title: Arthroscopic validation of radiographic minimum joint space width associated with the subchondral bone exposure in symptomatic hip dysplasia.
abstract: OBJECTIVE
  The purpose of this study was to clarify the minimum joint space width (MJSW) that leads to subchondral bone exposure (SBE) in patients with hip dysplasia.
  
  
  METHODS
  We included 82 subjects (86 hips) who had hip dysplasia with center-edge angle less than 20° and who underwent periacetabular osteotomy combined with hip arthroscopy. The acetabular and femoral cartilages were divided into three regions: anterosuperior, superior, and posterosuperior; for each region, we analyzed the correlation between the incidence of SBE and the MJSW measured on plain radiographs. The disease stage was defined according to the Kellgren and Lawrence grades (KL grade).
  
  
  RESULTS
  SBE was found in 51 hips (59.3%) in total, involved the acetabulum in 49 hips (57.0%), and involved the femoral head in 26 hips (30.2%). SBE was more frequent in the acetabulum, with the highest incidence in the anterosuperior region, followed by the superior region. SBE was present in six hips (22.2%), 17 hips (56.7%), and 28 hips (96.5%), at KL-1, KL-2, and KL-3, respectively. MJSW of hips with SBE was significantly smaller than those without SBE (2.3 vs 4.0 mm, p < 0.001), and the cut-off value for MJSW that led to SBE was 3.7 mm (sensitivity: 0.902, 1 - specificity: 0.343). SBE was present in 23.3% in patients with MJSW ≥3.7 mm, whereas 76.7% in those <3.7 mm.
  
  
  CONCLUSIONS
  Cartilage degeneration is more advanced than would be predicted on plain radiographs. The cut-off value of MJSW for SBE was 3.7 mm in patients with symptomatic hip dysplasia.
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Nakashima
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Masanori
authors.initials: M
authors.lastname: Fujii
authors.affiliation: b Department of Orthopaedic Surgery , Fukuoka Houeikai Hospital , Fukuoka , Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Kenya
authors.initials: K
authors.lastname: Suenaga
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Jun-Ichi
authors.initials: JI
authors.lastname: Fukushi
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Goro
authors.initials: G
authors.lastname: Motomura
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hamai
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hara
authors.affiliation: a Department of Orthopaedic Surgery , Kyushu University , Fukuoka , Japan and.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology; D006617:Hip Dislocation / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography / Q000592:standards*
keywords: Hip arthroscopy; Hip dysplasia; Minimum joint space width; Periacetabular osteotomy; Subchondral bone exposure