title: The Otto Aufranc Award. On the etiology of the cam deformity: a cross-sectional pediatric MRI study.
abstract: BACKGROUND
  Femoroacetabular impingement (FAI) has been recognized as a common cause of hip pain as well as a cause of hip arthritis, yet despite this, little is known about the etiology of the cam morphology or possible risk factors associated with its development.
  
  
  OBJECTIVE
  The purposes of our study were to determine when the cam morphology associated with FAI developed in a cross-sectional cohort study of pediatric patients pre- and postphyseal closure using MRI and whether increased activity level during the period of physeal closure is associated with an increased likelihood that the cam deformity will develop.
  
  
  METHODS
  Alpha angles were measured at the 3 o'clock (anterior head-neck junction) and 1:30 (anterosuperior head-neck junction) positions in both hips with a cam deformity defined as an alpha angle ≥ 50.5° at the 3 o'clock position. Forty-four volunteers (88 hips) were studied: 23 with open physes (12 females, mean age 9.7 years; 11 males, age 11.7 years) and 21 with closed physes (five females, age 15.2 years; 16 males, age 16.2 years). Daily activity level using the validated Habitual Activity Estimation Scale was compared for patients in whom cam morphology did and did not develop.
  
  
  RESULTS
  None of the 23 (0%) patients prephyseal closure had cam morphology, whereas three of 21 (14%, p = 0.02; all males) postclosure had at least one hip with cam morphology. Daily activity level was higher (p = 0.02) for patients with the cam morphology (7.1 hours versus 2.9 hours). Mean alpha angles at the 3 o'clock head-neck position were 38° (95% confidence interval [CI], 37.2°-39.1°) in the open physes group and 42° (95% CI, 40.16°-43.90°) in the closed physes group; at the 1:30 head-neck position, they were 45° (95% CI, 44.0°-46.4°) in the open physes group and 50° (47.9°-52.3°) in the closed physes group.
  
  
  CONCLUSIONS
  The fact that cam morphology was present exclusively in the closed physeal group strongly supports its development during the period of physeal closure with increased activity level as a possible risk factor.
authors.affiliation: Division of Orthopedic Surgery, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Sasha
authors.initials: S
authors.lastname: Carsen
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Moroz
authors.forename: Kawan
authors.initials: K
authors.lastname: Rakhra
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Ward
authors.forename: Hal
authors.initials: H
authors.lastname: Dunlap
authors.forename: John A
authors.initials: JA
authors.lastname: Hay
authors.forename: R Baxter
authors.initials: RB
authors.lastname: Willis
authors.forename: Paul E
authors.initials: PE
authors.lastname: Beaulé
mesh_terms: D000077:Acetabulum / Q000473:pathology; D000203:Activities of Daily Living; D000293:Adolescent; D000367:Age Factors; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016009:Chi-Square Distribution; D002648:Child; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D057925:Femoracetabular Impingement / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D005270:Femur Head / Q000473:pathology* / Q000601:surgery; D005272:Femur Neck / Q000473:pathology* / Q000601:surgery; D006621:Hip Joint / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010808:Physical Examination; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012307:Risk Factors; D016896:Treatment Outcome