title: Topographic deformation patterns of knee cartilage after exercises with high knee flexion: an in vivo 3D MRI study using voxel-based analysis at 3T.
abstract: OBJECTIVE
  To implement a novel voxel-based technique to identify statistically significant local cartilage deformation and analyze in-vivo topographic knee cartilage deformation patterns using a voxel-based thickness map approach for high-flexion postures.
  
  
  METHODS
  Sagittal 3T 3D-T1w-FLASH-WE-sequences of 10 healthy knees were acquired before and immediately after loading (kneeling/squatting/heel sitting/knee bends). After cartilage segmentation, 3D-reconstruction and 3D-registration, colour-coded deformation maps were generated by voxel-based subtraction of loaded from unloaded datasets to visualize cartilage thickness changes in all knee compartments.
  
  
  RESULTS
  Compression areas were found bifocal at the peripheral medial/caudolateral patella, both posterior femoral condyles and both anterior/central tibiae. Local cartilage thickening were found adjacent to the compression areas. Significant local strain ranged from +13 to -15 %. Changes were most pronounced after squatting, least after knee bends. Shape and location of deformation areas varied slightly with the loading paradigm, but followed a similar pattern consistent between different individuals.
  
  
  CONCLUSIONS
  Voxel-based deformation maps identify individual in-vivo load-specific and posture-associated strain distribution in the articular cartilage. The data facilitate understanding individual knee loading properties and contribute to improve biomechanical 3 models. They lay a base to investigate the relationship between cartilage degeneration patterns in common osteoarthritis and areas at risk of cartilage wear due to mechanical loading in work-related activities.
  
  
  CONCLUSIONS
  • 3D MRI helps differentiate true knee-cartilage deformation from random measurement error • 3D MRI maps depict in vivo topographic distribution of cartilage deformation after loading • 3D MRI maps depict in vivo intensity of cartilage deformation after loading • Locating cartilage contact areas might aid differentiating common and work-related osteoarthritis.
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Marchioninistr. 15, 81377, Munich, Germany, Annie.Horng@med.uni-muenchen.de.
authors.forename: Annie
authors.initials: A
authors.lastname: Horng
authors.forename: J G
authors.initials: JG
authors.lastname: Raya
authors.forename: M
authors.initials: M
authors.lastname: Stockinger
authors.forename: M
authors.initials: M
authors.lastname: Notohamiprodjo
authors.forename: M
authors.initials: M
authors.lastname: Pietschmann
authors.forename: U
authors.initials: U
authors.lastname: Hoehne-Hueckstaedt
authors.forename: U
authors.initials: U
authors.lastname: Glitsch
authors.forename: R
authors.initials: R
authors.lastname: Ellegast
authors.forename: K G
authors.initials: KG
authors.lastname: Hering
authors.forename: C
authors.initials: C
authors.lastname: Glaser
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D005269:Femur / Q000502:physiology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000503:physiopathology; D010329:Patella / Q000502:physiology; D011187:Posture; D016059:Range of Motion, Articular / Q000502:physiology; D013977:Tibia / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology