Introduction: Non-union/Pseudoarthrosis can be a significant problem following instrumented spinal fusion. Direct current electrical stimulation (DCES) of bone growth represents a unique surgical adjunct to promote and accelerate bone healing. Existing spinal fusion DCES systems utilize permanent electronic components, are invasive, and carry significant safety risks. The present study describes the design and implementation of a novel implantable bioresorbable DCES device and its application to a rodent femoral injury model.
Methods: Non-critical femoral defects were created in 15 Lewis rats. Animals were randomized into three treatment groups (n=5 each). Group I did not receive any stimulation, and Groups II and III received daily continuous 50uA DCES through permanent and bioresorbable femoral electrodes, respectively. All animals were euthanized two weeks post implantation and the injured femurs were harvested. Qualitative and quantitative analysis for regional bone formation was performed using morphometric and density parameters, as assessed by high resolution micro-computed tomography (micro-CT).
Results: Micro-CT morphometric analysis demonstrated increased overall bone formation, total tissue and bone volume, bone volume fraction, cross-sectional area, and cortical bone area after two weeks of DCES (Figure 1). The performance of bioresorbable stimulators compared favorably with that of permanent devices.
Conclusions: The results of the study suggest a trend toward increased bone formation with DCES in line with previous work, and highlight the possibility for integrating implantable bioresorbable technology to enhance bone healing. Further work is needed to examine the impact of varying DCES on osteogenesis and the optimization of bio-degradable hardware systems.
Patient Care: We hope that our research in accelerating bone growth and repair will have a significant impact on the management of bone fractures and spinal fusions. The potential therapy is aimed towards the treatment of complex or recalcitrant cases where bone formation is impaired or insufficient. Successful implementation of effective and biodegradable bone growth stimulators has the potential to improve fracture and spinal fusion outcomes and address the common burden of morbidity from delayed or compromised bone healing. Biophysical stimulation, as a therapeutic modality, could be considered for primary treatments of bone disease or as adjuncts to standard orthopedic procedures, such as bone fractures and spinal fusions. Future research aims to optimize the device-bone interface, assess biocompatibility in greater detail, and investigate more critical defects and injury models.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of translating experimental findings into clinical practice, specifically the use of biophysical stimulation as an adjunct to spine surgery, 2) Discuss, in small groups, the potential for integrating biophysical stimulation and biodegradable hardware into the existing paradigms of spinal surgical instrumentation and post-operative management algorithms, and 3) Identify effective therapies to address the morbidity from clinically significant rates of pseudoarthrosis / non-union following spinal fusion surgery.
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