Clinical studies in spinal surgery.

There is a growing interest in applying evidence-based approaches also in orthopedic surgery. Despite many challenges to the validity of clinical trials in orthopedic surgery, it is possible to conduct well-designed trials in this field and to produce clinically important findings and reasonably valid conclusions about effectiveness, prognosis and diagnosis in orthopedic surgery. We describe the main principles for conducting clinical trials in this field as well as some of the most common errors and ways to avoid them.