Effectiveness of Wallis Interspinous Dynamic Stability System for Lumbar Disc Herniation: a Prospective Randomised Controlled Study

The most commonly used therapy for lumbar disc herniation (LDH) are partial discectomy or discectomy with fusion if there was an additional mechanical disorder in the underlying functional spinal unit. However, the problems associated with discectomy are intervertebral disc height loss and the segmental instability, thought to be a risk for failed back surgery syndrome or recurrence lumbar disc herniation. Fusion has also been criticised for its side effects of adjacent segment degeneration(ASD), pseudarthrosis and bone-graft morbidity. To prevent such complications , a new family of dynamic implants have been established. Wallis interspinous implant (Abbott Laboratories, Bordeaux, France) , invented by J. Senegas, is one of them. It consisted of a interspinous blocker made out of polyetheretherketone (PEEK) to limit extension and two dacron tapes around the spinous processes in order to secure the implant and limit flexion. The aim of using this device is to unload the facet joints, to restore foraminal height and to provide sufficient stability especially in extension but still allow motion in the treated segment. Previous clinical trials and biomechanical studies are promising, however, the superiority of a discectomy with Wallis in comparison to a discectomy alone for primary lumbar disc herniation has yet to be determined. The purpose of this prospective controlled study was to evaluate the clinical effect of lumbar discectomy combined with Wallis interspinous device, comparing with posterior lumbar discectomy alone. Our hypothesis was that the use of the Wallis device would have better clinical and radiological outcomes than lumbar discectomy alone.