The aim of this research was to investigate the causes of the emergence of sports injuries and to explain the differences in psychological response with regard to the severity of the injury. We examined 68 competing Slovene athletes with surgically treated knee injury. The estimated time of rehabilitation of the more severely injured athletes was six months, while those who sustained less severe injuries faced a month-long rehabilitation. We measured the athletes' personality traits, their athletic identity, coping with pain, rehabilitation beliefs, motivation and social support provided by their family and their coach as well as their colleagues. The results showed that the group of more severely injured athletes demonstrated behaviour that is less inhibited in response than the group of athletes with less severe injuries. The psychological response proved to be almost the same in both groups, except for the higher levels of catastrophizing, and a higher individual coping response found in the group of more severely injured athletes. Furthermore, masculinity was found to predict self-efficacy and the individual coping response, the strength of athletic identity predicted motivation and rehabilitation value, while emotional lability predicted catastrophizing and self-efficacy. Athletes with lower athletic identity, lower masculinity and higher emotional lability are more exposed to adjustment difficulties after sustaining an athletic injury. In our opinion, the strategies for successful rehabilitation after a sports injury should be aimed at the identification of athletes with personality traits that pose a higher risk of experiencing adjustment difficulties, at promoting adequate motivation, increasing coach support and at the application of cognitive-behavioural strategies.