One of the worse thing about getting older is not so much the age itself as much as the disease that are usually associated with advancing in age.
Falling for no reason and breaking bones is one of the common simptome associated with advancing in age.
Falls are the leading cause of death from injury among people 65 and older. Approximately 9,500 deaths in older Americans are associated with falls each year. More than half of all fatal falls involve people 75 or over. Among people aged 65 to 69, one out of every 200 falls results in a hip fracture.
As we age because our sedimentary lifestyle and thousands of hours accumulated of sitting.
There will be some muscular imbalances in your body, that will deform your body, in particular will make you lean forward.
Early on while you are still young the fact that you are leaning forward more, it won't bother You to much or feel that much different, because your body has the capacity to overcompensate for that.
If your head has fallen of your shoulders, which means that you now have weight pressing down in front of your body, you will overarch your lower back to pull the weight of your head back at the centre.
However your ability to overcompensate is limited, there is a limit to how far you can overarch your back.
If you keep doing things that make you develop further muscular imbalances, you are going to eventually exceed the capacity of your body to compensate for the muscular imbalance.
Which will make you lean forward more and more, until the centre of gravity of your body moved forward so much that you have a very unstable structure, that will easily lose equilibrium and be overwhelmed by situations that should offer no challenge to a normal body.
Think of it like this if you are trying to balance a drinking straw on one of the end of the straw you should have no problem with that, however if you put a bend in the straw balancing the straw becomes nearly impossible the dipper the bend is.
Bad posture makes your body unstable, and causes you to have a higher chance to fall and break a bone, it is not the age itself.
In theory if you maintain your posture for the entire duration of your life you shouldn't fall easy for no apparent reason, no matter how old you are, since the age itself is not the cause of the fall but the bad posture.