Australian rules football is a sport known for its high level of physical body contact compared to other ball sports such as soccer and basketball. High-impact collisions can occur from any direction, although deliberate collisions sometimes occur from a front-on direction (known specifically within the code as a "shirtfront" when the contact is a body-on-body collision). In addition, players of the code typically wear no protective padding of any kind except for a mouthguard or, occasionally, a helmet (unlike the full-body gear in gridiron football codes or the shin guards in soccer). As such, injury rates tend to be high. Soft tissue injuries are the most frequent, including injuries to the thighs and calf muscles. Osteitis pubis is a condition which particularly affects Australian rules footballers. Injuries to the knee, ankle and shoulders are also common. Hospital-treated injuries account for 40 percent of all injuries. Knee reconstructions are among the career-threatening injuries for professional and amateur players. Full-contact play with the potential to be tackled or bumped from any angle means that the risk of a knee being twisted or caught on a dangerous angle is high. Historically, players who historically had their careers ended prematurely (such as VFL/AFL legend John Coleman) can often be nursed back to full health with modern science. While many players choose not to wear protective padding, players do occasionally suffer head injury resulting in loss of consciousness; however, spinal injury is extremely uncommon and comparatively much lower than rugby football. In recent years, the AFL has commissioned official studies as well as introduced new rules and precautions aimed at reducing the number and severity of injuries in the sport. One example of a player that has suffered a large share of injuries is Essendon Hall of Famer James Hird, who has literally suffered injuries from head to foot and many between, including a hip injury that delayed his debut. The high levels of injuries that take place during the course of many games of football are so much so that not only during a player's career are they susceptible to injuries but the effects afterwards are detrimental to their post-career health. Like the concussions in NFL, brain injuries, while relatively rare in Australian rules football, can occur, especially over time without sufficient precautions. Shane Tuck is one example. While suffering a severe case of the degenerative brain disease chronic traumatic encephalopathy, Tuck decided to