PEMF: Clinical Evidences Of Benefits In Bone Healing

Author:

Bruce Gelerter

Abstract:

Bone growth stimulators

Much literature regarding bone growth stimulators involves the use of PEMF. The early investigator, Bassett et al. first published the acceleration of fracture repair using electromagnetic fields, and the first clinical trial using this surgically noninvasive method was conducted in 1977. In 1982, the confirmed final results of 1007 ununited fractures and 71 failed arthrodesis treated with PEMF by over 500 surgeons worldwide were published. Seventy-five percent of 332 patients were effectively treated with PEMF, averaging 4.7 years disability, previous operative failures, and with a 35% infection rate.

A meta-analysis of four randomized, controlled trials for electromagnetic field stimulation for treatment of long-bone delayed unions and nonunions concluded that the effect of bone stimulation was small, not statistically significant, and provided insufficient evidence to make a definitive practice recommendation. The heterogeneity of study designs and lack of functional outcome measures limited conclusions.

Sharrard published the results of 45 tibial shaft nonunions after initial conservative management in a multicenter, double-blinded trial. After 12 weeks of PEMF or placebo stimulation, the authors found a statistically significant number of healed fractures by PEMF compared with controls after radiographic evaluation. The mean age of the treatment group was significantly lower than the control group (34.7–45.4 years), a possible cofounder in the results.

A randomized, double-blinded, controlled trial by Borsalino et al. was completed by 31 patients undergoing femoral intertrochanteric osteotomy for degenerative hip arthritis. At 90 days, increases in bone callus, callus density, and trabecular bridging were all statistically significant in the stimulated group.

Barker reported the results of 17 adults with tibial shaft nonunions treated with either PEMF or a control stimulator, reporting no significant differences between groups at 24 weeks. This study excluded a significant group of patients with sepsis, internal or external fixation, fracture gap greater than 0.5 cm, or operative procedure within 6 months.

Heckman et al. published a report on 149 patients treated with PEMF, noting a 64.4% success rate and the importance of anatomic location and patient compliance. Gossling et al. published a comparison of surgery and PEMF for tibial fracture nonunion in 1992. After reviewing 44 articles, the authors concluded that PEMF treatment of nonunited tibial fractures is more successful than noninvasive management, and at least equally effective as surgery.

Results

Copious Level IV evidence exists for the use of PEMF in delayed and nonunited fractures. Meskens et al. reported 67.7% successful unions in a case series with the use of PEMF in patients with nonunions, but reported unfavorable results in patients with atrophic nonunions or fractures of the humerus. In 57 tibial pseudarthroses treated with intramedullary nailing, PEMF increased the union rate from 83 to 91%, and decreased the time to union from 4.9 to 3.3 months. The authors concluded that neither value was statistically significant. The results were clinically significant by a relative risk of 0.53, which confers a 47% reduction in the appearance of events. In a case series of proximal fifth metatarsal fractures treated with nonweightbearing cast immobilization and PEMF, all fractures healed within 3 months. A follow-up study for scaphoid nonunions treated with PEMF showed a decreased successful union rate from the initially reported 80 to 69%, with only 50% of proximal pole fractures uniting, and decreased success in nonunions associated with avascular necrosis. The authors concluded that PEMF should be a secondary alternative to traditional bone grafting.

Colson et al. published a prospective cohort of 33 longbone nonunions treated with either PEMF alone or combined with surgery, resulting in 83% and 100% unions, respectively. The authors noted the regimen of PEMF was simpler than prior studies but equally efficacious. PEMF used greater than 3 hours per day was 80% successful in 139 nonunions, compared with 35.7% successful unions in patients who used PEMF less than 3 hours per day. Most recently, Assiotis et al. reported a 77.3% fracture union rate in a prospective cohort of 44 tibial delayed unions or nonunions without infection.

Electric stimulation has been used successfully to treat a wide range of bone disorders. However, the mechanism by which the electric fields can influence the bone cells behavior remains poorly understood. The purpose of this research was to assess the possible mechanism of the stimulatory effect of pulsed electromagnetic field (PEMF) on bone cells. A PEMF with a frequency of 15 Hz (1 G [0.1 mT]; electric field strength 2 mV/cm) were applied to neonatal mouse calvarial bone cell cultures for 14 days. The temporal effects of PEMF on the osteoblasts were evaluated by the status of proliferation, differentiation, mineralization, and gene expression on the 3rd, 5th, 7th, and 14th days of culture. The results demonstrated that PEMF stimulation significantly increased the osteoblasts’ proliferation by 34.0, 11.5, and 13.3% over the control group after 3, 5, and 7 days’ culture. Although the alkaline phosphatase (ALP) staining and the mineralization nodules formation did not change, the ALP activity of the bone cells decreased significantly after PEMF stimulation. Under the PEMF stimulation, there was no effect on the extracellular matrix synthesis, while the osteoprotegerin (OPG) mRNA expression was up regulated and the receptor activator of NF-κB ligand (RANKL) mRNA expression were down regulated, compared to the control.

Conclusion

In conclusion, the treatment by PEMF of osteoblasts may accelerate cellular proliferation, but did not affect the cellular differentiation. The effect of PEMF stimulation on the bone tissue formation was most likely associated with the increase in the number of cells, but not with the enhancement of the osteoblasts’ differentiation.

Gossling et al. also compared surgery and PEMF in the treatment of nonunited tibial fractures. They reviewed 42 articles, 14 using surgical treatment and 28 using PEMF. The overall treatment success rate from surgery was 82% in 258 tibias, while the overall treatment success rate for PEMF was 81% in 143 tibias. The success rate for nonunion surgery, therefore, drops dramatically with the successive number of operations, while it does not seem to affect the results of PEMF treatment.

References

1. Behrens, S. B., Deren, M. E., &Monchik, K. O. (2013). A review of bone growth stimulation for fracture treatment. Current Orthopaedic Practice, 24(1), 84-91.

2. Chang, W. H. S., Chen, L. T., Sun, J. S., & Lin, F. H. (2004). Effect of pulse‐burst electromagnetic field stimulation on osteoblast cell activities. Bioelectromagnetics, 25(6), 457-465.