RT Journal T1 Randomized trials in orthopaedics: why, how, and when? JF The Journal of Bone & Joint Surgery JO The Journal of Bone & Joint Surgery YR 1989 FD April 1 VO 71 IS 4 SP 535 OP 543 DO UL http://dx.doi.org/ AB There is increasing recognition that major new medical therapies should be rigorously evaluated before they are put into general clinical use. Randomized controlled trials provide the most unbiased assessment of the risks and benefits of such therapies. In this article, the most important aspects of the design and execution of a randomized clinical trial in orthopaedics are discussed. These include the reasons for and mechanisms of randomization, appropriate selection of patients and therapy, reasons for the blinding of therapy, types of measures of outcome that can be used, aspects of sample-size calculation and analysis of data, and ethics of randomized controlled trials.