**Warning:**	The NCBI web site requires JavaScript to function. 	more...

An official website of the United States government

**The .gov means it's official.**							Federal government websites often end in .gov or .mil. Before							sharing sensitive information, make sure you're on a federal							government site.						

**The site is secure.**							The **https://** ensures that you are connecting to the							official website and that any information you provide is encrypted							and transmitted securely.						

Log in

#### Account

                          - Dashboard
                          - Publications
                          - Account settings
                          - Log out

Access keysNCBI HomepageMyNCBI HomepageMain ContentMain Navigation

# Bookshelf

## 

                -  Browse Titles 
                -  Advanced 
                -  Help 
                -  Disclaimer 

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

AHCPR Health Technology Reviews. Rockville (MD): Agency for Health Care Policy and Research (US); 1992-1995. 

                        - This publication is provided for historical reference only and the information may be out of date.

**This publication is provided for historical reference only and the information may be out of date.**

## AHCPR Health Technology Reviews.

Show details

Agency for Health Care Policy and Research (US)

                            - Contents

< PrevNext >

#  8Electrical Bone-Growth Stimulation and Spinal Fusion

S Steven Hotta, MD, PhD.

Published: January 1994.

## Report

Since 1911, fusion of the spine by a variety of techniques has been used to restore                stability in a number of congenital, acquired, and degenerative spinal disorders.                The failure to obtain spinal fusion has persisted over the years as a relatively                common problem. The documented failure of solid fusion 1 year after surgery is                referred to as pseudoarthrosis. Pseudoarthrosis has been attributed to inadequate                surgical technique, failure to neutralize excessive motion or shear stresses at the                segment to be fused, or underlying metabolic abnormalities in the patient. (1). Some have even suggested that the                responsibility for the occurrence of pseudoarthrosis may be entirely within the                hands of the surgeon.(2).

Estimates of the incidents of pseudoarthrosis in lumbar spinal fusion procedures                range from 0 to greater than 30%, depending on the type of procedure. Cameron and                    Bridges(3). reviewed the results                published from 1948 to 1979 and estimated the incidence of pseudoarthrosis according                to the type of procedure (Table 1).

#### Table

Table 1. Posterior spinal fusion: Incidence of pseudoarthrosis according                        to type of procedure. 

Steinmann and Herkowitz(1). noted the                incidence of pseudoarthrosis reported in some of the same studies and other more                recent reports as follows: 4%-68% for anterior interbody fusion, 3%-25.5% for                intertransverse fusion, and 6%-27% for posterior interbody fusion. They pointed out                that, short of surgical exploration, the detection of pseudoarthrosis before the                occurrence of late signs of fusion failure (such as pain or recurrence of spinal                instability) often necessitated the use of more than one of the following                procedures: conventional roentgenograms, tomography, discography, bone scintigraphy,                computed tomography, or magnetic resonance imaging. They considered the following                criteria as being most useful for establishing the presence of pseudoarthrosis: (1)                lack of trabecular bone continuity, (2) collapse of the graft height, (3) shift in                position of the graft, (4) loss of fixation, and (5) unexplained pain in the area of                fusion.

The clinical significance of pseudoarthrosis is, however, questionable. For example,                DePalma and Rothman(2). found that 39 (9%)                of their 448 patients who had lumbar intertransverse spinal fusion had evidence of                pseudoarthrosis. The 39 patients with pseudoarthrosis demonstrated the ability to                return to work and resumed a level of activity similar to that of a group of 39                age-matched patients with solid fusion. Relief from back pain and sciatica was only                slightly and insignificantly better in the patients with solid fusion. Other studies                have also noted that approximately 40%-50% of patients with pseudoarthrosis are                    asymptomatic.(4,5).

Direct electrical current has been demonstrated to have stimulatory effects on bone                formation in in vitro biologic models and animal models. In humans, constant,                direct-current stimulation has been accepted as a standard for treating long-bone                nonunion and as an adjunct in the treatment of congenital pseudoarthrosis of the                tibia. (6).

The results of two studies done in animals suggest that direct-current application                may have stimulatory effects on spinal fusion. Kahanovitz and Arnoczky(7). studied the effect of a direct-current                electrical stimulator on the fusion of the posterior lumbar facets in dogs. They                noted little or no roentgenographic or histologic differences between the control                and stimulated fusion at 2, 4, and 6 weeks, but found that all of the stimulated                facet joints showed solid bony fusion at 12 weeks while none of the eight control                facet joints showed any osseous bridging of the fusion site. Nerubay et al(8). found evidence at 2 months, but not at 1                month, that the constant-current stimulator enhanced the fusion of the lower lumbar                spine in 1-month-old pigs.

The suggestion that a substantial number of pseudoarthroses may be the result of                inadequate surgical technique may be of concern as the data on the possible effects                of direct-current therapy on enhancing spinal fusion are examined. For example,                Steinmann and Herkowitz(1). cited a number                of studies that suggest that identification of the factors that lead to nonunion,                and adjustment for these factors before repair was attempted, resulted in                significantly improved outcomes. For example, Brodsky et al(9). found that 95% of their patients with failed anterior                cervical fusion had successful fusion after a subsequent posterior procedure, in                contrast to a 47% success rate in similar patients who underwent a second anterior                procedure. Edwards and Weigel(10). treated                51 low lumbar nonunions in 28 patients with reexploration, regrafting, and internal                fixation with compression rods that resulted in 84 of the repairs proceeding to                solid fusion.

The earliest demonstration that direct current may stimulate lumbosacral fusion was                described in 1974 by Dwyer and Wickham of Australia.(11). They reported that direct-current stimulation resulted                in successful fusion in 11 (91.7%) of 12 patients. In a later study, published in                1975, Dwyer(12). reported that fusion was                documented radiographically in 40 (85.1%) of 47 patients, 27 of whom were at high                risk for fusion failure because of the need for multiple-level fusion and previous                fusion failures.

After these demonstrations by Dwyer,(11,12). a multicenter clinical                trial was initiated in the United States in 1978 to study the role of implantable                bone-growth stimulators in spinal fusion surgery. Although the data did not formally                appear in the literature, Kane(13).                briefly reviewed the data that were available in 1981 on 84 stimulated patients from                the study and on 159 historical control patients. The 84 patients were from 23                orthopaedic surgeons in 18 clinical centers in 12 States, and 82 of these patients                were available for followup. The 159 historical control patients were from the                University of South Carolina and Northwestern University, Chicago. The two groups                were comparable in age and sex, but the incidence of previous surgery and that of                pseudoarthrosis were 2-4 times higher in the stimulated group (80% and 55% vs. 28%                and 20%, respectively). This difference in patient characteristics might have led to                a bias against finding successful fusion in the stimulated group. Fusion was                successful, however, in 75 (91%) of 82 patients in the stimulated group compared                with 128 (81%) of 159 in the control group (p = .02). In a subgroup of 46 patients                who had pseudoarthrosis and were included in the stimulated group, 42 (91%) achieved                successful fusion. Kane noted that the results of the control group were comparable                to the overall success rate of 74% that was derived from 31 papers on lumbosacral                fusions in 3,383 patients, which were reviewed in a presentation "at the                International Society for the Study of the Lumbar Spine in 1981," but not published,                by Evans of England.

Kane(13). then directed a randomized,                prospective, controlled trial that showed that the rate of radiographically                successful spinal fusion was higher when the direct-current implantable stimulator                was used as an adjunct to the conventional spinal fusion procedure than when the                surgery was performed alone. This multi-investigator trial included only patients                who were classified as "difficult" spinal fusion patients with (1) one or more                previous failed spinal fusions, (2) grade II or worse spondylolisthesis, (3)                extensive bone grafting necessary for multiple-level fusion, or (4) other high-risk                factors for failure of fusion, including gross obesity. Randomization was in blocks                of four patients per investigator, with two patients implanted with the stimulator                and two without. To maintain randomization validity, investigators were required to                enter at least four patients. Measurement of success was based on radiographic                assessments for fusion.

Of 99 patients entered into the trial, 63 were from investigators meeting the                criterion of submitting at least four patients. Of the 63 patients, 59 from seven                investigators were available for followup. Thirty-one patients received stimulation                therapy and 28 control patients had the usual surgical procedures. The randomization                procedure succeeded in the assignment of subjects with comparable characteristics,                such as age and other entry criteria, into the treatment and control groups.                Eighteen months after surgery, successful fusion was achieved in 25 (81%) of 31                treated patients compared with 15 (54%) of 28 in the control group (p = .026). Kane                presented a table on the rate of successful fusions obtained in the control and                treatment groups to illustrate that "higher success rates were seen in the treatment                groups for all entry criteria" (Table 2).

#### Table

Table 2. Random study results by entry criteria. 

The data show that, among patients who had had failed fusion or extensive grafting                (two or more levels of fusion), successful fusion occurred in more patients in the                stimulated group than in the control group; however, for patients meeting the other                two entry criteria, the rate of successful fusion was essentially the same in the                stimulated and control groups.

Kane also reported that 13 (81%) of 16 electrically stimulated patients who were not                included in the former analysis had successful fusion; this rate was comparable with                that in those randomized treated group described above. Similar data on the                remaining 20 of 36 excluded patients were not given.

The Food and Drug Administration's (FDA) summary of data on the safety and                effectiveness of the implantable bone-growth stimulator(14). contained the data on all of the patients in Kane's                randomized trial. The FDA report noted that, of the original 99 patients, 8 were                lost to followup, 4 did not complete the treatment, and 2 did not meet the entry                criteria. Of the 36 patients who were not included in the randomized group, 26 were                available for analysis (10 controls and 16 treated patients). As Kane had noted, 13                of the 16 treated patients had successful fusions. However, 10 (100%) of the 10                untreated control patients also had successful fusions.

Kane(13). also reported briefly on a                nonrandom study that took place at the same time as his randomized study described                above. The number of surgeons contributing data for this study was not stated. Kane                reported that 108 (93%) of 116 patients treated with the implantable stimulator                achieved successful fusion. The poorest result, 26 (87%) of 30, was seen in the                subgroup of patients who had the highest risk of fusion failure according to the                criteria for patients selected for the randomized trial.

Cameron and Bridges(3). reported                qualitative radiologic evidence for an increased rate of bone graft incorporation in                41 scoliosis patients who received electrical bone-growth stimulation. An                intertransverse fusion procedure with the lowest known failure rate of 11.5% was                accomplished with bone grafted on both sides of the spine. The cathode from an                implantable stimulator was applied to one side, with the other side serving as                "control." Radiologic examinations were done at 3 months, 6 months, and 1 year and                then at 6-month intervals until fusion occurred and the battery was removed. Only 1                patient (2.5%) failed to achieve fusion, although the theoretically expected rate of                failure was 16%. Visually significant differences between the two sides were said to                have been evident in 80% of the patients at the 3-and 6-month followup examinations.                The differences became less apparent with time, and "fusion" in 40 of the 41                patients was reported by the hospital radiologist 12 months after surgery.

It appears clear that direct electrical current stimulates bone formation, and it has                been used as a standard of care in the treatment of long-bone fractures that have                failed to fuse. Direct-current stimulation may play a similar role in spinal fusion,                especially in patients who have had fusion failures or are at high risk for fusion                failure. Although many of the spinal fusion failures may be the result of                less-than-optimal surgical technique, the available data appear to indicate that                direct-current stimulation increases the chances for obtaining solid fusion in these                patients. This seemed apparent from results with high-risk patients reported by                    Dwyer(12). and by Kane.(13). However, the highly varied rate of                unsuccessful spinal fusion that had been reported (ranging from 0 to 30% following                initial surgery) makes it difficult to assess the effects, if any, of direct-current                stimulation on initial spinal fusion attempts. For example, the uncontrolled study                by Nerubay and Katznelson(15). that showed                that a solid fusion was obtained in all five children with spondylolisthesis cannot                be readily interpreted as a demonstration of the influence of the implanted                electrical stimulator. Perhaps a study of electrical stimulation in smokers might                yield definitive information regarding the possible benefit of electrostimulation as                an adjunct for spinal fusion in high-risk patients such as smokers, who have been                shown to have a five-fold increased risk for fusion failure compared with nonsmokers                in a retrospective study of patients who had had spinal surgery during 1977 and                    1978.(16).

Although the published data on the effects of direct-current stimulators in lumbar                spinal fusion are old and involve a relatively small number of patients, they                indicate that the use of a direct-current stimulators as an adjunct to spine surgery                may result in a better chance for solid fusion, especially in patients at high risk                for fusion failure. Most studies purporting to demonstrate the beneficial effect of                direct-current stimulation on lumber spinal fusion have indicated that they did not                report the fusion results separately for these patients. The only controlled study                that gave data on patients identified with specific high-risk criteria(13). showed that direct-current stimulation                appeared to influence spinal fusion only in patents with two of the four entry                criteria for high risk.

Direct-current application has been shown to stimulate osteogenesis in spinal fusion                studies with animal models(7,8). and appears to increase the rate of bone                graft incorporation in humans. (3).                Although these studies and reports of better fusion success rates in uncontrolled                    studies(11-13). imply that direct-current electrical stimulation may                increase the success rate of spinal fusion, other studies that were cited by                Steinmann and Herkowitz(1). indicate that                improved surgical technique may obviate the need for using electrical stimulators.                On the other hand, direct-current stimulation may optimize the chances for solid                fusion in patients who are considered to be at high risk for fusion failure.

The available data appear to suggest that an implantable bone-growth stimulator may                be a useful adjunct that could enhance the probability of fusion success in patients                who have had previous fusion failure or need extensive bone grafting for                multiple-level fusion. Although direct-current stimulation might also increase the                likelihood for successful spinal fusion in other high-risk patients such as those                who have severe spondylolisthesis, are obese, or are smokers, there are insufficient                data available at the present time to include these latter patients among those who                may benefit from electrical stimulation.

## References

                        - 1.
                        - Steinmann JC, Herkowitz HN. Pseudoarthrosis Pseudarthrosis of the spine.  Clin Othrop.  1992; ;284:80–90. [PubMed: 1395317]
                        - 2.
                        - DePalma AF, Rothman RH. The nature of pseudoarthrosis pseudarthrosis.  Clin Orthop.  1968; ;59:113–118. [PubMed: 5665452]
                        - 3.
                        - Cameron HU, Bridges A. Pseudoarthrosis in lumbar spine fusion.  Prog Clin Biol Res.  1985;187:479–484. [PubMed: 3903765]
                        - 4.
                        - Watkins MB, Bragg C. Lumbosacral fusion: Results with early ambulation.  Surg Gynecol Obstet.  1956;102:604–606. [PubMed: 13311749]
                        - 5.
                        - Hannon KM. Wetta WJ. Failure of technetium bone scanning to detect pseudoarthroses in                        spinal fusion scoliosis.  Clin Orthop.  1977;123:42–44. [PubMed: 856519]
                        - 6.
                        - Connolly JF.  Selection evaluation and indications for electrical stimulation                        of ununited fractures.  Clin Orthop.  1981;101:39–53. [PubMed: 6975690]
                        - 7.
                        - Kahanovitz N, Arnoczky SP. The efficacy of direct current electrical stimulation to enhance                        canine spinal fusions.  Clin Orthop.  1990;251:295–299. [PubMed: 2295188]
                        - 8.
                        - Nerubay J, Mrganit Marganit B, Bubis JJ, et al. Stimulation of bone formation by electrical current on spinal                        fusion.  Spine.  1986; ;11:167–169. [PubMed: 3486485]
                        - 9.
                        - Brodsky AE, Khalil MA, Neuman BP. Comparison of posterior vs anterior repair of pseudoarthrosis of                        anterior interbody fusions of the cervical spine.  Orthop Trans.  1988;12:–.
                        - 10.
                        - Edwards CC, Weigel MC. A prospective study of 51 low lumbar nonunions.  Orthop Trans.  1988;12:–.
                        - 11.
                        - Dwyer AF, Wickham GG. Direct current stimulation in spinal fusion.  Med J Aust.  1974;1:73–74. [PubMed: 4544556]
                        - 12.
                        - Dwyer AF. The use of electrical current stimulation in spinal                        fusion.  Orthop Clin North Am.  1975;6:265–273. [PubMed: 1113970]
                        - 13.
                        - Kane WJ. Direct current electrical bone growth stimulation for spinal                        fusion.  Spine.  1988; ;13:363–365. [PubMed: 3291140]
                        - 14.
                        - Food and Drug Administration. Summary of safety and effectiveness data: Implantable electrical                        bone growth stimulator (unpublished report).  1987. 
                        - 15.
                        - Nerubay, J Katznelson A. Clinical evaluation of an electrical current stimulator in spinal                        fusions.  Int Orthop.  1984;7:239–242. [PubMed: 6611315]
                        - 16.
                        - Brown CW, Orme TJ, Richardson HD.  The rate of pseudoarthrosis pseudarthrosis (surgical nonunion)                        in patients who are smokers and patients who are nonsmokers: A comparison                        study.  Spine.  1986;11:942–943. [PubMed: 3824072]

                        - 
AHCPR Pub. No. 94-0014

Copyright Notice

Bookshelf ID: NBK63972

Contents
< PrevNext >

Share

### Views

                    - PubReader
                    - Print View
                    - Cite this Page Hotta SS. Electrical Bone-Growth Stimulation and Spinal Fusion. 1994 Jan. In: AHCPR Health Technology Reviews. Rockville (MD): Agency for Health Care Policy and Research (US); 1992-1995.  8.

### In this Page

                    - Report
                    - References

### Other titles in this collection

                    - Health Services/Technology Assessment Text (HSTAT)

### Recent Activity

ClearTurn OffTurn On
                      - Electrical Bone-Growth Stimulation and Spinal Fusion - AHCPR Health Technology R... Electrical Bone-Growth Stimulation and Spinal Fusion - AHCPR Health Technology Reviews 
                      - External and Implantable Infusion Pumps - AHCPR Health Technology Reviews External and Implantable Infusion Pumps - AHCPR Health Technology Reviews 
                      - Cochlear Implantation in Outpatient Settings - AHCPR Health Technology Reviews Cochlear Implantation in Outpatient Settings - AHCPR Health Technology Reviews 
                      - Pressure Ulcers in Adults: Prediction and Prevention Pressure Ulcers in Adults: Prediction and Prevention 
                      - Treatment of Pressure Ulcers Treatment of Pressure Ulcers 

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on
See more...

TwitterFacebookLinkedInGitHubNCBI Insights Blog

Connect with NLM
                      - Twitter
                      - Facebook
                      - Youtube

National Library of Medicine8600 Rockville Pike							Bethesda, MD 20894

Web PoliciesFOIAHHS Vulnerability Disclosure

HelpAccessibilityCareers

-  NLM 
-  NIH 
-  HHS 
-  USA.gov