Mechanics means relating to or caused by movement or physical forces. In this paper, I shall contend that osteoarthritis (OA) is almost always caused by increased physical forces causing damage to a joint. While examples of joint injury causing OA are numerous, I shall contend that most or almost all OA is caused in part by mechanically induced injury to joint tissues. Further, once joint pathology has developed, as is the case for almost all clinical OA, pathomechanics overwhelms all other factors in causing disease progression. Treatments which correct the pathomechanics have long lasting favorable effects on pain and joint function compared with treatments that suppress inflammation which have only temporary effects. I shall lastly contend that the mechanically induced joint injury leads to variable inflammatory responses but that the role of this inflammation in worsening structural damage in an already osteoarthritic joint has not yet been proven.
This paper is derived from a debate at the 2012 OARSI meetings in Barcelona on whether osteoarthritis is a disease of mechanics or an inflammatory disease.
