Revised Pediatric Reference Data for the Lateral Distal Femur Measured by Hologic Discovery/Delphi Dual-Energy X-Ray Absorptiometry

Zemel, Babette S.; Stallings, Virginia A.; Leonard, Mary B.; Paulhamus, Donna R.; Kecskemethy, Heidi H.; Harcke, H. Theodore; Henderson, Richard C.

doi:10.1016/j.jocd.2009.01.005

« Previous Next »Journal of Clinical Densitometry
Volume 12, Issue 2 , Pages 207-218, April 2009

Revised Pediatric Reference Data for the Lateral Distal Femur Measured by Hologic Discovery/Delphi Dual-Energy X-Ray Absorptiometry

Babette S. Zemel
- Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Address correspondence to: Babette S. Zemel, PhD, Division of GI, Hepatology and Nutrition, The Children's Hospital of Philadelphia, 3535 Market Street, Room 1560, Philadelphia, PA 19104-4399.
Virginia A. Stallings
- Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
Mary B. Leonard
- Division of Nephrology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
Donna R. Paulhamus
- Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
Heidi H. Kecskemethy
- Department of Biomedical Research, A.I. duPont Hospital for Children, Wilmington, DE, USA
H. Theodore Harcke
- Medical Imaging, A.I. duPont Hospital for Children, Wilmington, DE, USA
Richard C. Henderson
- Department of Orthopedics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

Received 29 July 2008; received in revised form 26 January 2009; accepted 26 January 2009. published online 26 March 2009.

Abstract

Lateral distal femur (LDF) scans by dual-energy X-ray absorptiometry (DXA) are often feasible in children for whom other sites are not measurable. Pediatric reference data for LDF are not available for more recent DXA technology. The objective of this study was to assess older pediatric LDF reference data, construct new reference curves for LDF bone mineral density (BMD), and demonstrate the comparability of LDF BMD to other measures of BMD and strength assessed by DXA and by peripheral quantitative computed tomography (pQCT). LDF, spine and whole body scans of 821 healthy children, 5–18yr of age, recruited at a single center were obtained using a Hologic Discovery/Delphi system (Hologic, Inc., Bedford, MA). Tibia trabecular and total BMD (3% site), cortical geometry (38% site) (cortical thickness, section modulus, and strain-strength index) were assessed by pQCT. Sex- and race-specific reference curves were generated using LMS Chartmaker (LMS Chartmaker Pro, version 2.3. Tim Cole and Huiqi Pan. Copyright 1997-2006, Medical Research Council, UK) and Z-scores calculated and compared by correlation analysis. Z-scores for LDF BMD based on published findings demonstrated overestimation or underestimation of the prevalence of low BMD-for-age depending on the region of interest considered. Revised LDF reference curves were generated. The new LDF Z-scores were strongly and significantly associated with weight, body mass index, spine and whole body BMD Z-scores, and all pQCT Z-scores. These findings demonstrate the comparability of LDF measurements to other clinical and research bone density assessment modes, and enable assessment of BMD in children with disabilities, who are particularly prone to low trauma fractures of long bones, and for whom traditional DXA measurement sites are not feasible.