title: Does periacetabular osteotomy for hip dysplasia modulate cartilage biochemistry?
abstract: BACKGROUND
  The aim of periacetabular osteotomy is to improve joint mechanics in patients with developmental dysplasia of the hip. In our study, we tried to determine whether the proteoglycan content, as measured with delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), can be modulated with the alteration of the hip joint biomechanics.
  
  
  METHODS
  In this prospective cohort study, thirty-seven patients (thirty-seven hips) with no or minimal osteoarthritis were treated with periacetabular osteotomy for symptomatic acetabular dysplasia. All patients had preoperative and one-year follow-up dGEMRIC scans. Twenty-eight of the thirty-seven also had two-year scans. The changes in dGEMRIC findings and hip morphology between the preoperative visit and the examinations at one and two years following the periacetabular osteotomy were assessed.
  
  
  RESULTS
  The mean preoperative dGEMRIC index (and standard deviation) was 561.6 ± 117.6 ms; this decreased to 515.2 ± 118.4 ms at one year after periacetabular osteotomy but subsequently recovered to 529.2 ± 99.1 ms at two years postoperatively. The decrease in the dGEMRIC index of the acetabular cartilage after surgery appears to be most pronounced at the superior aspect of the acetabulum, where the decrease in mechanical loading after periacetabular osteotomy would be most pronounced. All domains of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) demonstrated significant improvement from the preoperative to the postoperative visits (all p < 0.001).
  
  
  CONCLUSIONS
  Periacetabular osteotomy for developmental dysplasia of the hip appears to alter the mechanical loading of articular cartilage in the hip, which in turn alters the cartilage matrix composition, as demonstrated by dGEMRIC.
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Hingsammer
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Kalish
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: David
authors.initials: D
authors.lastname: Stelzeneder
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: Sarah
authors.initials: S
authors.lastname: Bixby
authors.affiliation: Department of Orthopaedic Surgery, Inselspital Bern, University of Bern, 3010 Bern, Switzerland.
authors.forename: Tallal Charles
authors.initials: TC
authors.lastname: Mamisch
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: Patricia
authors.initials: P
authors.lastname: Connell
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Millis
authors.affiliation: Department of Orthopaedic Surgery, Child and Adult Hip Program (A.M.H., D.S., P.C., M.B.M., and Y.-J. K.), Clinical Research Program (L.A.K.), and Department of Radiology (S.B.), Boston Children's Hospital, 300 Longwood Avenue, Hunnewell 225, Boston, MA 02115. E-mail address for Y.-J. Kim: young-jo.kim@childrens.harvard.edu.
authors.forename: Young-Jo
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000328:Adult; D002358:Cartilage, Articular / Q000737:chemistry*; D005260:Female; D006617:Hip Dislocation / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010027:Osteotomy / Q000379:methods*; D011446:Prospective Studies; D011509:Proteoglycans / Q000032:analysis*
chemical_list: D011509:Proteoglycans