Stress fractures occur with repetitive loading… creating a stress that causes the hard spindles of bone in the foot to fail.
Jim’s 30. He ran cross-country in college and hasn’t done much since. A natural runner, within a week of starting a fitness program, he’s running a mile and feeling good. Two weeks later he kicks it up to 5 miles and at mile 4, begins experiencing pain at the base of the 5th (little toe) metatarsal. X-rays are normal but an MRI shows a stress fracture. Successful treatment is protected weight bearing in a cam walking boot for 6 weeks and no running. Jim was surprised that this happened, but the orthopedic surgeon isn’t.
As this article explains, most commonly stress fractures occur following an abrupt increase in cyclic loading activity (e.g. running).
Joe is 50 and a healthy guy. Halfway to the bathroom in the middle of the night, abrupt pain in the same spot on the foot as Jim. No injury but the metatarsal breaks. An x-ray at the urgent care center the next day is negative but an MRI confirms the same nondisplaced fracture as Jim. Learning this is a stress fracture and assured these are common he is referred to an orthopedic surgeon for follow-up.
Hearing Joe’s history, the orthopedic surgeon appears concerned. He agrees with the urgent care’s diagnosis of a stress fracture, but more importantly labels it “a fragility fracture”. A fracture that occurs without apparent sufficient stress/force. A bone density scan confirms Joe has osteoporosis (thin bones). Subsequent labs document an endocrine disorder that will respond to treatment.
The lesson here: stress fractures are usually benign, but should all be evaluated by an orthopedic surgeon.