Stress Fracture Sites Related to Underlying Bone Health in Athletic Females Robert G. Marx, MD, MSc, Deborah Saint-Phard, MD, Lisa R. Callahan, MD, Jaime Chu, and Jo A. Hannafin, MD, PhD Women’s Sports Medicine Center, Hospital for Special Surgery, New York, New York, U.S.A. Objective: The study tested the hypothesis that females who sustain stress fractures of cancellous bone have decreased bone density. Design: A retrospective, controlled, cross-sectional study. Setting: The setting of the study was a tertiary care center for Women’s Sports Medicine. Patients: 20 female patients under the age of 40 who had suffered a stress fracture and who had a positive diagnostic study (radiograph, bone scan, or magnetic resonance imaging) were included in the study. Interventions: Patients who had a positive diagnostic study (radiograph, bone scan, or magnetic resonance imaging) for the diagnosis of stress fracture also underwent dual energy X-ray absorptiometry (DEXA) scans. Main Outcome Measure: Bone density measured by the DEXA scan, as defined by the World Health Organization cri- teria for osteopenia (greater than one standard deviation from the standard age-matched control). Results: 8 of 9 patients with cancellous stress fractures had DEXA scans indicating osteopenia while only 3 of 11 patients with stress fractures of cortical bone had a scan indicating osteopenia (p  0.01). Conclusions: A cancellous stress fracture in a female may be a warning sign of early onset osteopenia. We recommend that young females who have documented stress fractures of cancellous bone or cortical bone (with risk factors for osteo- penia) undergo bone density evaluation. Key Words: Fracture—Stress—Female—Bone Density. Clin J Sport Med 2001;11:73–76. INTRODUCTION It has long been recognized that moderate exercise is a positive factor in bone health. However, exercise- related injury to bone may occur, frequently in the form of stress fractures. 1–3 In the female athlete, stress frac- tures have been reported in a wide variety of sports, especially running, gymnastics, and track and field. 4–6 The most commonly described sites for stress fracture are cortical ones, including the shaft of tubular bones such as the tibia, the metatarsals, and less commonly, the femoral shaft. Stress fractures have also been described in areas of cancellous bone, such as the femoral neck, pelvis, and sacrum. At our center, we began to question whether an association existed between location of stress fracture (i.e., cortical or cancellous) in the female athlete and underlying bone health. This query grew in part from our familiarity with the female athlete triad, a term re- cently coined to describe the association of disordered eating, amenorrhea, and osteoporosis in young athletic women. 7–13 In the athlete suffering from disordered eating, includ- ing low calcium intake, the menstrual cycle abnormali- ties are one of the first changes. These lead to low es- trogen levels and subsequent changes in bone mineral density. 14,15 This premature bone loss is likely related to decreased estrogen levels and may not be reversible. 8 Postmenopausal osteoporosis, which is also related to decreased estrogen, affects primarily areas of cancellous bone, as opposed to cortical bone. We hypothesized that patients who were suffering stress fractures of cancellous bone had a lower bone mineral density than those suf- fering stress fractures of cortical bone, and we began obtaining dual energy X-ray absorptiometry (DEXA) scans 16 for these patients. METHODS We retrospectively identified all patients who were seen at our Women’s Sports Medicine Center with a diagnosis of stress fracture. To ensure that the study was specific for stress fractures, only patients who had a posi- tive diagnostic study (radiograph, bone scan, or magnetic resonance imaging [MRI]) as well as a DEXA scan were included. 17 Chart review, carried out over a 2-month pe- riod, indicated that patients with stress fractures were generally referred for DEXA scan if they were deemed to be at high risk of osteopenia. Patients were believed to be at high risk if they had a history of multiple stress frac- Received December 20, 2000; accepted February 14, 2001. Address correspondence and reprint requests to Deborah Saint-Phard, MD, Women’s Sports Medicine Center, Hospital for Spe- cial Surgery, 535 East 70th Street, New York, NY 10021, U.S.A. E-mail: saintphardd@hss.edu Clinical Journal of Sport Medicine, 11:73–76 © 2001 Lippincott Williams & Wilkins, Inc., Philadelphia 73