This passage is found in the RCL, Epiphany Season, Year C (Most recently: January 24, 2016) It is also found in the narrative lectionary year of Luke, most recently January 15, 2017.
Summary: Home run point, here but it will take a full count to get there...Most times the New Testament quotes from the Greek version of the Old Testament. On rare, rare occasions, the New Testament writers seem to be quoting from the Old Testament Hebrew in their own translations (Proverbs 10:12 vs 1 Peter 4:8 eg). In this case, Jesus seems neither to be translating directly from the Old Testament Hebrew, nor is he reading directly from the Greek. He is intentionally adding to the Word of God. This is a bold move. He does so, I would argue, out of a Trinitarian conception of his mission, whereby the people will be brought into the mission of God. (If you are saying to yourself, this is too much for a sermon, the basic point remains: The Spirit of the Lord on Jesus is also the Spirit of the Lord in the church!)
Two little Greek appetizers before the main course:
φημη (pheme, meaning "fame," 4:14) The word for "news" is "pheme" or perhaps better in English "fama." This is the root of our word fame. Jesus is famous!
δοξαζομενος (from δοξαζω, doxaz-oo, meaning "praise", 4:15) The people "praise" Jesus. Interestingly, in the rest of the Gospel, the only one praised is God. This is the only instance of Jesus being praised in the Gospels.
Digging into 4:18-19 vs Isaiah 61:1-2
This sentence is rather complex. Two nouns worth looking at are worth looking at. Perhaps the most interesting word here is "captive" which comes from the Greek "αιχμαλωτος" which means "spear." Literally, those who are speared. Also the word for oppressed (τεθραυσμενους, participle form of θραυω) is only used once in the NT and literally means "shattered." I wonder who in our congregations feels speared and shattered?
This text is really tricky though. This is a case where what Jesus says and the Biblical quote don't exactly match up. The problem here isn't really a Septuagint (aka LXX, the OT Greek version of the Hebrew Bible) problem. In fact, Jesus words compile (sort-of) the Septuagint and Hebrew Bible here! He likely also pulls in a snippet (edited nonetheless) from Isaiah 58:6.
Side note: It is fascinating to look at the details of the passages to see how Jesus edits/combines/remixes Isaiah; but the don't miss the forest for the trees. This passage lays out the source of the mission (God in the Spirit) and the direction (the downtrodden). Furthermore, it alludes to the fact that we will be brought into this mission.
So, a few points of significant agreement:
A) Jesus words and the OT begin the same. The Spirit of the Lord (πνενμα κυριου) is upon me; he has annointed (εχρισεν, ie "Christed") me. It does well to remember the Hebrew words here: Ruach Adonai (רוח אדני) for Spirit of the Lord and Messiah (משך) for annoint.
B) Both have an obvious material/physical aspect. The blessings and impact of God are not simply spiritual, they relate to this world.
C) The blessings focus on the downtrodden.
However, we have some slight differences worth noting
A) In the OT, Isaiah never talks about sight to the blind. Jesus does (the Septuagint does also).
B) Isaiah (in both the Hebrew and LXX) plays on the idea of binding -- the broken-hearted are bound; the captive are freed. Jesus alters this image. The NRSV translates this sentiment as "free the captives" and "he will let the oppressed go free." Jesus, thus, seems to by-pass the image of repairing/releasing the broken-hearted.
C) Jesus puts in the idea that he is sent to send others. The word send in fact, appears twice, "He sent me...to send." So why don't English bibles use the word "send" twice? It is because they cover it up! The phrase "to let the oppressed go free" literally reads, "to send those shattered, in forgiveness, to proclaim the year of the Lord's favor." The translators are combing the phrase "send in forgiveness" into a single verb "free." Not only is this in itself a sermon worth unpacking, I think the deeper and better sermon point is that Jesus has come to send those who are oppressed, in forgiveness, to proclaim the year of the Lord's favor.
Note: This may seem to technical for a sermon. But it fits more broadly into the case Luke makes in Luke-Acts, that the work of the Spirit is to bring us into the triune Mission of God.
D) Jesus drops the line immediately following this passage in Isaiah (...a year of the Lord's favor and day of vengeance). Here the LXX does not use such striking language, but in any case, Jesus avoids this idea all together.