[Dislocation of the patella--causality in legal accident insurance]

Fifty-two expertises on connections between cause and effect of patellar dislocations were examined with a view to improving the standards of medical expertizing. On principle, the mechanism of injury is the decisive criterion in determining whether the injury can be considered capable of causing the dislocation. It was found that in about one-half of the cases the dislocation was wrongly attributed to the event and that a reasonable connection existed in only one-quarter of the cases. The typical causes of error in reasoning - first dislocation, impressive pattern of injury, no degenerative changes - are listed and discussed. The importance of the pattern of damage for the first occurrence of a dislocation is demonstrated. The suitability of different courses of events for contributing essentially to the dislocation is discussed.