[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Bones, joints and soft tissue](https://durgical.com/en/general-pathology/areas/bone-soft/) › Osteoarthritis # Osteoarthritis - Lesion In osteoarthritis the joint cartilage wears and breaks down; the bone beneath thickens, grows spurs and becomes polished like ivory. Updated Nov 12, 2026 ## Key points - Risk: age, obesity, joint injury, malalignment, repetitive loading, genetics; women more for hands and knees. - Sequence: cartilage softening and fibrillation, fissures, loss of cartilage, eburnated (polished) subchondral bone, subchondral cysts and sclerosis, osteophytes. - Joint mice: fragments of cartilage and bone floating in the joint. - Hands: Heberden nodes (distal interphalangeal) and Bouchard nodes (proximal interphalangeal); first carpometacarpal joint. - Large joints: knees, hips, lumbar and cervical spine; spares the wrists and metacarpophalangeal joints (unlike RA). - X-ray: asymmetric joint-space narrowing, osteophytes, subchondral sclerosis and cysts. ## What it is Osteoarthritis is the commonest joint disease, a degeneration of articular cartilage with reactive changes in the subchondral bone, synovium and joint capsule. It is not simple wear and tear: chondrocytes respond to mechanical and genetic stress by making matrix-degrading enzymes and inflammatory mediators, and the cartilage loses proteoglycans and type II collagen. Primary osteoarthritis appears with age in weight-bearing joints and the hands; secondary osteoarthritis starts younger after injury, deformity, obesity, crystal disease or other joint disease. ## Structure - Early: chondrocytes proliferate in clusters, matrix loses proteoglycan and water, the surface becomes fibrillated. - Vertical fissures extend into deep cartilage; fragments break off. - Exposed subchondral bone becomes thick and shiny (eburnation); synovial fluid forced through cracks forms subchondral cysts. - Osteophytes (bony spurs covered by cartilage) grow at the joint margins. - Synovium shows only mild chronic inflammation and fragments of cartilage. ## Step by step - Mechanical overload and genetic and aging factors stress chondrocytes. - Chondrocytes produce MMPs (notably MMP-13), ADAMTS aggrecanases, IL-1, TNF and nitric oxide. - Proteoglycans and type II collagen are degraded faster than they are made; cartilage softens and fibrillates. - Chondrocytes die by apoptosis and repair fails; cartilage is lost down to bone. - Bone remodels under the load: sclerosis, cysts and marginal osteophytes form; the joint becomes painful and stiff. ## Clinical notes - Deep aching joint pain worse with use and relieved by rest, short morning stiffness (under 30 minutes), crepitus and loss of motion. - Spinal osteophytes can narrow foramina and the canal: radiculopathy, spinal stenosis and cervical myelopathy. - No systemic features; ESR and CRP normal; synovial fluid non-inflammatory. - Treatment: weight loss, exercise, analgesics, and joint replacement for end-stage disease. ## Memory aid OA is a cartilage that has worn out and a bone that answers by polishing, cracking and growing spurs. ## Test yourself Think of the answer, then tap the question to see it. ## What is eburnation? Polished, ivory-like subchondral bone exposed after loss of the articular cartilage. ## Which finger joints form Heberden nodes? The distal interphalangeal joints. ## Which enzymes degrade cartilage in osteoarthritis? Matrix metalloproteinases (especially MMP-13) and ADAMTS aggrecanases made by chondrocytes. ## How long does morning stiffness usually last in osteoarthritis? Less than about 30 minutes, unlike the longer stiffness of rheumatoid arthritis. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/general-pathology/osteoarthritis/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Cartilage: hyaline, elastic, fibrocartilage](https://durgical.com/en/histology/cartilage-hyaline-elastic-fibrocartilage/) - [Synovial joints: capsule, synovial membrane and articular cartilage](https://durgical.com/en/histology/synovial-joints-capsule-synovial-membrane-and-articular-cartilage/) ## Connections ## Related 4 - [How organs age: normal changes vs disease](https://durgical.com/en/general-pathology/how-organs-age-normal-changes-vs-disease/) - [Rheumatoid arthritis: synovitis and pannus](https://durgical.com/en/general-pathology/rheumatoid-arthritis-synovitis-and-pannus/) - [Osteonecrosis (avascular necrosis)](https://durgical.com/en/general-pathology/osteonecrosis/) - [Pseudogout (CPPD disease)](https://durgical.com/en/general-pathology/pseudogout/) ## Related conditions 5 - [Knee Osteoarthritis](https://durgical.com/en/conditions/knee-osteoarthritis/) - [Hip Osteoarthritis](https://durgical.com/en/conditions/hip-osteoarthritis/) - [Cervical Spondylosis](https://durgical.com/en/conditions/cervical-spondylosis/) - [Lumbar spinal stenosis](https://durgical.com/en/conditions/lumbar-spinal-stenosis/) - [Hallux valgus (bunion)](https://durgical.com/en/conditions/hallux-valgus/) [← All of general pathology](https://durgical.com/en/general-pathology/) Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Primary Osteoarthritis](https://www.ncbi.nlm.nih.gov/books/NBK557808/) (StatPearls (NCBI Bookshelf), 2025); [Osteoarthritis | OA | MedlinePlus](https://medlineplus.gov/osteoarthritis.html) (MedlinePlus, US National Library of Medicine, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/general-pathology/osteoarthritis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/osteoarthritis/