Joints
Arthritis
Arthritis general

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 23 August 2017, last major update March 2013

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: [Arthritis] joints "loattrfree full text"[sb]

Cite this page: Shankar, V. Arthritis general. PathologyOutlines.com website. http://pathologyoutlines.com/topic/jointsarthritisgeneral.html. Accessed September 26th, 2017.
Definition / general
  • Joint pain, limitation of motion or instability, due to dysfunctional articulating surfaces, loss of integrity of muscles / tendons around joint or their innervation or mechanical properties of cartilaginous or bony extracellular matrix
  • When specimen is received, disease is usually advanced, making precise cause difficult to determine
Etiology
  • If etiology is not known, examine synovial fluid before biopsy to detect TB or other granulomatous lesions
Clinical images

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Loose body

Gross description
  • Cartilage has irregular surface with pitting and loss of cartilage
  • Subchondral bone shows eburnation (polishing due to friction of bone against bone in joint), fractures
  • Bony spurs (osteophytes), loose bodies (detached cartilage or cartilage/bone within joint space with necrotic calcified centers, may become attached to synovial membrane, revascularize and convert to viable bone)
Gross images

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Osteophytes

Microscopic (histologic) description
  • Findings are related to either injury or reparative change
  • Injury:
    • Death of chondrocytes (no visible nuclei) or necrotic chondrocytes, marked irregularity and thickening of tidemark (indicates disturbed calcification) or duplication of tidemark
    • Surface of cartilage may be intact
    • Diminution of basophilic staining due to proteoglycan depletion
    • Vertical and horizontal clefts within cartilage matrix extending from articular surface
    • If rapid injury, synovium often contains pieces of bone or cartilage and chronic inflammatory cells
    • Loose bodies may have concentric rings of calcification and may grow into enormous size
    • Endochondral ossification can occur in loose bodies
    • Subchondral bone has superficial bone necrosis, microfractures, replacement of bone by solid or cystic fibromyxomatous tissue
  • Repair:
    • Chondrocyte proliferation within damaged cartilage or from underlying bone and periphery of joint
    • Bone / joint proliferative cartilage is cellular fibrocartilage, more coarse and disorganized with polarized light
    • Usually marked osteoblastic activity, new bone formation, thickening of superficial trabeculae
    • Marked synovial cell hyperplasia with multilayering or papillary folds, often containing hemosiderin (evidence of bleeding)
    • Polarized microscopy demonstrates discontinuity between collagen network of repair cartilage and preexisting cartilage
Microscopic (histologic) images

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Sheep with cylindrical metal implant