title: Is the contralateral hip at risk in patients with unilateral symptomatic cam femoroacetabular impingement? A quantitative T1ρ MRI study.
abstract: OBJECTIVE
  To assess the profile of weight-bearing cartilage of hips with a cam deformity using T1ρ magnetic resonance imaging (MRI) and evaluate for a side-to-side difference in the T1ρ profile of patients with bilateral cam morphology but only unilateral hip pain.
  
  
  METHODS
  19 patients with bilateral cam morphology undergoing osteochondroplasty for unilateral hip pain were prospectively recruited. Anterior and anterosuperior alpha angles were measured using computer tomography. All patients underwent bilateral 1.5T T1ρ MRI. The cartilage bilayer of the hip joint was evaluated and the mean T1ρ relaxation time calculated for each quadrant of the weight-bearing surface.
  
  
  RESULTS
  Mean T1ρ relaxation times were not significantly different when each quadrant was compared to the rest of the weight-bearing surface of the symptomatic (P = 0.068) and asymptomatic hips (P = 0.102). There was also no significant side-to-side difference between the same quadrants of symptomatic and asymptomatic hips. No correlation was detected between alpha angle and the mean T1ρ relaxation time in each quadrant. There was no significant difference in mean alpha angles between the symptomatic and asymptomatic sides at the anterior (54.2 vs 56.0°; P = 0.382) and anterosuperior positions (65.1 vs 65.2°; P = 0.971).
  
  
  CONCLUSIONS
  We conclude that previously observed regional variation in T1ρ values of normal hips is altered in hips with cam morphology. No difference in T1ρ values between symptomatic and asymptomatic cam hips was demonstrated. Therefore, regardless of the presence of hip pain, a cam deformity may predispose to hip joint cartilage degradation and increase the risk of hip osteoarthritis.
authors.affiliation: Division of Orthopaedic Surgery, University of Ottawa, Canada. Electronic address: smcguffin@ottawahospital.on.ca.
authors.forename: W S
authors.initials: WS
authors.lastname: McGuffin
authors.affiliation: Department of Medical Imaging, The Ottawa Hospital, Canada; Department of Radiology, University of Ottawa, Canada. Electronic address: gmelkus@ottawahospital.on.ca.
authors.forename: G
authors.initials: G
authors.lastname: Melkus
authors.affiliation: Department of Medical Imaging, The Ottawa Hospital, Canada; Department of Radiology, University of Ottawa, Canada. Electronic address: krakhra@ottawahospital.on.ca.
authors.forename: K S
authors.initials: KS
authors.lastname: Rakhra
authors.affiliation: Division of Orthopaedic Surgery, University of Ottawa, Canada. Electronic address: pbeaule@ottawahospital.on.ca.
authors.forename: P E
authors.initials: PE
authors.lastname: Beaulé
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000209:etiology; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D057925:Femoracetabular Impingement / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016474:Weight-Bearing; D055815:Young Adult
keywords: Cartilage; Femoroacetabular impingement; Hip; Osteoarthritis; T1ρ magnetic resonance imaging