Q. can a person from standing position going to sujdah do so with hands going before the knee in sajdah? Would it not be better to perform salaah on a chair instead of doing it this way?

A. Doing so can be done with a valid reason and would prove more worthy then performing salaah on a chair. Sayidinah ibn Umar (RA) used place his hands before his knees. This was due to a valid health reason. A boy did tried to emulate him (RA) and he stopped the boy claiming that he did so due to a valid excuse. It was not the correct way for a healthy person.

Thus, for a valid reason, a person can do so as you have described.

Allah Certainly Knows Best.