title: Age and gender as determinants of the bone quality of the greater tuberosity: a HR-pQCT cadaver study.
abstract: BACKGROUND
  Age-dependent trabecular changes of the humeral head might weaken the fixation of suture anchors used for rotator cuff (RC) repair. This might lead to suture anchor loosening and thus compromise the integrity of the repair. The aim of this study was to analyze whether the trabecular microstructure within the RC footprint is influenced by age, gender or handedness.
  
  
  METHODS
  Axial HR-pQCT scans (Scanco Medical) of 64 freshly frozen cadaveric human humeral head specimens (age 72.3 ± 17.4 years) were analyzed to determine the bone volume-to-total volume ratio (BV/TV), trabecular thickness (Trab Th), trabecular number (Trab N) and connectivity density (Conn Dens). Within the RC footprint, 2 volumes of interest (VOI), posteromedial (PM) and anterolateral (AL) and one control VOI in the subarticular bone (SC) were set.
  
  
  RESULTS
  The highest BV/TV was found in SC: 0.22 ± 0.06% vs. PM: 0.04 ± 0.05% vs. AL: 0.02 ± 0.04%; p < 0.05. Trab Th accounted for 0.26 ± 0.05 μm in SC, 0.23 ± 0.09 μm in AL and 0.21 ± 0.05 μm in PM. In parallel, Trab N and Conn Dens were found to be the highest in SC. Gender analysis yielded higher values for BV/TV, Trab Th, Trab N and Conn Dens for PM in males compared to females (p < 0.05). There were no significant findings when comparing both sides. We furthermore found a strong inverse correlation between age and BV/TV, which was more pronounced in the female specimens (r = -0.72, p < 0.00001).
  
  
  CONCLUSIONS
  The presented microarchitectural data allow for future subtle biomechanical testing comprising knowledge on age- and sex-related changes of the tuberosities of the humeral head. Furthermore, the insights on the trabecular structure of the humeral head of the elderly may lead to the development of new fixation materials in bone with inferior bone quality.
authors.affiliation: Department of Trauma Surgery, Klinikum rechts der Isar, Technische Universitaet Muenchen, Ismaningerstrasse 22, D-81675, Munich, Germany. Chlodwig.kirchhoff@mri.tum.de
authors.forename: Chlodwig
authors.initials: C
authors.lastname: Kirchhoff
authors.forename: Volker
authors.initials: V
authors.lastname: Braunstein
authors.forename: Stefan
authors.initials: S
authors.lastname: Milz
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Sprecher
authors.forename: Sonja
authors.initials: S
authors.lastname: Kirchhoff
authors.forename: Mathias
authors.initials: M
authors.lastname: Graw
authors.forename: Andreas B
authors.initials: AB
authors.lastname: Imhoff
authors.forename: Stefan
authors.initials: S
authors.lastname: Hinterwimmer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015519:Bone Density / Q000502:physiology*; D002102:Cadaver; D005260:Female; D006801:Humans; D058430:Humeral Head / Q000000981:diagnostic imaging* / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D014057:Tomography, X-Ray Computed / Q000379:methods*