Complex sentence: His broken sternum resulted in a six month absence from the slopes, but on return to competitive skiing in New Zealand he broke his wrist, leading to a lack of slope time ahead of the 2014 Winter Paralympics.
Split into simpler sentences: His broken sternum resulted in a six month absence from the slopes. However, on return to competitive skiing in New Zealand he broke his wrist, leading to a lack of slope time ahead of the 2014 Winter Paralympics.