Radiological Changes after Interspinous Dynamic Stabilisation for Lateral Stenosis of Lumbar Spinal Canal: A Parallel Group Randomised Trial.

PURPOSE OF THE STUDY Interspinous dynamic stabilisation devices (IDSDs) are used for stabilisation and indirect decompression of the spinal motion segment in minimally invasive treatment of degenerative conditions of lumbar spine. Good methodological quality studies on biomechanical effects of IDSDs are lacking in scientific literature. The purpose of this study was to evaluate the biomechanical effect of dynamic IDSD implantation on a spinal motion segment. MATERIAL AND METHODS We conducted a parallel group randomised trial (RT) on twelve patients, comparing radiological stabilisation and indirect decompression outcome measures between groups of patients with an isolated degenerative condition of L4-L5 motion segment and unilateral L5 nerve root radiculopathy. One group of six patients was operated by decompression and dynamic IDSD implantation and the other group of six patients by decompression alone. The radiological assessment was performed 6 months postoperatively in all patients. RESULTS Dynamic IDSD implantation significantly decreased segmental intervertebral angle (IA) and significantly increased segmental foraminal height (FH) and foraminal width (FW). The implantation had no effect on segmental range of motion (ROM) and posterior disc height (PDH). CONCLUSIONS The studied dynamic IDSD improved radiological indirect decompression outcome measures while only partially improved radiological stabilisation outcome measures. Oxford Centre for Evidence-Based Medicine 2011 Level 3: randomised trial with small effect size. Key words: lumbar spine, degenerative lateral stenosis, interspinous dynamic stabilisation, DIAM, randomised trial.