title: Characterization of Human Anterosuperior Acetabular Depression in Correlation With Labral Tears.
abstract: BACKGROUND
  Labral tears often occur in the same quadrant of the acetabulum at a small depression previously referred to as the psoas valley. Understanding the anatomic variations of this depression could help us understand the etiology of labral tears.
  
  
  OBJECTIVE
  To describe the location and dimensions of the depression located in the anterosuperior acetabular rim. The hypothesis was that the location of this depression would be consistent with the common location of acetabular labral tears described in the literature.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A total of 240 pelvic specimens were divided into 2 groups (n = 120 for each) according to age (younger age group: 21.36 ± 3.12 years [range, 14-24 years]; older age group: 42.30 ± 10.27 years, [range, 25-60 years]).Specimens were also categorized based on sex (mean age: 31.93 ± 12.31 years [male]; 32.08 ± 13.66 years [female]) and race (mean age: 31.45 ± 13.16 years [black]; 32.57 ± 12.82 years [white]). The depth and width of the acetabular depression were measured using a digital caliper, and the location was measured using a goniometer.
  
  
  RESULTS
  The psoas valley was observed in every specimen and was located in the anterosuperior quadrant of the acetabulum. Its depth was significantly greater (P < .001) in males (5.35 ± 1.60 mm) than in females (3.95 ± 1.31 mm). The width of the psoas valley was also greater (P < .001) in males (29.39 ± 3.98 mm) than in females (24.49 ± 4.80 mm). There were no differences in size or location of the depression between races or age groups. The psoas valley was located between 3.92 ± 0.42 o'clock anteriorly and 2.12 ± 0.77 o'clock posteriorly.
  
  
  CONCLUSIONS
  The differences observed in the study data are believed to be a result of the different anatomic morphologies of the pelvis in males and females. This loss of bony support, caused by the depression, could be the underlying cause of weakening of the acetabular labrum as people age.
  
  
  CONCLUSIONS
  The loss of bony support in the anterosuperior acetabular depression could contribute to the labral tears that commonly occur in this area. Understanding the normal anatomy of this area could be important in determining the risk of labral tears as well as treatment options.
authors.affiliation: University of Michigan Medical School, Ann Arbor, Michigan, USA.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Kopydlowski
authors.affiliation: Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Tannenbaum
authors.affiliation: Department of Orthopaedic Surgery, Washington University in St Louis, Chesterfield, Missouri, USA.
authors.forename: Matthew V
authors.initials: MV
authors.lastname: Smith
authors.affiliation: MedSport, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Jon K
authors.initials: JK
authors.lastname: Sekiya
keywords: acetabular labrum; acetabulum; femoroacetabular impingement; iliopsoas; pelvis morphology; psoas valley