My siblings and I had begun to notice how ascending the stairs had grown more difficult for Mom and Dad.  They huffed and wheezed and groaned.  A wear pattern emerged on the wall where hands had sought some added traction and stability.  My sister Sarah arranged for a company to install a railing on the wall side of the stairs, at equal height with the wood banister.  Now it is much easier for them to push and pull their way up, using all four limbs, and to lean forward as they descend, easing the arthritis pains in their knees.  I will not lie: I use the railing, too.