title: Three-dimensional distribution of articular cartilage thickness in the elderly talus and calcaneus analyzing the subchondral bone plate density.
abstract: OBJECTIVE
  To unveil the three-dimensional (3D) distribution of talocrural and posterior subtalar articular cartilage thickness in the elderly cadavers using 3D computed tomography (CT) and a 3D-digitizer and to evaluate the relationship between subchondral bone plate density and the overlying cartilage thickness.
  
  
  METHODS
  Sixteen tali and 16 calcanei from eight cadavers were scanned with 3D-CT to create bone surface models, and with a 3D-digitizer to make cartilage surface models. These two surface models were merged using surface registration method. Articular cartilage thickness was evaluated as the distance between the two models, and the distribution was mapped. The anatomic cartilage thickness of five tali and five calcanei was compared with the distance between the cartilage and bone surface models to calculate optimum threshold for extracting the subchondral bone plate. Generalized estimating equations were used for comparison and measurement errors. Canonical correlation analysis was performed to determine the strength of association between subchondral bone plate threshold and cartilage thickness.
  
  
  RESULTS
  The talar-subtalar articular cartilage tended to be the thickest of the three joints. In the talocrural joint, the anterior region was the thinnest, and increasing cartilage thickness was seen toward the posterior. In the talar-subtalar joint, the central region was the thickest. Mean measurement errors were 0.059±0.066 mm, 0.038±0.040 mm, and 0.018±0.065 mm in the talocrural, talar-subtalar, and calcaneal-subtalar joints, respectively. The canonical correlation coefficient was 0.995 (P<0.001).
  
  
  CONCLUSIONS
  The articular cartilage thickness was distributed in the elderly hindfoot. The subchondral bone plate density was significantly correlated with the anatomic cartilage thickness.
authors.affiliation: Department of Orthopaedic Biomaterial Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Japan. k.aki@hotmail.co.jp
authors.forename: K
authors.initials: K
authors.lastname: Akiyama
authors.forename: T
authors.initials: T
authors.lastname: Sakai
authors.forename: N
authors.initials: N
authors.lastname: Sugimoto
authors.forename: H
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: K
authors.initials: K
authors.lastname: Sugamoto
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D002111:Calcaneus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D013499:Surface Properties; D013628:Talus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed / Q000379:methods