Stress fractures of the lower extremity

Causes and the Female Athlete Triad

Stress fractures are rooted in an imbalance between bone micro-damage and its repair. Normally, cyclic loading (such as running) induces microfractures that subsequently heal through the coordinated action of osteoclasts and osteoblasts. If the load is excessive, microtraumas coalesce into a full fracture.

In young female athletes, this process is frequently exacerbated by the female athlete triad (Female Athlete Triad), which comprises:

• Energy deficiency: caloric deficit, sometimes associated with eating disorders (anorexia nervosa, bulimia).
• Menstrual irregularities: ranging up to amenorrhea due to dropping estrogen levels.
• Decreased bone mineral density: osteoporosis or its precursors.

Energy deficiency and low estrogen disrupt normal bone remodeling, rendering the bone fragile.

Clinical presentation and examination

There is no history of acute trauma. The patient typically reports gradually worsening pain that began a few weeks after a sharp increase in training volume. Pain is clearly correlated with impact loading and resolves at rest.

Physical examination often reveals no specific signs. Local tenderness or swelling may be present. To clarify the localization, clinicians use:

• Three-point fulcrum test (3-point fulcrum test) — to detect femoral shaft fractures.
• Calcaneal squeeze test (calcaneal squeeze test) — when calcaneal injury is suspected.

The physician also assesses BMI (high risk if below 17.5 kg/m²) and looks for indirect signs of malnutrition: fine lanugo hair (lanugo), knuckle scars, enlarged parotid glands, bradycardia, and hypotension.

Laboratory and instrumental diagnostics

A comprehensive evaluation includes assessment of all components of the triad:

1. Laboratory tests: pregnancy test, electrolyte panel (screening for hypokalemia/hyponatremia), and hypothalamic-pituitary-adrenal axis function (LH, FSH, prolactin, TSH).
2. Densitometry (DXA): essential for assessing bone mineral density. A Z-score < -1.0 in an athlete is a red flag.
3. Diagnostic Imaging:
4. Radiography: ineffective in early stages. Later, cortical lucency, thickening, periosteal reaction, or, less commonly, the fracture line itself may be observed.
5. MRI: visualizes bone marrow edema and a distinct fracture line (occult fractures).
6. Technetium bone scintigraphy: demonstrates focal radiotracer uptake at the fracture site.

What else to study on this topic

• Pathophysiology of bone remodeling: balancing osteoclast and osteoblast activity
• Eating disorders in female athletes: diagnosis and consequences
• Hormonal profile in the female athlete triad
• Technique for performing the three-point fulcrum test and the calcaneal squeeze test
• Interpretation of densitometry (DXA) results in young patients

Other topics in the "Specialized Adult Traumatology" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.