing; and (4) allowing for the foot to function as a rigid lever during heel rise.
The midfoot's inherent stability comes from a combination of the (1) dense plantar ligaments and (2) the numerous bony interdigitations that create a longitudinal and transverse arch. For example, the second TMT joints stability as the “keystone” of the foot is due to its recessed position at the level of the Lisfranc joint when compared to the first and third TMT joints. In addition, the stout Lisfranc ligament complex anchors the second metatarsal to the neighboring middle cuneiform.
When dealing with athletic injuries boundaries of the midfoot are expanded to include the Lisfranc joint (the TMT joint), the intercunieform joints, and Chopart's joint (calcaneocuboid and talonavicular joints). Another important point is that the mechanism of midfoot trauma occurring in the typical athletic injury is a low velocity, loading type. This is in contrast to the typical traumatic, high-velocity midfoot fracture-dislocation that is seen in motor vehicle crashes.2 Furthermore, athletic midfoot injuries are characterized by primarily ligamentous damage (sprains) with occasional fractures, whereas traumatic midfoot injuries usually involve fractures with or without dislocations.3
The physical examination of the injured athlete's midfoot typically reveals pain over the dorsal or occasionally plantar aspect of the foot. The midfoot squeeze test (side-to-side compression) in which the examiner places his/her hand over the dorsum of foot and then squeezes it and the single leg hop (athlete is instructed to perform a single leg hop 15 times on the injured leg without pain) are good initial examinations that can be used to triage an athlete during competition. Should the athlete be unable to successfully pass these 2 tests, a thorough examination of the patient should be performed. It is during this next examination that meticulous attention should be paid to the various structures of the midfoot, and radiographs will be necessary.
Weight-bearing radiographs of the injured foot should be obtained if possible. Even though many fractures of the foot can be noted with non–weight-bearing radiographs, weight-bearing or if needed, stress x-rays will provide more information on the ligamentous stability of the foot's numerous joints, and thereby better delineate potential pathology.4 If radiographs are unable to locate a suspected injury or more information regarding the injury is needed, magnetic resonance imaging (MRI), bone scan, or computed tomography (CT) may give more detailed information.
Treatment of midfoot injuries is guided by certain basic principles. These include ensuring that the 5 midfoot bones are in their normal anatomic alignment, recognizing that the ligamentous midfoot injuries often have a prolonged healing time, and attempting to maintain motion at Chopart's joint.
Lisfranc Injuries/TMT Injuries
The Lisfranc complex is made of the articulations at the TMT joints. The “classic” Lisfranc injury originates at the ligamentous structures that secure the joint between the distal, lateral aspect of the medial cuneiform, and the proximal, medial base of the second metatarsal. This area is the site of the Lisfranc ligament. The base of the second metatarsal sits in a recessed position against the middle cuneiform in its TMT joint. Along with the Lisfranc ligament, this gives stability along the longitudinal and transverse arch of the foot. The joint's stability has been compared to the “keystone” in a Roman arch, for it allows the transmission of forces and confers mechanical integrity to the foot. Injuries to this part of the foot are also called “midfoot sprains.” This is a common area of the foot to be injured in athletics. In fact, injuries to the Lisfranc joint are the second most common foot injuries to occur in athletes, surpassed only by injuries to the metatarsophalangeal joints.5 Four percent of football players sustain midfoot sprains, and offensive lineman had the highest reported incidence at nearly 30%.5
In most Lisfranc injuries that occur during sports, the injury will cause a rupturing or avulsion of the Lisfranc ligament. The amount of damage to this ligament and instability noted will dictate whether the injury can be treated conservatively or operatively.6, 7 Most of the Lisfranc ligament's strength comes from the plantar division of this ligament.1 Fractures and displacement at the first and second proximal metatarsal joint are uncommon in this type of injury.3 As part of the initial evaluation, weight-bearing radiographs should be obtained, and a “fleck sign” may be observed at the lateral base of the second metatarsal. This bony fragment represents an avulsion of the Lisfranc ligament from the base of the medial second metatarsal. This indicates an unstable Lisfranc complex, which usually requires operative fixation for optimal recovery.
Damage to the Lisfranc ligament complex in athletes can be broken down into 3 stages based on the amount of diastasis between the first and second metatarsal bones and loss of longitudinal arch height.7 Stage 1 injuries are essentially Lisfranc ligament sprains, with no increase in intermetatarsal space, no loss of arch height, but increase in bone scan uptake. Stage 2 injuries are described as rupture of the Lisfranc ligament with a diastasis of the intermetatarsal space of 1-5 mm but no loss in arch height. Stage 3 injuries show a greater than 5 mm diastasis with a loss in arch height. Stage 2 and 3 injuries may also show an intercunieform subluxation or dislocation, in addition to the Lisfranc joint disruption (Fig.1; Table 1).
Figure 1.
Weight bearing radiograph showing subtle Lisfranc joint widening.
Table 1. Midfoot sprain classification
Data from Nunley JA, Vertullo CJ. Am J Sports Med 30: 871-878, 2002.7| Radiographic Findings | |
|---|---|
| Stage 1 | No diastasis or loss of arch height |
| Stage 2 | 1 to 5 mm diastasis at I-II intermetatarsal space |
| No arch height loss | |
| Stage3 | Greater than 5 mm 1-2 intermetatarsal diastasis |
| Loss of arch height |
Treatment of grade 1 injuries is conservative. Non–weight-bearing in a cast or cast boot for 6 weeks is usually sufficient. After removal with adequate time for healing, the athlete is given either a semi-rigid orthotic or a carbon fiber insert if they are asymptomatic. However, if they are still symptomatic, an ankle-foot orthosis worn for 4 weeks is recommended. Grade 2 and 3 Lisfranc injuries require open reduction with internal fixation of the Lisfranc and possibly the intercunieform joint. Strict non–weight-bearing after surgery is maintained for 8 weeks, then weight-bearing as tolerated in a walking boot is allowed for the next 4 weeks. Once the walking cast is removed, an orthotic with a medial arch is worn. Patients should be enrolled in a sport-specific physical therapy program before being allowed to return to sports. Hardware removal may be allowed as early as 12 weeks, but some authors advocate leaving the hardware in place. Of note, a recent study noted that primarily ligamentous Lisfranc-complex injuries treated with initial TMT joint arthrodesis had better short-term and long-term outcomes when compared to the same type of ligamentous injury treated with open reduction and internal fixation.8 Return to sports is often prolonged, from 4 months to a year depending on the magnitude of the injury.9
Navicular Injuries
The shape of the navicular bone is complex, but can be simplified to an “oblong bowl.” It connects with the head of the talus proximally, the posterior tibialis tendon medially, and the 3 cuneiforms distally. Most of the navicular is covered with articular cartilage, so its blood supply comes primarily from the medial plantar and dorsalis pedis arteries, which cause a “watershed” area of perfusion.10 Therefore, navicular injuries are often associated with delayed healing due to this relatively avascular central area.
Injuries to the navicular are common in athletes. Fractures through the body of the navicular are a well-described entity in the orthopaedic trauma literature and are out of the scope of this chapter. However, 2 common navicular injuries in athletes are avulsion fractures and stress fractures.
Dorsal avulsion fractures of the navicular are the most common type (nearly 50%) of fracture to this bone. They are typically produced by acute plantar flexion and inversion mechanisms. This causes the dorsal talonavicular joint capsule to avulse a fragment of bone off the dorsal aspect of the navicular. These injuries can be seen in conjunction with inversion ankle sprains. Tenderness over the dorsum of the navicular is common. When the fragment is small it can be treated in a walking cast or boot. However, if the fragment is 25% or more of the articular surface, it should be treated with open reduction and internal fixation. CT of the foot should be ordered if there is any question about the size or extent of the fracture, and can used for preoperative planning.
Stress fractures of the navicular can be difficult to diagnose because of their insidious onset and nebulous symptomatology. Typically, patients report pain during athletic activities that resolves with rest. Navicular stress fractures occur in individuals who perform repetitive loading of their feet while they are up on their toes such as occurs in middle distance runners, or loading through their forefoot such as occurs with the lead foot in a golfer. Risk factors include a long second metatarsal, a stiff high-arched foot (subtle cavus foot), or a tarsal coalition. A long second metatarsal is a risk factor, as this will increase the force that is channeled through the second metatarsal, into the middle cuneiform and subsequently into the central aspect of the navicular. A stiff foot or a tarsal coalition is a risk factor because these foot types have relatively little motion through the talonavicular joint so the position of the navicular against the talus ends up being relatively fixed serving to concentrate the force that the navicular receives.
On physical examination, the pain (if present) is located dorsally over the navicular in the so-called “N-spot.” Hopping on 1 foot while turning may exacerbate the symptoms and increase a physicians “index of suspicion.” Plain radiographs are often negative for fractures. For these reasons, the typical patient has a delay of approximately 4 months before being diagnosed a navicular stress fracture. Navicular stress fractures are responsible for about 14%-35% of all stress fractures. Stress fractures of the navicular have been given 3 grades depending on the extent of the fracture as seen on CT (Fig. 2).11
Figure 2.
CT of Navicular showing stress fracture.
Type I navicular stress fractures show an isolated crack in the dorsal cortex. Type II stress fractures show an extension of the dorsal fracture into the navicular body, and type III fractures penetrate a second cortex. These fractures respond well to conservative treatment—a short leg cast or boot with strict non–weight-bearing for 6 weeks.12 The “N-spot” should be re-examined, and if asymptomatic then physical therapy may begin. The patient should be reassessed for pain every 2 weeks.13 Approximately 86% show healing with return to sports at 3 months.13 A custom orthosis is also recommended when athletic activities are resumed. Type III fractures may require more aggressive treatment if conservative methods fail.
Open reduction and internal fixation is the preferred method for fractures that fail conservative treatment; however, many surgeons have touted percutaneous methods. Supplemental autogenous bone graft may be used if the fracture is significantly displaced, there is a central cavitary lesion, or the fracture site looks sclerotic. Surgically, the interval between the dorsal neurovascular bundle and the extensor digitorum longus is developed. Two 4.0 mm screws placed from dorsolateral to plantar medially allow excellent compression and stability to the fracture. Also, placement of the hardware from lateral to medial facilitates better purchase of bone because the navicular is wider medially than laterally.
Postoperatively, patients are kept strict non–weight-bearing for at least 6 weeks, and then may begin weight-bearing with boot and crutches. Average time for return to sports was noted at approximately 4 months for the operative group and 6 months for the nonoperative group in 1 study (Table 2).11
Table 2. Computed Tomography Classification of Navicular Stress Fractures
Data from Saxena A, Fullem B, Hannaford D. J Foot Ankle Surg 39:96-103, 2000.11| CT Findings | |
|---|---|
| Type I | Dorsal cortical fracture |
| Type II | Fracture propagates to navicular body |
| Type III | Fracture propagation into another cortex |
Cuboid Stress Fracture
Stress fractures to the cuboid bone are uncommon.14 They are usually due to the same type of mechanisms that cause other types of stress fractures in athletes, for example, repetitive jumping and running activities. Diagnosis relies on radiographs, and often bone scans or MRIs. A cavus hindfoot can be a predisposing factor for development of this injury. Treatment relies on cessation of athletic activities, and a walking boot or cast immobilization until symptoms regress. Identifying and correcting any underlying mechanical problems of the foot (ie, cavus hindfoot) before when sports are resumed is critical to lessen the chances of recurrence. Like other stress fractures of the foot, complete resolution of symptoms may take up to several months.14
C–C Joint Sprains
Sprains to the calcaneocuboid joint typically occur after a plantar flexed, inversion-type injury occurs. When the magnitude of injury is sufficient, they can be associated with lateral ankle sprains. Often they occur as an isolated injury; they are often initially diagnosed as an “ankle sprain,” and therefore do receive appropriate treatment. These injuries can be quite debilitating, and delay in treatment can be detrimental.
On examination, the lateral foot over the calcaneocuboid joint will be painful to touch. Testing the calcaneocuboid joint with a varus and valgus stress with the examiner's thumbs on either side of the joint, will illicit pain. Weight-bearing radiographs may show a “fleck” sign, which represents an avulsion of the joint's capsule. Treatment is a short-leg non–weight-bearing cast for 6 weeks; it includes placement into a walking cast or boot for 2-4 weeks, and then use of a carbon fiber insert for athletic shoe wear. If the patient continues to have pain and disability after the initial casting, an MRI may be in order.
Conclusions
The athlete who presents with a midfoot injury should be carefully examined, as not all midfoot injuries are alike. Subtle clues on the physical examination, coupled with the appropriate radiographic examinations will enable an accurate diagnosis and treatment plan. Failure of a proper diagnosis will likely result in a delay treatment and returning to sports. Medial-sided injuries are the most common and can often take the longest to heal. Most of these types of injuries can be treated conservatively; however, surgical intervention for unstable ligamentous injuries should not be delayed. Regardless, injuries to the midfoot complex can take several weeks, if not months to heal.
References
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PII: S1060-1872(09)00139-7
doi:10.1053/j.otsm.2009.11.006
© 2010 Elsevier Inc. All rights reserved.
