View source for Osteochondritis dissecans

:''For other uses, see [[OCD (disambiguation)]].''
{{Infobox disease
|Name = Osteochondritis dissecans
|Image = Head of femur avascular necrosis.jpg
|Caption = A large [[Osteochondritis dissecans#Hinged lesions|flap lesion]] in the [[femur head]] typical of late stage Osteochondritis dissecans. In this case, the lesion was caused by [[avascular necrosis]] of the [[wikt:subchondral|subchondral]] bone.
|DiseasesDB = 9320
|ICD10 = {{ICD10|M|93|2|m|91}}
|ICD9 = {{ICD9|732.7}}
|ICDO =
|OMIM = 165800
|MedlinePlus =
|eMedicineSubj = radio
|eMedicineTopic = 495
|eMedicine_mult = {{eMedicine2|sports|57}} {{eMedicine2|orthoped|639}}
|MeshID = D010008
}}
'''Osteochondritis dissecans''' ({{pron-en|ˌɒsti.oʊkɒnˈdraɪtɪs ˈdɪsɨkænz}}, and often abbreviated to '''OCD''' or '''OD''') is a [[joint]] disorder in which cracks form in the [[articular cartilage]] and the underlying [[subchondral bone]].<ref>{{cite web|url=http://www.medterms.com/script/main/art.asp?articlekey=11789|title=Definition of Osteochondritis dissecans|accessdate=2009-02-20|author=Shiel WC Jr|publisher=MedicineNet, Inc.}}</ref> OCD is caused by blood deprivation in the subchondral bone. This loss of blood flow causes the subchondral bone to die in a process called [[avascular necrosis]]. The bone is then reabsorbed by the body, leaving the articular cartilage it supported prone to damage. The result is fragmentation ([[dissection]]) of both cartilage and bone, and the free movement of these [[wikt:osteocartilaginous|osteochondral]] fragments within the joint space, causing pain and further damage.<ref name="pmid7273527">{{cite journal|author=Pappas AM|title=Osteochondrosis dissecans|journal=Clinical Orthopaedics and Related Research|issue=158|pages=59–69|year=1981|pmid=7273527}}</ref><ref name="pmid1157398">{{cite journal|author=Woodward AH, Bianco AJ|title=Osteochondritis dissecans of the elbow|journal=Clinical Orthopaedics and Related Research|issue=110|pages=35–41|year=1975|pmid=1157398|doi=10.1097/00003086-197507000-00007|volume=110}}</ref><ref>{{Cite book|last=Pettrone|first=FA|year=1986|title=American Academy of Orthopaedic Surgeons Symposium on Upper Extremity Injuries in Athletes|location=St. Louis, Missouri|publisher=CV Mosby|isbn=978-0801600265|pages=193–232}}</ref>

In humans OCD is a [[rare disease]], occurring in only 15 to 30 people per 100,000 in the general population each year.<ref name="pmid9012566"/> Although rare, it is an important cause of joint pain in physically active [[adolescent]]s.<ref name="Inoue1991">{{cite journal|author=Inoue, Goro|title=Bilateral osteochondritis dissecans of the elbow treated by Herbert screw fixation|journal=British Journal of Sports Medicine|volume=25|issue=3|pages=142–144|year=1991|month=|url=http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1478853/pdf/brjsmed00027-0032.pdf|pmid=1777781|accessdate={{Nowrap|9 January}} 2010|doi=10.1136/bjsm.25.3.142|pmc=1478853}} See introduction and discussion sections on incidence</ref> Because their bones are still growing, adolescents are more likely than adults to recover from OCD; recovery in adolescents can be attributed to the bone's ability to repair damaged or dead bone tissue and cartilage in a process called bone remodeling. While OCD may affect any joint, the knee tends to be the most commonly affected, and constitutes 75% of all cases. OCD is also a growing concern, especially amongst women, in rural areas of [[Nigeria]], according to research done by the [[University of Port Harcourt]].<ref name="ijrr">{{cite journal|doi=10.1097/00004356-198406000-00004|last=Enwemeka|first=Chukuka S.|date=June 1984|title=Physical deformities in Nigerian schools: the Port Harcourt Cohort study|journal=International Journal of Rehabilitation Research|volume=7|issue=2|pages=163–172|issn=0342-5282|oclc=4554227|pmid=6238005|accessdate=August 18, 2010}}</ref> This is due to the chemical pollution of primary sources of water used for drinking and irrigation in the area.<ref name="ijrr"/>

OCD also is found in animals, and is of particular concern in horses, as there may be a hereditary component in some [[horse breed]]s.<ref name="Thomas2002">{{cite journal|author=Thomas, Heather Smith|title=Osteochondritis Dissecans in Thoroughbreds. Weanlings: A Field Study |journal=California Thoroughbred |volume=|issue=|pages=65–67|year=2002|month=August|url=http://www.ctba.com/02magazine/aug02/HORSECARE.pdf|pmid=|accessdate={{Nowrap|9 January}} 2010|archiveurl = http://web.archive.org/web/20061021235616/http://www.ctba.com/02magazine/aug02/HORSECARE.pdf |archivedate = October 21, 2006|deadurl=yes}}</ref> Feeding for forced growth and [[selective breeding]] for increased size are also factors. OCD has also been studied in other animals—mainly dogs, especially the [[German Shepherd Dog|German Shepherd]]<ref name="Ch.84OCD"/>—where it is a common primary cause of [[elbow dysplasia]] in medium-large breeds.<ref name="Pead and Guthrie">{{cite web|last=Matthew Pead and Sue Guthrie|title=Elbow Dysplasia in dogs – a new scheme explained|url=http://www.bva.co.uk/public/documents/chs_elbow.pdf|publisher=[[British Veterinary Association]] (BVA)|accessdate=2010-07-16}}</ref>

OCD usually causes pain and [[Swelling (medical)|swelling]] of the affected joint which catches and locks during movement. [[Physical examination]] typically reveals an [[Effusion (disambiguation)|effusion]], tenderness, and [[crepitus]]. OCD can be difficult to diagnose because these symptoms are found with other diseases. However, the disease can be confirmed by [[Radiography|X-rays]], [[computed tomography]] (CT) or [[magnetic resonance imaging]] (MRI) scans. OCD is classified by these imaging techniques, or by [[arthroscopy]] of the joint, and represented in stages (I, II, III and IV) of disease progression. Following diagnosis the problem may be treated, depending on its severity, by [[articular cartilage repair|repairing the cartilage]].<ref name="pmid3886172">{{cite journal|author=Cahill B|title=Treatment of juvenile osteochondritis dissecans and osteochondritis dissecans of the knee|journal=Clinical Journal of Sports Medicine|volume=4|issue=2|pages=367–84|year=1985|month=April|pmid=3886172}}</ref><ref name="pmid9397273">{{cite journal|author=Anderson AF, Pagnani MJ|title=Osteochondritis dissecans of the femoral condyles. Long-term results of excision of the fragment|journal=American Journal of Sports Medicine|volume=25|issue=6|pages=830–4|year=1997|pmid=9397273|doi=10.1177/036354659702500617}}</ref> Non-surgical treatment is rarely an option as the capacity for articular cartilage to heal is limited. As a result, even moderate cases require some form of surgery. When possible, non-operative forms of management such as protected weight bearing (partial or non-weight bearing) and immobilization are used. Surgical treatment varies widely and includes arthroscopic drilling of intact lesions, securing of cartilage flap lesions with pins or screws, drilling and replacement of cartilage plugs, [[Stem cell transplantation for articular cartilage repair|stem cell transplantation]], and joint replacement.

Post-operative rehabilitation is usually a two-stage process of [[Lying (position)|immobilization]] and [[physical therapy]]. Most rehabilitation programs combine protection of the joint's cartilage surface and underlying subchondral bone with maintenance of muscle strength and range of motion. During the immobilization period, [[isometric exercise]]s, such as straight leg raises, are commonly used to restore muscle lost to [[atrophy]] without disturbing the cartilage of the affected joint. Once the immobilization period has ended, physical therapy involves continuous passive motion (CPM) and/or low impact activities, such as walking or swimming. Post-operative [[analgesics|pain killers]], namely a mix of [[opioids]] and [[NSAIDs]], are usually required to control pain during recovery.

[[Franz König (surgeon)|Franz König]] coined the term osteochondritis dissecans in 1887, describing it as an [[inflammation]] of the bone–[[cartilage]] interface. Many other conditions were once confused with OCD when attempting to describe how the disease affected the joint, including osteochondral fracture, [[osteonecrosis]], accessory ossification center, [[osteochondrosis]], and hereditary epiphyseal [[dysplasia]]. Some authors have used the terms ''osteochondrosis dissecans'' and ''osteochondral fragments'' as [[synonym]]s for OCD.

==Classification==
OCD is classified by the progression of the disease in stages.
There are two main staging classifications used; one is determined by MRI diagnostic imaging while the other is determined [[Arthroscope|arthroscopically]]. However, both stagings represent the pathological conditions associated with OCD's natural progression.<ref name="pmid10643956"/>

While the arthroscopic classification of [[wikt:osteocartilaginous|osteochondral]] lesions is considered standard, the Anderson MRI staging is the main form of staging used in this article.<ref name="pmid10887249">{{cite journal|author=Takahara M, Ogino T, Takagi M, Tsuchida H, Orui H, Nambu T|title=Natural progression of osteochondritis dissecans of the humeral capitellum: initial observations|journal=Radiology|volume=216|issue=1 |pages=207–12|date={{Nowrap|1 July}} 2000|pmid=10887249|url=http://radiology.rsnajnls.org/cgi/content/full/216/1/207?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=1&andorexacttitle=and&titleabstract=osteochondritis+dissecans&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT}}</ref> Stages&nbsp;I and II are stable lesions. Stages&nbsp;III and IV describe unstable lesions in which a lesion of the cartilage has allowed [[synovial fluid]] between the fragment and bone.

{| class="wikitable"
|+ '''Anderson MRI staging of osteochondritis dissecans'''<ref name="pmid2777840">{{cite journal|author=Anderson IF, Crichton KJ, Grattan-Smith T, Cooper RA, Brazier D|title=Osteochondral fractures of the dome of the talus|journal=Journal of Bone and Joint Surgery (American)|volume=71 |issue=8|pages=1143–52|year=1989|month=September|pmid=2777840|accessdate=2008-11-14}}</ref>
! Stage
! Evaluation
! Findings
|-
| I
| Early
| Subchondral bone flattening in the [[epiphyseal plate]] before growth plate closure
|-
| IIA
| Stable
| Subchondral cyst present
|-
| IIB
| Unstable
| Incomplete separation of the [[wikt:osteocartilaginous|osteochondral]] fragment due to repetitive trauma
|-
| III
| Unstable
| Effusions (fluid around an undetached, undisplaced osteochondral fragment)
|-
| IV
| Terminal
| Complete separation (detachment) of osteochondral fragment(s); mechanical irregularities and formation of loose bodies
|}

{| class="wikitable"
|+ '''Cheng [[arthroscopy|arthroscopic]] staging of osteochondritis dissecans'''<ref name="cheng">{{cite paper |author=Cheng MS, Ferkel RD, Applegate GR | title=Osteochondral lesion of the talus: A radiologic and surgical comparison |location=New Orleans, LA |year=1995 }} Paper presented at Annual Meeting of the Academy of Orthopaedic Surgeons.</ref>
! Grade
! Findings
|-
| A
| Articular cartilage is smooth and intact but may be soft or ballottable
|-
| B
| Articular cartilage has a rough surface
|-
| C
| Articular cartilage has fibrillations or fissures
|-
| D
| Articular cartilage with a flap or exposed bone
|-
| E
| Loose, nondisplaced osteochondral fragment
|-
| F
| Displaced osteochondral fragment
|}

==Signs and symptoms==
In osteochondritis dissecans, fragments of [[cartilage]] or bone become loose within a joint, leading to pain and [[inflammation]]. These fragments are sometimes referred to as joint mice.<ref name="pmid10643956-patient information handout">{{cite journal|author=Hixon AL, Gibbs LM|title=What Should I Know About Osteochondritis Dissecans?|journal=American Family Physician|volume=61|issue=1|page=158|year=2000|month=January|url=http://www.aafp.org/afp/20000101/20000101d.html}}</ref> OCD is a type of [[osteochondrosis]] in which a [[lesion]] has formed within the cartilage layer itself, giving rise to secondary inflammation. OCD most commonly affects the knee, although it can affect other joints such as the ankle or the elbow.<ref name="pmid6807595"/>

People with OCD report activity-related pain that develops gradually. Individual complaints usually consist of mechanical symptoms including pain, swelling, catching, locking, and giving way; the primary presenting symptom may be a restriction in the range of movement.<ref name="pmid10643956">{{cite journal|author=Hixon AL, Gibbs LM|title=Osteochondritis dissecans: a diagnosis not to miss|journal=American Family Physician|volume=61|issue=1|pages=151–6, 158|year=2000|month=January|pmid=10643956|url=http://www.aafp.org/afp/20000101/151.html}}</ref> Symptoms typically present within the initial weeks of stage&nbsp;I; however, the onset of stage&nbsp;II occurs within months and offers little time for diagnosis. The disease progresses rapidly beyond stage&nbsp;II, as OCD lesions quickly move from stable cysts or fissures to unstable fragments. Non-specific symptoms, caused by similar injuries such as [[sprain]]s and [[strain (injury)|strains]], can delay a definitive diagnosis.<ref name="urlOCDofKNEE">{{cite web|url=http://www.eorthopod.com/public/files/Osteochondritis_Dissecans_of_the_Knee.pdf|title=Adolescent Osteochondritis Dissecans of the Knee|accessdate=2008-09-21|last=Anon|format=PDF|publisher=Medical Multimedia Group, LLC}}{{dead link|date=August 2010}}</ref>

Physical examination typically reveals an [[wikt: effusion|effusion]], tenderness, and [[crepitus]]. The tenderness may initially spread, but often reverts to a well-defined focal point as the lesion progresses. Just as OCD shares symptoms with common maladies, acute osteochondral fracture has a similar presentation with tenderness in the affected joint, but is usually associated with a fatty [[hemarthrosis]]. Although there is no significant [[pathologic]] gait or characteristic alignment abnormality associated with OCD, the patient may walk with the involved leg externally rotated in an attempt to avoid [[tibia]]l spine impingement on the [[Laterally|lateral]] aspect of the [[Medial condyle of femur|medial condyle of the femur]].<ref name="pmid8613454">{{cite journal|author=Schenck RC Jr, Goodnight JM|title=Osteochondritis dissecans |journal=Journal of Bone and Joint Surgery (American)|volume=78|issue=3|pages=439–56|date={{Nowrap|1 March}} 1996|pmid=8613454|url=http://www.ejbjs.org/cgi/content/full/78/3/439}}</ref>

==Causes==
{{seealso|Osteochondrosis}}
Despite much research, the [[etiology|causes]] remain unclear but include repetitive [[physical trauma]], [[ischemia]] (restriction of blood flow), [[hereditary]] and [[endocrine]] factors, [[avascular necrosis]] (loss of blood flow), rapid growth, deficiencies and imbalances in the ratio of calcium to phosphorus, and [[anomalies]] of [[ossification|bone formation]].<ref name="pmid2206181">{{cite journal|doi=10.1016/0749-8063(90)90074-N|author=Federico DJ, Lynch JK, Jokl P|title=Osteochondritis dissecans of the knee: a historical review of etiology and treatment|journal=Arthroscopy|volume=6|issue=3|pages=190–7|year=1990 |pmid=2206181}}</ref><ref name="pmid10513356">{{cite journal|author=Hefti F, Beguiristain J, Krauspe R, Möller-Madsen B, Riccio V, Tschauner C, Wetzel R, Zeller R|title=Osteochondritis dissecans: a multicenter study of the European Pediatric Orthopedic Society|journal=Journal of Pediatric Orthopaedics B|volume=8|issue=4|pages=231–45|year=1999|month=October|pmid=2206181|doi=10.1097/00009957-199910000-00001}}</ref><ref name="pmid4996078">{{cite journal|author=Langer F, Percy EC|title=Osteochondritis dissecans and anomalous centres of ossification: a review of 80 lesions in 61 patients|journal=Canadian Journal of Surgery|volume=14|issue=3|pages=208–15|year=1971|month=May|pmid=4996078}}</ref><ref>{{Cite book|last=Geor|first=RJ|coauthors=Kobluk CN, Ames TR|year=1995|title=The Horse: Diseases and Clinical Management|location=Philadelphia, PA|publisher=W.B. Saunders|isbn=0-443-08777-6}}</ref> Although the name "osteochondritis" implies [[inflammation]], the lack of inflammatory cells in [[Histology|histological]] examination suggests a non-inflammatory cause. It is thought that repetitive [[microtrauma]], which leads to microfractures and sometimes an interruption of blood supply to the subchondral bone, may cause subsequent localized loss of blood supply or alteration of growth.<ref name="pmid17606505">{{cite journal|author=Ytrehus B, Carlson CS, Ekman S|title=Etiology and pathogenesis of osteochondrosis |journal=Veterinary Pathology|volume=44|issue=4|pages=429–48|year=2007|month=July|pmid=17606505|url=http://www.vetpathology.org/cgi/reprint/44/4/429.pdf|format=PFD|doi=10.1354/vp.44-4-429}}</ref>

[[Physical trauma|Trauma]], rather than avascular necrosis, is thought to cause osteochondritis dissecans in juveniles.<ref name="pmid622473">{{cite journal|author=Milgram JW|title=Radiological and pathological manifestations of osteochondritis dissecans of the distal femur. A study of 50 cases|journal=Radiology|volume=126|issue=2|pages=305–311|year=1978|month=February|pmid=622473}}</ref> In adults, trauma is thought to be the main or perhaps the sole cause, and may be [[endogenous]], [[exogenous]] or both.<ref name="pmid18556892">{{cite journal|author=Roberts N|title=Book Reviews|journal=Journal of Bone and Joint Surgery (British)|volume=43|issue=2|page=409|year=1961|month=March |url=http://www.jbjs.org.uk/cgi/reprint/43-B/2/409.pdf|format=PDF}}</ref> The incidence of [[repetitive strain injury]] in young athletes is on the rise and accounts for a significant number of visits to primary care;<ref name="pmid18605393">{{cite journal|author=Powers R|title=An ice hockey player with an unusual elbow injury. Osteochondritis dissecans|journal=Adolescent Medicine: State of the Art Reviews|volume=18|issue=1|pages=95–120|year=2007|month=May|pmid=18556892}}</ref> this reinforces the theory that OCD may be associated with increased participation in sports and subsequent trauma.<ref name="pmid18556892"/><ref name="pmid16794036">{{cite journal|author=Kocher MS, Tucker R, Ganley TJ, Flynn JM|title=Management of osteochondritis dissecans of the knee: current concepts review|journal=American Journal of Sports Medicine|volume=34|issue=7|pages=1181–91|year=2006|month=July|pmid=16794036|doi=10.1177/0363546506290127}}</ref> High-impact sports such as Gymnastics, soccer, basketball, lacrosse, football, tennis, squash, baseball and weight lifting may put participants at a higher risk of OCD in stressed joints (knees, ankles and elbows).<ref name="pmid10643956"/><ref>{{cite web|url=http://www.emedicine.com/sports/TOPIC51.HTM|title=Humeral Capitellum Osteochondritis Dissecans|accessdate=2008-11-16|last=Patel|first=S|coauthors=Fried GW, Marone PJ|date=2008-08-06|work=[[eMedicine]]|publisher=[[Medscape]]}}</ref>

Recent case reports suggest that some people may be genetically predisposed to OCD.<ref name="pmid18929205">{{cite journal|author=Kenniston JA, Beredjiklian PK, Bozentka DJ|title=Osteochondritis dissecans of the capitellum in fraternal twins: case report|journal=Journal of Hand Surgery (American)|volume=33|issue=8|pages=1380–3 |year=2008|month=October|pmid=18929205|accessdate=2008-11-22|doi=10.1016/j.jhsa.2008.05.008}}</ref><ref name="pmid1428308">{{cite journal|author=Livesley PJ, Milligan GF|title=Osteochondritis dissecans patellae. Is there a genetic predisposition?|journal=International Orthopaedics|volume=16|issue=2|pages=126–9|year=1992|pmid=1428308|accessdate=2008-11-22}}</ref><ref name="pmid13475409">{{cite journal|author=Tobin WJ|title=Familial osteochondritis dissecans with associated tibia vara|journal=Journal of Bone and Joint Surgery (American)|volume=39|issue=5|pages=1091–1105|year=1957|month=October|pmid=13475409|url=http://www.ejbjs.org/cgi/reprint/39/5/1091.pdf|format=PDF|accessdate=2008-11-22}}</ref> Studies in horses have implicated specific genetic defects.<ref name="pmid18227080">{{cite journal|author=Wittwer C, Dierks C, Hamann H, Distl O |title=Associations between candidate gene markers at a quantitative trait locus on equine chromosome 4 responsible for osteochondrosis dissecans in fetlock joints of South German Coldblood horses |journal=Journal of Heredity |volume=99 |issue=2 |pages=125–9|year=2008|month=March–April|pmid=18227080|doi=10.1093/jhered/esm106 }}</ref>

==Pathophysiology==
[[Image:Osteochondritis dissecans diagram.JPEG|thumb|Tunnel or notch view X-ray of the right knee from a patient with osteochondritis dissecans—cystic changes and irregular border are indicated by arrows on the [[Anatomical terms of location|medial]] side compared to the [[Anatomical terms of location|lateral]] side]]
Osteochondritis dissecans differs from "wear and tear" degenerative [[osteoarthritis|arthritis]], which is primarily an articular surface problem. Instead, OCD is a problem of the underlying [[wikt:subchondral|subchondral]] bone, which may secondarily affect the articular cartilage. Left untreated, OCD can lead to the development of degenerative arthritis secondary to joint incongruity and abnormal wear patterns.<ref name="pmid18500061">{{cite journal|author=Detterline AJ, Goldstein JL, Rue JP, Bach BR Jr|title=Evaluation and treatment of osteochondritis dissecans lesions of the knee.|journal=Journal of Knee Surgery|volume=21|issue=2|pages=106–15|year=2008|pmid=18500061}}</ref>

OCD occurs when a loose piece of bone or cartilage partially (or fully) separates from the end of the bone, often because of a loss of blood supply ([[osteonecrosis]]) and decalcification of the [[Trabecular bone|trabecular bone matrix]]. The loose piece may stay in place or slide around, making the [[joint]] stiff and unstable. OCD in humans most commonly affects the knees,<ref name="pmid6807595">{{cite journal|author=Clanton TO, DeLee JC |title=Osteochondritis dissecans. History, pathophysiology and current treatment concepts|journal=Clinical Orthopaedics and Related Research|volume=167 |pages=50–64|year=1982|month=July|pmid=6807595|issue=167}}</ref> ankles, and elbow but can affect any joint.<ref name="pmid17980849">{{cite journal|author=Kadakia AP, Sarkar J|title=Osteochondritis dissecans of the talus involving the subtalar joint: a case report|journal=Journal of Foot and Ankle Surgery|volume=46|issue=6|pages=488–92|year=2007|pmid=17980849|accessdate=2008-11-22|doi=10.1053/j.jfas.2007.06.005}}</ref>

In skeletally immature individuals, the blood supply to the [[epiphyseal plate|epiphyseal bone]] is good, supporting both [[osteogenesis]] and [[chondrogenesis]]. With disruption of the epiphyseal plate vessels, varying degrees and depth of [[necrosis]] occur, resulting in a cessation of growth to both [[osteocytes]] and [[chondrocytes]]. In turn, this pattern leads to disordered ossification of cartilage, resulting in subchondral [[avascular necrosis]] and consequently OCD.<ref name="topic57webmd"> {{cite web|url=http://www.emedicine.com/sports/TOPIC57.HTM|title=Knee Osteochondritis Dissecans|accessdate=2008-10-02|author=Jacobs B, Ertl JP, Kovacs G, Jacobs JA|work=eMedicine|publisher=Medscape }} {{dead link| date=June 2010 | bot=DASHBot}}</ref>

Four minor stages of OCD have been identified after trauma. These include [[revascularization]] and formation of granulation (scar) tissue, absorption of necrotic fragments, intertrabecular osteoid deposition, and remodeling of new bone. With delay in the revascularization stage, an OCD lesion develops. A lesion can lead to articular-surface irregularities, which in turn may cause progressive [[arthritis|arthritic]] deterioration.<ref name="topic57webmd"/>

==Diagnosis==
To diagnose osteochondritis dissecans, an [[X-ray]], [[CT scan]] or [[MRI scan]] can be performed to show necrosis of subchondral bone, formation of loose fragments, or both.<ref name="pmid12591666">{{cite journal|author=Boutin RD, Januario JA, Newberg AH, Gundry CR, Newman JS|title=MR imaging features of osteochondritis dissecans of the femoral sulcus|journal=American Journal of Roentgenology|volume=180|issue=3|pages=641–5|year=2003|month=March|pmid=12591666|url=http://www.ajronline.org/cgi/reprint/180/3/641.pdf|format=PDF}}</ref> Occasionally a [[nuclear medicine]] [[bone scan]] is used to assess the degree of loosening within the joint.<ref name="Mesgarzadeh">{{cite journal|author=Mesgarzadeh M, Sapega AA, Bonakdarpour A, Revesz G, Moyer RA, Maurer AH, Alburger PD|title=Osteochondritis dissecans: analysis of mechanical stability with radiography, scintigraphy, and MR imaging|journal=Radiology|volume=165|issue=3|pages=775–80|date={{Nowrap|1 December}} 1987|pmid=3685359|url=http://radiology.rsnajnls.org/cgi/reprint/165/3/775}}</ref>

===Physical examination===
{{FixBunching|beg}}
[[Image:OCD WalterReed MRI-Sagital-T1.jpeg|thumb|[[Sagittal plane|Sagittal MRI]]: Linear low [[Relaxation (NMR)|T1]] signal at the articular surfaces of the [[Anatomical terms of location|lateral]] aspects of the [[Medial condyle of femur|medial condyle of the femur]] confirms the presence of OCD.]]
{{FixBunching|mid}}
[[Image:OCD WalterReed MRI-Sagital-T2.jpeg|thumb|Sagittal MRI: High [[Relaxation (NMR)|T2]] signal at the articular surfaces of the lateral aspect of the medial femoral condyle confirms the presence of OCD. Diffuse increase in T2 signal at the medial femoral condyle indicates [[Bone marrow|marrow]] [[edema]].]]
{{FixBunching|end}}
Physical examination often begins with examination of the patient's [[Gait (human)|gait]]. In OCD of the knee, people may walk with the involved leg externally rotated in an attempt to avoid [[tibia]]l spine impingement on the [[Laterally|lateral]] aspect of the [[Medial condyle of femur|medial condyle of the femur]].<ref name="pmid8613454"/>

Next, the examining physician may check for weakness of the [[quadriceps]]. This examination may reveal an [[wikt: effusion|effusion]], tenderness, and crepitus. The [[Wilson test]] is also useful in locating OCD lesions of the [[Lower extremity of femur|femoral condyle]].<ref name="pmid6022357">{{cite journal|author=Wilson JN|title=A diagnostic sign in osteochondritis dissecans of the knee|journal=Journal of Bone and Joint Surgery (American)|volume=49|issue=3|pages=477–80|year=1967|month=April|pmid=6022357|url=http://www.ejbjs.org/cgi/reprint/49/3/477.pdf|format=PDF}}</ref> The test is performed by slowly extending the knee from 90 degrees, maintaining internal rotation. Pain at 30 degrees of [[flexion]] and relief with tibial external rotation is indicative of OCD.<ref name="pmid12975201">{{cite journal|author=Conrad JM, Stanitski CL|title=Osteochondritis dissecans: Wilson's sign revisited|journal=Am J Sports Med|volume=31|issue=5 |pages=777–8|year=2003|pmid=12975201|accessdate=2008-11-22}}</ref>

Physical examination of a patient with ankle OCD often returns symptoms of joint effusion, [[crepitus]], and diffuse or localized tenderness. Examination often reveals symptoms of generalized joint pain, [[Swelling (medical)|swelling]], and times with limited range of motion. Some with loose body lesions may report catching, locking, or both.<ref name="cooperwebmd"/> The possibility of microtrauma emphasizes a need for evaluation of biomechanical forces at the knee in a physical examination. As a result, the alignment and rotation of all major joints in the affected extremity is common, as are [[extrinsic]] and intrinsic abnormalities concerning the affected joint, including laxity.<ref name="OCDPatella-IO">{{cite journal|author=Livesley PJ, Milligan GF|date={{Nowrap|29 November}} 2004|title=Osteochondritis dissecans patellae|journal=International Orthopaedics|volume=16|issue=2|pages=126–129|publisher=Springer Berlin / Heidelberg|location= |issn=0341-2695|accessdate=2009-02-16|pmid=1428308}}</ref>

===Diagnostic imaging===
X-rays show lucency of the [[ossification]] front in juveniles. In older people, the lesion typically appears as an area of [[Osteosclerosis|osteosclerotic]] bone with a [[radiolucent]] line between the osteochondral defect and the [[epiphysis]]. The visibility of the lesion depends on its location and on the amount of knee [[flexion]] used. Harding described the lateral X-ray as a method to identify the site of an OCD lesion.<ref name="pmid852179">{{cite journal|author=Harding WG 3rd.|title=Diagnosis of osteochondritis dissecans of the femoral condyles: the value of the lateral x-ray view|journal=Clinical Orthopaedics and Related Research|volume=123|pages=25–6|year=1977|month=March–April|pmid=852179|issue=123}}</ref>

[[Magnetic resonance imaging]] (MRI) is useful for staging OCD lesions, evaluating the integrity of the joint surface, and distinguishing normal variants of bone formation from OCD by showing bone and cartilage [[edema]] in the area of the irregularity. MRI provides information regarding features of the [[wikt:Articular Cartilage|articular cartilage]] and underlying [[wikt:subchondral|subchondral]] bone, including edema, fractures, fluid interfaces, [[Articular cartilage damage|articular]] surface integrity, and fragment displacement.<ref name="pmid2117355">{{cite journal|doi=10.1016/0749-8063(91)90087-E|author=De Smet AA, Fisher DR, Graf BK, Lange RH|title=Characterizing osteochondral lesions by magnetic resonance imaging|journal=Arthoscopy|volume=7|issue=1|pages=101–4|year=1991|pmid=2117355|url=http://www.ajronline.org/cgi/reprint/155/3/549.pdf|format=PDF}}</ref><ref name="pmid2009106">{{cite journal|author=Dipaola JD, Nelson DW, Colville MR|title=Osteochondritis dissecans of the knee: value of MR imaging in determining lesion stability and the presence of articular cartilage defects|journal=American Journal of Roentgenology|volume=155|issue=2|pages=549–53|year=1990|month=September|pmid=2009106}}</ref> A low T1 and high T2 signal at the fragment interface is seen in active lesions. This indicates an unstable lesion or recent microfractures.<ref name="pmid12591666"/> While MRI and [[arthroscopy]] have a close correlation, X-ray films tend to be less inductive of similar MRI results.<ref name="pmid2009106"/>

[[Computed tomography]] (CT) scans and [[Technetium-99m]] [[bone scan]]s are also sometimes used to monitor the progress of treatment. Unlike plain radiographs (X-rays), CT scans and MRI scans can show the exact location and extent of the lesion.<ref name="pmid11044029">{{cite journal|author=Bui-Mansfield LT, Kline M, Chew FS, Rogers LF, Lenchik L |title=Osteochondritis dissecans of the tibial plafond: imaging characteristics and a review of the literature|journal=American Journal of Roentgenology|volume=175|issue=5|pages=1305–8|date={{Nowrap|1 November}} 2000|pmid=11044029|url=http://www.ajronline.org/cgi/content/full/175/5/1305}}</ref> Technetium bone scans can detect regional blood flow and the amount of [[osseous]] uptake. Both of these seem to be closely correlated to the potential for healing in the fragment.<ref name="pmid6638247">{{cite journal|author=Cahill BR, Berg BC|title=99m-Technetium phosphate compound joint scintigraphy in the management of juvenile osteochondritis dissecans of the femoral condyles|journal=American Journal of Sports Medicine|volume=11|issue=5|pages=329–35|year=1983|pmid=6638247|doi=10.1177/036354658301100509}}</ref><ref>{{cite web|url=http://www.eorthopod.com/public/files/Adolescent_Osteochondritis_Dissecans_of_the_Elbow.pdf|archiveurl=http://web.archive.org/web/20071027030205/http://www.eorthopod.com/public/files/Adolescent_Osteochondritis_Dissecans_of_the_Elbow.pdf|archivedate=2007-10-27|title=Adolescent Osteochondritis Dissecans of the Elbow|accessdate=2008-10-02|first=eOrthopod.com|format=PDF|publisher=Medical Multimedia Group, LLC}}</ref>

==Treatment==
{{seealso|Knee cartilage replacement therapy}}
Treatment options include modified activity with or without weight bearing; immobilization; [[Cryotherapy (chamber therapy)|cryotherapy]]; [[non-steroidal anti-inflammatory drug|anti-inflammatory medication]]; drilling of subchondral bone; [[Microfracture surgery|microfracture]]; removal or reattachment of loose bodies; mosaicplasty and osteoarticular transfer system (OATS) procedures.<ref name="pmid16794036"/><ref name="pmid10028116">{{cite journal|author=Kish G, Módis L, Hangody L|title=Osteochondral mosaicplasty for the treatment of focal chondral and osteochondral lesions of the knee and talus in the athlete. Rationale, indications, techniques, and results|journal=Clinical Journal of Sports Medicine|volume=18|issue=1|pages=45–66, vi|year=1999|month=January|pmid=10028116|accessdate=2008-11-16|doi=10.1016/S0278-5919(05)70129-0}}</ref> The primary goals of treatment are:<ref name="pmid13438964">{{cite journal|author=Smillie I|title=Treatment of osteochondritis dissecans|journal=Journal of Bone and Joint Surgery|volume=39|issue=2|pages=248–260 |year=1957|pmid=13438964|url=http://www.jbjs.org.uk/cgi/reprint/39-B/2/248.pdf|format=PDF}}</ref>
# Enhance the healing potential of subchondral bone;
# Fix unstable fragments while maintaining joint congruity; and
# Replace damaged bone and cartilage with implanted tissues or cells that can grow cartilage.
The articular cartilage's capacity for repair is limited:<ref name="pmid17530379">{{cite journal |author=Moriya T, Wada Y, Watanabe A, ''et al.''|title=Evaluation of reparative cartilage after autologous chondrocyte implantation for osteochondritis dissecans: histology, biochemistry, and MR imaging|journal=Journal of Orthopaedic Science|volume=12|issue=3|pages=265–73|year=2007|month=May|pmid=17530379|accessdate=2008-11-22 |doi=10.1007/s00776-007-1111-8}}</ref> partial-thickness defects in the articular cartilage do not heal spontaneously, and injuries of the articular cartilage which fail to penetrate subchondral bone tend to lead to deterioration of the articular surface.<ref name="urlMedscape-ACT">{{cite web|url=http://www.medscape.com/viewarticle/420393|title=Autologous chondrocyte transplantation|accessdate=2008-09-17|author=Bobic V|date=2000|publisher=Medscape}}</ref> As a result, surgery is often required in even moderate cases where the osteochondral fragment has not detached from the bone (Anderson Stage&nbsp;II, III).<ref name="orthogateKNEEOCD"/>

===Non-surgical treatment===
Candidates for non-operative treatment are limited to skeletally immature teenagers with a relatively small, intact lesion and the absence of loose bodies. Non-operative management may include activity modification, protected weight bearing (partial or non-weight bearing), and immobilization. The goal of non-operative intervention is to promote healing in the subchondral bone and prevent potential chondral collapse, subsequent fracture, and crater formation.<ref name="pmid13438964"/>

Once candidates for treatment have been screened, treatment proceeds according to the lesion's location. For example, those with OCD of the knee are immobilized for four to six weeks in [[Extension (kinesiology)|extension]] to remove shear stress from the involved area;<ref>{{cite web |url=http://www.sofop.org/data/Upload/Images/file/POSNA%20Curriculum/2.8.5%20osteochondritisDissecansLower.pdf |title=Osteochondritis dissecans|accessdate=2008-11-21|format=PDF|publisher=Société Française d'Orthopédie Pédiatrique}}</ref> however, they are permitted to walk with weight bearing as tolerated. X-rays are usually taken three months after the start of non-operative therapy; if they reveal that the lesion has healed, a gradual return to activities is instituted.<ref name="orthogateKNEEOCD"/><ref>{{cite web|url=http://www.cedars-sinai.edu/12907.html|title=Treating osteochondritis dissecans|accessdate=2008-11-22|publisher=Cedars-Sinai Health}}</ref> Those demonstrating healing by increased radiodensity in the subchondral region, or those whose lesions are unchanged, are candidates to repeat the above described three-month protocol until healing is noted.<ref name="pmid17980849"/>

===Surgical treatment===
[[Image:OATS-Arthroscopic Scan1.jpg|thumb|Arthroscopic image of OATS surgery on the [[medial condyle of femur|medial femoral condyle]] of the knee]]

The choice of surgical versus non-surgical treatments for osteochondritis dissecans is controversial.<ref name="pmid18509814">{{cite journal|author=Nobuta S, Ogawa K, Sato K, Nakagawa T, Hatori M, Itoi E|title=Clinical outcome of fragment fixation for osteochondritis dissecans of the elbow|journal=Upsala Journal of Medical Sciences|volume=113|issue=2|pages=201–8|year=2008|pmid=18509814|url=http://www.diva-portal.org/diva/getDocument?urn_nbn_se_pub_diva-232-2__fulltext.pdf|format=PDF|doi=10.3109/2000-1967-232}}</ref> Consequently, the type and extent of surgery necessary varies based on patient age, severity of the lesion, and personal bias of the treating surgeon—entailing an exhaustive list of suggested treatments. A variety of surgical options exist for the treatment of persistently symptomatic, intact, partially detached, and completely detached OCD lesions. Post-surgery reparative cartilage is inferior to healthy [[hyaline]] cartilage in [[glycosaminoglycan]] concentration, [[Histology|histological]], and [[Immunohistochemistry|immunohistochemical]] appearance.<ref name="pmid18006675">{{cite journal |author=LaPrade RF, Bursch LS, Olson EJ, Havlas V, Carlson CS|title=Histologic and immunohistochemical characteristics of failed articular cartilage resurfacing procedures for osteochondritis of the knee: a case series|journal=American Journal of Sports Medicine |volume=36|issue=2|pages=360–8|year=2008|month=February|pmid=18006675|accessdate=2008-11-23|doi=10.1177/0363546507308359}}</ref> As a result, surgery is often avoided if non-operative treatment is viable.

====Intact lesions====
If non-surgical measures are unsuccessful, drilling may be considered to stimulate healing of the subchondral bone. [[Arthroscopic]] drilling may be performed by using an antegrade (from the front) approach from the joint space through the articular cartilage, or by using a retrograde (from behind) approach through the bone outside of the joint to avoid penetration of the articular cartilage. This has proven successful with positive results at one-year follow-up with antegrade drilling in nine out of eleven teenagers with the juvenile form of OCD,<ref name="pmid2768313">{{cite journal|author=Bradley J, Dandy DJ|title=Results of drilling osteochondritis dissecans before skeletal maturity |journal=Journal of Bone and Joint Surgery (British)|volume=71|issue=4|pages=642–4|year=1989|month=August|pmid=2768313|url=http://www.jbjs.org.uk/cgi/reprint/71-B/4/642.pdf|format=PDF}}</ref> and in 18 of 20 skeletally immature people (follow-up of five years) who had failed prior conservative programs.<ref name="pmid9195028">{{cite journal|doi=10.1016/S0749-8063(97)90028-1|author=Anderson AF, Richards DB, Pagnani MJ, Hovis WD|title=Antegrade drilling for osteochondritis dissecans of the knee|journal=Arthroscopy|volume=13|issue=3|pages=319–24|year=1997|month=June|pmid=9195028}}</ref>

====Hinged lesions====
Pins and screws can be used to secure flap (sometimes referred to as hinged) lesions.<ref name="pmid2206180">{{cite journal|doi=10.1016/0749-8063(90)90073-M|author=Johnson LL, Uitvlugt G, Austin MD, Detrisac DA, Johnson C|title=Osteochondritis dissecans of the knee: arthroscopic compression screw fixation |journal=Arthroscopy|volume=6|issue=3|pages=179–89|year=1990|pmid=2206180}}</ref> Bone pegs, metallic pins and screws, and other bioresorbable screws may be used to secure these types of lesions.<ref name="pmid3665256">{{cite journal|author=Thomson NL|title=Osteochondritis dissecans and osteochondral fragments managed by Herbert compression screw fixation|journal=Clinical Orthopaedics and Related Research|issue=224|pages=71–8|year=1987|month=November|pmid=3665256}}</ref>

====Full thickness lesions====
{{FixBunching|beg}}
[[Image:Paste Graft Surgery-1.jpg|thumb|Morselization of the articular cartilage lesion]]
{{FixBunching|mid}}
[[Image:Paste Graft Surgery-2.jpg|thumb|Harvesting of the articular cartilage and bone]]
{{FixBunching|mid}}
[[Image:Paste Graft Surgery-3.jpg|thumb|Manual crushing used to make a paste graft]]
{{FixBunching|mid}}
[[Image:Paste Graft Surgery-4.jpg|thumb|Impacting the paste graft into the morselized defect]]
{{FixBunching|end}}

The three methods most commonly used in treating full thickness lesions are arthroscopic drilling, abrasion, and microfracturing.

In 1946, Magnusson established the use of stem cells from [[bone marrow]] with the first surgical [[debridement]] of an OCD lesion. These cells typically differentiate into [[fibrocartilage]] and rarely form hyaline cartilage. While small lesions can be resurfaced using this form of surgery, the repair tissue tends to have less strength than normal [[hyaline cartilage]] and must be protected for 6 to 12 months. Results for large lesions tend to diminish over time; this can be attributed to the decreased resilience and poor wear characteristics of the fibrocartilage.<ref name="pmid9850792">{{cite journal|author=Mandelbaum BR, Browne JE, Fu F, ''et al.''|title=Articular cartilage lesions of the knee|journal=American Journal of Sports Medicine|volume=26|issue=6|pages=853–61|year=1998|pmid=9850792|accessdate=2008-09-17}}</ref>

In attempts to address the weaker structure of the reparative fibrocartilage, new techniques have been designed to fill the defect with tissue that more closely simulates normal hyaline articular cartilage. One such technique is [[autologous]] [[chondrocyte]] implantation (ACI), which is useful for large, isolated [[femur|femoral]] defects in younger people. In this surgery, chondrocytes are arthroscopically extracted from the [[Intercondylar fossa of femur|intercondylar notch]] of the articular surface. The chondrocytes are grown and injected into the defect under a periosteal patch. ACI surgery has reported good to excellent results for reduced swelling, pain and locking in clinical follow-up examinations.<ref name="pmid8078550">{{cite journal|author=Brittberg M, Lindahl A, Nilsson A, Ohlsson C, Isaksson O, Peterson L|title=Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation|journal=New England Journal of Medicine |volume=331|issue=14|pages=889–95|year=1994|month=October|pmid=8078550|url=http://content.nejm.org/cgi/content/full/331/14/889|accessdate=2008-09-17|doi=10.1056/NEJM199410063311401}}</ref><ref name="pmid10818982">{{cite journal|author=Peterson L, Minas T, Brittberg M, Nilsson A, Sjögren-Jansson E, Lindahl A|title=Two to Nine-year outcome after autologous chondrocyte transplantation of the knee|journal=Clinical Orthopaedics and Related Research|issue=374|pages=212–34|year=2000|month=May|pmid=10818982|accessdate=2008-09-17|doi=10.1097/00003086-200005000-00020|volume=374}}</ref> However, some physicians have preferred to use undifferentiated pluripotential cells, such as periosteal cells and bone marrow stem cells, as opposed to chondrocytes. These too have demonstrated the ability to regenerate both the cartilage and the underlying subchondral bone.<ref name="pmid9875939">{{cite journal|author=O'Driscoll SW|title=The healing and regeneration of articular cartilage|journal=Journal of Bone and Joint Surgery (American)|volume=80|issue=12|pages=1795–1812|year=1998|month=December|pmid=9875939|url=http://www.ejbjs.org/cgi/reprint/80/12/1795.pdf|format=PDF}}</ref>

Another method used to promote normal articular cartilage replacement is the technique of transplanting autologous osteochondral plugs. The [[Autologous|autografts]] are taken from a relatively non-weight-bearing region of the knee, such as the area just above the intercondylar notch or the edge of the [[patellar groove]], and inserted in the defect. OATS has reported good clinical results with plugs taken from the lateral facet of the patella when treating ten cases with large femoral OCD lesions.<ref name="pmid7822357">{{cite journal|author=Outerbridge HK, Outerbridge AR, Outerbridge RE|title=The use of a lateral patellar autologous graft for the repair of a large osteochondral defect in the knee|journal=Journal of Bone and Joint Surgery (American)|volume=77|issue=1|pages=65–72|year=1995|month=January|pmid=7822357}}</ref><ref name="pmid15346108">{{cite journal|author=Chow JC, Hantes ME, Houle JB, Zalavras CG|title=Arthroscopic autogenous osteochondral transplantation for treating knee cartilage defects: a two- to five-year follow-up study|journal=Arthroscopy|volume=20|issue=7|pages=681–90|year=2004|month=September|pmid=15346108|accessdate=2009-02-07|doi=10.1016/j.arthro.2004.06.005}}</ref> OATS is limited by donor site morbidity, plug damage from insertion, and the challenge of placing the plug edges flush with adjacent cartilage.<ref name="pmid16125942">{{cite journal |author=Karataglis D, Green MA, Learmonth DJ |title=Autologous osteochondral transplantation for the treatment of chondral defects of the knee|journal=Knee |volume=13 |issue=1 |pages=32–5 |year=2006 |month=January|pmid=16125942 |doi=10.1016/j.knee.2005.05.006}}</ref> Fresh osteocartilaginous [[allografts]] have also been used for the treatment of OCD defects. In a study of 126 people with OCD of the knee, Ghazavi ''et al.'' reported an 85% success rate 7.5 years after OATS surgery with allografts. This procedure may be an option when other treatments have failed and symptoms persist.<ref name="pmid9393922">{{cite journal |author=Ghazavi MT, Pritzker KP, Davis AM, Gross AE |title=Fresh osteochondral allografts for post-traumatic osteochondral defects of the knee |journal=Journal of Bone and Joint Surgery (British) |volume=79 |issue=6 |pages=1008–13 |year=1997 |month=November |pmid=9393922 |url=http://www.jbjs.org.uk/cgi/reprint/79-B/6/1008|doi=10.1302/0301-620X.79B6.7534}}</ref>

Similar to OATS, arthroscopic articular cartilage paste grafting is a relatively new surgical procedure offering cost-effective, long-lasting results for stage IV lesions. An [[wikt:osteocartilaginous|osteocartilaginous]] paste derived from crushed plugs of the non-weight-bearing intercondylar notch can achieve pain relief, repair damaged tissue, and restore function.<ref name="pmid16517314">{{cite journal |author=Stone KR, Walgenbach AW, Freyer A, Turek TJ, Speer DP |title=Articular cartilage paste grafting to full-thickness articular cartilage knee joint lesions: a 2- to 12-year follow-up |journal=Arthroscopy |volume=22 |issue=3 |pages=291–9 |year=2006 |month=March |pmid=16517314 |doi=10.1016/j.arthro.2005.12.051}}</ref>

====Unstable lesions====
Some methods of fixation for unstable lesions include countersunk compression screws and [[Timothy Herbert|Herbert screws]] or pins made of stainless steel or [http://en.wiktionary.org/wiki/bioabsorption bioabsorbable] materials.<ref name="pmid17337729">{{cite journal |author=Kocher MS, Czarnecki JJ, Andersen JS, Micheli LJ |title=Internal fixation of juvenile osteochondritis dissecans lesions of the knee |journal=American Journal of Sports Medicine |volume=35 |issue=5 |pages=712–8 |year=2007 |month=May |pmid=17337729 |doi=10.1177/0363546506296608}}</ref> If loose bodies are found, they are removed. Although each case is unique and treatment is chosen on an individual basis, ACI is generally performed on large defects in skeletally mature people.

====Rehabilitation====
Continuous passive motion (CPM) has been used to improve healing of the articular surface during the postoperative period for people with full-thickness lesions. It has been shown to promote articular cartilage healing for small (< 3&nbsp;mm in diameter) lesions in rabbits.<ref name="pmid7440603">{{cite journal|author=Salter RB, Simmonds DF, Malcolm BW, Rumble EJ, MacMichael D, Clements ND|title=The biological effect of continuous passive motion on the healing of full-thickness defects in articular cartilage. An experimental investigation in the rabbit |journal=Journal of Bone and Joint Surgery|volume=62 |issue=8 |pages=1232–51 |year=1980 |month=December|pmid=7440603 |url=http://www.ejbjs.org/cgi/reprint/62/8/1232.pdf |format=PDF}}</ref> Similarly, Rodrigo and Steadman reported that CPM for six hours per day for eight weeks produced an improved clinical outcome in humans.<ref name="pmid8590122">{{cite journal |author=Rodrigo JJ, Steadman JR, Syftestad G, Benton H, Silliman J |title=Effects of human knee synovial fluid on chondrogenesis in vitro |journal=American Journal of Knee Surgery |volume=8 |issue=4 |pages=124–9 |year=1995|pmid=8590122}}</ref>

A rehabilitation program often involves protection of the compromised articular surface and underlying subchondral bone combined with maintenance of strength and range of motion. Post-operative [[analgesics]], namely a mix of [[opioids]] and [[NSAIDs]], are usually required to control pain, inflammation and swelling.<ref>{{cite web|url=http://emedicine.medscape.com/article/89718-treatment|title=Knee Osteochondritis dissecans: treatment & medication |accessdate=2009-02-14|last=Jacobs B, Ertl JP, Kovacs G, Jacobs JA |date=2006-07-28|work=eMedicine |publisher=Medscape}}</ref> Straight leg raising and other [[isometric exercise]]s are encouraged during the post-operative or immobilization period. A six to eight-week home or formal [[physical therapy]] program is usually instituted once the immobilization period has ended, incorporating range of motion, stretching, progressive strengthening, and functional or sport-specific training. During this time, patients are advised to avoid running and jumping, but are permitted to perform low impact activities, such as walking or swimming. If patients return to activity before the cartilage has become firm, they will typically complain of pain during maneuvers such as squatting or jumping.<ref name="orthogateKNEEOCD">{{cite web |url=http://www.orthogate.org/index2.php?option=com_content&do_pdf=1&id=185 |title=Osteochondritis dissecans of the knee |accessdate=2008-11-16 |date=2006-07-28 |format=PDF |publisher=Orthogate}}</ref>

==Prognosis==
The prognosis after different treatments varies and is based on several factors which include the age of the patient, the affected joint, the stage of the lesion and, most importantly, the state of the growth plate.<ref name="cooperwebmd">{{cite web|url=http://www.emedicine.com/orthoped/topic639.htm|title=Definition of osteochondritis dissecans|accessdate=2008-09-18|author=Cooper G, Russell W|work=eMedicine|publisher=Medscape}}</ref> It follows that the two main forms of osteochondritis dissecans are defined by skeletal maturity. The juvenile form of the disease occurs in open growth plates, usually affecting children between the ages of 5 and 15 years.<ref>{{Cite book|author=Fleisher GR, Ludwig S, Henretig FM, Ruddy RM, Silverman BK|year=2005|title=Textbook of Pediatric Emergency Medicine|publisher=Lippincott Williams & Wilkins|isbn=0-781-75074-1|url=http://books.google.com/?id=oA7qSOvYZxUC&pg=RA2-PA1703&lpg=RA2-PA1703&dq=free+ebook+osteochondritis|page=1703}}</ref> The adult form commonly occurs between ages 16 to 50, although it is unclear whether these adults developed the disease after skeletal maturity or were undiagnosed as children.<ref>{{Cite book|author=Simon RR, Sherman SC, Koenigsknecht SJ|year=2006|title=Emergency Orthopedics: The Extremities|publisher=McGraw-Hill Professional|isbn=0-071-44831-4|url=http://books.google.com/?id=nMXRDsufkMwC&pg=PA254&dq=osteochondritis+dissecans|page=254}}</ref>

The prognosis is good for stable lesions (stage&nbsp;I and II) in juveniles with open growth plates; treated conservatively—typically without surgery—50% of cases will heal.<ref name="pmid10795030">{{cite journal|author=Cahill BR|title=Osteochondritis dissecans of the knee: Treatment of juvenile and adult forms|journal=Journal of the American Academy of Orthopaedic Surgeons|volume=3|issue=4|pages=237–47|year=1995|month=July|pmid=10795030}}</ref> Recovery in juveniles can be attributed to the bone's ability to repair damaged or dead bone tissue and cartilage in a process called bone remodeling. Open growth plates are characterized by increased numbers of undifferentiated chondrocytes ([[Mesenchymal stem cell|stem cells]]) which are precursors to both bone and cartilaginous tissue. As a result, open growth plates allow for more of the stem cells necessary for repair in the affected joint.<ref name="Cartilage+GrowthPlates">{{cite book |author=Bogin B|title=Patterns of Human Growth|url=http://books.google.com/?id=ScfPjwF3BngC|accessdate=2009-02-20|edition=2|year=2008|month=January|publisher=Cambridge University Press|isbn=0521564387|page=102|chapter=Mammalian Growth|chapterurl=http://books.google.com/books?id=ScfPjwF3BngC&pg=PA102&lpg=PA102&dq=growth+plates+bone+remodeling&source=web&ots=gGxVx5XMbV&sig=KvWHnkgb5y7IktTLmoCcHNlqIF8&hl=en&ei=xCefSc-cGY-EtgeWjJz_DA&sa=X&oi=book_result&resnum=3&ct=result#PPA101,M1}}</ref> Unstable, large, full-thickness lesions (stage&nbsp;III and IV) or lesions of any stage found in the skeletally mature are more likely to fail non-operative treatment. These lesions offer a worse prognosis and surgery is required in most cases.<ref name="pmid2722949"/><ref name="pmid17680233">{{cite journal|author=Lützner J, Mettelsiefen J, Günther KP, Thielemann F|title=Treatment of osteochondritis dissecans of the knee joint|language=German|journal=Der Orthopäde|volume=36|issue=9|pages=871–9; quiz 880|year=2007|month=September|pmid=17680233|doi=10.1007/s00132-007-1130-3}}</ref>

==Epidemiology==
OCD is a relatively rare disorder, with an estimated [[incidence (epidemiology)|incidence]] of 15 to 30 cases per 100,000 persons per year.<ref name="pmid9012566">{{cite journal|author=Obedian RS, Grelsamer RP|title=Osteochondritis dissecans of the distal femur and patella|journal=Clinical Journal of Sports Medicine|volume=16|issue=1|pages=157–74|year=1997|month=January|pmid=9012566|doi=10.1016/S0278-5919(05)70012-0}}</ref> Widuchowski W ''et al.'' found OCD to be the cause of articular cartilage defects in 2% of cases in a study of 25,124 knee arthroscopies.<ref name="pmid17428666">{{cite journal|author=Widuchowski W, Widuchowski J, Trzaska T|title=Articular cartilage defects: study of 25,124 knee arthroscopies |journal=The Knee|volume=14|issue=3|pages=177–82|year=2007|month=June|pmid=17428666|accessdate=2008-11-16|doi=10.1016/j.knee.2007.02.001}}</ref> Although rare, OCD is noted as an important cause of joint pain in active adolescents. The juvenile form of the disease occurs in children with open growth plates, usually between the ages 5 and 15 years and occurs more commonly in males than females, with a ratio between 2:1 and 3:1.<ref name="pmid6807595"/><ref name="KonigNOPMID">{{cite journal|author=Nagura S|title=The so-called osteochondritis dissecans of Konig|journal=Clinical Orthopaedics and Related Research|volume=18|pages=100–121|year=1960}}</ref> However, OCD has become more common among adolescent females as they become more active in sports.<ref name="pmid8917149">{{cite journal |author=Williamson LR, Albright JP|title=Bilateral osteochondritis dissecans of the elbow in a female pitcher|journal=Journal of Family Practice|volume=43|issue=5|pages=489–93|year=1996|month=November|pmid=8917149}}</ref> The adult form, which occurs in those who have reached skeletal maturity, is most commonly found in people 16 to 50 years old.<ref name="pmid2722949">{{cite journal|author=Bradley J, Dandy DJ|title=Osteochondritis dissecans and other lesions of the femoral condyles|journal=Journal of Bone and Joint Surgery (British)|volume=71|issue=3|pages=518–22|year=1989|month=May|pmid=2722949|url=http://www.jbjs.org.uk/cgi/reprint/71-B/3/518.pdf|format=PDF}}</ref>

While OCD may affect any joint, the knee—specifically the [[Medial condyle of femur|medial femoral condyle]] in 75–85% of knee cases—tends to be the most commonly affected, and constitutes 75% of all cases.<ref name="pmid6807595"/><ref name="pmid6501330">{{cite journal|author=Hughston JC, Hergenroeder PT, Courtenay BG|title=Osteochondritis dissecans of the femoral condyles|journal=Journal of Bone and Joint Surgery (American)|volume=66|issue=9|pages=1340–8|year=1984|month=December|pmid=6501330|url=http://www.ejbjs.org/cgi/reprint/66/9/1340.pdf|format=PDF}}</ref><ref name="pmid5562371">{{cite journal|author=Aichroth P|title=Osteochondritis dissecans of the knee. A clinical survey|journal=Journal of Bone and Joint Surgery (British)|volume=53|issue=3|pages=440–7|year=1971|month=August|pmid=5562371 |url=http://www.jbjs.org.uk/cgi/reprint/53-B/3/440.pdf|format=PDF}}</ref><ref name="pmid1015263">{{cite journal|author=Lindén B |title=The incidence of osteochondritis dissecans in the condyles of the femur|journal=Acta Orthopaedica Scandinavica|volume=47|issue=6|pages=664–7|year=1976|month=December|pmid=1015263|doi=10.3109/17453677608988756}}</ref> The elbow (specifically the [[capitulum]] of the [[humerus]]) is the second most affected joint with 6% of cases; the [[Talus bone|talar dome]] of the ankle represents 4% of cases.<ref>{{cite web|url=http://www.emedicine.com/orthoped/topic639.htm|title=Osteochondritis Dissecans|accessdate=2008-11-16|author=Cooper G, Warren R|date=2008-05-15|work=eMedicine|publisher=Medscape}}</ref> Less frequent locations include the [[patella]], [[vertebrae]], the femoral head, and the [[glenoid]] of the scapula.<ref name="pmid7803070">{{cite journal|author=Tuite MJ, DeSmet AA|title=MRI of selected sports injuries: muscle tears, groin pain, and osteochondritis dissecans|journal=Seminars in Ultrasound, CT and MRI|volume=15|issue=5|pages=318–40|year=1994|month=October|pmid=7803070|doi=10.1016/S0887-2171(05)80002-2}}</ref>

==History==
The condition was initially described by [[Alexander Monro (primus)]] in 1738.<ref>{{cite journal|journal=Medical Essays and Observations |title=Part of the cartilage of the joint separated and ossified|author=Munro A|year=1738 |volume=4|page=19}} cited in {{cite journal |author=Burns RC |year=1939 |month=September |title=Osteochondritis dissecans |journal=CMAJ |volume=41 |issue=3 |pages=232–5 |pmc=537458}}</ref>
In 1870, [[James Paget]] described the disease process for the first time, but it was not until 1887 that [[Franz König (surgeon)|Franz König]] published a paper on the cause of loose bodies in the joint.<ref name="pmid1868560">{{cite journal|author=Garrett JC|title=Osteochondritis dissecans|journal=Clinical Journal of Sports Medicine|volume=10|issue=3|pages=569–93|year=1991|month=July|pmid=1868560}}</ref> In his paper, König concluded that:<ref name="konig">{{cite journal|author=König F|title=Uber freie Korper in den gelenken|journal=Deutsche Zeitschrift für Chirurgie |volume=27|issue=1–2|pages=90–109|year=1888|month=December|url=http://www.springerlink.com/content/m57696053j598h56/fulltext.pdf?page=1|language=German}}</ref>
# Trauma had to be very severe to break off parts of the joint surface.
# Less severe trauma might contuse the bone to cause an area of necrosis which might then separate.
# In some cases, the absence of notable trauma made it likely that there existed some spontaneous cause of separation.
König named the disease "osteochondritis dissecans",<ref name="pmid3316236">{{cite journal|author=Barrie HJ|title=Osteochondritis dissecans 1887–1987. A centennial look at König's memorable phrase|journal=Journal of Bone and Joint Surgery (British)|volume=69|issue=5|pages=693–5|year=1987|month=November|pmid=3316236|url=http://www.jbjs.org.uk/cgi/reprint/69-B/5/693.pdf|format=PDF}}</ref> describing it as a subchondral inflammatory process of the knee, resulting in a loose fragment of cartilage from the femoral condyle. In 1922, Kappis described this process in the ankle joint.<ref name="kappis">{{cite journal|author=Kappis M|title=Weitere beitrage zur traumatisch-mechanischen entstehung der "spontanen" knorpela biosungen|journal=Deutsche Zeitschrift für Chirurgie |volume=171|pages=13–29|year=1922|language=German}}</ref> On review of all literature describing transchondral fractures of the [[Talus bone|talus]], Berndt and Harty developed a classification system for staging of osteochondral lesions of the talus (OLTs).<ref name="pmid15173311">{{cite journal|author=Berndt AL, Harty M|title=Transchondral fractures (osteochondritis dissecans) of the talus|journal=Journal of Bone and Joint Surgery (American)|volume=86|issue=6|page=1336|year=2004|month=June|pmid=15173311}}</ref> The term osteochondritis dissecans has persisted, and has since been broadened to describe a similar process occurring in many other joints, including the knee, hip, elbow, and [[Metatarsophalangeal articulations|metatarsophalangeal joints]].<ref>{{Cite book|author=Morrey BF|year=2000|title=The Elbow and Its Disorders|place=Philadelphia, PA|publisher= W.B. Saunders|isbn=0-7216-7752-5|pages=250–60}}</ref><ref>{{Cite book|author=Walzer J, Pappas AM|year=1995|title=Upper Extremity Injuries in the Athlete|location=Edinburgh, UK|publisher=Churchill Livingstone|isbn=0-443-08836-5|page=132}}</ref>

==Veterinary aspects==
{{main|Elbow dysplasia}}
[[Image:Osteochondritis dissecans pathology Danish sow.png|thumb|Pathological specimen from a sow— the arrow points to a fracture in the [[lateral epicondyle of the humerus]].<br />[[H&E stain|Hematoxylin and eosin staining]]. Bar = 200 [[micrometre|μm]].]]
In animals, OCD is considered a developmental and metabolic disorder related to cartilage growth and endochondral [[ossification]]. Osteochondritis itself signifies the disturbance of the usual growth process of cartilage, and OCD is the term used when this affects joint cartilage causing a fragment to become loose.<ref name="Pubmed1">{{cite journal|author=Berzon JL |title=Osteochondritis dissecans in the dog: diagnosis and therapy|journal=Journal of the American Veterinary Medical Association|volume=175|issue=8|pages=796–9|year=1979|pmid=393676}}</ref>

According to the Columbia Animal Hospital the frequency of affected animals is dogs, humans, pigs, horses, cattle, chickens, and turkeys, and in dogs the most commonly affected breeds include the German Shepherd, Golden and Labrador Retriever, Rottweiler, Great Dane, Bernese Mountain Dog, and Saint Bernard.<ref name="CAH">{{cite web|title=Osteochondrosis, osteochondritis dissecans (OCD)|url=http://www.petshealthrx.com/encycEntry.cfm?ENTRY=8&COLLECTION=EncycIllness&MODE=full|work=Category: Canine |publisher=Columbia Animal Hospital|date=undated|accessdate=2008-09-13}} {{Dead link|date=September 2010|bot=H3llBot}}</ref> Although any joint may be affected, those commonly affected by OCD in the dog are: shoulder (often bilaterally), elbow, knee and [[Hock (zoology)|tarsus]].<ref name="CAH"/>

The problem develops in puppyhood although often subclinically, and there may be pain or stiffness, discomfort on extension, or other compensating characteristics. Diagnosis generally depends on X-rays, [[arthroscopy]], or [[MRI]] scans. While cases of OCD of the stifle go undetected and heal spontaneously, others are exhibited in acute lameness. Surgery is recommended once the animal has been deemed lame.<ref name="Ch.84OCD">{{cite book |author=Lenehan TM, Van Sickle DC|editor=Nunamaker DM, Newton CD (eds.)|chapter=Chapter 84: Canine osteochondrosis|chapterurl=http://cal.vet.upenn.edu/projects/saortho/chapter_84/84mast.htm|title=Textbook of small animal orthopaedics|url=http://cal.vet.upenn.edu/projects/saortho/index.html|publisher=Lippincott|location=Philadelphia|year=1985|isbn=0-397-52098-0}}</ref>

Osteochondritis dissecans is difficult to diagnose clinically as the animal may only exhibit an unusual gait. Consequently, OCD may be masked by, or misdiagnosed as, other skeletal and joint conditions such as [[Hip dysplasia (canine)|hip dysplasia]].<ref name="Ch.84OCD"/>

==See also==
* [[Knee osteoarthritis]]
* [[Knee pain]]

==References==
{{Reflist|2}}

==External links==
{{commons}}
{{Osteochondropathy}}
{{featured article}}
{{DEFAULTSORT:Osteochondritis Dissecans}}
[[Category:Chondropathies]]
[[Category:Dog diseases]]
[[Category:Horse diseases]]
[[Category:Inflammations]]
[[Category:Rare diseases]]

[[de:Osteochondrosis dissecans]]
[[es:Osteocondritis disecante]]
[[fa:استئوکندریت دیسکان]]
[[ja:離断性骨軟骨炎]]
[[pt:Osteocondrite dissecante]]
[[ru:Рассекающий остеохондрит]]
[[Category:2Fix]]