title: Evaluation of local bone turnover in painful hip by 18F-fluoride positron emission tomography.
abstract: OBJECTIVE
  The diagnosis of painful hip without remarkable radiographic findings is still challenging. In recent years, femoroacetabular impingement (FAI) has been recognized as an important cause of painful hip. The hypothesis of this study was that local bone turnover may be accelerated in painful hip, especially in FAI lesions. To test this, patients with unilateral symptomatic hip underwent F-fluoride PET, which directly correlates with osteoblast activity and therefore bone turnover.
  
  
  METHODS
  In total, 27 patients with unilateral symptomatic painful hip were enrolled. The diagnosis included 15 cam-type FAI cases, six labral tear cases, and six early-stage osteoarthritis cases. The region of interest for cam and pincer lesions was identified and the maximum standardized uptake value (SUVmax) in these regions and the contralateral asymptomatic regions were measured by F-fluoride PET. The SUVmax ratio was defined as symptomatic side SUVmax/asymptomatic side SUVmax. The α angle and center-edge angle were measured by plain radiograph.
  
  
  RESULTS
  The SUVmax of both cam and pincer lesions were significantly higher than the SUVmax of the contralateral regions (P<0.0001). The cam SUVmax ratio correlated positively with the α angle (r=0.5, P=0.007). Patients with an α angle of more than or equal to 60° had a significantly higher cam SUVmax ratio than the less than 60° group (P=0.017).
  
  
  CONCLUSIONS
  This study showed the accelerated local bone turnover in painful hip, partly in FAI cases. Accelerated bone turnover may play a significant role in FAI pathophysiology; therefore, its recognition by imaging modality may contribute toward a more sensitive diagnosis in painful hip.
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University, Yokohama, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Inaba
authors.forename: Taro
authors.initials: T
authors.lastname: Tezuka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ike
authors.forename: So
authors.initials: S
authors.lastname: Kubota
authors.forename: Masaki
authors.initials: M
authors.lastname: Kawamura
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saito
mesh_terms: D000328:Adult; D000368:Aged; D016723:Bone Remodeling; D005260:Female; D057925:Femoracetabular Impingement / Q000150:complications; D005459:Fluorides; D005462:Fluorine Radioisotopes; D006615:Hip / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D049268:Positron-Emission Tomography; D055815:Young Adult
chemical_list: D005462:Fluorine Radioisotopes; D005459:Fluorides