There are 2 different types of metatarsal fractures. Those 2 types of fractures include stress or fatigue fractures
and traumatic fractures.
Metatarsal stress fractures
Metatarsal stress fractures occur as the result of applied load to the bone in an amount, or at a rate, that is greater than the ability of the bone to repair and heal itself. Metatarsal stress fractures are also known as march fractures.
Metatarsal stress fractures are most commonly seen in the second and third metatarsals. Stress fractures are less commonly found in the 4th and 5th metatarsals. Stress fractures of the 1st metatarsal are rare.
Traumatic metatarsal fractures
Each of the metatarsal bones are very strong when load is applied in a usual and customary manner. But
when load is applied in an abrupt or atypical manner, the bone is unable to sustain the load and fractures
(breaks). The central three metatarsals tend to accept load as a group, while the 5th metatarsal often acts independently
of the central 3 metatarsals. As a result, it is not unusual to see several fractures of the central three metatarsals at the same time. Also, the fifth metatarsal shows fracture patterns that are unique to that one specific bone.
Traumatic metatarsal fractures of the central three metatarsals usually occur as the result of a fall. Falls are often forward with the foot fixed and anchored on the ground by an object such as a pallet or hole in the ground. In this case, the foot is unable to roll forward with the body resulting in a fracture of the metatarsal(s). The opposite can also hold true where the foot is fixed but the body falls back, resulting in fracture of one or more of the metatarsals.
Crush fractures of the forefoot often include traumatic fractures of the metatarsals. Crush fractures have no pattern of injury as previously described in the preceding traumatic fractures. Examples of crush fractures would include auto accidents or dropping heavy loads on the forefoot.
Lisfranc’s fractures are fractures of the metatarsal bases. Jacques Lisfranc
was a 19 century French surgeon in Napoleon's army who studied fracture patterns
found when a person fell from a horse and was drug by the horse with their foot
still in the stirrup. This abrupt force resulted in fracture patterns that
would partially or completely dislocate the metatarsal bases from the cuneiform
bones. The most common metatarsal fracture in a Lisfranc's dislocation
would be a fracture of the second metatarsal base.
As mentioned, the 5th metatarsal is unique in that it alone displays a number of fracture patterns not seen in the lesser metatarsals
(2-4). The most common 5th metatarsal fracture is a spiral oblique fracture of the mid shaft of the metatarsal. A recent study found an exceedingly high number of oblique fractures of the 5th metatarsal on Martha’s Vineyard. Subsequently, these fractures have recently been called vineyard fractures. An oblique midshaft fracture of the 5th metatarsal occurs as the result of a mechanism much like a sprained ankle. With the foot slightly adducted (pigeon toed), the body weight is carried over the lateral foot resulting in an unsustainable load applied to the 5th metatarsal.
Jones fractures are fractures of the 5th metatarsal base that occur more than 1 ½ cm distal to the base but are not considered to be mid shaft. Jones fractures are usually transverse and appear on x-ray to be perpendicular to the long axis of the metatarsal. Jones fractures also occur by adduction of the foot and rolling the ankle to carry the body weight over the lateral aspect of the foot.
Avulsion fractures are fractures that occur as the result of a tendon or other structure pulling away from the bone and taking a small piece of bone with it. Avulsion fractures of the 5th metatarsal occur when the peroneus brevis tendon pulls on the base of the 5th metatarsal. The size of the avulsed piece of bone does vary but is typically less than 1 cm in size.
The term dancer’s fracture is applied to a number of different 5th metatarsal fractures. Classically,
the term dancer’s fracture has been used to described a spiral oblique fracture
of the distal 5th metatarsal. Others refer to a dancer’s fracture as an avulsion
fracture or Jones fracture. Due to the ambiguity of the term dancer’s fracture,
it may be best to simply avoid this term when discussing 5th metatarsal
fractures.
Treatment of metatarsal fractures
Metatarsal stress fractures
Diagnosis and treatment of a metatarsal stress fracture requires a high degree of suspicion. X-rays are
and unreliable tool in early metatarsal stress fractures and are not helpful in actually confirming the fracture until 3-4 weeks post onset of symptoms. At this stage, the healing of the fracture
called bone callus, is seen on x-ray. In some cases, stress fractures of the proximal metatarsal cannot be seen at any stage of healing with x-rays. An MRI is needed to determine bone edema, or swelling to confirm the presence of a fracture. An MRI study would be indicated if there was a suspicion of stress fracture that has not responded to 6-8 weeks of conservative care.
Initial treatment of a metatarsal stress fracture include rest,
ice and the use of an anti-inflammatory medication. Limitation of the forefoot while walking can be accomplished with a
fracture shoe or
cam-walker walking cast. Swelling can be compressed with a
forefoot compression sleeve.
The healing of stress fractures can vary. The most common metatarsal stress fracture found at the surgical neck of the metatarsal does tend to heal within 6-8 weeks. Metatarsal stress fractures at more proximal locations in the metatarsal tend to take longer to heal and can take up to 8-12 months become asymptomatic.
It's not uncommon for runners to become frustrated due to the return of symptoms
of a metatarsal stress fracture when increasing activity from walking to
running.
Traumatic metatarsal fractures
Fracture patterns of traumatic metatarsal fractures vary so that conservative and surgical care cannot be consistent in each case. When dealing with fractured bone, the key to decision making hinges upon the apposition and alignment of the fracture. To heal, bone needs to be apposed. It can be apposed but be in bad alignment. The decision as to treating with conservative care
vs. surgical care really hinges on apposition and alignment of the fracture.
Stable metatarsal fractures with good apposition and alignment can typically be
treated with a period of immobilization with casting. Depending upon the nature
of the fracture, casting may be in a walking cast or may require a period of
non-weight bearing in a hard cast. Periodic x-rays are taken to confirm the progress of healing.
Unstable fractures, or those fractures that show evidence on x-ray of poor
apposition or alignment will require surgical correction call ORIF or open
reduction with internal fixation. Techniques vary and may include the insertion
of a screw, straight K wire or plate. Healing of fractures depends upon the
success of the surgery and the stability of the fixation. Most cases of ORIF
will require a period of several weeks non-weight bearing in a hard cast.
The follow images show the ORIF of a distal oblique fracture of the 5th
metatarsal. The first two x-ray images show poor apposition and alignment
of the fracture on x-ray. The second two show post-op correction of the
alignment. Image 1 shows exposure of the fracture. Image two shows
stabilization of the fracture with a K wire. Image three shows the plate
in place and image 4 show final closure. This procedure was done on an
outpatient basis under local anesthesia with sedation. The procedure took
approximately and hour to complete. The post-op course of treatment would
include 6-8 weeks non-weight bearing in a hard cast. The plate will need
to be removed in a second surgery 4-6 months post-op.
The following images show ORIF of an avulsion fracture of the 5th metatarsal.
This particular fracture had initially been treated with casting but failed to
heal. At twelve months post fracture, the ORIF was performed. Pre-op
x-rays show fragmentation of the fracture with evidence of non-union. the
post-op x-rays shows reduction of the fracture with a single 3.5 mm screw.
