Ouch! My tarsus.

I feel this article is important as we don’t know enough about mantids anatomy. 

The tarsus and tarsa is a very fine hair like “toe” on the feet of a mantis
The tarsus is hardly visible especially on nymphs and smaller species. You’ll find while observing a mantis how the hook the tarsus on the edge of a surface to hold on. 
Commonly seen they will hold on the edge of a container or habitat or a surface that if not carefully considered when caring for your mantis can hurt them. The tarsus can be easily damaged, ripped off even crippling insects if your not careful. 
I was in a rush picking a mantis up and brushed he off a piece of mesh a little too rough and the hair like tarsus was stuck to the mesh. fortunately she could still eat and molt though ive learned these small injuries can be fatal.
I hope you will take care regarding this issue as I’m certain this is a painful experience for your pet is mishandled.
Don't rip your mantis from surfaces, mantids will climb aboard your hand or a stick if offered with patience. Remember they are delicate and special animals more evolved than most. For such an aggressive hunter, mantis can be strangely docile with their owners. A further benefit of praying mantis as pets therefore is that they can generally be handled quite safely. In general, a praying mantis will happily walk from hand to hand.
Praying mantis anatomy