Lumbar rocking test: A new clinical test for predicting lumbar instability

Significant number of low back pain is caused by spinal instability. Clinical and radiological tests are used to diagnose lumbar instability, but the practical utility of clinical tests has not been studied extensively. Hence, it was decided to study lumbar rocking test and passive lumbar extension (PLE) clinical tests to identify their accuracy for lumbar instability, in comparison to the radiological assessment.

This cross-sectional prospective study was conducted in 2017 at an Indian tertiary care center, after Ethics Committee approval. No financial transection involved anywhere at any stage of the study. Patients of 30-65 years having low back pain were included following informed consent. Clinical tests conducted were rocking test and PLE tests. All patients were subjected to a neutral anteroposterior, lateral and flexion-extension X-rays of lumbosacral spine. The association between clinical tests and lumbar instability was represented by Chi-square analysis. The rest of the findings were represented as descriptive statistics.

Fifty patients enrolled in the study, of which 28 (56%) were females. On X-rays, the maximum angular rotation and sagittal translation were seen at L5-S1 level. 35 (70%) and 46 (92%) patients showed positive PLE and rocking test, respectively. Significant association (P < 0.05) was seen between rocking test and lumbar instability. The sensitivity of rocking test was 95.56% and positive predictive value as 93.47%.

Clinical tests can be used effectively for the diagnosis of lumbar spine instability. Rocking test was found to be accurate and sensitive for detecting subtle lumbar instability.