Changes

On radiography, it is normal to see thin radiolucent areas of less than 2&nbsp;mm around hip prosthesis components, or between a cement mantle and bone. However, these may still indicate loosening of the prosthesis if they are new or changing, and areas greater than 2&nbsp;mm may be harmless if they are stable.<ref name="RothMaertz2012"/> The most important prognostic factors of cemented cups are absence of radiolucent lines in DeLee and Charnley zone I, as well as adequate cement mantle thickness.<ref>{{cite book|title=The Well-Cemented Total Hip Arthroplasty: Theory and Practice|url=https://books.google.se/books?id=PQ6NZAeJUXcC&pg=PA337&lpg=PA336|author=Steffen Breusch, Henrik Malchau|publisher=Springer Science & Business Media|year=2005|isbn=978-3-540-24197-3|page=336}}</ref> In the first year after insertion of uncemented femoral stems, it is normal to have mild subsidence (less than 10&nbsp;mm).<ref name="RothMaertz2012">{{cite journal|last1=Roth|first1=Trenton D.|last2=Maertz|first2=Nathan A.|last3=Parr|first3=J. Andrew|last4=Buckwalter|first4=Kenneth A.|last5=Choplin|first5=Robert H.|title=CT of the Hip Prosthesis: Appearance of Components, Fixation, and Complications|journal=RadioGraphics|volume=32|issue=4|year=2012|pages=1089–1107|issn=0271-5333|doi=10.1148/rg.324115183}}</ref> <gallery widths=200 heights=200>>File:Hip prosthesis zones by DeLee and Charnley system, and Gruen system.jpg|Hip prosthesis zones according to DeLee and Charnley,<ref>{{cite book|title=The Adult Hip, Volume 1|url=https://books.google.com/books?id=-fwULYB1gJIC&pg=PA958|author=John J. Callaghan, Aaron G. Rosenberg, Harry E. Rubash|publisher=Lippincott Williams & Wilkins|year=2007|isbn=978-0-7817-5092-9|page=958}}</ref> and Gruen.<ref>{{cite journal|last1=Neumann|first1=Daniel R.P.|last2=Thaler|first2=Christoph|last3=Hitzl|first3=Wolfgang|last4=Huber|first4=Monika|last5=Hofstädter|first5=Thomas|last6=Dorn|first6=Ulrich|title=Long-Term Results of a Contemporary Metal-on-Metal Total Hip Arthroplasty|journal=The Journal of Arthroplasty|volume=25|issue=5|year=2010|pages=700–708|issn=0883-5403|doi=10.1016/j.arth.2009.05.018}}</ref> These are used to describe the location of for example areas of loosening.</gallery>