How to strengthen hands to avoid hand breaks?

Well, my hands seem to weak, I broke my right hand 2 years ago in a fight, the knuckle by my little finger, then broke it again in a fight about 6 months ago, then I punched a wall 2 months ago, and broke it again, it breaks so easy, how can I stop it? will I need surgery?
How to strengthen hands to avoid hand breaks?
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