McKenzie lumbar classification: inter-rater agreement by physical therapists with different levels of formal McKenzie postgraduate training. Spine (Phila Pa 1976). 2014 Feb 1;39(3):E182-90. Werneke MW, Deutscher D, Hart DL, Stratford P, Ladin J, Weinberg J, Herbowy S, Resnik L.
Inter-rater chance-corrected agreement study.
The aim was to examine the association between therapists’ level of formal precredential McKenzie postgraduate training and agreement on the following McKenzie classification variables for patients with low back pain: main McKenzie syndromes, presence of lateral shift, derangement reducibility, directional preference, and centralization.
SUMMARY OF BACKGROUND DATA:
Minimal level of McKenzie postgraduate training needed to achieve acceptable agreement of McKenzie classification system is unknown.
Raters (N = 47) completed multiple sets of 2 independent successive examinations at 3 different stages of McKenzie postgraduate training (levels parts A and B, part C, and part D). Agreement was assessed with κ coefficients and associated 95% confidence intervals. A minimum κ threshold of 0.60 was used as a predetermined criterion for level of agreement acceptable for clinical use.
Raters examined 1662 patients (mean age = 51 ± 15; range, 18-91; females, 57%). Data distributions were not even and were highly skewed for all classification variables. No training level studied had acceptable agreement for any McKenzie classification variable. Agreements for all levels of McKenzie postgraduate training were higher than expected by chance for most of the classification variables except parts A and B training level for judging lateral shift and centralization and part D training level for judging reducibility. Agreement between training levels parts A and B, part C, and part D were similar with overlapping 95% confidence intervals.
Results indicate that level of inter-rater chance-corrected agreement of McKenzie classification system was not acceptable for therapists at any level of formal McKenzie postgraduate training. This finding raises concerns about the clinical utility of the McKenzie classification system at these training levels. Additional studies are needed to assess agreement levels for therapists who receive additional training or experience at the McKenzie credentialed or diploma levels.
This new study on McKenzie method of physical therapy shows regardless of how well physical therapists are trained in the method, they don’t agree very well on a diagnosis. Robin McKenzie’s primary idea in the 1980s was that bending forward too much caused posterior migration of the nucleus in spinal discs leading to bulges, herniations, and subsequent neck and low back pain. That much has been confirmed by subsequent research, but a 2006 meta-analysis (a study that combines and comparing a number of smaller studies) found his method of treatment had little to no benefit in treating low back pain.
This study found there was little agreement among physical therapists who took advanced training in McKenzie method as to which of McKenzie’s categories a patient fell into with regards to their particular type of low back pain. Regardless, I enjoyed McKenzie’s books and I think they should be read by all physical therapists specializing in low back or neck pain. However, as I commented in my earlier blog, I think he started off with a good idea that went too far. I often comment that his books are great if you only read the first half where he talks about avoiding spine flexion using lumbar support, and maybe doing some mild spine extension stretches. However, when he gets into end-range spine extension with overpressure and later advocates a return of lumbar flexion stretches I think he runs into problems. His treatment does not do anything to restore spine or extremity strength and endurance, which has been shown to reduce low back and neck pain.
I always thought his evaluations were a bit drawn out, and often left a patient with low back or neck pain feeling worse after the first day, so I’m a little happy to see I’m not missing anything by not adopting the majority of them. I’ll do a future blog on Stuart McGill’s study where they found spine extension did sometimes help to reverse disc bulges, and how milder extension stretches can be implemented into a comprehensive low back rehabilitation program with positive effects, so maybe McKenzie will find at least limited redemption. This does illustrate a pretty good caution about avoiding particular “methods” because eventually it’s founder dies, science moves on, and followers are left carrying on an outdated legacy.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.