I'm 37 and just starting to develop arthritis in my knees. As a kid I played serve and volley, but am now trying to develop more skill along the baseline. What playing style have you found to be easiest on the knees? S&V, allcourt, aggressive baseline, junkballer, etc. Are there any particular strokes associated with high knee stress? Any personal experiences/anecdotes and/or links to academic or instructional info most welcome. I'd like to enjoy tennis into old age if possible, and will adjust my style to that end if necessary.