By August of 1964, the defending World Champion Dodgers were foundering in seventh place.
On August 8, Sandy Koufax―the Dodgers’ lone bright spot―made his 26th start of the season against the Braves in a Saturday afternoon game in Milwaukee. Five weeks after pitching his third career no-hitter, Koufax appeared to be on his way to a second consecutive Cy Young Award. A notoriously bad hitter, he led off the fifth with a line drive single off the surprised―and annoyed―opposing starter Tony Cloninger. After Koufax was sacrificed to second, Cloninger attempted to pick him off. Koufax dove back safely to the bag, but he jammed his elbow when he landed hard on the County Stadium infield surface. While the elbow “stung” when Koufax returned to the dugout, the pain subsided, allowing him to stay in the game and pitch a complete game win. The next day he woke up with a lump on his elbow from the joint area filling with liquid. It is believed the blow to Koufax’s elbow on that day in Milwaukee caused an “arthritic change”—the beginning of a traumatic arthritis condition that would cut short his career. Despite increasing pain and swelling, Koufax won two more games until he had to be shut down after throwing his seventh shutout on August 16. He finished 1964 with a 19-5 record and a 1.74 ERA.
This story is told in the book, Koufax Throws a Curve: The Los Angeles Dodgers at the End of an Era, 1964-1966 https://www.amazon.com/gp/product/B07CR5H9XC/ref=dbs_a_def_rwt_bibl_vppi_i2
Los Angeles Dodgers History in the Koufax Era 