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Fracture, Metatarsal

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Fracture, Metatarsal
Andrew Hunt
Basics
The anatomy of the foot is divided into the hind-foot, the mid-foot, and the forefoot:
  • The hind-foot includes the calcaneus and talus.
  • The mid-foot includes the navicular, cuboid, and cuneiform bones.
  • The forefoot includes the metatarsals and phalanges:
    • The forefoot functions to transmit ground reaction forces to the mid-foot with weight-bearing activities.
    • Fractures in the forefoot, specifically to the metatarsals, can alter the normal distribution of weight and lead to secondary metatarsalgia (pain) as well as transfer lesions such as plantar callouses and stress lesions.
Description
  • A metatarsal fracture can be described as being extra-articular, partial intra-articular, or articular, depending on where on the metatarsal the fracture occurs. Extra-articular fractures may be transverse (straight across the long axis), oblique, or spiral. An articular or partial intra-articular may be a simple isolated fracture extending into the joint, comminuted, or an avulsion fracture.
  • A stress injury with normal radiographs but a positive exam (pain to palpation) may be categorized as macrotrabecular (visible fracture lines on MRI) or stress reaction (T2 signal change on MRI without visible fracture lines).
Epidemiology
  • Metatarsal fractures are likely more common in athletes involved in weight-bearing exercise such as dancers, runners, or contact sport athletes.
  • Any direct trauma, however, can cause fracture, and lower-risk athletes such as swimmers or bikers still may present with this injury.
Incidence
Overall incidence of metatarsal fractures is unclear, as a wide variety of physicians treat this injury:
  • This includes internists, pediatricians, family practice physicians, emergency physicians, and orthopedic surgeons.
Risk Factors
  • Same as for bone fractures in general
  • Those with osteopenia or osteoporosis have a greater risk.
  • Any activity that increases the likelihood of direct trauma to the foot increases the risk of metatarsal injury.
  • Excessively rapid progressions of training volume and/or stress on the foot can also increase the risk of metatarsal stress injury.
General Prevention
  • Gradual increases in workload allow a bone to adapt to mechanical stress and become stronger.
  • Bone is a dynamic organ that is subject to anabolic forces tending to build it up, as well as to catabolic forces tending to break it down.
  • This balance allows a bone to remodel and adapt to stress, but may also cause progressive weakening if catabolic forces outweigh the anabolic ones, such as with too-rapid progression of training load.
Etiology
  • When the cortical bone's mechanical strength is exceeded acutely by direct trauma, such as a heavy object falling on the foot, it will fracture.
    • When this acute stress is a shear force secondary to twisting on a plantar flexed foot, the fracture pattern may be a spiral in shape.
  • A fracture may also occur when the bone-tendon interface is acutely stressed past its mechanical failure point.
    • A typical example of this is at the base of the 5th metatarsal where the peroneus brevis muscle inserts and acts to evert the foot.
  • An additional mechanism for fracture occurs when repetitive subthreshold forces are incompletely healed and the additive damage eventually causes an overt fracture.
    • Prior to an overt fracture, however, such stress may cause macrotrabecular fracturing not evident on plain radiographs but seen on MRI.
Commonly Associated Conditions
  • The same forces that cause fracturing of the metatar-sals may also injure adjacent structures such as the mid-foot joint (between the row of cuneiform bones articulating with the 1st through 4th metatarsals and the cuboid articulating with the 4th and 5th metatarsal). At the other end, the metatarsophalan-geal joints (MTP joint) may be involved when a fracture extends into the joint or when the joint capsule or ligamentous structures are disrupted.
  • Other injuries to consider:
    • Mid-tarsal joint injury (calcaneo-cuboid or talo-navicular): Can include lateral process of talus or anterior process of calcaneus
    • Navicular or cuboid contusion/fracture
    • Metatarso-cuneiform/cuboid injury (MTC): Lisfranc joint injury may include ligamentous disruption and/or fracture of surrounding bone.
    • Metatarso-phalangeal joint (MTP) injury: Can include capsular or ligamentous sprain (turf toe) or fracture of adjacent bone
    • Phalangeal fracture
    • Sesamoid contusion or fracture
  • Predisposing conditions:
    • Hallux valgus/hallux rigidus: Altered mechanics at the 1st MTP joint leads body weight shifting laterally over the lesser caliber 2nd metatarsal
    • Osteopenia/osteoporosis: Decreased mechanical strength of the bone increases susceptibility to stress fracture and acute fracture
Diagnosis
  • Diagnosis of overt metatarsal fracture is by radiograph.
  • Standard views include the anteroposterior (AP), lateral, and oblique views.
  • Addition of weight-bearing views may help identify subtle lesions as well as Lisfranc injuries if the patient tolerates them.
  • Diagnosis of radiographically negative stress injury is via a technetium-99 bone scan or by MRI.
    • Advantages of MRI over bone scan include differentiation of stress reaction without fracture lines vs macrotrabecular fracture.
Pre Hospital
  • Prehospital/on-field care includes minimizing weight bearing on the affected extremity as well as icing to reduce swelling and inflammation.
  • If there is no evidence for open fracture or vascular compromise, plain radiographs may be obtained at the patient's convenience.
  • If there is visible bone penetrating the skin or the extremity is cool indicative of vascular compromise, immediate transport to the emergency room is advisable.
History
  • With acute injury, the patient will usually be able to point to a direct trauma to the foot or a twisting injury causing pain.
  • More subtle stress injuries will typically have a history of recent increases in training volume or impact load and possibly a prior history of other stress fractures, disordered eating, or menstrual irregularities.
Physical Exam
  • Point-tenderness directly over the metatarsal is the typical finding on exam.
  • The foot will usually show some swelling in comparison to the unaffected foot and possibly some bruising as well.
  • Gross displacement is not common. Open fractures will present with bone penetrating through the skin.
Diagnostic Tests & Interpretation
  • Focal tenderness and/or swelling over the metatarsals after an injury is a clear indication for plain radiographs to rule out a fracture.
  • Chronic symptoms of foot pain with weight bearing and negative radiographs warrants further imaging such as bone scan or MRI.
  • An urgent need for a clear diagnosis after an acute injury and negative radiographs also suggests the need for further imaging.
Imaging
  • Plain radiographs will show cortical disruption if a significant fracture has occurred.
  • The findings may be subtle with mild injury.
  • A stress fracture may show subtle sclerotic borders/periosteal elevation or be entirely normal.
  • Plain films only become positive once healing has progressed enough to produce visible bony callus. In the interim, an MRI should show changes on T2 images and a bone scan should be positive for focal hot spot over the painful area.
  • A CT scan may be indicated for an intra-articular fracture to delineate any articular step-off.
Differential Diagnosis
  • MTP joint synovitis: Inflammation of the joint rather than stress reaction in the bone itself. Bone scan will show distal uptake around MTP joint. MRI is diagnostic. Claw toe may also cause synovitis with plantar displacement of metatarsal head or a metatarsal stress reaction.
  • MTP capsular strain and/or chip fracture of 1st metatarsal head (turf toe)
  • Lisfranc sprain/fracture: Injury to the 2nd MTC articulation. Any pain at the proximal 2nd metatarsal in association with a twisting injury in plantar flexion should raise concern for this injury.
  • Mid-foot sprain: Injury to MTC ligamentous structures
  • Forefoot mass (ganglion or tumor)
  • Metatarsalgia
  • Morton's neuroma (interdigital neuroma)
  • Freiberg's infarction: Osteonecrosis of 2nd metatarsal head. More common in adolescent athletes with unilateral (usually) pain in 2nd metatarsal head.

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Treatment
The goal of treatment is to stabilize the fracture such that normal length, rotation, and declination of the metatarsal is maintained and the area is protected from further injury until healing has occurred.
Pre-Hospital
  • If possible, the foot should be elevated and cooled with ice as soon as possible after injury.
  • Limited or crutch-assist weight bearing is advisable until emergency department (ED) or physician evaluation has occurred.
  • Chronic complaints can be evaluated in a physician's office rather than an ED.
ED Treatment
  • Evaluation of acute injury to the foot in the ED includes AP, lateral, and oblique plain radiographs. Good neurovascular status must be verified, as compartment syndrome can occur with a forefoot crush injury. The need for closed or open reduction is then assessed. Multiple metatarsal fractures with more than 4 mm of displacement or an apical angulation of the metatarsal head of more than 10° on the lateral view could require open/closed reduction to ensure a normal weight-bearing position of the metatarsal head.
  • Open reduction of metatarsal, phalangeal, and MTP joint injuries can cause scarring and stiffness in addition to the original trauma. It is used to largely to maintain a plantigrade foot for normal weight bearing. An open fracture requires surgical intervention for debridement and stabilization.
  • Nondisplaced fractures of the metatarsal neck and shaft may be treated with a short leg cast, fracture brace, or a cast shoe. Weight bearing is permitted as tolerated on discharge from ED. The minimum amount of immobilization necessary for comfort should be used. Fractures at the base of the 5th metatarsal may be treated with an ankle stirrup brace, cast shoe, or fracture brace to maintain comfort.
Medication
  • Depending on the severity of the injury, NSAIDs are a 1st-line drug to treat pain.
  • Acetaminophen is also used.
  • More severe pain may require narcotic pain relief.
First Line
  • NSAIDs
  • Acetaminophen
Second Line
  • Oral low- to mid-potency narcotics such as hydrocodone, codeine, or propoxyphene
  • Tramadol is also an option.
Additional Treatment
  • Proximal 5th metatarsal avulsion fracture (pseudo-Jones Fx):
    • Mechanism is usually due to an acute inversion injury to the ankle in plantar flexion. This can cause avulsion of the peroneus brevis or lateral plantar aponeurosis at the metatarsal tuberosity. May be a stress injury. They tend to be nondisplaced and experience relatively rapid union with symptomatic treatment. More distal injuries (without being a Jones Fx) may require short leg casting with nonweight-bearing (NWB) status for up to 6–8 wks. Use open reduction/internal fixation (ORIF) for delayed union or nonunion, significant displacement, or if cuboid 5th metatarsal joint involved.
  • Jones fracture (proximal shaft of 5th metatarsal):
    • The metaphyseal/diaphyseal junction is a watershed zone for blood flow and is susceptible to delayed union or nonunion. Consider ORIF in higher-level athletes primarily and if nonunion occurs. Treat initially with short leg cast/fracture brace with no weight bearing until evidence of bony callus formation is seen. Progress to weight bearing at that point. May present with preinjury symptoms similar to stress fracture exacerbated by inversion injury.
  • Spiral fracture of 5th metatarsal:
    • This is typically treated nonsurgically with a fracture brace or cast shoe. Weight bearing is allowed as tolerated. Radiographic healing may take up to 12 wks. Called a “dancer's fracture” when it occurs in the distal part of the bone.
Referral
  • Multiple metatarsal fractures
  • Single metatarsal fracture with >4 mm of displacement
  • Single metatarsal fracture with >10° of dorsal angulation of distal segment
  • Possible compartment syndrome
  • Displaced/comminuted fracture of the 1st metatarsal
  • Open fracture
  • Proximal 5th metatarsal fracture nonunion after 12 wks of conservative care
Surgery/Other Procedures
  • Proximal 5th metatarsal Fx/Jones Fx: ORIF with malleolar screw Kirschner wires.
  • Bone grafting may be required in nonunions.
  • Lisfranc fracture/dislocation: Involves 2nd through 5th MTC joints. ORIF with cortical screws and kirschner wires
In-Patient Considerations
  • Metatarsal fractures rarely require inpatient care.
  • Open fractures and multiple traumatic injuries that include a metatarsal likely require IV antibiotics and observed care.
Ongoing Care
  • Upon discharge from the ED or after initial diagnosis, a patient with a metatarsal fracture should be seen in the office for follow-up radiographs in 1 wk to document correct bony alignment and adequacy of the treatment mode. Assuming radiographs show stability, follow-up films can be obtained at 6 wks, when full healing should be expected.
  • The least-limiting form of immobilization should be considered. With the exception of a Jones fracture, most metatarsal fractures tolerate weight bearing with use of a cast shoe/wooden-soled shoe fairly quickly, if not at the time of diagnosis. If fracture brace/CAM boot use is required initially, transition to a stiff-soled or cast shoe should be considered when tolerated. A steel shank insert into a gym shoe may also be used.
  • Restriction from full weight-bearing stress without protection should continue for at least 4 wks for a stress fracture and for 4–6 wks for a nondisplaced metatarsal fracture. Pain to palpation and forefoot swelling should subside as the fracture heals. Evidence for radiographic healing, resolution of edema, and pain-free direct palpation are needed for return to sports.
  • Jones fracture:
    • Once diagnosis is made, an NWB fracture brace/cast is used for 6 wks to allow for healing to occur. Repeat radiographs are done at this point to assess progress, but up to 12 wks may be needed. Nonunions at 12 wks may require ORIF. The decision to pursue ORIF for a Jones fracture in a competitive athlete may occur at the time of initial diagnosis.
Patient Education
The patient should be advised to:
  • Elevate the leg frequently to minimize forefoot edema
  • Use ice up to 20 min/hr to control swelling
  • Notify the physician if there is any significant increase in pain/swelling during the recovery process
  • Reduce their activity level to remain pain-free and use stiff-soled shoe for all weight-bearing activity until healing is complete
Prognosis
Good
Complications
  • Nonunion
  • Malunion with painful plantar calluses under the metatarsal head
  • Dorsal corns secondary to friction over prominent metatarsal head
Additional Reading
Brockwell J, Yeung Y, Griffith JF. Stress fractures of the foot and ankle. Sports Med Arthrosc. 2009;17:149–159.
Garrick JG. Athletic foot disorders. Orthopedic knowledge update-sports medicine, 3rd ed. American Academy of Orthopedic Surgeons. 2004:249–261.
Goulart M, O'Malley MJ, Hodgkins CW, et al. Foot and ankle fractures in dancers. Clin Sports Med. 2008;27(2):295–304.
Greene WB. Ed., Essentials of Musculoskeletal Care, 2nd ed. American Academy of Orthopedic Surgeons, 2001:453–455.
Judd DB, Kin DH. Foot fractures frequently misdiagnosed as ankle sprains. Am Fam Physician. 2002;66(5):785–794.
Kaeding CC, Yu JR, Wright R, et al. Management and return to play of stress fractures. Clin J Sport Med. 2005;15(6):442–447.
Koval KJ. Orthopedic Knowledge Update 7 2002 American Academy of Orthopedic Surgeons. Chapter 45 Ankle and Foot: Pediatric Aspects pgs 537–545, Chapter 46 Ankle and Foot: Trauma pgs 547–563.
Koval KJ, Zuckerman JD. Handbook of Fractures 2nd Ed. Lippincott Williams & Wilkins; 2002:267–287, 402–406.
Meardon SA, Edwards B, Ward E, et al. Effects of custom and semi-custom foot orthotics on second metatarsal bone strain during dynamic gait simulation. Foot Ankle Int. 2009;30:998–1004.
Ribbans WJ, Natarajan R, Alavala S. Pediatric foot fractures. Clin Orthop Relat Res. 2005;(432):107–115.
Safran MR, McKeag DM, Van Camp SP. The foot. Manual of Sports Medicine. Lippincott-Raven Publishers. 1998:476–486.
Codes
ICD9
  • 825.0 Fracture of calcaneus, closed
  • 825.20 Fracture of unspecified bone(s) of foot (except toes), closed
  • 825.21 Fracture of astragalus, closed


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