Anterior cervical spinal fusion with the Intromed ZWE System: preliminary experience

The implantation of a spacer is common practice after ventral discectomy in the cervical spine. Besides bone or bone cement (Palacos, Sulfix, and Allofix), the surgeon has the choice of a variety of factory-made implants (cages). We report on our experience with the Intromed ZWE [Zwischenwirbel-Ersatzsystem (Intervertebral Replacement System)] implant. The ZWE implant (Intromed Medizintechnik GmbH, 15754, Senzig, Germany), made from titanium 6AL 4V, consists of a flat quadrangular body with a large supporting surface on the bottom and top and a central hole. We report the first 100 cases treated with their 1- or 2-year follow-up completed (mean follow-up, 1.7 years). The mean age was 47+/-9 years (range: 27-73 years). The implantation was performed without filling the central hole. In addition to the clinical investigation of neurological alterations and the range of movement, X-rays were taken, and the clinical result was determined by an independent investigator according to the Odom Scale. After the minimum follow-up of 1 year, 32 patients scored excellent on the Odom scale, 38 patients good, 25 patients satisfactory, and 5 patients bad. In 74 cases, fusion occurred radiologically as bony bridging around the implant. In 21 cases, the cage showed no change and no radiolucency. In five cases, radiolucency around the implant occurred without instability at flexion-extension X-ray views. In CT scans done in two patients with complaints, we confirmed bony bridging inside the centre hole implanted empty. The Intromed-ZWE-System performs well in routine clinical use. Compared to bone or bone cement, the operating time is reduced. The Intromed System offers an easy fusion method for a competitive price.