title: Decreased and increased relative acetabular volume predict the development of osteoarthritis of the hip: an osteological review of 1090 hips.
abstract: OBJECTIVE
  Recently, there has been considerable interest in quantifying the associations between bony abnormalities around and in the hip joint and osteoarthritis (OA). Our aim was to investigate the relationships between acetabular undercoverage, acetabular overcoverage, and femoroacetabular impingement (FAI) with OA of the hip, which currently remain controversial.
  
  
  METHODS
  A total of 545 cadaveric skeletons (1090 hips) from the Hamann-Todd osteological collection were obtained. Femoral head volume (FHV), acetabular volume (AV), the FHV/AV ratio, acetabular version, alpha angle and anterior femoral neck offset (AFNO) were measured. A validated grading system was used to quantify OA of the hip as minimal, moderate, or severe. Multiple linear and multinomial logistic regression were used to determine the factors that correlated independently with the FHV, AV, and the FHV/AV ratio.
  
  
  RESULTS
  Female cadavers had smaller FHVs (standardised beta -0.382, p < 0.001), and AVs (standardised beta -0.351, p < 0.001), compared with male patients, although the FHV/AV ratio was unchanged. Every 1° increase in alpha angle increased the probability of having moderate OA of the hip compared with minimal OA by 7.1%. Every 1 mm decrease in AFNO increased the probability of having severe or moderate OA of the hip, compared with minimal OA, by 11% and 9%, respectively. The relative risk ratios of having severe OA of the hip compared with minimal OA were 7.2 and 3.3 times greater for acetabular undercoverage and overcoverage, respectively, relative to normal acetabular cover.
  
  
  CONCLUSIONS
  Acetabular undercoverage and overcoverage were independent predictors of increased OA of the hip. The alpha angle and AFNO had modest effects, supporting the hypothesis that bony abnormalities both in acetabular dysplasia and FAI are associated with severe OA. Cite this article:Bone Joint J2017;99-B:432-9.
authors.affiliation: Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH, 44106, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Weinberg
authors.affiliation: Case Western Reserve University, 2109 Adelbert Rd, Cleveland, OH 44106, USA.
authors.forename: D F K
authors.initials: DF
authors.lastname: Williamson
authors.affiliation: Boston Children's Hospital, 300 Longwood Avenue, Boston MA 02115, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Millis
authors.affiliation: Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH, 44106, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Liu
mesh_terms: D000077:Acetabulum / Q000473:pathology*; D000328:Adult; D000368:Aged; D000886:Anthropometry / Q000379:methods; D002102:Cadaver; D005260:Female; D057925:Femoracetabular Impingement / Q000150:complications; D005270:Femur Head / Q000473:pathology; D005272:Femur Neck / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000209:etiology / Q000473:pathology*; D012307:Risk Factors; D012720:Severity of Illness Index
keywords: Acetabular cover; Acetabular dysplasia; Alpha angle; FAI; Femoroacetabular impingement; Osteoarthritis of the hip