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INVITED COMMENTARY

Osteoporosis in a Female Cross-country Runner with Femoral Neck Stress Fracture

Cooper, Leslie MD*; Joy, Elizabeth A. MD

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Current Sports Medicine Reports: December 2005 - Volume 4 - Issue 6 - p 321-322
doi: 10.1097/01.CSMR.0000306293.64954.93
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Introduction

Osteoporosis is a common finding in postmenopausal women. In premenopausal women it can be seen in conjunction with the female athlete triad. The female athlete triad is a continuum of disordered eating, menstrual dysfunction, and low bone mineral density. Endurance athletes and athletes in aesthetic-type sports such as gymnastics, diving, and dance, develop the female athlete triad after attempting to maintain low weights to become more competitive in their respective sports. Many cases of the female athlete triad are identified by the physician after the patient develops stress fractures. This case demonstrates the importance of screening for all components of the female athlete triad in any woman who develops a stress fracture.

Case Report

An 18-year-old female cross-country runner with history of recent left femoral neck stress fracture was discovered at University of Utah preparticipation physical to have a history of amenorrhea and no previous dual-energy x-ray absortiometry (DEXA) scan. She began having severe-left sided hip pain beginning in May of 2004. She went to see her primary care physician who ordered a left hip radiograph that showed a femoral neck stress fracture. She was referred to a sports medicine primary care physician who ordered an MRI, which showed an incomplete compression side fracture of the femoral neck. She was treated conservatively with non–weight-bearing status for 6 weeks. At 6 weeks the fracture demonstrated signs of healing and she was allowed to bear weight. Around this time she began college and had her preparticipation physical for the cross-country team. During the preparticipation physical she was found to have had an 8-month history of amenorrhea during her junior year in high school after a 15-pound weight loss during that year. She slowly regained the weight over her senior year and her periods began to regulate. She had approximately four to six periods during her senior year of high school. Because of her menstrual irregularities her primary care physician started her on a birth control pill from February 2004 to April 2004. After having 2 months of normal periods her primary care physician took her off of the oral contraceptives to see if her periods would resume. At that time her periods were regulated. She denies any current history of eating disorder, anorexia, or bulimia. She began her menses at age 15. She also had a history of bilateral stress fractures of the feet.

On examination she was 64 inches tall and currently weighed 120 lbs (body mass index [BMI] = 20.6). Her HEENT (head, eyes, ears, nose, throat) examination showed normal sclera, no parotid hypertrophy, moist mucous membranes, and no abnormal erosion of tooth enamel. Skin examination demonstrated no lanugo, dryness, or bruising. Her knuckles did not demonstrate any calluses. Her cardiac examination demonstrated regular rate and rhythm without any murmurs. Her breast examination showed no evidence of atrophy or abnormal discharge. Her musculoskeletal examination demonstrated a normal gait without a limb. She had no pain with palpation over her greater trocanter or pelvis. She had normal pain-free range of motion of her hip. She had a negative log roll test result. She had a negative hop test result. The rest of her preparticipation physical was negative.

Because of her history of amenorrhea and weight loss a DEXA was ordered. Her lumbar anteroposterior view (L1, L2, L3, L4) showed a t-score = -2.8, Z-score = -2.6; her lumbar spine lateral view (L2, L3, L4) showed a t-score = -2, Z-score = n/a; and her right proximal femur showed a t-score = -1.4, Z-score = n/a. Her treatment was calcium 1500 mg/d and vitamin D 800 IU/d. She also had counseling with a nutritionist who specialized in eating disorders and she was monitored carefully for eating disorders, weight loss, and overtraining. There was no further treatment with hormone replacement therapy as she was since menstruating normally.

She participated in spring track season without pain, maintaining weight, and normal menstrual function. In early summer, she became amenorrheic again, took oral contraceptives for 1 month, and did not refill the prescription, having lost it. She has not had another menstrual period since then. She presented for her fall preparticipation evaluation in August 2005, at which time her weight was 118 lbs (BMI = 20). She was having no pain in the low back, hip, or pelvis. She plans to restart oral contraceptives. She will undergo repeat testing of her bone mineral density in Fall 2007.

Discussion

This case demonstrates the importance of screening for amenorrhea and disordered eating when seeing a female patient with a stress fracture. The case also demonstrates the importance of not only asking about current menstrual history and weight, but to ask about previous menstrual history and weight. It also elaborates the importance of obtaining a DEXA scan on any patient with a history of a stress fracture and any history of amenorrhea.

Osteoporosis is a very important cause of long-term morbidity and mortality for young women in sports. Osteoporosis is a skeletal disorder that is characterized by compromised bone strength predisposing a person to an increased risk of fracture [1]. This case shows that even a short history of menstrual dysfunction can result in significant bone mineral density loss. Because of the fact that 90% of a women's peak skeletal mass is deposited by age 18, this can significantly disable this person and predispose them to stress fractures and insufficiency fracture for the rest of their life [2].

Early bone health is an important determinant of future osteoporosis. Chronic malnutrition, inactivity, and menstrual disturbances can cause significant disturbances in attaining peak bone mass. Menstrual history has been found to be a significant predictor for bone mineral density in the lumbar spine as well as the hip [3]. Femoral neck stress fractures are very commonly associated with bone mineral density loss. The treatment of hypothalamic-hypoestrogenic amenorrhea should involve appropriate nutrition leading to a positive energy balance with eventual resumption of menses. Low body weight should also be avoided. In this case, the athlete had resumed her menses, thus already re-establishing a positive energy balance. She had also regained her weight loss. The most important treatment for this runner is to prevent the weight loss and loss of menstrual function from happening again. The athlete was monitored carefully through the season and is well educated about the condition.

Conclusions

In conclusion, screening female athletes with a history of a stress fracture for all components of the female athlete triad is very important. It is also important to obtain both a good current history of weight and menstrual function, as well as the past medical history. In this case asking about the current history only would have potentially missed the important diagnosis of osteoporosis.

References

1. NIH consensus panel: Osteoporosis prevention, diagnosis, and therapy.JAMA 2001, 285:785–795.
2. Pizurki L, Rizzoli R, Caverzasio J, Bonjour JP: Stimulation by parathyroid hormone-related protein and transforming growth factor-alpha of phosphate transport in osteoblast-like cells.J Bone Miner Res 1991, 6:1235–1241.
3. Drinkwater BL, Bruemner B, Chesnut CH: Menstrual history as a determinant of current bone density in young athletes. JAMA 1990, 263:545–548.
© 2005 American College of Sports Medicine