Meta-Analysis of the McKenzie Method
Two phrases always catch the eye of research scientists: meta-analysis and random controlled trial (RCT). This study on the McKenzie Method for low back pain is a meta-analysis of RCTs.

Meta-analysis means that the authors reviewed a large number of trials and combined the data. This gives the highest level of evidence possible in research. In this study every RCT study published on the topic was included for the period of time listed. Four major databases were searched up to the year 2003.

RCT means the subjects were placed in each group by chance. Neither the patients nor the researchers knew who was in each group. In other words, patients were randomly assigned to a group. And there's always a control group -- subjects who don't get the treatment being studied. In a blinded RCT, the subjects or patients don't know if he or she is or isn't getting the treatment. In a double-blind RCT, the researchers don't know who is assigned to each group. RCTs allow scientists to test directly for the effect of a specific treatment.

The McKenzie Method is a way of treating low back pain (LBP) based on how the pain and/or symptoms respond to changes in movement in a specific direction. Patients are grouped or classifed for treatment based on the results of movement testing. For example, if the patient feels better when the spine moves in one direction, then treatment begins with that position. Over time the patient is taught how to move from a the comfortable position to all other positions without pain.

Does the McKenzie Method really work? Is it effective in treating LBP? By comparing the results of many studies the authors try to answer this question. They reviewed how well McKenzie treatment worked compared to passive therapy (pamphlets, brochures), advice to stay active, spinal manipulation, and back school.

The authors report that the McKenzie method works a little better than passive therapy, ice packs, or massage. They aren't sure that the small amount of difference really means anything. More studies are needed in which patients are classified according to the McKenzie Method before treatment is started.
References
Luciana Andrade Carneiro Machado, BScPT (Honours), et al. The McKenzie Method for Low Back Pain. In Spine. April 20, 2006. Vol. 31. No. 9. Pp. E254-E262.