A displaced stress fracture of the femoral neck in an adolescent female distance runner with female athlete triad: A case report
© Okamoto et al; licensee BioMed Central Ltd. 2010
Received: 10 November 2009
Accepted: 5 March 2010
Published: 5 March 2010
This report presents a case of a displaced stress fracture of the femoral neck in an adolescent female distance runner with amenorrhea. Both reduction and internal fixation were performed early after the injury. At 24 months postoperatively, magnetic resonance imaging and bone scintigraphy showed no positive signs of femoral head necrosis and bone union was confirmed on plain X-ray. A medical examination for the presence of the signs of the female athlete triad by checking weight, calorie intake and menstrual cycles is most important to prevent such stress fractures. Athletes as well as their coaches or parents therefore need to understand female athlete triad.
Stress fractures of the limbs frequently occur in adolescent female distance runners who develop amenorrhea, an eating disorder, and osteopenia, the so-called "female athlete triad" . While most stress fractures are found in the tibia, they can rarely occur in the femoral neck. This report presents a case of a displaced stress fracture of the femoral neck in an adolescent female distance runner with "female athlete triad". To the authors' knowledge, this is the first case report that untreated female athlete triad caused a displaced stress fracture of the femoral neck in an adolescent female distance runner.
Serum biochemistry profile FSH, LH and estradiol, were all relatively decreased, indicating pituitary dysfunction.
Stress fractures occur due to repetitive cyclical loading to the same bone site, in contrast to traumatic fractures caused by external force. A stress fracture is the usual injury seen in athletes, particularly in long distance runners. Stress fractures primarily affect the lower extremities , with involvement of the tibia in 49%, the tarsals in 25%, and the metatarsals in 8.8% . A femoral neck stress fracture is a rare injury (approximately 1%) , and there have been few reports of displaced type femoral neck stress fractures. The primary presenting symptom of a femoral neck stress fracture is usually anterior groin pain. The pain is often exacerbated by training, such as jogging or running, and is relieved by rest. The current case had all of these symptoms.
Exercise-induced amenorrhea was thought to be a normal part of high-intensity training in 1980, and that once stressful training was discontinued, the menstrual cycle would return to normal . However, some female athletes with amenorrhea also have an eating disorder and osteopenia. The American College of Sports Medicine first defined the female athlete triad in 1992, which includes an eating disorder, amenorrhea, and osteoporosis, and stressed that the three components of the triad were associated . One of the mechanisms that is thought to occur in these patients is suppression of the hypothalamic-pituitary-ovarian axis secondary to hypothalamic dysfunction [9, 10]. Hypothalamic pulsatile release of gonadotropin releasing hormone (GnRH) decreases both with excessive dieting, which the athlete considers necessary to optimize performance, and the psychological stress caused by external forces, such as coaches, teammates, and parents. Subsequently, the reduced secretion of luteinizing hormone (LH) and follicular stimulating hormone (FSH) from the pituitary gland leads to ovarian suppression, which in turn can lead to hypoestrogenism. The current patient had her caloric intake restricted by her coach since junior high school to optimize her performance and she was under added pressure due to worries about her athletic ranking, her times, and the expectations of others. The mean BMI of an adolescent female athlete has been reported 21.6 or 20.1 [11, 12]. Her BMI was relatively low in comparison to these reports. Her FSH was 3.0 mIU/ml, and her LH was 2.1 mIU/ml, which indicated suppression of secretion from the pituitary gland, and her estradiol was 39.4 pg/ml, which indicated ovarian suppression. These results suggest that hypothalamic dysfunction due to physical and psychological factors cause primary amenorrhea.
A long-term hypoestrogenic state due to untreated amenorrhea decreases bone mineral density, which can predispose the patient to stress fractures of the femoral neck or vertebral bodies . The stress fracture in the current patient might have been due to hypoestrogenic state since her the amenorrhea had not been treated even though she had not yet reached menarche at the age of 17 years.
In contrast to the insufficiency fractures seen in postmenopausal women, stress fractures in female athletes frequently occur in the cortical bone of the lower limbs rather than in the cancellous bone . This suggests that osteopenia occurs in the cortical bone in female athletes. The femoral neck stress fracture in this patient may have arisen as the result of a different mechanism than that seen in postmenopausal osteoporosis, since an X-ray of the right femoral neck showed no bone atrophy and the BMD of the cancellous bone was also in the normal range.
Sustained low calorie intake in young athletes undergoing excessive training may pose a risk of increased muscular fatigue, and reduced muscular support of the long bones of the lower extremity . The patient in this report sustained her injury nine days before a prefectural track meet; thus, the muscle fatigue of lower limbs caused by an increase in her training schedule before the meet may have also contributed this fracture.
The fundamental treatment for female athlete triad is weight restoration and a decrease in exercise compatible with energy intake or an associated increase in caloric intake . Hormone replacement therapy (HRT) is often used for the treatment for hypothalamic amenorrhea, however, the effectiveness of HRT on bone mineral density remains controversial [17–19]. HRT in these younger athletes is not routinely recommended. However, a female over the age of 16 with hypothalamic amenorrhea should be given estrogen supplementation . HRT should be administered after bone growth is complete in younger amenorrheic athletes . If a normal menstrual cycle cannot be obtained after an increase in body weight and bone maturation, HRT may thereafter be recommended.
A displaced fracture of the femoral neck leads to a 60% reduction in the patient's activity level in sport and a 30% incidence of avascular necrosis . Magnetic resonance imaging and bone scintigraphy showed no positive signs of femoral head necrosis and bone union was confirmed on plain X-ray in the current patient. Furthermore, the patient returned to her same athletic level prior to injury at 24 months postoperatively, with no clinical symptoms. However, this patient will be needed follow up in the future due to the femoral head necrosis after the femoral neck fracture.
A medical examination for the presence of signs of the female athlete triad by the checking weight, calorie intake and menstrual cycles is crucial to prevent such stress fractures. Athletes as well as their couches or parents need to understand female athlete triad. The fundamental treatment for female athlete triad is to decrease intense exercise and increase daily calorie intake. HRT may be recommended in an athlete in whom the normal menstrual cycle is not restored after an increase in body weight and bone maturation.
Adolescent female distance runners with amenorrhea or eating disorders are may therefore tend to suffer stress fractures of general bones. In particular, a displaced stress fracture of the femoral neck may cause an irreversible disability, such as femoral head necrosis. A medical examination to check the weight, calorie intake and menstrual cycles is important to prevent such injuries. Athletes as well as their coaches or parents need to understand the female athlete triad.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images.
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