Consequences of knees injuries constitute a substantial number of personal claims within the PZU Group. In 2004 physicians cooperating with PZU gave about 53 thousand opinions, concerning injuries to the knee in adults and about 14 thousnd in children and adolescents. In accidental and TPL insurances physicians are obligated to treat separatly consequences of accidents due to impact from illness or earlier injuries. The lack of a good method of how to distinguish these often leads to the disaccords between the physician, client and insurance company. The aim of this research is to indicate and to define the medical problems during rating of permanent impairment, based on the analysis of hundreds of difficult claims. This may help to start a discussion on how to perform objective and repetitive method of rating permanent accidental impairment in the knee ailments. In our opinion, current rules of rating permanent impairment after injury in a damaged organ, do not guarantee a detailed assessment of accidental loss of knee function during medical examination.