OR11-5 Hip Structural Analysis in Adolescent and Young Adult Oligo-amenorrheic and Eumenorrheic Athletes and Non-athletes

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: OR11-Pediatric Endocrinology
Saturday, June 15, 2013: 11:30 AM-1:00 PM
Presentation Start Time: 12:30 PM
Room 104 (Moscone Center)
Kathryn Elizabeth Ackerman*1, Lisa Pierce1, Gabriela Guereca1, Meghan Slattery1, Mark Goldstein2 and Madhusmita Misra1
1Massachusetts General Hospital/Harvard Medical School, Boston, MA, 2Masschusetts General Hospital
Background:  Stress fractures of the foot, tibia and femur are common in endurance athletes. Although studies have described microarchitecture of the distal tibia in athletes, there are few data regarding hip structure and strength in athletes and non-athletes. Hip structural analysis (HSA) using dual energy x-ray absorptiometry (DXA) is a validated technique to assess hip geometry and strength parameters while avoiding the radiation associated with quantitative CT.

Objectives: Our objective was to compare hip geometry and strength estimates in oligo-amenorrheic athletes (AA), eumenorrheic athletes (EA) and non-athletes (NA) using HSA. We hypothesized that AA would have impaired geometry compared with EA.

Methods: We enrolled 55 AA, 24 EA and 23 NA between 14-22 years of normal weight. Athletes ran ≥20 miles/week or were engaged in weight-bearing sports for ≥4 hours/week, whereas NA were not engaged in any organized sports and exercised for <2 hours/week. DXA was used to assess hip bone density and for HSA.

Results: Although subjects were of normal weight, BMI was lower in AA compared with EA and NA (20.1±2.2, 22.4±2.4 and 21.7±2.5 kg/m2, p<0.0001). Groups did not differ for height. Hip Z-scores were lower in AA and NA than EA (p= 0.002).  However, a larger proportion of AA compared with EA and NA had hip Z-scores <-1 (30.9% vs. 4.2 and 17.4%, p=0.01). Reported caloric intake did not differ among groups, however, reported energy expenditure was higher in athletes compared with non-athletes. 25(OH)D levels were highest in AA, followed by EA and NA (p<0.0001). At the narrow neck, trochanteric region and femoral shaft, subperiosteal width, cross sectional moment of inertia (CSMI) (estimate of resistance to bending forces) and section modulus (Z) (index of strength of bending) were higher in EA than NA, whereas AA did not differ from NA. Cross sectional area (CSA) (estimate of resistance to axial forces) was lower in AA and NA than EA. In addition, at the trochanteric region, endocortical width was higher in EA than NA, whereas AA did not differ from NA. Groups did not differ for cortical thickness, buckling ratio and hip axis length. Subjects with hip Z<-1 had lower CSA, CSMI, Z and cortical thickness, and higher buckling ratio at the narrow neck and trochanteric region than subjects with Z>-1, whereas subperiosteal and endocortical width did not differ. On multivariate analysis, after controlling for hip Z-scores, differences persisted between EA and NA for most parameters. Lean mass correlated with most measures of HSA, and differences between groups were lost after adjusting for lean mass.

Conclusions: In an eugonadal state, athletic activity confers benefits at the hip for most geometric parameters independent of areal bone density. This advantage is lost in AA, who do not differ from non-athletes for most parameters, and fare worse than eumenorrheic, estrogen-replete athletes for cross-sectional area.

Nothing to Disclose: KEA, LP, GG, MS, MG, MM

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: This study was supported by NIH grants 1 UL1 RR025758-01 and 1 R01 HD060827-01A1