This document discusses the concept of distinct endotypes or subtypes of osteoarthritis (OA), including "metabolic OA", "post-traumatic OA", "inflammatory OA", and "site-specific OA". However, the author argues that currently there is no strong evidence that these proposed endotypes exist or have clinical utility. The author believes that mechanical injury is the common pathogenic pathway in OA, which can be promoted by factors like age, trauma, metabolism, inflammation, and genetics. Rather than distinct pathways, these factors may influence OA through common pathways like "mechanoflammation" and reducing the ability to repair.