Complex sentence: The next two seasons, Koivu continued to miss time with various leg injuries; however, in each year, he managed to play in more than 60 regular season games, scoring 57 and 44 points in 1997--98 and 1998--99 respectively.
Split into simpler sentences: The next two seasons, Koivu continued to miss time with various leg injuries. In each year, however, he managed to play in more than 60 regular season games, scoring 57 and 44 points in 1997--98 and 1998--99 respectively.