What is the difference between primary and secondary osteoarthritis?

Osteoarthritis, also known as degenerative joint disease, is categorized into two types based on the underlying cause of the cartilage deterioration.12

Primary Osteoarthritis

Primary osteoarthritis is age-related and occurs without a clear, identifiable external cause. It is highly prevalent in older populations, affecting approximately 85 percent of individuals between 75 and 79 years of age. Pathologically, it is associated with a decrease in the water-retaining capacity of the cartilage, which weakens the tissue and makes it prone to degradation over time. In many instances, even rigorous clinical examination fails to disclose a specific structural or postural abnormality to explain the condition.12

Secondary Osteoarthritis

Secondary osteoarthritis develops as a direct consequence of an antecedent condition or specific external factor that compromises joint integrity. Known causes include:12
* Joint trauma: Including single injuries that leave permanent deformities or repetitive microtrauma from occupational or athletic activities.12
* Structural abnormalities: Such as congenital joint malalignment or dysplasia.12
* Systemic factors: Including obesity, hormonal disorders, and osteonecrosis.12