title: Morphometric analysis of superior articular facets of atlas vertebra and its clinical applications in ergonomics of atlanto-occipital joints.
abstract: OBJECTIVE
  The classic variants in superior articular facets of atlas such as, variability in shape, presence of notch, constrictions, partial or complete separation of facets, and presence of pressure facets, have been reported to a limited extent in relation to ergonomics of cranio-vertebral joint.
  
  
  OBJECTIVE
  The objectives of the present study were to report the analyzed morphological features and metrical values of superior articular facets of the atlas. The morphological features which were included in this study were variability in shapes, constrictions and partial or complete separation of facets. The metrical measure included the surface area measurement of the facets.
  
  
  METHODS
  This study was carried out on 50 (100 sides) dry atlas vertebrae from the Department of Anatomy, St John's Medical College, Bangalore, India. The superior articular facets were studied for the shape and symmetry, constrictions and partial or complete separation of facets. The surface area of the facets were measured by using Image J (Image processing and analysis in JAVA) tool, that was primarily designed to measure and analyze different metrics.
  
  
  RESULTS
  The mean surface area on the right side was 157.3 ± 29.02, and on the left side, it was 158.5 ± 24.85. Oval, irregular, kidney and figure of eight shapes were observed either on both sides or on one side. Bilateral constrictions of facets were seen in 58 % of vertebrae. Bilateral, complete separations of facets were seen in 30% of vertebrae.
  
  
  CONCLUSIONS
  The observations of the present study are important to understand the ergonomics of the cranio-vertebral joint and they are helpful for academicians, neuro-surgeons, clinicians and radiologists in day to day clinical practice.
authors.affiliation: Assistant Professor, Department of Anatomy, Amala Medical College, Kerala University of Health Sciences , Kerala-680555, India .
authors.forename: Manjunath V
authors.initials: MV
authors.lastname: Motagi
authors.affiliation: Senior Lecturer, Newcastle University Medicine Malaysia , Johor, Malaysia .
authors.forename: Vallabhajosyula
authors.initials: V
authors.lastname: Ranganath
keywords: Cranio-vertebral junction; Surface area of superior articular facet (SAF)