With any kind of kick, it is important to massage your leg, knee, ankle and feet after any impact training. Especially to the knee, ankle and shin, make it a habit.
TKD is good martial art and depend on who is practicing it. Some do it well even at the age of 80th while some barely can kick when 50th.
There is sports TKD, based in South Korea, and martial art TKD, the founder goes to North Korea and teach their troops after disagreement with South Korean TKD community. With sports TKD, there is little hand work sparing while the martial art one you need to use hand for combat too.
I hope I get the info right.
Over