Hip structural analysis in adolescent and young adult oligoamenorrheic and eumenorrheic athletes and nonathletes

Abstract

Context: Stress fractures are common in endurance athletes. Whereas studies have described distal tibia bone structure in athletes, there are few data regarding hip geometric parameters. Hip structural analysis (HSA) using dual-energy x-ray absorptiometry is a validated technique to assess hip bone structure.

Objectives: The purpose of this study was to compare hip geometry in young oligoamenorrheic athletes (AAs), eumenorrheic athletes (EAs), and nonathletes using HSA. We hypothesized that AAs would have impaired bone structure compared with that of EAs.

Design: This was a cross-sectional study.

Setting: The setting was a clinical research center.

Subjects: We enrolled 55 AAs, 24 EAs, and 23 nonathletes of normal weight who were 14 to 22 years old. Athletes ran ≥20 miles/wk or were engaged in weight-bearing sports for ≥4 hours/wk.

Main outcome measures: Dual-energy x-ray absorptiometry was used for HSA and hip areal bone mineral density (aBMD).

Results: Hip aBMD Z-scores were lower in AAs and in nonathletes than in EAs (P = .002). A larger proportion of AAs than EAs and nonathletes had hip Z-scores <-1 (30.9, 4.2, 17.4%, P = .01). At the narrow neck, trochanteric region, and femoral shaft, subperiosteal width, cross-sectional moment of inertia, and section modulus were higher in EAs than in nonathletes; values in AAs did not differ from those of nonathletes. Cross-sectional area was lower in AAs and in nonathletes than in EAs. Groups did not differ for cortical thickness or buckling ratio. Group differences were lost after adjustment for lean mass but not aBMD.

Conclusions: In an eugonadal state, athletic activity confers benefits for hip structure independent of aBMD. This advantage is lost in AAs, who do not differ from nonathletes for most parameters and fare worse than EAs for cross-sectional area.

Figure 1.

Cross-sectional area of the narrow neck, trochanteric region, and femoral shaft in athletes and nonathletes. EAs, who are eugonadal, had greater cross-sectional area (a measure of resistance to axial forces) at all regions than nonathletes (NA). In contrast, AAs, who are hypogonadal, did not differ from nonathletes and had lower cross-sectional area than EAs. *P < .05.