Intertester Reliability of the McKenzie Evaluation in Assessing Patients with Mechanical Low-back Pain

Study Design: Prospective intertester reliability study investigating the ability of 2 therapists to agree on a low back pain diagnosis using examination techniques and the classification system described by McKenzie.

Objectives: To investigate intertester agreement in determining McKenzie diagnostic syndromes, subsyndromes, presence, and relevance of the spinal deformities.

Background: Reliability of the McKenzie approach for determining diagnostic categories is unclear. Previous studies have been characterized by inconsistency of test protocols, criterion measures, and level of training of the examiners, which confounds the interpretation of results.

Methods: Patients were assessed simultaneously by 2 physical therapists trained in the McKenzie evaluation system. The therapists were randomly assigned as examiner and observer. Agreement was estimated by Kappa statistics.

Results: Forty-five subjects (47 +/- 14 years), composed of 25 women and 20 men with acute, subacute, or chronic low back pain were examined. The agreement between raters for selection of the McKenzie syndromes was kappa = 0.70, and for the derangement subsyndromes was kappa = 0.96. Interrater agreement for presence of lateral shift, relevance of lateral shift, relevance of lateral component, and deformity in sagittal plane was kappa = 0.52, 0.85, 0.95, and 1.00, respectively. Intertester agreement on syndrome categories in 17 patients under 55 years of age was excellent, with kapp = 1.00.

Conclusions: A form of low back evaluation, using patterns of pain response to repeated end range spinal test movements, was highly reliable when performed by 2 properly trained physical therapists.