title: Obesity is associated with greater valgus knee alignment in pubertal children, and higher body mass index is associated with greater variability in knee alignment in girls.
abstract: OBJECTIVE
  In adults, osteoarthritis (OA) is associated with obesity and knee alignment. Whether knee alignment differences develop during childhood and are associated with obesity is unknown. We assessed the distribution of knee alignment in children and adolescents, and determined how knee alignment differs between obese and nonobese children.
  
  
  METHODS
  This cross-sectional study examined knee alignment in 155 healthy weight and 165 obese subjects. Knee alignment [metaphyseal-diaphyseal angle (MDA) and anterior tibiofemoral angle (ATFA)] and fat mass were measured using whole body dual-energy X-ray absorptiometry (DEXA). National reference data were used to generate age- and sex-specific body mass index (BMI, kg/m(2)) Z-scores. Multivariable linear regression was used to identify independent factors associated with ATFA and MDA.
  
  
  RESULTS
  The mean MDA and ATFA were similar between obese and nonobese subjects. In stratified analyses, females had greater variability in MDA and ATFA values (p < 0.001 and p = 0.04, respectively) at higher BMI Z-scores. Compared with healthy weight controls, obese subjects had less valgus of the MDA prior to the onset of puberty (+ 2.0°, p = 0.001), but had greater valgus at later pubertal stages (-1.9°, p = 0.01).
  
  
  CONCLUSIONS
  We found significantly greater variability in knee alignment among females at higher BMI Z-scores, and greater valgus alignment in obese adolescents in late puberty. The major limitation is the use of DEXA for assessment of alignment, which needs validation against longstanding radiographs. Longitudinal studies are needed to determine whether childhood obesity is a risk factor for progressive malalignment that may predispose to pain and risk of early osteoarthritis.
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine. sharon.bout-tabaku@nationwidechildrens.org.
authors.forename: Sharon
authors.initials: S
authors.lastname: Bout-Tabaku
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine.
authors.forename: Justine
authors.initials: J
authors.lastname: Shults
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine.
authors.forename: Babette S
authors.initials: BS
authors.lastname: Zemel
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine.
authors.forename: Mary B
authors.initials: MB
authors.lastname: Leonard
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine.
authors.forename: Robert I
authors.initials: RI
authors.lastname: Berkowitz
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Stettler
authors.affiliation: From the Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital; the Ohio State University College of Medicine, Columbus, Ohio; Department of Pediatrics, Division of Rheumatology, Division of Gastroenterology and Nutrition, Division of Nephrology, The Children's Hospital of Philadelphia; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; the Lewin Group, Falls Church, Virginia, USA.S. Bout-Tabaku, MD, MSc, Assistant Professor, Department of Pediatrics, Division of Rheumatology, Nationwide Children's Hospital, and the Ohio State University College of Medicine; J. Shults, PhD, Associate Professor of Biostatistics, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, B.S. Zemel, PhD, Professor of Pediatrics, Department of Pediatrics, Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine; M.B. Leonard, MD, MSCE, Professor of Pediatrics, Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine; R.I. Berkowitz, MD, Professor of Psychiatry, University of Pennsylvania School of Medicine; N. Stettler, MD, MSCE, Managing Consultant, the Lewin Group; J.M. Burnham, MD, MSCE, Associate Professor of Pediatrics, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, and the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine.
authors.forename: Jon M
authors.initials: JM
authors.lastname: Burnham
mesh_terms: D000293:Adolescent; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D009765:Obesity / Q000150:complications / Q000000981:diagnostic imaging*; D020370:Osteoarthritis, Knee / Q000150:complications / Q000000981:diagnostic imaging*; D011859:Radiography; D012307:Risk Factors; D055815:Young Adult
keywords: DUAL X-RAY ABSORPTIOMETRY; OBESITY; OSTEOARTHRITIS; PEDIATRIC; VALGUS; VARUS