Posterior dynamic neutralization and hybrid stabilization in degenerative spine diseases: long-term clinical and radiological outcomes

Dynamic spinal stabilization aims to reduce some of the problems inherent with traditional fusion. The aim of our study is to analyse clinical and radiological outcomes and to identify the causes of clinical failure in patients who underwent posterior dynamic neutralization or posterior hybrid stabilization because of degenerative lumbar spine diseases. We retrospectively analysed 80 patients at 7.1 years mean follow-up (Range: 5.1 - 8.3 years): 50 were treated with Dynamic Stabilization System (Dynesys) (mean age 47 years old) and 30 with Dynamic Transition Option (mean age 48 years old). We performed clinical pre-and post-operative evaluation using Visual Analogue Scale (VAS), Oswestry Low Back Pain Scale (ODI) and X-rays study. Results: we reported an important reduction of VAS from 7 to 2 (p<.001) and minimal disability in 65% of the patients, moderate disability in 18.2%, severe disability in 12.5% and crippling back pain in 4.3%. X-ray analysis showed a significative decrease of 3.5° with respect to the preoperative values, exactly 2° in neutral position postop, 1.2° in flexion postop and 2.5° in extension postop. Data showed greater reduction of extension than flexion in postoperative period. Dynamic neutralization limits more the extension than flexion. The correct preoperative planning, the careful selection of patients and the meticulous surgical technique are mandatory to avoid clinical failures. It is very important to identify the correct screw positioning and to avoid excessive pre-tensioning of the implant. Posterior dynamic neutralization and hybrid stabilization are valid alternative to spinal fusion in degenerative spine disease.