STRESS FRACTURES OF THE FOOT

Stress fractures of the foot and ankle are extremely common.  The most common fractured bone is a metatarsal (usually the second or third). Stress fractures however can also occur in cuneiforms, navicular, talus, distal tibia and distal fibula.

The comments below relate to metatarsal stress fractures:

• The patient will complain of pain and swelling on the top of their foot.
• The pain can be excruciating and prevent the patient from walking.

Stress fractures generally occur in two situations:

• They were described in military recruits with normal bone who were marching and overloaded their metatarsals. They were known as “March fractures”.
• They also occur in the presence of low bone density such that normal walking can produce a stress fracture.

Often in the history the patient will report trying to get fit, going to the gym and performing high-impact activity though this is not invariably the case.

A dietary history of the patient is important as certain diets low in calcium can predispose patients to stress fracture.

On examination:

• The patient has swelling on the dorsum of the foot.
• They are usually exquisitely tender to palpation over the affected metatarsal.

Investigations:

• Plain x-rays are always taken but are often normal.
• In the past bone scan was the preferred investigation but these days MRI has superseded bone scan.
• Most often however the diagnosis is clinical.
• An MRI scan is not usually indicated.

Recommended treatment:

• Resting the affected foot is the mainstay of treatment.
• If the patient is in excruciating pain then crutches nonweight bearing for two weeks
• However, if the patient is not in excruciating pain then rest in a short walking boot for 3-4 weeks. The boot ought to be taken off to shower, to go to bed and to move the patients foot up-and-down a hundred times a day to prevent a DVT.
• I will generally follow the patient up with a further x-ray a month to 6 weeks later. This x-ray will often show callus and confirm the diagnosis.
• If I am in doubt about the diagnosis then an MRI scan is indicated.

Return to activity:  once the stress fracture has healed any biomechanical anomalies in the foot should be corrected with a change of shoes and orthotics. I also suggest to the patients that they mix up their training regime to include cycling and swimming i.e. low-impact sports.

If there is a question of low bone density then the patient will need a bone density assessment with blood tests and a scan. The blood tests recommended are calcium, phosphate, parathyroid hormone, 25 hydroxy vitamin D, an MBA 20 and a spot urinary DPD/creatinine.