J Med Eng Technol. 1981 Mar;5(2):73-9
Electrical phenomena associated with bones and fractures and the therapeutic use of electricity in fracture healing.
Living bones have small electrical potentials on their surfaces, the magnitudes of which change only slightly with the reaching of adulthood. When using a limb stresses are put on the bones inside, and these create piezo-electric potentials which may themselves cause bone growth along the lines of stress, hence making the bone stronger. Voltages also appear at fracture sites and may be important in causing the bone to heal its wound. Fractures that have not healed properly can be stimulated into repair by the passage of small electric currents through them. The factors involved in these processes are discussed.
Clin Podiatr Med Surg. 1991 Oct;8(4):923-35
Electrical stimulation of bone repair
Albert SF, Wong E.
Department of Podiatry, Department of Veterans Affairs Medical Center, Denver, Colorado.
Interest in methods of accelerating bone healing persists. Electrical stimulation has demonstrated consistently high success rates in recalcitrant, complicated nonunions. The promise of successful noninvasive alternatives for treating nonunions continues to be realized. Given the rapidity of advances in this field, it appears likely that acceleration of fracture repair by electrical stimulation will become more widespread in the future.
J Am Acad Dermatol. 1991 Jul;25(1 Pt 1):40-6
The effect of electrical stimulation on the number of mast cells in healing wounds
Reich JD, Cazzaniga AL, Mertz PM, Kerdel FA, Eaglstein WH.
Department of Dermatology and Cutaneous Surgery, University of Miami School of Medicine, FL 33101
Many cutaneous disorders are associated with activation or increased numbers of mast cells. Electrical stimulation has been shown to be effective in treating many of these disorders. This study is designed to examine the effect of electrical stimulation on mast cells in acute wounds. Four pathogen-free pigs received 20 wounds, each of which was subjected to biopsy at various times after wounding. Half of the wounds were treated with electrical stimulation and the other half were treated with a sham electrode. The biopsy specimens were fixed in Carnoy's medium and stained with alcian blue and Nuclear Fast Red. Mast cells from both sets of wounds were counted and analyzed. Highly significant reductions in the number of mast cells were seen with electrical stimulation on days 1 and 2 compared with nonstimulated control wounds. Electron microscopy was performed to compare the stimulated and control mast cells for characteristic features in morphology, location, and evidence of degranulation. Electrical stimulation did not appear to induce degranulation. The ability of electrical stimulation to decrease the number of mast cells may be related to a reduction of either proliferation or migration of these cells and may prove to be a valuable therapeutic technique.
Clin Podiatr Med Surg. 2001 Jan;18(1):79-95, vi
Electrical stimulation with bone and wound healing
Evans RD, Foltz D, Foltz K.
Department of Podiatric Medicine, College of Podiatric Medicine and Surgery, Des Moines University-Osteopathic Medical Center, Des Moines, Iowa,
Electrical stimulation has been used to heal fractures and ulcers and reduce pain through modulation of local body processes. It has been recognized that mechanical forces and bioelectricity have an intimate relationship in influencing the production of bone. Science has developed techniques to affect change in the electrical charge of fractures to positively affect the healing process. Electrical stimulation, through invasive and noninvasive applications, has produced excellent results in the treatment of nonunions and ulcer care. A thorough review of the electrical properties of bone and soft tissue and the influence of electrical stimulation on healing is presented here.
Adv Wound Care. 1996 Sep-Oct;9(5):42-5
Promotion of wound healing with electrical stimulation
Kloth LC, McCulloch JM.
Program of Physical Therapy, Marquette University, Milwaukee, Wis, USA.
Clinicians involved in the conservative care of chronic wounds have many treatment interventions from which to choose, including debridement/irrigation, dressings, pressure-relieving devices, hyperbaric or topically applied oxygen, whirlpool/pulsed lavage, ultrasound, topical antibiotics, and cytokine growth factors. All except the last two interventions are physical treatments that create a wound-tissue environment conducive to healing. Unfortunately, many chronic wounds heal very slowly, do not heal, or worsen despite the best efforts of caregivers to promote tissue repair. An intervention commonly used to treat chronic wounds, especially by physical therapists, is electrical stimulation (ES). The rationale for use of this method is based on the fact that the human body has an endogenous bioelectric system that enhances healing of bone fractures and soft-tissue wounds. When the body's endogenous bioelectric system fails and cannot contribute to wound repair processes, therapeutic levels of electrical current may be delivered into the wound tissue from an external source. The external current may serve to mimic the failed natural bioelectric currents so that wound healing can proceed. Certain chemotaxic factors found in wound substrates contribute to tissue repair processes by attracting cells into the wound environment. Neutrophil, macrophage, fibroblast, and epidermal cells involved in wound repair carry either a positive or negative charge. When these cells are needed to contribute to autolysis, granulation tissue formation, anti-inflammatory activities, or epidermal resurfacing, ES may facilitate galvanotaxic attraction of these cells into the wound tissue and thereby accelerate healing.
J Hand Ther. 2005 Apr-Jun;18(2):292-6
Is there a role for ultrasound and electrical stimulation following injury to tendon and nerve?
Department of Physical Therapy, Temple University, Philadelphia, Pennsylvania 19140, USA. Susan.Michlovitz@temple.edu
Ultrasound (US) and electrical stimulation have been widely used in hand therapy to promote recovery after nerve and tendon injuries. There is support for the use of low-dosage continuous wave and pulsed US for carpal tunnel syndrome and tendonitis. Iontophoresis with dexamethasone sodium phosphate can relieve pain in acute elbow tendonitis, but there is no support for phonophoresis for any tendonitis. Animal model research supports the use of low-dosage US to improve the mechanical properties of the Achilles tendon when initiated immediately after tenorrhaphy. There are no studies available which have examined US applied to tendons in humans after repair. Electrical stimulation has been extensively studied in animal models after nerve axonotmesis and neurotmesis with nerve repair, with some support of enhancing recovery. There is a void in the literature on the use of electrical stimulation for humans after nerve transection and repair.
DJ Altern Complement Med. 1999 Feb;5(1):5-26
Carpal tunnel syndrome: clinical outcome after low-level laser acupuncture, microamps transcutaneous electrical nerve stimulation, and other alternative therapies--an open protocol study.
Branco K, Naeser MA.
Acupuncture Healthcare Services, Westport, Massachusetts, USA.
OBJECTIVE: Outcome for carpal tunnel syndrome (CTS) patients (who previously failed standard medical/surgical treatments) treated primarily with a painless, noninvasive technique utilizing red-beam, low-level laser acupuncture and microamps transcutaneous electrical nerve stimulation (TENS) on the affected hand; secondarily, with other alternative therapies. DESIGN: Open treatment protocol, patients diagnosed with CTS by their physicians. SETTING: Treatments performed by licensed acupuncturist in a private practice office.
SUBJECTS: Total of 36 hands (from 22 women, 9 men), ages 24-84 years, median pain duration, 24 months. Fourteen hands failed 1-2 surgical release procedures.
INTERVENTION/TREATMENT: Primary treatment: red-beam, 670 nm, continuous wave, 5 mW, diode laser pointer (1-7 J per point), and microamps TENS (< 900 microA) on affected hands. Secondary treatment: infrared low-level laser (904 nm, pulsed, 10 W) and/or needle acupuncture on deeper acupuncture points; Chinese herbal medicine formulas and supplements, on case-by-case basis. Three treatments per week, 4-5 weeks.
OUTCOME MEASURES: Pre- and posttreatment Melzack pain scores; profession and employment status recorded. RESULTS: Posttreatment, pain significantly reduced (p < .0001), and 33 of 36 hands (91.6%) no pain, or pain reduced by more than 50%. The 14 hands that failed surgical release, successfully treated. Patients remained employed, if not retired. Follow-up after 1-2 years with cases less than age 60, only 2 of 23 hands (8.3%) pain returned, but successfully re-treated within a few weeks.
CONCLUSIONS: Possible mechanisms for effectiveness include increased adenosine triphosphate (ATP) on cellular level, decreased inflammation, temporary increase in serotonin. There are potential cost-savings with this treatment (current estimated cost per case, $12,000; this treatment, $1,000). Safe when applied by licensed acupuncturist trained in laser acupuncture; supplemental home treatments may be performed by patient under supervision of acupuncturist.
Arch Phys Med Rehabil. 2002 Jul;83(7):978-88
Arch Phys Med Rehabil. 2002 Dec;83(12):1806; author reply 1806-7.
Carpal tunnel syndrome pain treated with low-level laser and microamperes transcutaneous electric nerve stimulation: A controlled study.
Naeser MA, Hahn KA, Lieberman BE, Branco KF.
Department of Neurology, Boston University School of Medicine, Psychology Research Service, MA, USA. firstname.lastname@example.org
OBJECTIVE: To investigate whether real or sham low-level laser therapy (LLLT) plus microamperes transcutaneous electric nerve stimulation (TENS) applied to acupuncture points significantly reduces pain in carpal tunnel syndrome (CTS).
DESIGN: Randomized, double-blind, placebo-control, crossover trial. Patients and staff administered outcome measures blinded. SETTING: Outpatient, university-affiliated Department of Veterans Affairs medical center.
PARTICIPANTS: Eleven mild to moderate CTS cases (nerve conduction study, clinical examination) who failed standard medical or surgical treatment for 3 to 30 months.
INTERVENTION: Patients received real and sham treatment series (each for 3-4wk), in a randomized order. Real treatments used red-beam laser (continuous wave, 15mW, 632.8nm) on shallow acupuncture points on the affected hand, infrared laser (pulsed, 9.4W, 904nm) on deeper points on upper extremity and cervical paraspinal areas, and microamps TENS on the affected wrist. Devices were painless, noninvasive, and produced no sensation whether they were real or sham. The hand was treated behind a hanging black curtain without the patient knowing if devices were on (real) or off (sham).
MAIN OUTCOME MEASURES: McGill Pain Questionnaire (MPQ) score, sensory and motor latencies, and Phalen and Tinel signs.
RESULTS: Significant decreases in MPQ score, median nerve sensory latency, and Phalen and Tinel signs after the real treatment series but not after the sham treatment series. Patients could perform their previous work (computer typist, handyman) and were stable for 1 to 3 years.
CONCLUSIONS: This new, conservative treatment was effective in treating CTS pain; larger studies are recommended. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation
Phys Ther. 2007 Jan;87(1):44-51. Epub 2006 Dec 1
Transcutaneous electrical nerve stimulation at both high and low frequencies reduces primary hyperalgesia in rats with joint inflammation in a time-dependent manner.
Vance CG, Radhakrishnan R, Skyba DA, Sluka KA.
Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, IA 52242, USA.
BACKGROUND AND PURPOSE: Clinical studies of transcutaneous electrical nerve stimulation (TENS) have used a variety of outcome measures to assess its effectiveness, with conflicting results. It is possible that TENS is effective on some measures of pain and not on others. The purpose of this study was to test the hypothesis that TENS reduces primary hyperalgesia of the knee induced by joint inflammation.
SUBJECTS: Male Sprague-Dawley rats were used in this study.
METHODS: Inflammation of the knee joint was induced by intra-articular injection of a mixture of 3% kaolin and 3% carrageenan. Primary hyperalgesia was measured as the compression withdrawal threshold of the knee joint before and after the induction of inflammation (4 hours, 24 hours, and 2 weeks) and after sham TENS treatment, treatment with high-frequency TENS (100 Hz), or treatment with low-frequency TENS (4 Hz).
RESULTS: The compression withdrawal threshold was significantly reduced at 4 hours, 24 hours, and 2 weeks after the induction of inflammation. Either high-frequency TENS or low-frequency TENS completely reversed the compression withdrawal threshold when applied at 24 hours or 2 weeks after the induction of inflammation but not when applied at 4 hours after the induction of inflammation.
DISCUSSION AND CONCLUSION: These data suggest that TENS inhibits primary hyperalgesia associated with inflammation in a time-dependent manner after inflammation has already developed during both acute and chronic stages.
Muscle Mass Loss
DJ Gerontol A Biol Sci Med Sci. 2005 Apr;60(4):416-24
Electrical stimulation attenuates denervation and age-related atrophy in extensor digitorum longus muscles of old rats.
Dow DE, Dennis RG, Faulkner JA.
Institute of Gerontology, University of Michigan, Ann Arbor, MI 48109-2007, USA.
Skeletal muscles of old rats and elderly humans lose muscle mass and maximum force. Denervation is a major cause of age-related muscle atrophy and weakness, because denervated fibers do not contract, and undergo atrophy. At any age, surgical denervation causes even more dramatic muscle atrophy and loss in force than aging does. Electrical stimulation that generates tetanic contractions of denervated muscles reduces the denervation-induced declines. We investigated whether a stimulation protocol that maintains mass and force of denervated extensor digitorum longus muscles of adult rats would also maintain these properties in denervated muscles of old rats during a 2-month period of age-induced declines in these properties. Contractile activity generated by the electrical stimulation eliminated age-related losses in muscle mass and reduced the deficit in force by 50%. These data provide support for the hypothesis that during aging, lack of contractile activity in fibers contributes to muscle atrophy and weakness.
J Muscle Res Cell Motil. 2007;28(4-5):203-17. Epub 2007 Sep 29
Effects of chronic electrical stimulation on long-term denervated muscles of the rabbit hind limb.
Ashley Z, Salmons S, Boncompagni S, Protasi F, Russold M, Lanmuller H, Mayr W, Sutherland H, Jarvis JC.
Muscle Research Group, Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of Liverpool, The Sherrington Building, Ashton Street, Liverpool L69 3GE, UK.
We investigated the extent to which activity induced by chronic electrical stimulation could restore the mass and contractile function of rabbit tibialis anterior (TA) muscles that had undergone atrophy as a result of prolonged denervation. Denervation was carried out by selectively interrupting the motor nerve branches to the ankle dorsiflexors in one hind limb. Stimulators were implanted, with electrodes on the superficial and deep surfaces of the denervated TA muscle. Ten weeks later, the mass and mid-belly cross-sectional area (CSA) of TA muscles subjected to denervation alone had fallen to approximately 40% of normal. At this stage, stimulators in the other rabbits were activated for 1 h/day to deliver 20-ms rectangular bipolar constant-current pulses of 4 mA amplitude at 20 Hz with a duty cycle of 1s ON/2s OFF, a total of 24,000 impulses/day. The animals were examined after a further 2, 6 or 10 weeks. Stimulation restored the wet weight of the denervated muscles to values not significantly different to those of normal, innervated controls. It increased CSA from 39% to 66% of normal, and there was a commensurate increase in maximum isometric tetanic force from 27% to 50% of normal. Light and electron microscopic examination revealed a marked improvement in the size, packing, and internal organization of the stimulated-denervated muscle fibres, suggestive of an ongoing process of restoration. Excitability, contractile speed, power, and fatigue resistance had not, however, been restored to normal levels after 10 weeks of stimulation. Similar results were found for muscles that had been denervated for 39 weeks and then stimulated for 12 weeks. The study demonstrates worthwhile benefits of long-term electrical stimulation in the treatment of established denervation atrophy.
Nerve Injury Recovery
Acta Neurochir Suppl. 2007;100:3-11
The potential of electrical stimulation to promote functional recovery after peripheral nerve injury--comparisons between rats and humans.
Gordon T, Brushart TM, Amirjani N, Chan KM.
Division of Physical Medicine & Rehabilitation, Centre for Neuroscience, Faculty of Medicine, University of Alberta, Alberta, Canada. email@example.com
The declining capacity for injured peripheral nerves to regenerate their axons with time and distance is accounted for, at least in part, by the chronic axotomy of the neurons and Schwann cell denervation prior to target reinnervation. A largely unrecognized site of delay is the surgical suture site where, in rats, 4 weeks is required for all neurons to regenerate their axons across the site. Low frequency stimulation for just 1 h after surgery accelerates this axon crossing in association with upregulation of neurotrophic factors in the neurons. We translated these findings to human patients by examining the number of reinnervated motor units in the median nerve-innervated thenar muscles before and after carpel tunnel release surgery in a randomized controlled trial. Motor unit number estimates (MUNE) in patients with moderate and severe carpal tunnel syndrome were significantly lower than normal. This number increased significantly by 6-8 months after surgery and reached normal values by 12 months in contrast to a non-significant increase in the control unstimulated group. Tests including the Purdue Pegboard Test verified the more rapid functional recovery after stimulation. The data indicate a feasible strategy to promote axonal regeneration in humans that has the potential to improve functional outcomes, especially in combination with strategies to sustain the regenerative capacity of neurons and the support of Schwann cells over distance and time.
Exp Neurol. 2007 Nov;208(1):137-44. Epub 2007 Aug 23
One hour electrical stimulation accelerates functional recovery after femoral nerve repair.
Ahlborn P, Schachner M, Irintchev A.
Zentrum für Molekulare Neurobiologie, Universität Hamburg, Falkenried 94, D-20251 Hamburg, Germany.
The clinical outcome of peripheral nerve injuries requiring surgical repair is usually poor and efficient therapies do not exist. Recent work has suggested that low-frequency electrical stimulation of the severed nerve which produces repeated discharges of the parent motoneuron perikarya positively influences axonal regeneration, even if applied once for a period of only 1 h. Here we provide the first evidence for locomotor functional benefits of such stimulation. We transected the femoral nerve of adult C57BL/6J mice proximal to the bifurcation of the quadriceps and saphenous branches and electrically stimulated the proximal nerve stump for 1 h at 20-Hz frequency prior to nerve repair with a silicone cuff. Three months later, the ability of the quadriceps muscle to extend the knee in sham-stimulated mice had recovered to 63% of the preoperative values as estimated by single-frame motion analysis. After electrical stimulation, the outcome was only slightly better (73%) but the rate of functional recovery was considerably accelerated. Near-maximum recovery was achieved 6 weeks earlier than in the control group. The beneficial effects were associated with larger motoneuron cell bodies and increased diameters of regenerated axons in the quadriceps nerve branch, but not with enhanced preferential reinnervation by motoneurons of muscle as opposed to skin. The observed acceleration of functional restoration and the positive effects on motoneurons and regenerated axons indicate the potential of a clinically feasible approach for improvement of nerve repair outcome in human patients in which delayed target reinnervation is a factor limiting recovery.
Osteoarthritic Knee Pain
J Rehabil Med. 2003 Mar;35(2):62-8
Optimal stimulation duration of tens in the management of osteoarthritic knee pain.
Cheing GL, Tsui AY, Lo SK, Hui-Chan CW.
Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. firstname.lastname@example.org
OBJECTIVE: This study examined the optimal stimulation duration of transcutaneous electrical nerve stimulation (TENS) for relieving osteoarthritic knee pain and the duration (as measured by half-life) of post-stimulation analgesia.
SUBJECTS: Thirty-eight patients received either: (i) 20 minutes (TENS20); (ii) 40 minutes (TENS40); (iii) 60 minutes (TENS60) of TENS; or (iv) 60 minutes of placebo TENS (TENS(PL)) 5 days a week for 2 weeks.
METHODS: A visual analogue scale recorded the magnitude and pain relief period for up to 10 hours after stimulation.
RESULTS: By Day10, a significantly greater cumulative reduction in the visual analogue scale scores was found in the TENS40 (83.40%) and TENS60 (68.37%) groups than in the TENS20 (54.59%) and TENS(PL) (6.14%) groups (p < 0.000), such a group difference was maintained in the 2-week follow-up session (p < 0.000). In terms of the duration of post-stimulation analgesia period, the duration for the TENS40 (256 minutes) and TENS60 (258 minutes) groups was more prolonged than in the other 2 groups (TENS20 = 168 minutes, TENS(PL) = 35 minutes) by Day10 (p < 0.000). However, the TENS40 group produced the longest pain relief period by the follow-up session.
CONCLUSION: 40 minutes is the optimal treatment duration of TENS, in terms of both the magnitude (VAS scores) of pain reduction and the duration of post-stimulation analgesia for knee osetoarthritis.
J Rehabil Med. 2004 Sep;36(5):220-5
Optimal stimulation frequency of transcutaneous electrical nerve stimulation on people with knee osteoarthritis.
Law PP, Cheing GL.
Physiotherapy Department, Chi Lin Care and Attention Home, Hong Kong.
OBJECTIVE: This is a double blind study that examined the optimal stimulation frequency of transcutaneous electrical nerve stimulation in reducing pain due to knee osteoarthritis.
SUBJECTS: Thirty-four subjects were randomly allocated into 4 groups receiving transcutaneous electrical nerve stimulation at either: (i) 2 Hz; (ii) 100 Hz; (iii) an alternating frequency of 2 Hz and 100 Hz (2/100 Hz); or (iv) a placebo transcutaneous electrical nerve stimulation.
METHODS: Treatment was administered 5 days a week for 2 weeks. The outcome measures included: (i) a visual analogue scale; (ii) a timed up-and-go test; and (iii) a range of knee motion.
RESULTS: The 3 active transcutaneous electrical nerve stimulation groups (2 Hz, 100 Hz, 2/100 Hz), but not the placebo group, significantly reduced osteoarthritic knee pain across treatment sessions. However, no significant between-group difference was found. Similarly, the 3 active transcutaneous electrical nerve stimulation groups, but not the placebo group, produced significant reductions in the amount of time required to perform the timed up-and-go test, and an increase in the maximum passive knee range of motion.
CONCLUSION: Our findings suggested that 2 weeks of repeated applications of transcutaneous electrical nerve stimulation at 2 Hz, 100 Hz or 2/100 Hz produced similar treatment effects for people suffering from osteoarthritic knee.