The female athletic triad has three components: (1) energy deficit, (2) menstrual irregularity, and (3) low bone mineral density. These symptoms exist on a spectrum of severity, but the extreme “textbook” case may be easier to remember: anorexia, amenorrhea, and osteoporosis-related stress fractures. Despite its classification as a “triad,” not all 3 components are necessary to diagnose a clinical problem and initiate treatment.

• Energy Deficit: Sports that require athletes to be “thin” or “light” (such as long-distance running) or have a special emphasis on physical appearance (such as gymnastics or ballet), place athletes at risk for consuming fewer calories than expended, creating “energy deficit.” Importantly, while eating disorders such as anorexia nervosa (severe limitation of caloric intake) and bulimia nervosa (binging and purging) may, in the extreme, be responsible for energy deficit, these conditions do not have to be present to make the diagnosis. “Innocent” over-exercising relative to intake is sufficient.
• Menstrual Irregularity: Normally, the hypothalamic-pituitary-ovarian axis controls release of estrogen and progesterone, leading to regular menstrual cycles approximately every 28 days. In low-energy states, this axis is down-regulated, leading to irregular menstrual cycles (oligomenorrhea) or lack of menstruation (amenorrhea).
• Low Bone Mineral Density: In women, estrogen is the primary mediator of bone remodeling via its effects on osteoblast and osteoclast activity. Low estrogen therefore disrupts bone building, leading to weaker bone. Additionally, athletes at risk typically have low fat mass (a peripheral producer of estrogen) worsening their estrogen deficit. Lastly, low caloric intake can often result in low serum calcium levels (due to low calcium intake). The bones are the body’s primary store of calcium, but metabolic needs are prioritized. This means bones are broken down to increase serum calcium, at the cost of weakening structural integrity.

Clinical Implications

• Stress fractures: The musculoskeletal practitioner most commonly sees the female athlete triad presenting as a stress fracture. The history and physical exam are important diagnostic tools to raise suspicion for a stress fracture, which is often confirmed with diagnostic imaging. For example, Figure 1 below demonstrates a physician performing a heel “squeeze” to detect a calcaneal stress fracture. These fractures are difficult to visualize on standard x-ray; they are best visualized on nuclear bone scan (Figure 2) or CT, MRI (Figure 3).
  

• Osteoporosis: Failure to attain peak bone mass in young adulthood predisposes to osteoporosis and associated problems later in life.
• Eating Disorders: May lead to electrolyte disturbances and malnutrition.
• Psychological: Compelling absence from sport or confronting issues of identity, body image and eating disorders contribute may cause duress.
  
• Infertility: Amenorrhea signals underlying reproductive dysfunction.

Management

• Stress Fractures: Mainstays of treatment include rest and activity modification. Athletes should not return to play until pain and tenderness have resolved after a gradually-progressed increase in athletic activities. Radiologic evidence of healing may also be warranted prior to clearance for athletic participation. Some specific fractures (metatarsal, femoral shaft, and tibia) can be managed with partial weight bearing. Open reduction and internal fixation may be considered in elite athletes who require a faster recovery or for fractures that are at high risk of displacement or nonunion, such as those on the tension side of the femoral neck or on the anterior cortex of tibia.
• Energy Deficit: The energy deficit may be addressed by decreasing the intensity of training and by increasing caloric intake throughout the day. Indeed, augmenting nutrition is a critical component of treatment. Including experts such as dietitians, psychologists in the treatment team may help ensure proper management. .
• Amenorrhea: In theory, with increased caloric intake amenorrhea should resolve as well. However, this may take some time. Gynecology, endocrinology and other specialists should be consulted where appropriate (and that means any time the presentation is beyond the expertise of the provider).

Additional Points to Consider

• The female athlete triad is not abbreviated “FAT,” perhaps due to the fact that this condition is usually seen precisely when fat is absent. Additionally, such a label can be psychologically harmful.
• The use of oral contraceptive pills (OCPs) or other hormonal replacement techniques chosen by many female athletes may confound the symptoms of the triad. For example, OCPs may cause a woman to still bleed monthly without truly ovulating, thus masking this facet of the triad.