title: Radiographic Identification of Arthroscopically Relevant Acetabular Structures.
abstract: BACKGROUND
  The anatomy of the acetabulum has been described extensively in the literature, but radiographic acetabular guidelines have not been well established. This study provides a radiographic map of acetabular landmarks in the hip.
  
  
  OBJECTIVE
  The purpose of this study was to quantify the precise radiographic location of arthroscopic landmarks around the acetabulum. The hypothesis was that their locations were reproducible despite variability in the anatomy and positioning of pelvic specimens.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Ten fresh-frozen cadaveric specimens were dissected, and radio-opaque hardware was placed for each landmark of interest. Anteroposterior (AP) and false-profile radiographs were obtained, and measurements were taken using a digital picture archiving and communication system.
  
  
  RESULTS
  On AP radiographs, the direct and indirect heads of the rectus femoris were a mean 48.2 ± 4.6 mm and 44.7 ± 4.3 mm proximal to the teardrop line, respectively. The mean radiographic distance between their insertions was 5.0 ± 3.4 mm. Moreover, the anterior inferior iliac spine was a mean 11.5 ± 3.8 mm from the acetabular rim. On false-profile radiographs, the mean distance between the direct and indirect heads of the rectus femoris was 31.4 ± 6.2 mm. The mean distance between the superior margin of the anterior labral sulcus (the psoas-u) and the midpoint of the transverse acetabular ligament was 41.0 ± 5.7 mm. Additionally, the direct and indirect heads of the rectus femoris corresponded to the 2:30 and 1:30 locations on the acetabular clockface, respectively. The midpoint of the transverse acetabular ligament was located at 7 o'clock on the clockface.
  
  
  CONCLUSIONS
  The most important finding of this study, determined by quantitative measurements, was that the described surgical landmarks had reliable locations on radiographs. Distances between landmarks as well as distances between landmarks and reference lines were reproducible in both AP and false-profile views.
  
  
  CONCLUSIONS
  An understanding of how acetabular structures present on radiographs could lead to more accurate portal and hardware placement intraoperatively during arthroscopic surgery as well as better preoperative and postoperative assessments.
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Lee
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: Adriana J
authors.initials: AJ
authors.lastname: Saroki
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA Department of Orthopaedics, Oslo University Hospital, Oslo, Norway.
authors.forename: Sverre
authors.initials: S
authors.lastname: Løken
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: Christiano A C
authors.initials: CA
authors.lastname: Trindade
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: Tyler R
authors.initials: TR
authors.lastname: Cram
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA.
authors.forename: Broc R
authors.initials: BR
authors.lastname: Schindler
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA The Steadman Clinic, Vail, Colorado, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: LaPrade
authors.affiliation: Steadman Philippon Research Institute, Vail, Colorado, USA The Steadman Clinic, Vail, Colorado, USA drphilippon@sprivail.org.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Philippon
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D059925:Anatomic Landmarks / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D001182:Arthroscopy; D002102:Cadaver; D006621:Hip Joint / Q000033:anatomy & histology; D006801:Humans; D007085:Ilium / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008023:Ligaments, Articular / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D015588:Observer Variation; D052097:Quadriceps Muscle / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011859:Radiography
keywords: femoroacetabular impingement (FAI); fluoroscopic guidance; hip acetabulum; hip arthroscopic surgery; radiology