Some years ago, there was a renewed discovery of a ligament [0] in the human knee, that is thought to be important for stability, especially after sport-related injuries.

Also, the mesentery [1] is only recently discovered as a separate organ, a sheet of connective tissue that supports and protects the intestine.

[0]: https://www.bbc.com/news/health-24826323

[1]: https://en.wikipedia.org/wiki/Mesentery