Standardized provocation of lumbar spine mobility: Three methods compared by radiostereometric analysis

Study Design. By radiostereometric analysis ( RSA), the intervertebral mobility was measured for the 3 most distal lumbar disc levels in 12 patients at 3 types of standardized provocation: changing body position from supine to standing, supine to standing with load, and supine to sitting. Objective. To study the validity and intervertebral mobility response to 3 types of standardized provocation of the lower lumbar spine. Summary of Background Data. Active flexion-extension is used in clinical practice to detect pathologic kinematics in the lumbar spine. However, the actual mobility response is affected by variations in pain level and muscular spasm. Standardizing the examinations reduces these confounding factors, and brings the possibility to study intervertebral mobility over time and between individuals. A standardized method using traction-compression was introduced earlier but questioned due to the insufficient mobility provided. Methods. After percutaneous application of tantalum indicators for RSA, the intervertebral mobility was measured for the 3 most distal lumbar disc levels in 12 adult patients with low back pain and disc degenerative disease. Each patient was examined in 4 separate positions: supine, normal standing, standing with sandbags ( total weight 20 kg) on the shoulders, and sitting. The translatory movements induced by the patient changing position from supine to the other 3 positions were measured and the mobility response compared for the 3 types of provocation. Results. The sagittal mobility induced by the sitting provocation was significantly higher than both the other types of provocation on all the 3 spinal levels measured. The same result was seen for the vertical translations except for the L3 - L4 level, where the standing with load provocation was equal to sitting. Transverse translations were small and did not differ for the 3 types of provocation. Conclusion. The intervertebral mobility response provided in the lumbar spine when changing position from supine to sitting is more pronounced than both to standing and to standing with a 20 kg load. By the supine to sitting provocation, mean lumbar mobility is increased, and mobility can be revealed in some cases being stable in the other 2 situations. Combined with RSA, the method brings a refined possibility for studying lumbar spine kinematics.