All his bones, i.e. all the parts and members of their bodies, which are synecdochically expressed by the bones, which are the stay and strength of the rest. God will not suffer any mischief to befall him; though he may be oft afflicted, yet he shall not be destroyed. But these words, though they are here spoken of the righteous men in general, of whom they are true in a metaphorical sense; yet they had a further meaning in them, being designed by the Spirit of God (which dictated to David, not only the matter, but the very words and expressions) to signify a great mystery, that none of Christ's bones should be broken; to which purpose they are alleged, 1 Thessalonians 19:36.
Related Commentaries of Psalms 34:20
Psalms 34:20
20 He keepeth all his bones: not one of them is broken.