Intertester reliability of a modified version of McKenzie's lateral shift assessments obtained on patients with low...

McKenzie described a two-step process for assessing patients with low back pain for a lateral shift. The purpose of this study was to determine whether reliable judgments about lateral shifts could be obtained.

Forty-nine patients with low back pain were each examined separately by two randomly paired physical therapists.

Assessments of the presence and direction of lateral shifts (step 1) were obtained by use of a simple instrument. The relevance of the lateral shifts to the patients' pain complaints (step 1) also was assessed by use of the side-glide test sequence.

Generalized kappa coefficients were calculated to determine reliability. The kappa value for the two-step process of lateral shift assessment was .16. The percentage of agreement was 47%.

Each step in this two-step process was examined separately for possible sources of error. The kappa value for determinations of the presence and direction of lateral shifts was .00, indicating very poor reliability. The kappa value for the determination of the presence of a positive side-glide test sequence was .74, indicating high reliability. The role of lateral shift assessment in the McKenzie system should be reconsidered, given the strong research evidence for poor reliability of determinations of the presence and direction of lateral shifts.