NONUNION FRACTURE and BONE HEALING

When bone is injured, it normally initiates a process of self-regeneration to form new bone, yet in up to 10% of fractures this process is disrupted or delayed. This nonunion, maybe due to age or poor circulation has been effectively addressed by electrical stimulation (ES) and low intensity pulsed ultrasound (US). Both electrical stimulation and ultrasound have shown to be effective aids to bone healing in a variety of orthopedic conditions such as delayed or nonunion fractures and fresh fractures.

Electrical stimulation

This typically involves either (DC) direct current or capacitive coupling (CC). DC typically involves surgical placement of both stimulator and electrodes which is uncomfortable and runs the risk of infection. The cathode is implanted at the bone defect while the anode in implanted in adjacent soft tissue. 

Capacitive coupling 

This is noninvasive and uses 2 or more surface electrodes to create an electric field. Capacitive coupling has been used to enhance bone healing in nonunion fracture, delayed unions, and spinal fusion.
Controlled studies by Impagliazzo A, Mattei A, Spurio Pompili GF, et al. (2006) and others, showed CC to be highly effective for treating long bone nonunion and in healing nonunion fracture.  Also, athletes with lower limb stress fractures were successfully treated with CC (See Amy Yoder Begley).

”Electrical stimulation has demonstrated consistently high success rates in recalcitrant, complicated nonunions.”
Albert S.F. and Wong E. stated in Clin. Podiatr. Med. Surg. 8, 923-935.

Ultrasound

Double-blind randomized controlled trials revealed that for fresh fractures, pulsed ultrasound accelerated the rate of fracture healing from 24% to 42%. Mayr et al (2000) reported the overall success rate for low intensity pulsed ultrasound in delayed union was 91% and for nonunion fracture 86%. A systematic review and meta-analysis Busse et al (2002) has shown that in fracture the ultrasound treated groups had accelerated healing versus the control groups with the mean difference in healing time being 64 days.  

Both US and ES

Ultrasound has a stimulatory effect on bone at low dose (0.1 W/cm2) and an inhibitory effect at a higher dose (1 to 2 W/cm2). Electrically, osteogenesis has been stimulated with currents between (5 to 100 µA) and by electric fields that ranged from (1 to 100 mV/cm2). This response to very low energy impulses shows that bone is very sensitive to both acoustic signals and electrical stimulation. 

Summary 

Ultrasound and electrical stimulation seem to work through complimentary mechanisms to enhance circulation, increase intracellular calcium and upregulate the synthesis of various bone growth factors.

This suggests that the synergistic combination of both modalities could accelerate healing and be very efficient for stimulating bone growth and regeneration even in delayed or nonunion fracture.