5 minute read
What Is the Evidence for Bone Growth Stimulators?
The estimated cost spent on bone growth stimulators in 2022 was $1.4 billion.1 The current projections are that expenditures on bone growth stimulators will continue to grow. The use of bone growth stimulators in spine fusion surgeries is a key contributor to the increase in expenditure on bone growth stimulators (Figure 1). However, the health care system is facing numerous challenges, one of which is the rising cost of health care. As the practice of medicine becomes more expensive, physicians will be asked to find ways to cut costs. So, what is the evidence for the use of bone growth stimulators?
The earliest studies on bone growth stimulators sought to determine their ability to aid in fracture healing. In 1966, Friedenberg and Brighton published an article in The Journal of Bone and Joint Surgery evaluating the effects of sustained direct currents on skin, the periosteum, growing bone, and fractured bone.2 Friedenberg et al subsequently published another article describing the use of direct currents on fracture healing in rabbits.3 The authors concluded that fracture healing was stimulated by the use of direct currents. In 1974, Dwyer and Wickham published an article describing the use of direct current to assist lumbar spinal fusion.4 The authors used direct current stimulation in 12 patients undergoing lumbar spinal fusion. They achieved successful fusion in 11 of those patients, noting a mature solid fusion. In 1988, Kane published an article evaluating the use of direct current bone stimulation in patients undergoing lumbar spinal fusions.5 Kane noted 82 patients in the direct current stimulation group had a successful fusion of 91.5% while a control group had an 80.5% fusion. Kane also had a cohort of patients who were considered challenging patients. Fusion conditions were considered difficult in patients who had one or more previous failed fusions, a grade II or worse spondylolisthesis, multilevel fusion, or the presence of another high-risk factor such as obesity. Successful fusion was achieved in 15 of 28 control patients (54%) compared with 25 of 31 (81%) of patients who were treated with direct current stimulation (p = 0.026).
The concept of bone stimulation with electric currents has evolved to pulsed electromagnetic field stimulation and capacitive coupled electrical stimulation because of the advantages of decreased operating time, instrumentation removal, and infection risk. Tong et al studied the cellular effects of pulsed electromagnetic fields on the proliferation and differentiation of osteoblasts.6 Pulsed electromagnetic field stimulation increased the proliferation and differentiation of osteoblasts and related gene expressions, such as insulin-like growth factor 1, alkaline phosphatase, runt-related transcription factor 2, and osteocalcin.
Clinical studies have also been performed evaluating the fusion rates with pulsed electromagnetic fields. Weinstein et al performed a prospective multicenter study investigating pulsed electromagnetic fields as an adjunct therapy to lumbar spinal fusion procedures in 142 patients at risk for pseudarthrosis.7 Patients with a prior failed fusion, multilevel fusion, nicotine use, osteoporosis, or diabetes were considered high risk patients. Fusion status was assessed at 12 months with 88.0% of patients (n = 125/142) demonstrating successful fusion. Fusion success for patients with 1, 2+, or 3+ risk factors were 88.5%, 87.5%, and 82.3%, respectively. In another study, Foley et al performed a prospective multicenter randomized study on 323 patients undergoing anterior cervical discectomy and fusion who were either smokers or undergoing multilevel cervical fusion. 8 The authors found that at 6 months postoperatively, the pulsed electromagnetic field group had a significantly higher fusion rate than the control group (83.6% vs. 68.6%, p = 0.0065). At 12 months after surgery, the stimulated group had a fusion rate of 92.8% compared with 86.7% for the control group (p = 0.1129). So, while there do seem to be beneficial effects with using a bone growth stimulator at 6 months, there was no significant difference at 1 year.
Hence, there is still some controversy regarding the use of bone growth stimulators. There is evidence for the use of bone growth stimulators, especially in high-risk patients such as patients with diabetes, smokers, and patients undergoing multilevel fusion. However, more studies are needed to have a better understanding of the benefit bone growth stimulators truly provide.
References
1. Bone growth stimulator market to reach $1.4 billion by 2022: growing inclination of patients toward non-invasive and minimally invasive surgical treatments - research and markets [press release]. Markets Insider. May 16, 2017.
2. Friedenberg ZB. Bioelectric potentials in bone. J Bone Jt Surg. 1966;48A:915.
3. Friedenberg ZB, Roberts PG, Didizian NH, Brighton CT. Stimulation of fracture healing by direct current in the rabbit fibula. J Bone Jt Surg. 1971;53A:1400.
4. Dwyer AF, Wickham GG. Direct current stimulation in spinal fusion. Med J Aust. 1974;1:73–75.
5. Kane WJ. Direct current electrical bone growth stimulation for spinal fusion. Spine (Phila Pa 1976). 1988;13(3):363-365.
6. Tong J, Sun L, Zhu B, et al. Pulsed electromagnetic fields promote the proliferation and differentiation of osteoblasts by reinforcing intracellular calcium transients. Bioelectromagnetics . 2017;38(7):541-549.
7. Weinstein MA, Beaumont A, Campbell P, et al. Pulsed electromagnetic field stimulation in lumbar spine fusion for patients with risk factors for pseudarthrosis. Int J Spine Surg. 2023;17(6):816-823.
8. Foley KT, Mroz TE, Arnold PM, et al. Randomized, prospective, and controlled clinical trial of pulsed electromagnetic field stimulation for cervical fusion. Spine J. 2008;8(3):436-442.
Contributors:
Adin Ehrlich, BA1
Andrea Pezzi, MD1
Kasra Araghi, BS1
Tomoyuki Asada, MD1,2
Sheeraz A. Qureshi, MD, MBA1,2
From the 1Hospital for Special Surgery and 2Weill Cornell Medical College, both in New York, New York.
