Meaning of 骨を折る in Japanese

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Definition of 骨を折る

ほねをおる(honewooru) 【骨を折る】

(exp, v5r) to make efforts; to take pains
君のためにできるだけ骨を折ろう。
I will do all I can for you.
to break one's bone

むだぼねをおる(mudabonewooru) 【無駄骨を折る】

(exp, v5r) to waste one's efforts; to work to no (useful) effect
彼は、しばしば、無駄骨を折る。
He often goes off on wild goose chases.

あ、そうだ。まゆに変なことしたらする、背骨せぼねを折るおる。

One more thing. If you try anything on Mayu I'll break your spine.