It is usually my preventative maintenance course of action to replace all front suspension components on my BMW's @ between 100,000 miles and 120,000 miles (with exception of the struts/shocks and upper strut/shock mounts, I wait for failure on those).

On the X5's that includes:
inner and outer tie rods (w/ new boot kits)
thrust arm ball joint and bushing
control arm
sway bar end links (I usually skip doing the sway bar bushings)

I just finished the above on my E53 @ 113,000 miles... and it feels like a new BMW.

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)