title: Reconsideration of the Effects of Age on Proximal Femur Structure: Implications for Joint Replacement and Hip Fracture.
abstract: OBJECTIVE
  In recent years quantitative computed tomography (QCT) has allowed precise non-invasive, three dimensional, in vivo measurement of hip structure in large numbers of individuals. The effects of ageing on proximal femur structure are reported and implications for the prevention of hip prosthesis loosening and hip fracture considered.
  
  
  METHODS
  An observational cross-sectional study of proximal femur QCT in 719 unselected female European descent aged 20 to 89 years recruited from US and Australian populations.
  
  
  METHODS
  QCT scans were obtained using software that separates cortical and cancellous bone by a thresholding technique. Voxel based mineral volume and mass was computed for the integral (external), cancellous and cortical compartments of 1 mm wide sections through the femoral neck (FN), trochanter (TR) and intertrochanter (IT) regions.
  
  
  RESULTS
  Over the adult life span total integral volumes at the FN, TR and IT sites expand linearly by between 18 and 37% at the same time as bone mass decreased by 22 to 25% resulting in massive reductions in true volumetric BMD (vBMD) of 40 to 50%. Cancellous volume expansion was larger at 65 to 79% at the three sites. Between the ages of 65 and 75 the average increase in cancellous volume at the IT site was 3.74 cm3 (12.1%). Voxel determined FN cortical volume decreased linearly by 43%, as did cortical bone mass so that vBMD did not change substantially. TR and IT cortical volumes decreased 54 and 28% respectively, small reductions in TR and IT cortical vBMD also occurred.
  
  
  CONCLUSIONS
  Large endosteal expansion in the area in which hip replacement stem placement occurs may contribute to loosening. Regarding the propensity to hip fracture, periosteal expansion contributes to increased resistance to bending but cortical thinning contributes to loss of bone to resistance to bending forces. Understanding individual hip structure may contribute to individualisation of risk and subsequent targeting of management using pharmaceutical agents.
authors: Medical Technology & Physics, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.|School of Physics, University of Western Australia, Perth, Western Australia, Australia.|School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Australia.
authors: B C C
authors: BC
authors: Khoo
authors: Mindways Software Inc., Austin, Texas, United States of America.
authors: J K
authors: JK
authors: Brown
authors: School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Australia.|Department of Endocrinology & Diabetes, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.
authors: R L
authors: RL
authors: Prince
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement; D001315:Australia; D015519:Bone Density; D003430:Cross-Sectional Studies; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006620:Hip Fractures / Q000000981:diagnostic imaging* / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008875:Middle Aged; D011475:Prosthesis Failure; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014481:United States; D055815:Young Adult