Lumbar instability clinical tests, pain and disability in subjects with symptomatic spondylolisthesis . A cross - sectional diagnostic test study

Objectives - The aim of this study was to verify the diagnostic accuracy of the main clinical tests used to investigate lumbar instability in subjects with symptomatic spondylolisthesis. Background – Spondylolisthesis is a condition in which a vertebra in the spine slips out of the proper position onto the bone below it, following structural and/or degenerative spinal changes. This displacement modifies the pathomechanical behaviour of the lumbar spine, inducing segmental instability. Several clinical tests are commonly employed to detect lumbar instability in common Low Back Pain, but their validity was not yet tested in subjects with symptomatic spondylolisthesis. Methods – This study involved three different centers specialized in lumbar diseases rehabilitation. 112 consecutive patients were included. Four clinical tests commonly used to detect segmental instability of the lumbopelvic muscles Prone Instability Test (PIT), Passive Lumbar Extension Test (PLT), Aberrant Movements (AM), and Active Straight Leg Raising (ASLR) were performed before the first session of rehabilitation. The results of these tests was compared with the Visual Analogue Scale (VAS) for pain intensity and the Oswestry Disability Index (ODI) for disability. Results –All clinical tests showed low correlations with VAS (ASLR Rho = 0,229, p <0.05; PIT Rho = -0,120, p <0.05; PLE Rho =-0,225, p <0.05; AM Rho =-0,095, p <0.05) and ODI (ASLR Rho = 0,218, p <0.01; PIT Rho = -0,367, p <0.05; PLE Rho = -0,310, p<0.05; AM Rho = -0,255, p <0.05). PIT was moderately correlated with PLT (Rho = 0.561, p <0.01). AM was moderately correlated with PIT Rho = 0.472, p <0.01) and PLT (Rho = 0.525, p<0.01). Subjects in which dynamic X-rays were positive showed a higher correlation between PIT and PLT (Rho = 0,772 p >0,01). However, any significant correlation between results of instability tests and grade of the spondylolisthesis, or positive Dynamic X-rays was not found. Conclusion – The results of this study suggest a low diagnostic accuracy of the lumbar instability clinical test to detect segmental instability in patients with spondylolisthesis and low relationship with pain and disability. The grade of spondylolistesis or the positive dynamic X-rays did not significantly influence these results.