I just read a pretty good article on the subject, after all we just entered the year of the Tiger! I think it answered most of your question pretty well.
Tigers are known to be very powerful animals. Because of this many different forms of strength and power are associated with them. I’m most familiar with the more concrete physical associations, which are most prevalent in the muscular skeletal system and your tendons and ligaments.
Tigers have extremely strong dense and heavy bones. Because of this, many practices exist within Tai Chi and Qigong along with other Chinese Martial Arts to strengthen the bones and ligaments, and gain strength or power equal to that of one with “Tiger Bones”.
Since Tiger Bones are perceived to have an energetic quality of strength, density and a strong muscular skeletal system they are also associated with healing various bone and muscular skeletal disorders. As a result many Chinese herbal remedies exist which use Tiger bones as their base ingredients. So for instance a classic cure for arthritis would utilize tiger bones.