The Passover Lamb and the Lamb of God
Old Testament: Exodus 12:5-7, 46
It shall be a lamb without blemish, a male, of one year... neither shall you break a bone thereof.
New Testament: John 19:36; 1 Corinthians 5:7
For these things were done, that the scripture might be fulfilled: You shall not break a bone of him. ... For Christ our pasch is sacrificed.
The connection
The unblemished lamb whose blood marks the doorposts and spares the firstborn from death prefigures Christ, the spotless Lamb whose blood marks believers for eternal life. John notes the unbroken bones as deliberate fulfilment.
Moral sense
Receive the sacrifice personally, in the Eucharist; apply the blood, don't just admire it from a distance.
Anagogical sense
The marriage supper of the Lamb, the Church's own exodus reaching its destination.
The Fathers
Tertullian, Against Marcion IV 40, writes that "the law prefigures His passion," and that Christ longed to eat this pasch because He wished "to accomplish the symbol of His own redeeming blood." St Cyprian, On the Unity of the Church 8, reads the law of the pasch to mean "that the lamb which is slain in the figure of Christ should be eaten in one house."
Warrant
Checked in the Greek, and the shared word is the whole point: osteon, bone, stands at Exodus 12:46 in the Septuagint and at John 19:36, and John cites it as a scripture being fulfilled rather than merely echoed.
Catechism of the Catholic Church, paragraph 608.
The verses
Exodus 12:5 · Exodus 12:6 · Exodus 12:7 · Exodus 12:46 · John 19:36 · 1 Corinthians 5:7
