Electrical Stimulation of Acute Fractures: A Narrative Review of Stimulation Protocols and Device Specifications

Abstract

Orthopedic fractures have a significant impact on patients in the form of economic loss and functional impairment. Beyond the standard methods of reduction and fixation, one adjunct that has been explored since the late 1970s is electrical stimulation. Despite robust evidence for efficacy in the preclinical arena, human trials have mixed results, and this technology is not widely accepted. The purpose of this review is to examine the body of literature supporting electrical stimulation for the purpose of fracture healing in humans with an emphasis on device specifications and stimulation protocols and delineate a minimum reporting checklist for future studies of this type. We have isolated 12 studies that pertain to the administration of electrical stimulation for the purpose of augmenting fracture healing in humans. Of these, one was a direct current electrical stimulation study. Six studies utilized pulsed electromagnetic field therapy and five used capacitive coupling. When examining these studies, the device specifications were heterogenous and often incomplete in what they reported, which rendered studies unrepeatable. The stimulation protocols also varied greatly study to study. To demonstrate efficacy of electrical stimulation for fractures, the authors recommend isolating a fracture type that is prone to nonunion to maximize the electrical stimulation effect, a homogenous study population so as to not dilute the effect of electrical stimulation, and increasing scientific rigor in the form of pre-registration, blinding, and sham controls. Finally, we introduce the critical components of minimum device specification reporting for repeatability of studies of this type.

Keywords: capacitive coupling; direct current; electrical stimulation; fracture; human; pulsed electromagnetic field.

FIGURE 1

Depicted is a schematic for DCES in the treatment of a midshaft tibial fracture. The device is comprised of a power source (which is typically placed subcutaneously) and the cathode (blue lead) and anode (red lead). The cathode is placed at the fracture site, and the anode is placed in nearby soft tissue.

FIGURE 2

Depicted is a schematic for PEMF in the treatment of a midshaft tibial fracture. The device is completely external and comprised of a power source and two solenoids oriented parallel to the skin surface. Current is pulsed through the solenoids and a magnetic field is produced (dotted lines), which induces a perpendicular electrical field (not depicted).

FIGURE 3

Depicted is a schematic for CC in the treatment of a midshaft tibial fracture. The device is completely external and comprised of a power source and two skin surface electrodes. The alternating current generates an electrical field between the electrodes (dotted lines) with significant falloff into tissue (dissipation of dotted lines).

FIGURE 4

This diagram represents the qualities of the ideal electronic bone growth stimulator. The characteristics of the different modalities of ES are listed under each type. The weaknesses of each type of ES are listed on the periphery of the figure. The strengths of each type of modality that should comprise the ideal EGBS are listed centrally. Purple text denotes qualities of PEMF. Red text denotes qualities of DCES. Blue text denotes qualities of CC. This figure is meant to emphasize the need for innovation in the field of bone growth stimulation, as the ideal EGBS does not yet exist.