Coverage Policy Manual
Policy #: 2009048
Category: Medicine
Initiated: December 2009
Last Review: October 2018
  Bone Growth Stimulation, Electrical, Adjunct to Spinal Fusion

Description:
Both invasive and noninvasive electrical bone growth stimulators have been investigated as an adjunct to spinal fusion surgery, with or without associated instrumentation, to enhance the chances of obtaining a solid spinal fusion.
 
Noninvasive devices have also been investigated to treat a failed fusion.
 
Background
Electrical and electromagnetic fields can be generated and applied to bones through the following methods:
 
    • Surgical implantation of a cathode at the fracture site with the production of direct current (DC) electrical stimulation. Invasive devices require surgical implantation of a current generator in an intramuscular or subcutaneous space, while an electrode is implanted within the fragments of bone graft at the fusion site. The implantable device typically remains functional for 6 to 9 months after implantation, and, although the current generator is removed in a second surgical procedure when stimulation is completed, the electrode may or may not be removed. Implantable electrodes provide constant stimulation at the nonunion or fracture site but carry increased risks associated with implantable leads.
    • Noninvasive electrical bone growth stimulators generate a weak electrical current within the target site using either pulsed electromagnetic fields, capacitive coupling, or combined magnetic fields. In capacitive coupling, small skin pads/electrodes are placed on either side of the fusion site and worn for 24 hours per day until healing occurs or up to 9 months. In contrast, pulsed electromagnetic fields are delivered via treatment coils that are placed into a back brace or directly onto the skin and are worn for 6–8 hours per day for 3 to 6 months. Combined magnetic fields deliver a time-varying magnetic field by superimposing the time-varying magnetic field onto an additional static magnetic field. This device involves a 30-minute treatment per day for 9 months. Patient compliance may be an issue with externally worn devices.
    • Semi-invasive (semi-implantable) stimulators use percutaneous electrodes and an external power supply obviating the need for a surgical procedure to remove the generator when treatment is finished.
 
Regulatory Status
The following implantable devices have received U.S. Food and Drug Administration (FDA) premarket approval (PMA):
    • The OsteoStim® (Electro-Biology, Inc.), which may also be marketed under the trade name SPF (Biomet), has received FDA PMA.
 
Noninvasive bone growth stimulators that have received FDA PMA include:
    • The SpinalPak® bone growth stimulator system from Biolectron (a subsidiary of Electro-Biology, Inc., Parsippany, NJ) is a capacitive coupling system, received PMA in 1999 for use as an adjunct to primary lumbar spinal fusion at 1 or 2 levels.
    • The EBI Bone Healing System® from Biolectron (a subsidiary of Electro-Biology, Inc., Parsippany, NJ) is a pulsed electromagnetic field system which was first approved in 1979 with FDA PMA and indicated for nonunions, failed fusions, and congenital pseudarthroses. The device is secured with a belt around the waist.
    • SpinaLogic Bone Growth Stimulator® (Regentek, a division of of Orthopedics, LLC (formerly OrthoLogic, Tempe, AZ) received PMA in 1994 as a combined magnetic field portable device. This device is secured with a belt around the waist.
    • Spinal-Stim Lite ® (Orthofix, Inc., Richardson, TX) received PMA in 1996 as a spinal adjunct to the Physio-Stim®. This device was approved to increase the probability of fusion success and as a non-operative treatment for the salvage of failed spinal fusion, where a minimum of 9 months has elapsed since the last surgery.
    • The Cervical-Stim® from Orthofix, Inc., Richardson, TX is a pulsed electromagnetic field system that was approved in 2004 as an adjunct to cervical fusion surgery in patients at high risk for non-fusion. An illustration of how this particular device is worn is available at online site; http://www.orthofix.com/products/spine_cervstim.asp.
 
No semi-invasive electrical bone growth stimulator devices were identified with FDA approval or clearance.
 
 

Policy/
Coverage:
Meets Primary Coverage Criteria Or Is Covered For Contracts Without Primary Coverage Criteria
 
Invasive or noninvasive methods of electrical bone growth stimulation meets Primary Coverage Criteria as an adjunct to lumbar spinal fusion surgery in patients at high risk for fusion failure, defined as any one of the following criteria:
 
    • one or more previous failed spinal fusion(s);
    • grade III or worse spondylolisthesis;
    • fusion to be performed at more than one level;
    • current smoking habit;
    • diabetes;
    • renal disease;
    • alcoholism;
    • steroid use.
 
Noninvasive electrical bone stimulation as a treatment of patients with failed lumbar spinal fusion meets member benefit Primary Coverage Criteria that there be scientific evidence of effectiveness in improving health outcomes.  Failed spinal fusion is defined as a spinal fusion that has not healed at a minimum of 6 months after the original surgery, as evidenced by serial x-rays over a course of 3 months.
 
Does Not Meet Primary Coverage Criteria Or Is Investigational For Contracts Without Primary Coverage Criteria
 
Semi-invasive electrical stimulation as an adjunct to lumbar fusion surgery and for failed lumbar fusion does not meet member benefit Primary Coverage Criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For contracts without Primary Coverage Criteria, semi-invasive electrical stimulation as an adjunct to lumbar fusion surgery and for failed lumbar fusion is considered investigational. Investigational services are exclusions in the member benefit certificate of coverage.
   
Invasive, semi-invasive, and noninvasive electrical stimulation as an adjunct to cervical fusion surgery and for failed cervical spine fusion does not meet member benefit Primary Coverage Criteria that there be scientific evidence of effectiveness in improving health outcomes.   
 
For contracts without Primary Coverage Criteria, Invasive, semi-invasive, and noninvasive electrical stimulation as an adjunct to cervical fusion surgery and for failed cervical spine fusion is considered investigational. Investigational services are exclusions in the member benefit certificate of coverage.
 
 
 

Rationale:
The 1992 and 1993 Blue Cross & Blue Shield   TEC Assessments offered the following conclusions:
 
    • Data from a randomized, controlled clinical trial of patients meeting the criteria for high risk for development of failed fusion suggest that invasive or noninvasive electrical bone stimulation as an adjunct to spinal fusion surgery is associated with a significantly higher spinal fusion success rate in the treated group compared with the control group (Kane, 1988) (Mooney, 1990).
    • Data from uncontrolled studies of patients with failed spinal fusion suggest that noninvasive electrical stimulation results in a significantly higher fusion rate. The lack of controlled clinical trials is balanced by the fact that these patients served as their own control.
 
Analysis of the data from clinical trials is limited by the following factors:
 
    • Trials frequently include heterogeneous groups undergoing a variety of surgeries, which may have different risk levels for fusion failure.
    • Trials frequently include patients undergoing spinal fusion both with and without additional surgical adjuncts, i.e., pedicle screws or back “cages,” both designed to increase the fusion rate. Therefore, those patients undergoing instrumented spinal fusion procedures may have a decreased risk of fusion failure compared to those without instrumented procedures.
    • While most trials have focused on “high-risk” patients, others have also included average-risk patients. The outcomes associated with average-risk patients are often not reported separately.
    • Trials have used different outcomes for spinal fusion, based on varying clinical and radiologic outcomes.
    • The presence or absence of spinal fusion may be considered an intermediate outcome, with the final health outcome typically focusing on relief of pain. Final health outcomes are typically not reported.
 
With the above limitations in mind, results of controlled trials are summarized below.
 
Implantable Electrical Stimulation
 
Instrumented Spinal Fusion
Kucharzyk reported on a controlled prospective nonrandomized trial of implantable electrical stimulation in patients undergoing instrumented posterior spinal fusion with pedicle screws Kucharzyk, 1999).   A series of 65 patients who did not use electrical stimulation were compared with a later series of similar patients who did receive implantable electrical stimulation. Fusion success was 95.6% in the stimulated group compared to 87% in the nonstimulated group, a statistically significant difference. It appears that all patients had at least one or more high-risk factors for failed fusion, i.e., smoking history, prior surgery, multiple fusion levels, diabetes, etc. While this trial supports the use of electrical stimulation as an adjunct to instrumented posterior lumber fusion, it did not specifically identify the outcomes in patients considered to be at low risk for failed fusion. Rogozinski and colleagues reported on the outcomes of two consecutive series of patients undergoing posterolateral fusions with autologous bone graft and pedicle screw fixation (Rogozinski, 1996).   The first series of 41 patients were treated without electrical stimulation, while the second group of 53 patients received invasive electrical stimulation. Those receiving electrical stimulation reported a 96% fusion rate, compared to an 85% fusion rate in the unstimulated group. The fusion rate for patients receiving stimulation versus no stimulation was also significantly higher among those considered at high risk due to previous back surgery or multiple fusion levels. No significant increase in the fusion rate was noted among non-smokers (i.e., without a risk factor), but the comparative fusion rates for all patients without high-risk factors is not presented.
 
No studies of semi-invasive (semi-implantable) stimulators were identified during the most recent literature search of MEDLINE through November  2009. In addition, none of these devices has U.S. Food and Drug Administration (FDA) clearance or approval.  
 
Noninvasive Electrical Stimulation
 
Lumbar Spine
Goodwin and colleagues reported on the results of a study that randomized 179 patients undergoing lumbar spinal fusions to receive or not receive capacitively coupled electrical stimulation (Goodwin, 1999).   A variety of surgical procedures both with and without instrumentation were used, and subjects were not limited to high-risk patients. The overall successful fusion rate was 84.7% for those in the active group compared to 64.9% in the placebo group, a statistically significant difference. While the actively treated group reported increased fusion success for all stratification groups (i.e., according to fusion procedure, single or multilevel fusion, smoking or nonsmoking group), in many instances the differences did not reach statistical significance because of small numbers. For example, the subgroups in which there was not a significant difference in fusion between the active and placebo groups included patients who had undergone previous surgery, smokers, and those with multilevel fusion. In addition, there were numerous dropouts in the study and a 10% noncompliance rate with wearing the external device for up to 9 months.
 
Mooney and colleagues reported on the results of a double-blind study that randomized 195 patients undergoing initial attempts at interbody lumber fusions with or without fixation to receive or not receive pulsed electromagnetic field electrical stimulation (Kucharzyk, 1999).  Patients were not limited to high-risk groups. In the active treatment group, the success rate was 92%, compared to 65% in the placebo group. On subgroup analysis, the treated group consistently reported an increased success rate. Subgroups included graft type, presence or absence of internal fixation, or presence or absence of smoking.
 
Linovitz and colleagues conducted a double-blind clinical trial that randomized 201 patients undergoing one- or two-level posterolateral fusion without instrumentation to undergo active or placebo electrical stimulation using a combined magnetic field device (Linovitz, 2002).  Unlike capacitively coupled or pulsed electromagnetic field devices, the combined magnetic field device requires a single 30-minute treatment per day with the device centered over the fusion site. Patients were treated for 9 months. Among all patients, 64% of those in the active group showed fusion at 9 months compared to 43% of those with placebo devices, a statistically significant difference. On subgroup analysis, there was a significant difference among women, but not men.
 
Moody and Linovitz excluded from their studies patients with severe osteoporosis and Goodman excluded patients with osteoporosis of unspecified severity.  None of the studies mentioned steroid use, however authors of 2 papers summarizing the available evidence on inhibition of bone healing  (Gaston, 2007) and the effects of drugs on bone healing (Pountos, 2008) agree that long-term (longer than 1 week) steroid use has an inhibitory effect on bone healing. Thus, steroid use is added as an additional condition that results in high risk of non-fusion.
 
Cervical Spine
In 2008, Foley et al published results of the investigational device exemption study of pulsed electromagnetic field (PEMF) stimulation as an adjunct to anterior cervical discectomy and fusion (ACDF) with anterior cervical plates and allograft interbody implants (Foley, 2008). This study described results using the Cervical-Stim device from Orthofix that received premarket approval (PMA) from the FDA in 2004. A total of 323 patients were randomized. All patients were active smokers (more than one pack of cigarettes per day, 159 patients) or were undergoing multilevel ACDF (192 patients). Patients with pertinent history of trauma, previous posterior cervical approach or revision surgery, and certain systemic conditions or steroid use, and regional conditions such as Paget’s disease or spondylitis were excluded. Beginning 1 week after surgery, patients in the treatment group wore the Cervical-Stim device for 4 hours per day for 3 months. Efficacy was measured by radiographic analysis at 1, 2, 3, 6, and 12 months. At 6 months, 122 patients in the treatment group and 118 in the control group were evaluable; 15 in the PEMF group and 13 in the control group voluntarily withdrew, 7 in the PEMF group and 1 control violated study protocol, and 19 in the PEMF group and 28 controls had radiographs that were not evaluable or radiographs that were not done within 2 weeks of the 6-month postoperative window. Fusion rates for the 240 evaluable patients at 6 months were 83.6% for the PEMF group and 68.6% for the control group (p=.0065). By intent-to-treat analysis, assuming that nonevaluable patients did not have fusion, PEMF and control groups fusion rates were 65.6% and 56.3%, respectively (p=.0835). Of 245 patients available for follow-up at 12 months, fusion was achieved in116 of 125 PEMF patients and 104 of 120 control patients (p=.1129). Patient compliance, which was automatically monitored by the device, was assessed at each visit; however, compliance data were not included in the paper. The large number of dropouts, non-significant difference in fusion rates by intent-to-treat analysis, and lack of data on functional outcomes (e.g., pain, return to usual activity) limit interpretation of these study results. No other studies of electrical stimulation as an adjunct to cervical fusion were identified in the literature search. Thus, this technique does not meet Primary Coverage Criteria of safety and effectiveness for the cervical spine.
 
Technology Assessments, Guidelines and Position Statements
The 2005 American Association of Neurological Surgeons and the Congress of Neurological Surgeons guideline states that there is Class II and III evidence (non-randomized comparative trials and case series) “to support the use of direct current stimulation or capacitative coupled stimulation for enhancing fusion rates in high-risk patients undergoing lumbar PLF. A beneficial effect on fusion rates in patients not at "high risk" has not been convincingly demonstrated, nor has an effect been shown for these modalities in patients treated with interbody fusion. There is limited evidence both for and against the use of pulsed electromagnetic field stimulation (PEMFS) for enhancing fusion rates following PLF. Class II and III medical evidence supports the use of PEMFS for promoting arthrodesis following interbody fusion. Although some studies have purported to demonstrate functional improvement in some patient subgroups, other studies have not detected differences. All of the reviewed studies are significantly flawed by the use of a four-point patient satisfaction scale as the primary outcome measure. This outcome measure is not validated. Because of the use of this flawed outcome measure and because of the conflicting results reported in the better-designed studies that assess functional outcome, there is no consistent medical evidence to support or refute use of these devices for improving patient outcomes (Reznick, 2005).”
 
Summary
Interpretation of clinical trial data is limited by the heterogeneous populations studied, and the variety of surgical procedures within the populations. The policy indicates that electrical stimulation, whether invasive or noninvasive, should be limited to those patients with high-risk features. A review of the literature suggests that the patients most likely to benefit are those at highest risk. In addition, electrical stimulation may improve the fusion rate in patients undergoing both instrumented and non-instrumented surgeries. However, scientific data are inadequate to determine the magnitude of benefit associated with electrical stimulation in patients considered at average risk for fusion failure.
 
At present, the evidence is insufficient that electrical stimulation as an adjunct to fusion of cervical vertebrae improves fusion rates or functional outcomes. Therefore, the  policy statement indicates that there is a lack of scientific evidence that this  technology improves health outcomes in the treatment of cervical spine fusion. In addition, there are no FDA-approved semi-invasive devices, therefore, there is a lack of scientific evidence that these devices are safe or that they improve health outcomes.
 
2012 Update
A search of the Medline database did not reveal any published literature that would prompt a change in the coverage statement.
 
2014 Update
A search of the MEDLINE database conducted through March 2014 did not reveal any new information that would prompt a change in the coverage statement.
 
2014 Update
A literature search conducted through September 2014 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
 
Updated 2014 guidelines from the American Association of Neurological Surgeons and the Congress of
Neurological Surgeons (AANS/CNS) state that there is no evidence published after their 2005 guidelines
that conflicts with the previous recommendations regarding bone growth stimulation (Kaiser, 2014).  Based on a single level II study from 2009, the routine use of direct current stimulation (DCS) in patients over the age of 60 years was not recommended. Use of DCS was recommended as an option for patients younger than 60 years of age, based on Level III and IV studies showing a positive impact on fusion rate. However, comments regarding the level III study were that it was a poorly designed and conducted cohort study consisting of an exceedingly small heterogeneous population of patients, and the overall recommendation was level C. There was insufficient evidence to recommend for or against the use of pulsed electromagnetic field stimulation (PEMFS) as a treatment alternative to revision surgery in patients presenting with pseudoarthrosis following posterolateral lumbar fusion (PLF, single level IV study). No additional studies investigating the efficacy of capacitive coupled electrical stimulation were identified.
 
2016 Update
A literature search conducted through September 2016 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
 
A 2014 systematic review by Park and colleagues included six RCTs through October 2013 that investigated the effect of electrical stimulation versus no electrical stimulation on fusion rates after lumbar spinal fusion for the treatment of degenerative disease (Park, 2014). The following types of electrical stimulation were included in the studies: direct current (3 studies), pulsed electromagnetic field (3 studies), and capacitive coupling (1 study). Control groups consisted of no stimulation (2 studies) or placebo (4 studies). A meta-analysis was not performed due to marked heterogeneity in the study populations, characteristics, and designs. Regardless of the type of electrical stimulation used, the cumulative incidences of fusion varied widely across RCTs and ranged from about 35% to 91% in the intervention groups and from about 33% to 82% in the control groups. Follow-up ranged from 9 to 24 months.
 
Ongoing and Unpublished Clinical Trials
A search of ClinicalTrials.gov in September 2016 did not identify any ongoing or unpublished trials that would likely influence this review.
 
2017 Update
A literature search conducted through September 2017 did not reveal any new information that would prompt a change in the coverage statement.  The key identified literature is summarized below.
 
ONGOING AND UNPUBLISHED CLINICAL TRIALS
A search of ClinicalTrials.gov in September 2017 did not identify any ongoing or unpublished trials that would likely influence this review.
   
2018 Update
A literature search was conducted through September 2018.  There was no new information identified that would prompt a change in the coverage statement.  The key identified literature is summarized below.
 
CERVICAL SPINE FUSION
Coric et al published results from an industry-sponsored multicenter cohort study of PEMF treatment in patients at high risk of cervical arthrodesis following anterior cervical discectomy and fusion procedures (Coric, 2018). The trial described results using the Cervical-Stim device (Orthofix) for 274 patients enrolled across 3 institutions. All patients had 1 or more risk factors, defined as nicotine user, osteoporosis, diabetes, age greater than 65 years or greater than 50 years, for pseudoarthrosis, and were treated with PEMF stimulation for 3 to 6 months. A historical control group was generated from a post hoc analysis of high-risk subjects from the original Food and Drug Administration investigational device exemption trial. The primary end point was bone fusion rates as assessed at 6 and 12 months by the treating surgeon not blinded to clinical symptoms and outcomes for subjects. At 6 months, statistically significant improvements in fusion rates were found for patients falling into the following risk factor groups; ie, at least 1 risk factor for: age over 50 years and 2-level arthrodesis (p=0.002); age over 50 years and 3-level arthrodesis (p<0.001); age over 65 years and 2-level arthrodesis (p=0.009); and age over 65 years and 3-level arthrodesis (p=0.002). Likewise, at 12 months, statistically significant improvements in fusion rates were found for patients falling into the following risk factor groups; ie, at least 1 risk factor for: age over 50 years and 2-level arthrodesis (p=0.002); age over 50 years and 3-level arthrodesis (p<0.001); age over 65 years and 2-level arthrodesis (p=0.001); and age over 65 years and 3 level arthrodesis (p<0.001). Study limitations included the use of a historical control group from the original investigational device exemption trial instead of a prospective control group, surgeons who were not blinded to clinical symptoms and outcomes, and surgeons who were not restricted as to the surgical procedures used during the study.

CPT/HCPCS:
20974Electrical stimulation to aid bone healing; noninvasive (nonoperative)
20975Electrical stimulation to aid bone healing; invasive (operative)
E0748Osteogenesis stimulator, electrical, noninvasive, spinal applications
E0749Osteogenesis stimulator, electrical, surgically implanted

References: Coric D, Bullard DE, Patel VV, et al.(2018) Pulsed electromagnetic field stimulation may improve fusion rates in cervical arthrodesis in high-risk populations. Bone Joint Res. Feb 2018;7(2):124-130. PMID 29437635

Foley KT, Mroz TE, Arnold PM et al.(2008) Randomized, prospective, and controlled clinical trial of pulsed electromagnetic field stimulation for cervical fusion. Spine J 2008; 8(3):436-42.

Gaston MS, Simpson AH.(2007) Inhibition of fracture healing. J Bone Joint Surg Br 2007; 89(12):1553-60.

Goodwin CB, Brighton CT, Guyer RD et al.(1999) A double-blind study of capacitively coupled electrical stimulation as an adjunct to lumbar spinal fusions. Spine 1999; 24(13):1349-57.

Kaiser MG, Eck JC, Groff MW, et al.(2014) Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 17: bone growth stimulators as an adjunct for lumbar fusion. J Neurosurg Spine. Jul 2014;21(1):133-139. PMID 24980594

Kane WJ.(1988) Direct current electrical bone growth stimulation for spinal fusion. Spine 1988; 13(3):363-5.

Kucharzyk DW.(1999) A controlled prospective outcome study of implantable electrical stimulation with spinal instrumentation in a high-risk spinal fusion population. Spine 1999; 24(5):465-9.

Linovitz RJ, Pathria M, Bernhardt M et al.(2002) Combined magnetic fields accelerate and increase spine fusion: a double-blind, randomized, placebo controlled study. Spine 2002; 27(13):1383-9.

Mooney V.(1990) A randomized double-blind prospective study of the efficacy of pulsed electromagnetic fields forinterbody lumbar fusions. Spine 1990; 15(7):708-12.

Park P, Lau D, Brodt ED, et al.(2014) Electrical stimulation to enhance spinal fusion: a systematic review. Evid Based Spine Care J. Oct 2014;5(2):87-94. PMID 25278882

Pountos I, Georgouli T, Blokhuis TJ et al(2008) Pharmacological agents and impairment of fracture healing: what is the evidence? Injury 2008; 39(4):384-94.

Rogozinksi A, Rogozinski C.(1996) Efficacy of implanted bone growth stimulation in instrumented lumbosacral spinal fusion. Spine 1996; 21(21):2479-83.


Group specific policy will supersede this policy when applicable. This policy does not apply to the Wal-Mart Associates Group Health Plan participants or to the Tyson Group Health Plan participants.
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