Pride goeth before destruction - Here pride is personified: it walks along, and has destruction in its train.
And a haughty spirit before a fall - Another personification. A haughty spirit marches on, and ruin comes after.
In this verse we find the following Masoretic note in most Hebrew Bibles. חצי הספר chatsi hassepher: "the middle of the book." This verse is the middle verse; and the first clause makes the middle of the words of the book of Proverbs.

Pride goeth before destruction,.... As it did in the angels that sinned, who, through pride, fell into condemnation, not being able to bear the thought that the human nature, in the person of the Son of God, should be advanced above theirs; and as it did in our first parents, who, not content with their present state and circumstances, and ambitious of being as gods, knowing good and evil, ruined themselves and all their posterity; and as it has done in many of their sons, as in Haman, Nebuchadnezzar, and others;
and a haughty spirit before a fall; or, "a high spirit", or "height of spirit" (i); a man that carries his head high; looks upwards, and not to his goings, sees not at what he may stumble, and so falls: moreover, the bigger a person or thing is, the greater is the fall; and very often when a man has got to the height of his riches and honour, and is swelling with pride and vanity on account of it, he is on the precipice of ruin, and his fall is immediate; which was the case of Nebuchadnezzar, who while he was expressing himself in the haughtiness of his spirit, being in the height of his glory, his kingdom departed from him, Daniel 4:30; and this will be the case of the man of sin, or antichrist, Revelation 18:7.
(i) "elitio spiritus", Pagninus, Montanus, Mercerus, Gejerus, Michaelis; "altitudo spiritus", Piscator; "celstudo aniimi", Cocceius; "altifrons elatio spiritus", Schultens.

When men defy God's judgments, and think themselves far from them, it is a sign they are at the door. Let us not fear the pride of others, but fear pride in ourselves.

(Compare Proverbs 15:33). Haughtiness and pride imply self-confidence which produces carelessness, and hence
a fall--literally, "sliding."

18 Pride goeth before destruction,
And haughtiness cometh before a fall.
The contrast is לפני כבוד ענוה, Proverbs 15:33, according to which the "haughtiness comes before a fall" in Proverbs 18:22 is expanded into the antithetic distich. שׁבר means the fracture of the limbs, destruction of the person. A Latin proverb says, "Magna cadunt, inflata crepant, tumefacta premuntur."
(Note: An expression of similar meaning is אחרי דרגא תביר = after Darga (to rise up) comes tebı̂r (breaking = destruction); cf. Zunz, in Geiger's Zeitschrift, vi. 315ff.)
Here being dashed in pieces and overthrown correspond. שׁבר means neither bursting (Hitzig) nor shipwreck (Ewald). כשּׁלון (like בּטּחון, זכּרון, etc.), from כּשׁל or נכשׁל, to totter, and hence, as a consequence, to come to ruin, is a ἅπαχ λεγ. This proverb, which stands in the very centre of the Book of Proverbs, is followed by another in praise of humility.