Outcome after Implantation of a Hydraulic Vertebral Body Replacement in Traumatic Vertebral Fractures

Abstract

Introduction The dorso-ventral stabilization is a frequently used procedure in traumatic vertebral body fracture treatment. The aim of the study was the analysis of radiological images and clinical outcome 3 years after implantation of an innovative hydraulic vertebral body replacement following a traumatic vertebral body fracture in the thoraco-lumbar spine. Materials and Methods The study includes all patients of our Level I trauma center which suffered a singular traumatic fracture of a thoracic or lumbar vertebral body (Th 5 - L 5) in the period from 11/2009 until 12/2010, that (i) underwent dorsal instrumentation and (ii) afterwards underwent implantation of a hydraulically expandable vertebral body replacement. The following radiological findings of all patients were evaluated (pre- and post-operatively and 3 years after implantation): sagittal angle, implants’ subsidence and implants’ position. Moreover, the clinical outcome 3 years after implantation was analyzed by the VAS spine scoring system. Details about trauma mechanism, current occupation, etc. were also documented. Statistical Analysis was performed with the software SAS 9.2. Results During the above mentioned period, n = 50 patients could be included in the study. The complete follow-up including the data 3 years after implantation of the vertebral body implant was successful for n = 47 (male: 26; female: 21) patients (follow-up rate: 89%). The mean age of all patients was 46.5 ± 17.0 years. The main reasons for spinal trauma were falls ( n = 28) and traffic accidents ( n = 14). The analysis of the radiological data showed an average sintering of the implants of 1.1 ± 1.2 mm (range 0.0 - 5.0 mm). After the initial operation, the local sagittal angle remained stable in the 3-years-follow up at thoracic spine (5.4 ± 4.8 ° versus 5.2 ± 4.8 °; p = 0.451) and lumbar spine (−7.2 ± 6.0 ° versus -7.0 ± 6.0 °; p = 0.451). Furthermore, no change in the implants’ position could be observed. Most of the patients ( n = 40) were “generally satisfied” or “very satisfied” with their outcome. The mean rating of the VAS spine score was 65.2 ± 23.1 (range: 20.5 - 100.0). Activities of daily life are less limited (83.0 ± 21.8) than activities concerning the patients' profession (49.5 ± 37.3). Taking analgesic medication is of clear effect (72.4 ± 27.4) and has a positive correlation ( p = 0.001) to a higher rated VAS spine score. Conclusion In summary, the current study shows that the implantation of that innovative hydraulic vertebral body replacement allows a permanent stable fixation after traumatic fractures of the thoracic and lumbar spine. General complications are rare and the local sagittal angle is fixed after 3 years. Secondary dislocation and serious sintering of the implant were not observed. The clinical outcome after implantation of the hydraulic vertebral body replacement is comparable to the outcome after the ventral stabilization with an iliac crest bone graft. Nevertheless, there is an obvious reduction in the VAS spine score after dorso-ventral stabilization in comparison to the healthy public.