Titanium versus polyetheretherketone implants for vertebral body replacement in the treatment of 77 thoracolumbar spinal fractures
- Department of Surgery, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Neurological and Neurosurgical Clinic, Santa Casa de Misericórdia de Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil
- Hôpital Pierre Wertheimer, Bron, Lyon, France
Rafael Augusto Castro Santiago Brandão
Hôpital Pierre Wertheimer, Bron, Lyon, France
DOI:10.4103/sni.sni_113_17Copyright: © 2017 Surgical Neurology International This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Rafael Augusto Castro Santiago Brandão, Warley Carvalho da Silva Martins, Aluízio Augusto Arantes, Sebastião Nataniel Silva Gusmão, Gilles Perrin, Cédric Barrey. Titanium versus polyetheretherketone implants for vertebral body replacement in the treatment of 77 thoracolumbar spinal fractures. 14-Aug-2017;8:191
How to cite this URL: Rafael Augusto Castro Santiago Brandão, Warley Carvalho da Silva Martins, Aluízio Augusto Arantes, Sebastião Nataniel Silva Gusmão, Gilles Perrin, Cédric Barrey. Titanium versus polyetheretherketone implants for vertebral body replacement in the treatment of 77 thoracolumbar spinal fractures. 14-Aug-2017;8:191. Available from: http://surgicalneurologyint.com/surgicalint-articles/titanium-versus-polyetheretherketone-implants-for-vertebral-body-replacement-in-the-treatment-of-77-thoracolumbar-spinal-fractures/
Background:Titanium and polyetheretherketone (PEEK) implants have been used in spinal surgery with low rejection rates. Compared to titanium, PEEK has many advantages, including a density more similar to that of bone, radiolucency, and a lack of artifacts in computed tomography (CT) and magnetic resonance imaging (MRI). In this study, we evaluated the effectiveness of PEEK cages as an alternative to titanium for bone fusion after fractures of the thoracolumbar spine. We also propose a classification to the impaction index.
Methods:We evaluated 77 patients with fractures of the thoracic or lumbar spine who were treated by anterior fixation with titanium cages (TeCorp®) in 46 (59.7%) patients or PEEK (Verte-stak®) in 31 (40.3%) patients from 2006 to 2012 (Neurological Hospital of Lyon).
Results:The titanium group achieved 100% fusion, and the PEEK group achieved 96.3% fusion. The titanium systems correlated with higher impact stress directed toward the lower and upper plateaus of the fused vertebrae; there were no nonunions for those treated with titanium group. Nevertheless, there was only one in the PEEK group. There was no significant difference in the pain scale outcomes for patients with ±10 degrees of the sagittal angle. Statistically, it is not possible to associate the variation of sagittal alignment or the impaction with symptoms of pain. The complication rate related to the implantation of cages was low.
Conclusions:Titanium and PEEK are thus equally effective options for the reconstruction of the anterior column. PEEK is advantageous because its radiolucency facilitates the visualization of bone bridges.
Keywords: Fractures of the thoracolumbar spine, implant, polyetheretherketone, titanium
The surgical treatment of spine fractures reduces deformity and restores spinal stability. If the patient has direct spinal cord compression, decompression of the spinal canal is also affected.[
A total of 77 patients [
This study evaluated patients with traumatic fractures who underwent vertebral body replacement using a titanium or PEEK cage. The patients were older than 16 years of age, and had a minimum of 8 months of follow-up. The indications for cage placement via the anterior route were spine fractures that affected the anterior and middle segments of the vertebra and where there were signs of substance loss due to vertebral body splintering (e.g., documented on CT).[
Patients with more than one fractured vertebra, reoperations for failed fusion of previous surgery, and children were excluded from the research.
The following variables were evaluated: age, cause and location of fracture, complications, type of implant, and fracture classification according to Magerl et al.[
Multiple factors were examined:
Coronal and sagittal segmental alignment Impaction of the implant on the plateaus [ Radiographic fusion was considered the presence of an intervertebral bone bridge upon radiographic examination.
Coronal and sagittal segmental alignment
Impaction of the implant on the plateaus [
Radiographic fusion was considered the presence of an intervertebral bone bridge upon radiographic examination.
All patients underwent emergent posterior fracture stabilization and, if necessary, spinal decompression. A second-stage surgery was performed to place the cage for vertebral body replacement to reinforce the arthrodesis. The second-stage surgery was performed anteriorly by thoracotomy for thoracic vertebra fractures and by L1 or lumbotomy for fractures to L2, L3, and L4. The minimum interval between the first and second approach was 3 days. All patients underwent partial resection of the vertebral body, followed by placement of a cylindrical titanium or PEEK cage.
In total, 77 patients were studied and classified into two groups: 31 in the PEEK group and 46 in the titanium group.
Sagittal alignment angle
Changes in the sagittal segmental angle of the adjacent vertebrae were analyzed at four time points [
Analogic visual scale of pain according to sagittal angle
A comparison of the analogic visual scale (AVS) of pain between the categories of sagittal angle (comparing stages 3 and 4) is presented in
Coronal alignment angle
The mean value of the coronal alignment angle remained close to zero, i.e., close to perfect alignment at all evaluations (P = 0.788), with no large differences between four stages. The coronal alignment angle measurements of the titanium group were significantly higher than those of the PEEK group (P = 0.041). Only the stage after the anterior approach exhibited a significant difference; the mean of the titanium group was higher than that of the PEEK group (P = 0.002).
Implant impaction on the lower vertebra
Only 19.0% of the cases had impaction on the lower plateau in the immediate postoperative period of cage placement (Stage 3,
(a) Mean percentage value of impaction on the lower plateau in the cage placement immediate postoperative stage (Stage 3) and at final follow-up. (b) Change in impaction on the lower plateau in the cage placement immediate postoperative stage (third evaluation) and at the final follow-up for the two groups. (c) Mean percentage value of impaction on the upper plateau in the cage placement immediate postoperative stage (Stage 3) and at the final follow-up. (d) Change in impaction in the upper plateau in the cage placement immediate postoperative stage (third evaluation) and at the final follow-up for the two groups. P value was calculated using the marginal log-linear model based on Chi-square analysis
Impaction of the implant on the upper vertebra
In the PEEK and titanium groups, 20 (80.0%) and 24 (68.6%) patients did not exhibit impaction on the upper plateau in the final follow-up, respectively. There was no significant difference between the groups [
Analogic visual scale of pain according to impaction
A comparison of the AVS of pain according to impaction in stage 4 is presented in
Including cases of probable fusion, the titanium group obtained 100% fusion, and the PEEK group achieved 96.3% fusion. As demonstrated in
There are still no guidelines or uniformity regarding the treatment of unstable fractures of the thoracolumbar spine. The most common treatment is posterior fixation with a pedicle screw.[
As a very rigid material with much greater density than bone, titanium does not have compliance compatible with a large overload area such as the thoracolumbar spine. Theoretically, titanium can, over time, impact the vertebral body and thus can lead the patient to suffer progressive kyphosis. Another drawback of titanium is difficulty in evaluating postoperative control X-ray because it is often not possible to confirm bone fusion due to the difficulty of visualizing the trabecular bones. In some cases, consolidation cannot be confirmed by CT scan due to the strong presence of artifacts.[
Although the osteogenic properties of autologous bone are undeniable, such grafts are not free from fracture and dislocation[
Considering as probable fusion a lack of material displacement in the radiograph in flexion and extension and an absence of translucency between the material and vertebral plateau, both implants achieved fusion levels of close to 100%, with 100% in the titanium group and 96.3% in the PEEK group. Viewing of the bone bridges is more difficult with a titanium implant because the implant is not radiolucent and presents artifacts in MRI and CT. Thus, 23.1% of the titanium group patients were classified as requiring probable radiographic arthrodesis because it was not possible to identify bone bridges in the intervertebral space, although this does not indicate failure of the bone fusion.
These data coincide with findings by Dvorak et al.[
Coronal and sagittal alignment
The mean alignment angle measurements on the coronal plane were thus always close to 0 at all studied stages, indicating good alignment of the spine at the time of the trauma that remained up to the final evaluation. The mean coronal plane angle was significantly greater in the titanium group than the PEEK group (P = 0.033); however, this effect depended significantly on the analyzed stage (P = 0.041). A significant difference was observed only after the anterior approach, in which the mean was higher in the titanium group than in the PEEK group (P = 0.002). At other stages, there was no difference. It should be noted that the measurements of the two groups were always close to zero degrees, i.e., near perfect alignment.
In relation to the sagittal plane, some authors have reported a correction loss of 7–16°, with spinal kyphosis during the first postoperative year, in exclusively posterior approach fixations, particularly in fractures with upper plateau injuries of the vertebra.[
Correction loss between the postoperative anterior approach and final follow-up was also observed in our series (P < 0.0001). In absolute numbers, this loss was 5.21°. No significant differences in sagittal alignment were detected when comparing the two implants. The PEEK group exhibited a 4.04° correction loss and the titanium group 5.93°, with no significant difference.
When also analyzing posterior instrumentation combined with a titanium cage, after 5 years of follow-up, Schnake, Stavridis, and Kandziora[
Impaction on the vertebral plateau
A classification to measure the impaction index could assist in the follow-up of patients with potential neurological damage. This is a critical problem mainly in cases in which the impaction is higher than 30%. The suggested index is presented below and the impaction level has a direct correlation with the increase of the symptoms.
Type I ⟶ <5%: no impaction;
Type II ⟶ 5–10%: minimum impaction;
Type III ⟶ 10–30%: moderate impaction;
Type IV ⟶ >30%: severe impaction.
The types of impaction were based on the proposed classification. There was a highest percentage of patients without impaction (type I). The impaction was higher in PEEK cages (80% in upper plateau and 81% in lower plateau) than in titanium (71% in upper plateau and 68.6% in lower plateau) [Tables
The cases classified as types II and III, for lower impaction, had strictly the same percentage for PEEK cage and titanium, i.e., 9.5% and 12.9%, respectively. The same was not observed for upper vertebral plateau: the percentage of impaction was smaller for PEEK cage group (4% - type II and 16% - type III) than for the titanium group (8.6% - type II and 17% - type III). Patients classified in severe cases, or type IV, were observed only in titanium group: 5.7% in upper plateau and 3.2% in lower plateau [Tables
Titanium is a more rigid material with less compliance, with more impaction on the vertebral plateau. Titanium tended to have greater impaction on the plateau. Both groups had a significant increase in the number of cases of impaction on the upper vertebra in the final follow-up. This increase was greater in the titanium group, with 31.4% of patients with impaction, compared to 20% in the PEEK group in the final follow-up. This increase in the lower vertebra was not significant.
Graillon et al.[
Schnake, Stavridis, and Kandziora[
In our study, there was one case of hemothorax in each group, with no long-term repercussions. One (3.2%) revision surgery was performed in the PEEK group and two (4.4%) in the titanium group. In other cases, where the posterior osteosynthesis material was removed, the reason was not instrumentation failure. Cage placement surgery resulted in no infections. Infections were related to the surgical placement of pedicle screws posteriorly, with one (3.2%) case in the PEEK group and two (4.4%) in the titanium group, and were only superficial scar infections. The posterior approach was generally performed in an emergency and was therefore susceptible to a higher infection rate.
Titanium and PEEK implants are effective options for the reconstruction of the vertebral body in the case of thoracolumbar spine fracture. Both have a similar fusion rate. PEEK offers the advantage of greater visibility of bone bridges due to its radiolucency. Titanium tends to have higher impaction on the vertebral plateau, but the difference between PEEK and titanium is not significant. A classification to measure the impaction index could assist in the follow-up of patients with potential neurological damage. There was no difference in pain scale for patients with or without compaction. There was no association in pain scale among those patients who had an increase in the sagittal angle bigger or smaller than 10 degrees. For both implants, both initial and later infection and complication rates were low.
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Conflicts of interest
There are no conflicts of interest.
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