[Added value of observational studies in surgery: the hierarchical structure of study designs requires a more refined approach].

The randomised placebo-controlled trial (RCT) is the gold standard for the evaluation of medical interventions. Observational studies, on the other hand, usually do not get much credit. For studies investigating surgical interventions this does not always seem entirely justified. A more refined approach might be needed for the often-used hierarchical structure of research designs. Instead of a strict separation of results from RCTs and other designs, results of the different designs should rather be regarded as complementary to each other when evaluating surgical interventions in traumatology.