Presentation and anatomy: Patients usually report pain with weight bearing and ambulation. Symptoms progress slowly over time (ie years) with pain precipitated by less activity (ie shorter distances walked) as the disease worsens. This tends to occur in patients > 50, as age increases the risk of wear and tear on the joint. Obesity, which chronically increases the load and stress that the joint must bear, is a major risk factor. There may also be a history of significant antecedent trauma that damaged the joint, "setting it up" for degenerative changes over time.