Abstract
Introduction
Current artificial discs include 1 or 2 bearing surfaces, providing 3 or 5 degrees of freedom. The ESP® is a one-piece e implant made of silicon and polycarbonate -urethane securely fixed to titanium endplates. It allows limited rotation and translation with elastic return. This cushion without fixed rotation center achieves 6 degrees of freedom including shock absorption. This objective of this study was to evaluate the safety and efficacy of the concept in a prospective nonrandomized trial.
Material and methods
Prior to clinical implantations, the device was endurance tested at least 40 millions cycles. The polymer core weight and properties, the geometrical characteristics and cohesion of the implants remained stable.
A prospective trial was initiated in 2004 for L3L4, L4L5 and L5S1 levels. Total disc replacements have been performed in 153 lumbar levels through extra-peritoneal mini-invasive anterior approach with a minimum 2 years follow-up.
Results
There was no clinical or radiological device related complication, except 2 early revisions for post-traumatic implant migrations (8, 17 days post-op.). When comparing the device to other implants, clinically relevant improvements in VAS, SF-36 and ODI scores were observed. At ultimate follow-up, the index level was mobile in 83% of the cases (5,3 ° ± 4.1). The mean centre of rotation was in the physiological area in 78% of cases without relevant modification of adjacent disc levels (Spineview® analysis)
Conclusion
The 6 years clinical follow-up demonstrate the reliability of the concept and the safety and forgiveness of the implant.
