Concerning the lamb for the Passover meal, the Lord said, 

In one house it shall be eaten; you shall not carry any of the flesh outside the house, nor shall you break one of its bones (Exodus 12.46).

Consider also these passages,

They shall leave none of it until morning, nor break one of its bones. According to all the ordinances of the Passover they shall keep it (Numbers 9.12).

He guards all his bones;
Not one of them is broken.
(Psalm 34.20).

The Israelites had no idea why they could not break the bones of the lamb.

However, they avoided doing it because God said not to do it. (Likewise we may not always see the reason for something, but later we do.)

Then in the New Testament, the Holy Spirit said this about Jesus of Nazareth during His crucifixion,

Therefore, because it was the Preparation Day, that the bodies should not remain on the cross on the Sabbath (for that Sabbath was a high day), the Jews asked Pilate that their legs might be broken, and that they might be taken away. Then the soldiers came and broke the legs of the first and of the other who was crucified with Him. But when they came to Jesus and saw that He was already dead, they did not break His legs. But one of the soldiers pierced His side with a spear, and immediately blood and water came out. And he who has seen has testified, and his testimony is true; and he knows that he is telling the truth, so that you may believe. For these things were done that the Scripture should be fulfilled, “Not one of His bones shall be broken” (John 19.31–36).

Therefore, Jesus is the Messiah.

Related Articles

• Messianic Prophecy Number 19: Exo 12.13, 21 – 27 – The Passover Lamb (theoldtestamentandthenewtestament.com)
• Messianic Prophecy Number 18: Exo 12.5 – An Unblemished Lamb (theoldtestamentandthenewtestament.com)
• Sermon: In the Wilderness (grantspasschurchofchrist.com)
• Sermon: Shammua and His Brethren, Numbers 13 and 14 (grantspasschurchofchrist.com)
• Numbers 29.32 – Seven bulls and fourteen lambs on the seventh day of the Feast of Tabernacles (sevensinthebible.com)