Electrical bone stimulators: New evidence supports treatment for bone healing

Written by Anuja Vaidya | August 30, 2016 | Print  |

Electrical bone stimulators are an evidence-based option to promote bone healing.   

"We live in an era where evidence-based practice is the dominant paradigm," says Mohit Bhandari, MD, MSc, PhD, FRSC, professor in the department of surgery and academic division head of orthopedic surgery at McMaster University in Hamilton, Canada. "In the 1990s evidence-based medicine (EBM) was defined as the conscientious use of clinical best evidence in the care of a patient. EBM is here to stay and we are using it to help healthcare practitioners drive better decision-making in healthcare."


There are many treatment options for patients and identifying the right treatment for the right patient at the right time demand good evidence. Studies and evidence allow surgeons and patients to make more informed decisions and achieve better outcomes.

"Better decision-making separates a good surgeon from a great surgeon and evidence driven clinical judgment is absolutely essential to ensure the highest standards of patient safety and care," he says.


Orthopedic providers looking for minimally invasive treatment options for fracture patients have considered numerous bone healing agents, including biologics. Many options are often too early in their development or have deficient evidence for clinical practice. However, bone stimulators have mounting evidence and can be applied externally as non-invasive devices. They have been used in the treatment of nonunions for decades.


"The mere fact that it has been around for decades suggests promise for bone stimulation," Dr. Bhandari says. "Other treatments, such as biologics, have come and gone, but a growing number of healthcare providers have been using bone stimulators because they have seen results consistent with evidence."


Evidence for bone stimulation
According to Dr. Bhandari, a bone stimulator is an externally applied, non-invasive device intended to "stimulate healing of damaged tissue." Primary treatments include extracorporeal shock waves, electrical stimulation and low-intensity pulsed ultrasound.

"We still think of extracorporeal shock waves therapy as being fairly preliminary, and although there are randomized trials that suggest there is benefit, there are not enough of them," said Dr. Bhandari. Dr. Bhandari said electrical bone stimulation, however, has a larger body of supporting evidence.


Electrical bone stimulation includes the following areas:


•    Capacitive Coupling, which involves the use of metal electrodes that are applied to the skin to deliver the current
•    Pulsed Electromagnetic Field devices, which use an externally applied coil to deliver the current that can be pulsed on and off
•    Combined Magnetic Field devices, which use an external coil system with a combination of direct and alternating current to produce both static and alternating magnetic fields


Each type of bone stimulation is backed by different levels of evidence in the literature. A 2009 study1 that examined 13 randomized trials evaluating low intensity pulsed ultrasound, published in The BMJ, found that the evidence for the effect of low-intensity pulsed ultrasonography on bone fracture healing "is moderate to very low in quality and provides conflicting results."


Dr. Bhandari and his colleagues conducted the largest randomized trial of low intensity pulsed ultrasound (called TRUST) that enrolled 501 patients, some of which were smokers.2 The study aimed to evaluate the use of low-intensity ultrasound in the treatment of tibial fractures. Enrolled patients had an average age of 38 years with a mix of closed and open fractures. The study found that there was no difference in patient function or time to radiographic healing at final follow up (SF36). However, compliance challenges did exist with the ultrasound devices that may have contributed to this lack of difference, although the investigators did not believe this was a major contributor.


Meta-analysis shows positive results
In 2015, Dr. Bhandari and his colleagues conducted a study3 of randomized sham-controlled trials testing the efficacy of electrical stimulators for bone healing in patients with fracture nonunions and spinal fusions. The meta-analysis examined patient-important outcomes, such as pain and function as well as bone healing. The researchers compared active treatment with an electrical stimulator to a control.


"When we look at the hierarchy of evidence, we find that randomized clinical trials top that hierarchy," says Dr. Bhandari. "So we focused only on randomized clinical trials, which we found to be the most valid and least biased of the approaches in healthcare research that we could use."


Dr. Bhandari and his colleagues included 15 randomized clinical trials and 1,247 patients. The researchers found electrical stimulation was associated with a 35 percent risk reduction in the development of nonunions.


"For every seven patients treated with an electrical stimulator, one non-union, or persistent non-union, can be prevented," says Dr. Bhandari. "That is an NNT (number needed to treat) of seven which is extremely, extremely small. This means that the benefit associated with an electrical stimulator is pretty high."


The researchers were also able to identify a significant pain reduction, which was "most novel in the area of bone stimulation," says Dr. Bhandari.


Pain management is a measure that is particularly important because pain is a measure of healing, overall function and patient satisfaction. The study also showed radiographic benefit with electrical stimulation, which suggests a biological effect, and correlated that clinically with a patient-reported benefit — pain.   


"Even if you look outside of fracture care, if you look at knee osteoarthritis, for example, overall patient satisfaction is correlated with pain," says Dr. Bhandari. "Pain is limiting."


Further research needed
Further evidence is required to differentiate between the specific types of bone stimulation. There isn't enough evidence to point to one type over another, as each one is different with respect to application and potential benefits. There have been some small network meta-analyses that have focused on an indirect comparison between the types of bone stimulation, says Dr. Bhandari.


For example, one small meta-analysis4 compared electrical bone stimulation to a placebo and then compared low-intensity pulsed ultrasound to a placebo to treat fractures. Through indirect mathematical assessment, the researchers determined electrical bone stimulation compared more favorably to low-intensity pulsed ultrasound in the management of nonunions. "But this data was based on a small study set and is hypothesis-generating," says Dr. Bhandari. "It is not definitive."


Going forward, orthopedic industry stakeholders will need to spend more time trying to understand what types of bone stimulators cause differentiating factors. Clinicians and researchers also need to understand how bone stimulators fit in the context of other bone healing technologies to provide the best care in a cost-effective manner.


"When we talk of the use of high-quality evidence, we look at randomized clinical trials. When we don't have single large clinical trials, we look to meta-analysis," he adds. "Until a large clinical trial is conducted, looking at more than 1,000 patients, these types of meta-analyses that combine smaller randomized trials are important. These types of studies can impact clinical care guidelines as well as policy."




1Jason W. Busse, Jagdeep Kaur, Brent Mollon, Mohit Bhandari, Paul Tornetta, Holger J Schünemann, Gordon H Guyatt (2009). Low intensity pulsed ultrasonography for fractures: systematic review of randomised controlled trials, BMJ 2009;338:b351
2Jason W. Busse, Mohit Bhandari, Thomas A. Einhorn, James D. heckman, Kwok-Sui-Leung, Emil Schemitsch, Paul Tornetta III, Stephen D. Walter, Gordon H. Guyatt (2014). Trial to re-evaluate ultrasound in the treatment of tibial fractures (TRUST): a multicenter randomized pilot study, Busse et al. Trials 2014, 15:206
3Ilyas Aleem, MD, Idris Aleem, MSc, Nathan Evaniew, MD, Michael J. Yaszemski, MD, PhD, Thomas A. Einhorn, MD, Mohit Bhandari, MD, FRCSC, PhD. Efficacy of Electrical Stimulators for Bone Healing: A Meta-Analysis of Sham-Controlled Randomized Trials, Presented at AAOS, 2016
4Shanil Ebrahim, MSc, PhD,Brent Mollon, MD,Sheena Bance, MSc, MA, Jason W. Busse, DC, PhD, and Mohit Bhandari, MD, PhD*,** Low-intensity pulsed ultrasonography versus electrical stimulation for fracture healing: a systematic review and network meta-analysis, Can J Surg. 2014 Jun; 57(3): E105–E118


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