Abstract
BackgroundTreating traumatic fractures in osteoporosis is challenging. Multiple clinical treatment options are found in literature. Augmentation techniques are promising to reduce treatment-related morbidity. In recent years, there have been an increasing number of reports about extended indication for augmentation techniques. However, biomechanical evaluations of these techniques are limited.MethodsNine thoracolumbar osteoporotic spinal samples (4 FSU) were harvested from postmortem donors and immediately frozen. Biomechanical testing was performed by a robotic-based spine tester. Standardized incomplete burst fractures were created by a combination of osteotomy-like weakening and high velocity compression using a hydraulic material testing apparatus. Biomechanical measurements were performed on specimens in the following conditions: 1) intact, 2) fractured, 3) bisegmental instrumented, 4) bisegmental instrumented with vertebroplasty (hybrid augmentation, HA) and 5) stand-alone vertebroplasty (VP). The range of motion (RoM), neutral zone (NZ), elastic zone (EZ) and stiffness parameters were determined. Statistical evaluation was performed using Wilcoxon signed-rank test for paired samples (p = 0.05).ResultsSignificant increases in RoM and in the NZ and EZ (p < 0.005) were observed after fracture production. The RoM was decreased significantly by applying the dorsal bisegmental instrumentation to the fractured specimens (p < 0.005). VP reduced fractured RoM in flexion but was still increased significantly (p < 0.05) above intact kinematic values. NZ stiffness (p < 0.05) and EZ stiffness (p < 0.01) was increased by VP but remained lower than prefracture values. The combination of short segment instrumentation and vertebroplasty (HA) showed no significant changes in RoM and stiffness in NZ in comparison to the instrumented group, except for significant increase of EZ stiffness in flexion (p < 0.05).ConclusionsStand-alone vertebroplasty (VP) showed some degree of support of the anterior column but was accompanied by persistent traumatic instability. Therefore, we would advocate against using VP as a stand-alone procedure in traumatic fractures.HA did not increase primary stability of short segment instrumentation. Some additional support of anterior column and changes of kinematic values of the EZ may lead one to suppose that additive augmentation may reduce the load of dorsal implants and possibly reduce the risk of implant failure.
Highlights
Treating traumatic fractures in osteoporosis is challenging
The objective of this study is to investigate the kinematic effects of different dorsal augmentation-related treatment options of incomplete burst fractures in osteoporosis
All specimens presented a significant increase of the measured range of motion (RoM) (p < 0.005) for all directions by induction of the cranial burst fracture in comparison to intact kinematic behavior
Summary
Treating traumatic fractures in osteoporosis is challenging. Multiple clinical treatment options are found in literature. Incomplete burst fractures in osteoporotic patients are one of the most upcoming and challenging issues in spinal traumatology and optimal treatment remains an unresolved question. There is a paucity of randomized control trials as well as biomechanical studies which address the question of appropriate treatment and the understanding of the mechanical stability of these common injuries. In osteopenic or even osteoporotic patients with traumatic incomplete burst fractures, treatment options are even more manifold, but again without sufficient supporting evidence for positive outcomes. Fractures are frequently accompanied by comorbidities, so that the anterior thoracic, retroperitoneal or abdominal approach is not preferable. In this patient population, prolonged immobilization needs to be averted and immediate primary stability is aspired [4]
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