A review of bone growth stimulation for fracture treatment

A systematic review of using electrical stimulation to improve clinical outcomes after hip fractures

BACKGROUND

Pain and muscles weakness often delays regaining independent mobility following hip fracture surgery. Electrical stimulation may relieve pain and improve muscle strength and function.

PURPOSE

To systematically review and evaluate available literature examining the effectiveness of using electrical stimulation to promote clinical outcomes after hip fractures.

METHODS

Two researchers independently searched MEDLINE, CINAHL, EMBASE, Web of Science, Cochrane Reviews, Physiotherapy Evidence Database, and PsycInfo from inception to July 1, 2018, with no restrictions. The quality and fidelity of the included interventions were assessed, and expert consultation was conducted to help explain the results.

RESULTS

We identified 432 records through database searching. Initial screening indicated 24 articles were appropriate for full-text review, and four articles met the inclusion criteria. In included studies, electrical stimulation (i.e. TENS) reduced pain (mean difference (MD) = 3.3 points on 10-point Visual Analogue Scale, p < .001), improved range of motion (ROM) (MD: 25.7°, p < .001), and accelerated functional recovery immediately after hip fracture (p < .001). Conflicting evidence existed when using neuromuscular electrical stimulation to improve muscle strength and other functional outcomes (e.g. mobility); however, nine experts advised that longer-term interventions might be necessary to achieve significant improvment in muscle strength.

CONCLUSION

Available evidence, albeit limited, supports the early application of noninvasive electrical stimulation (e.g. TENS) for improving clinical outcomes (i.e. reducing pain, improving ROM, and accelerating functional recovery after hip fractures). We could not find conclusive evidence on the effectiveness of using electrical stimulation to improve muscle strength. This review establishes the need for future additional high-quality trials in this field.

Direct electrical stimulation enhances osteogenesis by inducing Bmp2 and Spp1 expressions from macrophages and preosteoblasts

The capability of electrical stimulation (ES) in promoting bone regeneration has already been addressed in clinical studies. However, its mechanism is still being investigated and discussed. This study aims to investigate the responses of macrophages (J774A.1) and preosteoblasts (MC3T3-E1) to ES and the faradic by-products from ES. It is found that pH of the culture media was not significantly changed, whereas the average hydrogen peroxide concentration was increased by 3.6 and 5.4 µM after 1 and 2 hr of ES, respectively. The upregulation of Bmp2 and Spp1 messenger RNAs was observed after 3 days of stimulation, which is consistent among two cell types. It is also found that Spp1 expression of macrophages was partially enhanced by faradic by-products. Osteogenic differentiation of preosteoblasts was not observed during the early stage of ES as the level of Runx2 expression remains unchanged. However, cell proliferation was impaired by the excessive current density from the electrodes, and also faradic by-products in the case of macrophages. This study shows that macrophages could respond to ES and potentially contribute to the bone formation alongside preosteoblasts. The upregulation of Bmp2 and Spp1 expressions induced by ES could be one of the mechanisms behind the electrically stimulated osteogenesis.

Osteogenic Effect and Cell Signaling Activation of Extremely Low-Frequency Pulsed Electromagnetic Fields in Adipose-Derived Mesenchymal Stromal Cells

Extremely low-frequency pulsed electromagnetic field (ELF-PEMF) devices have been used in the clinic for the treatment of bone disorders over the past 30 years. However, the underlying mechanism of which ELF-PEMFs exert an effect on tissues at a cellular level is not well understood. Hence, in this study, we explored the potential of different ELF-PEMF signals in modulating human adipose-derived mesenchymal stromal cells' (hAMSC) osteogenic capability. The cell proliferation rate was assessed using carboxyfluorescein succinimidyl ester (CFSE) method. The osteogenesis potential of cells was determined by alkaline phosphatase (ALP) activity, Alizarin-Red S staining, and RT-qPCR. Finally, the intracellular signaling pathway of a selected ELF-PEMF signal was examined using the PathScan Intracellular Signaling Array. Among the tested ELF-PEMF signals, program 20 (26 Hz) showed activation of the Akt and MAPK/ERK signaling cascade and significant upregulations of collagen I, alkaline phosphatase, and osteocalcin when compared to nonstimulated cells. This study demonstrates the potential of certain ELF-PEMF signal parameters to induce osteogenic differentiation of hAMSC and provides important clues in terms of the molecular mechanisms for the stimulation of osteogenic effects by ELF-PEMF on hAMSC.

Smart electroconductive bioactive ceramics to promote in situ electrostimulation of bone

Biomaterials can still be reinvented to become simple and universal bone regeneration solutions. Following this roadmap, conductive CNT-based "smart" materials accumulate exciting grafting qualities for tuning the in vitro cellular phenotype. Biphasic electrical stimulation of human osteoblastic cells was performed in vitro on either dielectric bioactive bone grafts or conductive CNT-reinforced composites. The efficiency of the electrical stimuli delivery, as well as the effect of stimulation on cellular functions were investigated. Conductive substrates boosted the local culture medium conductivity and the confinement of the exogenous electrical fields. Hence, bone cell proliferation, DNA content and mRNA expression were maximized on the conductive substrates yielding superior stimuli delivering efficiency over dielectric ones. These findings are suggestive that bioactive bone grafts with electrical conductivity are capable of high spatial and temporal control of bone cell stimulation.

Healing in the new millennium: bone stimulators: an overview of where we've been and where we may be heading

Electromagnetic fields and their uses in bone healing have been fairly well studied, with most results showing improvement in healing of both bone and cartilage. Most supportive data are found in relation to the spine, femur, and tibia, but there is increasing evidence for its use in the foot and ankle for treatment of nonunions and as an adjunctive device in arthrodeses, particularly in high-risk populations. There are varying data and a significant variety of quality in the current research and publications concerning the use of electrical bone stimulation in the treatment of the foot and ankle. Thus, there is a definite need for further investigation and high-quality study designs to determine the most effective treatment modalities and pathologies best used with bone stimulation. Bone stimulation should be viewed as an adjunctive procedure in which the surgeon optimizes the high-risk patient both medically or surgically whenever possible. But when used appropriately, bone stimulation has the potential to influence outcomes and aid in bone healing when complications arise and in high-risk populations.

Up-regulation of expression of selected genes in human bone cells with specific capacitively coupled electric fields

The objective of the described experiments was to determine the electrical parameters that lead to optimal expression of a number of bone-related genes in cultured human bone cells exposed to a capacitively coupled electric field. Human calvarial osteoblasts were grown in modified plastic Cooper dishes in which the cells could be exposed to various capacitively coupled electric fields. The optimal duration of stimulation and optimal duration of response to the electrical field, and the optimal amplitude, frequency and duty cycle were all determined for each of the genes analyzed. Results indicated that a capacitively coupled electric field of 60 kHz, 20 mV/cm, 50% duty cycle for 2 h duration per day significantly up-regulated mRNA expression of a number of transforming growth factor (TGF)-β family genes (bone morphogenetic proteins (BMP)-2 and -4, TGF-β1, - β2 and -β3) as well as fibroblast growth factor (FGF)-2, osteocalcin (BGP) and alkaline phosphatase (ALP). Protein levels of BMP-2 and -4, and TGF-β1 and - β2 were also elevated. The clinical relevance of these findings in the context of a noninvasive treatment modality for delayed union and nonunion fracture healing is discussed.