Electrical Stimulation for Non-Healing Bone Fractures
Bone fractures are painful and slow to heal, often taking weeks to months before regular activities can be reintroduced. Unfortunately, complications during bone healing are common. These complications can include delayed healing and non-union, where the bone fracture does not fuse back together. In one study of long-bone fractures in the arm or leg, 8.1% of patients had a complication that occurred (Ekegren 2018). The majority of the complications were non-unions.
Effectively preventing and treating non-unions could significantly improve outcomes of bone fracture. And while electrical therapies have been showing promising results since the 1970s, they are not regularly incorporated into most treatment regimens. There are a number of different types of electrical stimulation that have been utilized for improving fracture healing outcomes. As such, it’s worth exploring each type to see their benefits and limitations.
Direct Current Stimulation and Fracture Healing
Much of the initial work on healing non-union bone fractures revolved around enhancing the current of injury. When bones are broken, the bone break becomes electronegative, creating an electrical current from the surrounding tissues during healing. This current is referred to as the current of injury. Direct current stimulation attempts to mimic this natural response by placing a negative electrode at the site of the fracture with a positive electrode further from the sight of injury (Borgens 1984).
While there are challenges to implementing direct current treatment, a clinical study found improved results with over 80% of non-union bone fractures achieving success (Brighton 1981). Infection, pain, the need for surgical placement and removal of electrodes, and dislodgement of the electrodes were common problems and concerns. To get around these issues, other forms of electrical and electromagnetic stimulation have also been explored, including pulsed electromagnetic fields and capacitive coupling.
Pulsed Electromagnetic Fields and Fracture Healing
Early work with pulsed electromagnetic fields that are applied over a non-union also found success. Pulsed electromagnetic fields are produced by a type of small electromagnet that is turned on and off repeatedly, usually with each pulse lasting fractions of a second. One study of 13 patients with non-unions succeeded in initiating bone healing in 11 patients (Syed 1999). The two failed patients had gaps between bones at the fracture site of one centimeter or more which was likely too large for the technique to successfully heal.
A study in postmenopausal women with long bone non-unions also found benefits with PEMF (Shi 2013). PEMF succeeded in treating 77% of patients as compared to success in just 48% of control patients.
Capacitive Coupling and Fracture Healing
Capacitive coupling is another type of electrical stimulation that avoids the implantation of electrodes. It works by placing a conductive surface near the skin, but not in contact with it. This conductor is then coupled to a source of rapidly changing electrical signals. These rapidly changing signals can conduct an alternating current into the skin in a process referred to as capacitive coupling.
A study on capacitive coupling and non-union found a 60% healing rate in those that received capacitive coupling treatment as compared to none in the placebo group (Scott 1994). A study comparing bone grafts, direct current stimulation and capacitive coupling for non-union fractures found all techniques to be equivalent in efficacy when risk factors for treatment failure were minimal (Brighton 1995).
Overall
Research evaluating electrical stimulation for non-unions suggests that the techniques significantly improve bone healing rates. A meta-analysis from 2016 found reduced pain with increased union rates of 35% with electrical stimulation treatment (Aleem 2016).
While electrical therapies are still not frequently utilized for patients with non-unions, the data suggests that they should likely be considered as a potential option. Hopefully, with time, electrical therapies can be an additional therapy that is readily available to help heal bone fractures and fracture complications.
