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===Osteoarthritis=Normal anatomy==[[<gallery>File:Hueftgelenk-gesund (crop).jpg|thumb|[[Hip joint]] with no signs of osteoarthritis.]]The most commonly used radiographic classification system for osteoarthritis of the [[hip joint]] is the '''Kellgren-Lawrence''' system (or K-L system).<ref>{{cite journal|title=Osteoarthritis of the hip: An overview|url=http://hrcak.srce.hr/139528?lang=en|journal=Periodicum biologorum|volume=117|issue=1|year=2015|author=Zdravko Jotanovic, Radovan Mihelic, Gordan Gulan, Branko Sestan, Zlatko Dembic}}</refgallery> It uses [[Projectional radiography|plain radiographs]].

{| class="wikitable"|+ Kellgren-Lawrence system|-! Grade! Description|-| 0| No radiographic features of [[osteoarthritis]]|-| 1| Possible [[joint space narrowing]] (normal joint space is at least 2&nbsp;mm at the superior acetabulum)<ref name="Lequesne2004">{{cite journal|last1=Lequesne|first1=M|title=The normal hip joint space: variations in width, shape, and architecture on 223 pelvic radiographs|journal=Annals of the Rheumatic Diseases|volume=63|issue=9|year=2004|pages=1145–1151|issn=0003-4967|doi=10.1136/ard.2003.018424|pmc=1755132}}</ref> and [[osteophyte]] formation|-| 2| Definite [[osteophyte]] formation with possible [[joint space]] narrowing|-| 3| Multiple [[osteophyte]]s, definite [[joint space]] narrowing, [[Osteosclerosis|sclerosis]] and possible bony deformity|-| 4| Large [[osteophyte]]s, marked [[joint space]] narrowing, severe [[Osteosclerosis|sclerosis]] and definite bony deformity|} Osteoarthritis of the [[hip joint]] may also be graded by '''Tönnis classification'''. There is no consensus whether it is more or less reliable than the Kellgren-Lawrence system.<ref name="TerjesenGunderson2012"gallery>{{cite journal|last1=Terjesen|first1=Terje|last2=Gunderson|first2=Ragnhild B|title=Radiographic evaluation of osteoarthritis of the hip|journal=Acta Orthopaedica|volume=83|issue=2|year=2012|pages=185–189|issn=1745-3674|doi=10.3109/17453674.2012.665331}}</ref> [[File:Severe (Tönnis grade 3) osteoarthritis of the hip.jpg|thumb|Severe (Tönnis grade 3) link=X-ray of osteoarthritis of the hip.]] {joint| class="wikitable"|+ Tönnis classification<ref>{{cite web|url=http://www.preventivehip.org/hip[[X-scores/tonnis-classification|title=Tönnis Classification ray of Osteoarthritis by Radiographic Changes|website=Society osteoarthritis of Preventive Hip Surgery|accessdate=2016-12-13}}</ref>|-! Grade! Description|-| 0 || No osteoarthritis signs|-| 1 || Mild: *increased [[osteosclerosisthe hip joint]]*minor joint space narrowing (normal joint space is at least 2&nbsp;mm at the superior acetabulum)<ref name="Lequesne2004"/gallery>*no or minor loss of head sphericity|-| 2 || Moderate: *small [[bone cyst]]*moderate joint space narrowing*moderate loss of head sphericity|-| 3 || Severe: *large bone cysts*severe joint space narrowing, or joint space obliteration* severe deformity of the head|} ==References=={{reflist}}