Bone is a living tissue, and it responds to stress by making
new bone. When the bone fails to respond adequately to stress, a fatigue
fracture may occur. The stress fracture occurs when the bone fails due to
repetitive small stresses (microtrauma). The fracture can present itself early
on as a minor injury with minor symptoms. If the fracture is not treated
adequately it can become very disabling. A high index of suspicion is necessary
for the diagnosis of stress fractures of the metatarsal bones. In athletes,
there may be localized pain that worsens with progressive activity such as
increased training, increased running mileage, a change in running surface, or
changing shoes. Early on, x-ray may be negative in the majority of patients.
Bone scan or MRI can be used to detect early activity in the bone. Usually the
patient will have vague symptoms. The patient may see different doctors in
order to obtain different opinions. A lot of tests may be done, and a neuroma
or metatarsalgia may be given as a diagnosis. Female athletes who have
decreased bone density and possible eating disorders will have an increased
incidence of stress fracture of the metatarsal bones. Female athletes with
stress fractures should have a complete dietary and menstrual history. There is
a correlation between eating disorders, amenorrhoea, and osteoporosis in female
athletes. This is the common areas for stress fractures of the metatarsal
bones. In runners, the fracture usually occurs in the metatarsal neck. In
dancers, the fracture occurs at the base of the 2nd metatarsal.
Fracture may result in delayed union. Restrict weight bearing for 6 weeks. Look
for anatomic causes of fracture in the 2nd and 3rd
metatarsal neck such as heel cord tenderness, a short 1st
metatarsal, or a long 2nd metatarsal. Check for metabolic bone
disease, osteoporosis, or osteomalacia. Upon physical examination, the patient
will have tenderness, induration, and maybe a mass. They will also have a cavus
foot, and the MRI and bone scan can be helpful. Metatarsal shaft stress
fractures can occur due to the stress of weight bearing or prolonged walking.
The fracture is sometimes called a “march” fracture that occurs in military
recruits and in runners who increase activity levels. It usually occurs in the
2nd metatarsal followed by the 3rd metatarsal in
frequency. The fracture is diaphyseal in location, and there will be localized
tenderness at the fracture site. The 2nd metatarsal is the longest
and most rigid of the metatarsal bones, and it is usually exposed to greater
repetitive stresses. X-rays are usually normal. A bone scan or MRI may be
needed. Fracture of the proximal 5th metatarsal occurs in a
watershed area of the blood supply that is susceptible to stress fracture
nonunion. The blood supply in this area is tenuous. Healing is difficult with a
high incidence of delayed and nonunion. The stress fracture occurs distal to
the 4th and 5th intermetatarsal joint. The Jones fracture is an acute fracture, and
a stress fracture is a chronic condition that will require surgery. There are
three types of fractures at the proximal fifth metatarsal: zone I, zone II, and
zone III. Zone I is a tuberosity avulsion fracture. Zone II is a Jones
fracture. Zone III is a stress fracture. The stress fracture occurs distal to
the ligament that connects the 4th and 5th metatarsal
together. The stress fracture can occur in cavus foot due to increased ground
reaction force over the 5th metatarsal. It will be overloaded on the
lateral border of the foot. There will be dull pain activity related symptoms
before the stress fracture shows up on x-ray. X-rays will show the fracture and
its location. The x-ray will show varying degrees of sclerosis and widening of
the fracture line. Treatment is a lag screw fixation with or without bone
graft.
