title: Patterns of joint damage seen on MRI in early hip osteoarthritis due to structural hip deformities.
abstract: OBJECTIVE
  The aim of this study was to evaluate differences in damage patterns assessed using magnetic resonance imaging (MRI) between hips with femoroacetabular impingement (FAI) and developmental dysplasia of the hip (DDH) as well as to correlate MRI findings with delayed Gadolinium enhanced MRI of cartilage (dGEMRIC) and with patient pain.
  
  
  METHODS
  This retrospective study included 40 patients (mean age 28.6 ± 11.2 years) who underwent dGEMRIC and morphological MRI of the hip. Twenty-one hips with FAI and 19 with DDH were investigated. A self-developed morphological grading (MRI score) and dGEMRIC evaluation were done on seven radial reformats obtained from an isotropic 3D True-fast imaging with steady state precession (FISP) sequence and an isotropic T1-mapping sequence. The observed damage patterns were summed up into sub-scores and a total MRI score.
  
  
  RESULTS
  Labrum damage, paralabral cysts, and acetabular rim bone cysts were more common in DDH patients than in FAI patients. No significant differences were seen in the occurrence of cartilage damage, bone cysts, or osteophytes. In DDH (but not in FAI), the dGEMRIC index demonstrated a tendency for lower values in areas next to cartilage defects. There was no association between labrum damage and dGEMRIC index. A moderate correlation was seen between Western Ontario and McMaster Universities (WOMAC) pain score and cartilage damage, paralabral cysts, and the total MRI score.
  
  
  CONCLUSIONS
  This study confirms a higher prevalence of labrum damage but not cartilage damage in patients with DDH in comparison to patients with FAI. In addition, our data suggests an association of cartilage damage and paralabral cysts with patient reported pain.
authors.affiliation: Department of Orthopaedic Surgery, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: D
authors.initials: D
authors.lastname: Stelzeneder
authors.forename: T C
authors.initials: TC
authors.lastname: Mamisch
authors.forename: I
authors.initials: I
authors.lastname: Kress
authors.forename: S E
authors.initials: SE
authors.lastname: Domayer
authors.forename: S
authors.initials: S
authors.lastname: Werlen
authors.forename: S D
authors.initials: SD
authors.lastname: Bixby
authors.forename: M B
authors.initials: MB
authors.lastname: Millis
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000077:Acetabulum / Q000473:pathology; D000293:Adolescent; D000328:Adult; D001845:Bone Cysts / Q000209:etiology; D002358:Cartilage, Articular / Q000473:pathology; D005260:Female; D057925:Femoracetabular Impingement / Q000150:complications* / Q000473:pathology; D006618:Hip Dislocation, Congenital / Q000150:complications* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000209:etiology* / Q000473:pathology; D054850:Osteophyte / Q000209:etiology; D010146:Pain / Q000209:etiology; D010147:Pain Measurement / Q000379:methods; D012189:Retrospective Studies; D012720:Severity of Illness Index; D055815:Young Adult