A look at the literature indicates that there is no statistically significant difference in the number of injuries sustained on turf versus grass. However, there is a slight difference in the types of injuries that predominate on the various surfaces. Muscle-tendon overload injuries (e.g., ankle sprains and Achilles tendon tears) seem to be more common on turf, while musculoskeletal injuries (muscle tears, fractures) seem to be more common on grass. In one paper I looked at, injuries due to head duels in soccer were significantly more common on turf than on grass. I wonder if that is a reflection of players' ability to achieve greater speed and launching power on artificial surfaces.