RT Journal Article SR Electronic T1 Human articular surface contours and related surface depression frequency studies. JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 15 OP 23 DO 10.1136/ard.30.1.15 VO 30 IS 1 A1 Clarke, I C YR 1971 UL http://ard.bmj.com/content/30/1/15.abstract AB