Complex sentence: Because of this injury he began re-fingering some passages for that hand in such a way as to avoid using the affected finger; unfortunately this altered technique exacerbated the injury rather than ameliorating it, ultimately forcing him to stop using his right hand altogether by around 1979.
Split into simpler sentences: Because of this injury he began re-fingering some passages for that hand in such a way as to avoid using the affected finger. Unfortunately, this altered technique exacerbated the injury rather than ameliorating it, ultimately forcing him to stop using his right hand altogether by around 1979.