Prospective study of a new dynamic stabilisation system in the treatment of degenerative discopathy and instability of the lumbar spine.

INTRODUCTION: Posterior dynamic stabilisation (PDS) aims at relieving lumbar discogenic pain and preserving adjacent levels from accelerated degeneration. PURPOSE: To evaluate the results of a novel PDS system in 32 adult patients affected by chronic low back pain (CLBP) due to degenerative lumbar spine instability (DLSI). METHOD: A progressive follow-up for 12 months of 32 patients, with collection of complete clinical (ODI and VAS back + leg) and radiological data (resting + functional radiographs and MRI). RESULTS: Mean ODI scores improved from 49 to 6%, VAS back from 5 to 1 and VAS leg from 7 to 2. Twenty-two patients underwent fusion of a lower lumbar segment and stabilisation of an upper segment (hybrid fusion) whereas ten underwent dynamic stabilisation. In 16/32 patients, decompression was added to treat radicular pain. Motion in non-fused instrumented levels was unrestricted on functional X-rays and MRIs did not show significant morphologic changes. Four patients (12.5%) had unchanged functional and pain scores while two (6.3%) suffered worsening low back pain necessitating implant removal and spinal fusion. No infection, no new neurologic deficit or implant failure was recorded. CONCLUSIONS: The 1 year follow-up shows that the tested PDS system is able to provide a significant improvement in pain and disability scores when applied to patients affected by DLSI. The system does not provide better clinical results when compared to similar trials on posterior fusion. Further follow-up is ongoing to investigate the potential preservation of adjacent levels from accelerated degeneration.