the pathogenesis underlying the development of costochondritis remains unclear. proposed mechanisms of injury include neurogenic inflammation, muscular imbalance, increased muscular pull on the rib, mechanical dysfunction at the costotransverse joint of the rib, or a derangement of the mechanical structure of the costochondral junction. a commonly held view in new zealand and australian manual physiotherapy regards hypomobility at the costovertebral and costotransverse joints as the driver of compensatory excessive movement at the more structurally delicate sternocostal joints, leading to strain and localised inflammatory response.  this mechanism is biologically plausible and would account for the extreme specificity of the symptoms at the sternocostal joints, which a systemic mechanism does not.