Even ignoring the effects of any trauma to the body, given that a person may well have spent may years doing a specific job that entailed repeated activaties or maintaining a specific posture for lengths of time, day in and day out, then we can understand why as we get older we experience pain in parts of our bodies.
Added to that a person may have been dedicated to a particular sport or hobby that may again have resulted in injuries over the time.
Trauma or the effect of scar tissue from an operation can cause us to favour a joint and accommodate for it by shifting our bodyweight which will cause stress on other parts of our bodies, which may result in longterm postural changes and wear on our joints.
Like a machine, the effects of use will result in wear and tear and maintaining the system throughout life is the best approach to reaching old age and to enjoy it in the fullest of health.
