Electrical Stimulation in Spinal Fusion

by Hunter Pharis

Each year there are approximately 400,000 spinal fusion surgeries that account for $13 billion in aggregate hospital costs, the highest of any procedure in the United States [1, 2].  Diseases that often lead to fusion include degenerative disc disease, cervical spondylotic myelopathy, scoliosis, and spondylolisthesis.  Posterior spinal fusion surgeries generally do well with reported fusion rates of 98.25%, 91%, and 94% in cervical, thoracic, and lumbar fusions respectively [3–5].  Despite this, nonunion, or pseudoarthrosis, remains a concern for surgeons and patients alike.  Those who experience pseudoarthrosis often have debilitating axial or radicular pain requiring further surgical treatment and increased healthcare spending.  In order to alleviate this burden, electrical stimulation therapies (EST) have been developed with the goal of improving fusion rates and patient outcomes [6].

EST has been proposed with several different modalities of action.  The first type of EST is direct current stimulation (DCS).  DCS works through a subcutaneous cathode implant into to the prospective fusion mass and an anode implant in the adjacent soft tissue [6].  This continuous stimulation aims to promote bone formation by reducing the oxygen tension, raising the pH, and upregulating osteoinductive growth factors[7, 8].  Secondly, capacitive coupling stimulation (CCS) has been used to induce fusion.  This noninvasive wearable device is active 24 hours per day and attempts to increase fusion rates by activating osteoblast activity and upregulating oseoinductive growth factors [9, 10].  The last type of EST is inductive coupling stimulation (ICS).  This device is wearable as well, but only requires 30 minutes to 2 hours of use per day [6].  The mechanism of action includes increased calcium release inducing bone formation and upregulation of osteoinductive growth factors [11, 12].

Each type of EST has been tested in the preclinical (animal) and clinical setting with varying results.  DCS has the benefit of 100% compliance due to its invasive nature; however, it comes with increased rates of discomfort, infection, and immune response [6].  Despite the possible side effects, DCS has shown to be the most effective implant resulting in consistent improvement in fusion rates in both preclinical and clinical trials [6].  ICS and CCS both appear to be a favorable choice for patients since they can be worn externally.  Because these devices are worn externally, they require active patient participation.  ICS was shown to be effective in clinical trials only and CCS has not displayed any significant effect on spinal arthrodesis [6].

Overall estimates on the effectiveness of EST appear to be promising, with rates of pseudoarthrosis in those receiving the treatment being almost half that as those who did not [6].  Even though results point to decreased rates of pseudoarthrosis, the question of cost effectiveness remains, as no high-level studies have analyzed this to date.  Current Medicare coverage of EST after fusion only includes those with multilevel fusions or those with a history of failed fusion [6].  Further studies analyzing the cost-effectiveness of EST for those at increased risk of pseudoarthrosis may aid the physician in the decision-making process and may help to improve the patient experience by reducing healthcare expenditure.


  1. Weiss AJ, Elixhauser A, Andrews RM (2006) Characteristics of Operating Room Procedures in U.S. Hospitals, 2011: Statistical Brief #170. Healthc. Cost Util. Proj. HCUP Stat. Briefs 
  2. Rajaee SS, Bae HW, Kanim LEA, Delamarter RB (2012) Spinal fusion in the United States: analysis of trends from 1998 to 2008. Spine 37:67–76
  3. Youssef JA, Heiner AD, Montgomery JR, Tender GC, Lorio MP, Morreale JM, Phillips FM (2019) Outcomes of posterior cervical fusion and decompression: a systematic review and meta-analysis. Spine J Off J North Am Spine Soc 19:1714–1729
  4. Yamasaki R, Okuda S, Maeno T, Haku T, Iwasaki M, Oda T (2013) Surgical outcomes of posterior thoracic interbody fusion for thoracic disc herniations. Eur Spine J 22:2496–2503
  5. Makanji H, Schoenfeld AJ, Bhalla A, Bono CM (2018) Critical analysis of trends in lumbar fusion for degenerative disorders revisited: influence of technique on fusion rate and clinical outcomes. Eur Spine J Off Publ Eur Spine Soc Eur Spinal Deform Soc Eur Sect Cerv Spine Res Soc 27:1868–1876
  6. Cottrill E, Pennington Z, Ahmed AK, Lubelski D, Goodwin ML, Perdomo-Pantoja A, Westbroek EM, Theodore N, Witham T, Sciubba D (2019) The effect of electrical stimulation therapies on spinal fusion: a cross-disciplinary systematic review and meta-analysis of the preclinical and clinical data. J Neurosurg Spine 1–21
  7. Fredericks DC, Smucker J, Petersen EB, Bobst JA, Gan JC, Simon BJ, Glazer P (2007) Effects of direct current electrical stimulation on gene expression of osteopromotive factors in a posterolateral spinal fusion model. Spine 32:174–181
  8. Bodamyali T, Bhatt B, Hughes FJ, Winrow VR, Kanczler JM, Simon B, Abbott J, Blake DR, Stevens CR (1998) Pulsed electromagnetic fields simultaneously induce osteogenesis and upregulate transcription of bone morphogenetic proteins 2 and 4 in rat osteoblasts in vitro. Biochem Biophys Res Commun 250:458–461
  9. Blackwell KA, Raisz LG, Pilbeam CC (2010) Prostaglandins in bone: bad cop, good cop? Trends Endocrinol Metab TEM 21:294–301
  10. Wang Z, Clark CC, Brighton CT (2006) Up-regulation of bone morphogenetic proteins in cultured murine bone cells with use of specific electric fields. J Bone Joint Surg Am 88:1053–1065
  11. Brighton CT, Wang W, Seldes R, Zhang G, Pollack SR (2001) Signal transduction in electrically stimulated bone cells. J Bone Joint Surg Am 83:1514–1523
  12. Aaron RK, Ciombor DM, Keeping H, Wang S, Capuano A, Polk C (1999) Power frequency fields promote cell differentiation coincident with an increase in transforming growth factor-beta(1) expression. Bioelectromagnetics 20:453–458

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