Complex sentence: A knee injury sidelined Jacobsen for most of September and he had to have a major knee surgery followed 8 months later with an arthroscopic surgery on it on May 12,2005, missing most of the season and not appearing in any major league games in 2005.
Split into simpler sentences: A knee injury sidelined Jacobsen for most of September, eventually resulting in arthroscopic surgery on it on May 12,2005. This caused him to miss the season, and not appearing in any major league games in 2005.