Movement system impairment-based categories for low back pain: Stage 1 validation

Study Design: Cross-sectional study of patients with mechanical low back pain (MLBP). Objective: To test the construct validity of 3 categories of a movement system impairment-based classification proposed for use with patients with MLBP. Background: A pathoanatomic basis for directing treatment has not proven useful in a wide variety of patients with MLBP. In addition, there is a paucity of data describing the movement system impairments that characterize many of the pathoanatomically based MLBP diagnoses. Because of the mechanical nature of MLBP, a system based on groups of signs and symptoms relevant to conservative management needs to be developed. Methods and Measures: A movement system impairment-based classification was proposed that defined 5 categories of MLBP based on the findings from a standardized examination. Using the examination, 5 physical therapists examined a total of 188 patients with MLBP. A principal components analysis with an oblique rotation was conducted. Eigenvalues were plotted and a scree test was used to determine the number of factors to retain. A split-sample cross-validation procedure was conducted to verify the factor structure. Results: Three factors were identified in both samples: 2 factors related to symptoms with lumbar rotation and lumbar extension alignments or movements, and 1 factor related to signs of lumbar rotation with different alignments and movements. Conclusion: Our results provide support for 3 factors related to 3 of the 5 proposed categories: lumbar rotation with extension, lumbar rotation, and lumbar extension. The existence of these 3 factors provides preliminary evidence for specific clusters of tests of alignment and movement impairments that could be used in classifying patients with MLBP into movement-system-related categories.