Osteoarthritis

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Osteoarthritis, abbreviated OA, is a degenerative disease of the joint.

Osteoarthritis
Diagnosis in short

Severe degenerative joint disease. H&E stain.

LM vertical clefts of the cartilage, +/-thickening of bony trabeculae, subchondral cysts (where there is cartilage loss), +/-mild inflammation (lymphocytes), +/-villous hyperplasia (synovium has finger-like projections into the joint space), osteophytes (ossified projections at the edge of the articular cartilage)
LM DDx rheumatoid arthritis, infectious arthritis, arthritis secondary to other disease (IBD, rheumatologic condition), trauma/deformity related, AVN-related
Gross thinning/loss of cartilage, osteophyte formation, subchondral cysts, subchondral sclerosis
Grossing notes femoral head grossing, knee replacement specimen grossing
Site joints, e.g. femoral head, knee, shoulder

Associated Dx trauma to joint, obesity (for knees), congenital disease (SCFE, Legg–Calvé–Perthes disease), complication of avascular necrosis of the femoral head
Clinical history old age
Signs joint pain
Prevalence very common
Radiology joint space narrowing, osteophyte formation, subchondral cysts, subchondral sclerosis
Prognosis benign
Clin. DDx other types of arthritis
Treatment pain medications, joint replacement

General

Risks

It is associated with:[1]

  • Advanced age.
  • Trauma.
  • Unusual loading (bony misalignment, obesity).

Gross pathology/radiology

Features - joints (internal):[2]

  1. Loss of cartilage, especially asymmetrical.
    • Marble-like appearance - polished appearance known as eburnation.
  2. Osteophyte formation.
  3. Subchondral cysts - located where there is loss of cartilage.[3]
  4. Subchondral sclerosis.

Memory device LOSS:

  • Loss of cartilage, Osteophyte formation, Subchondral cysts, Subchondral sclerosis.

Notes:

  • Osteophytes are classically medial and lateral in the hip.[4]
    • They tend to form in areas with high loading.
  • Subchondral cysts are also seen in rheumatoid arthritis.[3]

Clinical findings (external):

  • Heberden's node - swelling of distal interphalangeal joints.

Microscopic

Features:[5]

  • Vertical clefts of the cartilage - characteristic.
  • Thickening of bony trabeculae (reactive phenomenon) due to fibrosis.
  • Subchondral cysts (associated with cartilage loss).
  • +/-Mild inflammation (lymphocytes).
  • +/-Villous hyperplasia - synovium has finger-like projections into the joint space.
    • Normal synovium has a flat surface.
  • Osteophytes - ossified projections at the edge of the articular cartilage (bony spurs).

Note:

  • Cartilaginous calcification is seen with OA; however, it is thought to be due to aging.[6]

DDx:

Grading

A grading system exists from Pritzker and colleagues:[8]

Grade Key feature Additional findings
Grade 0 (normal) surface intact normal thickness
Grade 1 surface intact but uneven +/-surface fibrillation, +/-superficial proliferation/cellular enlargement
Grade 2 discontinuous surface (diffuse superficial fibrillation or surface abrasions) +/-chondron columns disoriented
Grade 3 vertical fissures (simple or branched) +/-new collagen formation (seen with polarized light)
Grade 4 erosion (cartilage loss) +/- cartilageous cyst formation
Grade 5 complete cartilage loss no deformation
Grade 6 deformed bone (osteophytes peripheral or central) +/-deformation of articular surface +/-microfractures

Images

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Hip

FEMORAL HEAD, RIGHT, HIP ARTHROPLASTY: 
- DEGENERATIVE JOINT DISEASE.

Gross only

FEMORAL HEAD AND JOINT CAPSULE, RIGHT, EXCISION:
- DEGENERATIVE JOINT DISEASE (GROSS ONLY).
FEMORAL HEAD AND JOINT CAPSULE, LEFT, EXCISION:
- DEGENERATIVE JOINT DISEASE (GROSS ONLY).

Knee

SYNOVIUM, LEFT KNEE, BIOPSY:
- SYNOVIUM WITH MILD CHRONIC INFLAMMATION AND VILLOUS HYPERPLASIA -- COMPATIBLE 
 WITH OSTEOARTHRITIS.

Micro

The sections show thinned cartilage composed of chrondrocytes clusters separated by vertical fibrous septa. The deep aspect of the cartilage is basophilic. An osteophyte is present.

The soft tissue shows a minimal, focal chronic inflammatory cells.

Note:

  • Noninflammatory degenerative joint disease is the term used by the ICD.[12]

See also

References

  1. Martel-Pelletier, J.; Pelletier, JP. (Apr 2010). "Is osteoarthritis a disease involving only cartilage or other articular tissues?". Eklem Hastalik Cerrahisi 21 (1): 2-14. PMID 20302555. http://www.ncbi.nlm.nih.gov/corehtml/query/egifs/http:--www.tevak.org-images-Eklemlinkout.png.
  2. Swagerty, DL.; Hellinger, D. (Jul 2001). "Radiographic assessment of osteoarthritis.". Am Fam Physician 64 (2): 279-86. PMID 11476273. http://www.aafp.org/afp/2001/0715/p279.html.
  3. 3.0 3.1 Resnick, D.; Niwayama, G.; Coutts, RD. (May 1977). "Subchondral cysts (geodes) in arthritic disorders: pathologic and radiographic appearance of the hip joint.". AJR Am J Roentgenol 128 (5): 799-806. PMID 404905.
  4. Claassen, H.; Tschirner, T. (Jan 2003). "Topographical and histological examination of osteophytes taken from arthrotic femoral heads.". Ann Anat 185 (1): 67-71. PMID 12597129.
  5. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 658. ISBN 978-0781765275.
  6. Mitsuyama, H.; Healey, RM.; Terkeltaub, RA.; Coutts, RD.; Amiel, D. (May 2007). "Calcification of human articular knee cartilage is primarily an effect of aging rather than osteoarthritis.". Osteoarthritis Cartilage 15 (5): 559-65. doi:10.1016/j.joca.2006.10.017. PMID 17276093.
  7. Abraham, E.; Gonzalez, MH.; Pratap, S.; Amirouche, F.; Atluri, P.; Simon, P.. "Clinical implications of anatomical wear characteristics in slipped capital femoral epiphysis and primary osteoarthritis.". J Pediatr Orthop 27 (7): 788-95. doi:10.1097/BPO.0b013e3181558c94. PMID 17878786.
  8. Pritzker, KP.; Gay, S.; Jimenez, SA.; Ostergaard, K.; Pelletier, JP.; Revell, PA.; Salter, D.; van den Berg, WB. (Jan 2006). "Osteoarthritis cartilage histopathology: grading and staging.". Osteoarthritis Cartilage 14 (1): 13-29. doi:10.1016/j.joca.2005.07.014. PMID 16242352.
  9. URL: http://www.medpath.info/MainContent/Skeletal/Joint_02.html. Accessed on: 10 November 2012.
  10. URL: http://www.med.nyu.edu/medicine/labs/abramsonlab/basic-arth-research.html. Accessed on: 10 November 2012.
  11. URL: http://www.medic.usm.my/~pathology/bonepath/bonepath/Osteoathritis.html. Accessed on: 22 November 2012.
  12. URL: http://www.icd9data.com/2012/Volume1/710-739/710-719/715/715.9.htm. Accessed on: 15 March 2013.