[Augmentation of VDS (ventral derotation spondylodesis) using double rod instrumentation: surgical method and early results].

INTRODUCTION AND AIM OF THE STUDY

The advantages of the VDS according to Zielke with excellent three dimensional correction and shorter fusion levels in comparison to posterior instrumentation techniques are well known. A disadvantage is the postoperatively necessary long immobilisation in a body cast due to lack of primary stability. Aim of the presented double-rod-VDS is to optimize the system by augmentation and allow a postoperative plaster cast- and brace-free treatment.

METHOD AND MATERIAL

Following thoracolumbar phrenotomy and ligation of the segmental vessels Kaneda-clamps are inserted. First VDS-screws are implanted into the posterior holes of these clamps. Using a M-4 compression rod, correction is obtained by centripetal compressive forces to the nuts. Next VDS-screws for the M-5 treated rod are inserted into the anterior holes of the Kaneda clamps. The rod is implanted in a slightly compressive manner and augments the system. Within a prospective study 12 patients with idiopathic and neuromuscular scoliosis underwent this surgical procedure. Three patients with thoracolumbar scoliosis have been followed for 12 months postoperatively and are presented as case reports. All patients were treated brace-free postoperatively, only using a semi-elastic vest for 4 months.

RESULTS

Remarkable intra- and postoperative complications have not been noted. Curve correction ranged from 75 to 86%. Implant related complications and loss of correction have not been noted so far. The sagittal plane was within physiological limits postoperatively. Scanning stereography demonstrated excellent three dimensional correction.

CONCLUSION

The results of the Double-rod-VDS allow the statement, that the advantages of the VDS according to Zielke are optimized by augmentation of the system with the possibility of plaster cast and brace-free postoperative treatment. Larger operation numbers and a longer follow-up period are needed for further assessment.