Augmentation of bone repair by inductively coupled electromagnetic fields.

Pulsing electromagnetic fields of low frequency and strength have been inductively coupled across skin, directly to bone, to enhance the repair of canine osteotomies. The induced voltage field in bone appears to increase the organization and strength of the repair process at 28 days after "fracture."

Electromagnetically induced focused heat in the treatment of surgically created aneurysm models.

A hand-held radiofrequency (rf) probe of a novel design based on the principle of the induced current convergence was used to treat aneurysm models using focused hyperthermia. Aneurysms were created surgically in rats by a side-to-side anastomosis between the inferior vena cava and the abdominal aorta or by grafting a donor abdominal aorta from one rat onto the abdominal aorta of another rat. Aneurysms were treated by inserting the 0.3-mm diameter probe tip into the fundus and applying the power for brief periods (0.5-1.5 sec) using a foot pedal. Collapse of the fundus was observed as the result of the heat-induced thrombosis. Thermal distribution in the immediate vicinity of the probe as well as the heating rate were measured in a uniformly dielectric phantom and in rat vessels. The aneurysms were histologically examined immediately, three days, and three weeks after the treatment. Complete obliteration of the aneurysms and patency of the parent arteries were confirmed. Partial integrity of the vessels around the lesion was also confirmed.

A 20-gauge intraocular electromagnetic tip for simplified intraocular foreign-body extraction.

A modified tip for the Bronson intraocular electromagnet has been developed. The tip was machined to a 20-gauge cylinder that can be inserted readily into the eye either through an entrance wound or through a pars plana incision. Placement of the tip of the magnet inside the eye allows the foreign body to impact the tip of the magnet rather than the wall of the eye.

Chronic lateral humeral epicondylitis--a double-blind controlled assessment of pulsed electromagnetic field therapy.

Pulsed electromagnetic fields (PEMF) have been shown to be beneficial in the treatment of rotator cuff tendinitis. As lateral humeral epicondylitis (tennis elbow) is a similar chronic tendon lesion, 30 patients with both clinical and thermographic evidence of tennis elbow were randomly allocated to receive either active or inactive PEMF therapy. Treatment was continued for a minimum period of eight weeks. At this time there was no statistical difference between the two groups.

Electromagnetic stimulation of canine bone grafts.

We evaluated the use of pulsed electromagnetic-field stimulation to affect the rate of healing or incorporation of segmental autogenous cortical bone grafts in the dog in vivo. This non-invasive method of electrical stimulation has been implicated in increasing bone osteogenesis or augmentation of the repair process in the canine fibular osteotomy. We utilized two-month and six-month stimulation protocols. At six months, all of the animals were evaluated biomechanically using rapid-loading torsional testing. Histological evaluation using tetracycline labeling was used to evaluate cumulative new-bone formation and porosity, while graft-host time to union was evaluated roentgenographically every two weeks. Recent reports have implied that particular pulse configurations might be effective in improving graft revascularization and incorporation. The results of our investigation indicated that there was no significant effect on the biomechanical strength, histological presentation, or time to union with either two months or six months of pulsed electromagnetic-field stimulation using the particular waveform described.

Prevention of osteoporosis by pulsed electromagnetic fields.

Using an animal model, we examined the use of pulsed electromagnetic fields, induced at a physiological frequency and intensity, to prevent the osteoporosis that is concomitant with disuse. By protecting the left ulnae of turkeys from functional loading, we noted a loss of bone of 13.0 per cent compared with the intact contralateral control ulnae over an eight-week experimental period. Using a treatment regimen of one hour per day of pulsed electromagnetic fields, we observed an osteogenic dose-response to induced electrical power, with a maximum osteogenic effect between 0.01 and 0.04 tesla per second. Pulse power levels of more or less than these levels were less effective. The maximum osteogenic response was obtained by a decrease in the level of intracortical remodeling, inhibition of endosteal resorption, and stimulation of both periosteal and endosteal new-bone formation. These data suggest that short daily periods of exposure to appropriate electromagnetic fields can beneficially influence the behavior of the cell populations that are responsible for bone-remodeling, and that there is an effective window of induced electrical power in which bone mass can be controlled in the absence of mechanical loading.

Modification of fracture repair with selected pulsing electromagnetic fields.

We assayed different pulsing electromagnetic fields for their effects on the mechanical and histological repair properties of an osteotomy of the radius of the rat fourteen days postoperatively. Highly significant differences were found in the control and experimental initial load values and their decay as a function of time. These results correlate well with the histological pattern in the bridging callus. A pulse that produces an increase (above the control level) in initial load by a factor of 2.4 and a slower decay was characterized by more extensive calcification of fibrocartilage and its replacement by fibrous bone at this early, but important, stage in fracture-healing.

Treatment of therapeutically resistant non-unions with bone grafts and pulsing electromagnetic fields.

This study reviews the cases of eighty-three adults with ununited fractures who were treated concomitantly with bone-grafting and pulsed electromagnetic fields. An average of 1.5 years had elapsed since fracture and the use of this combined approach. Nearly one-third of the patients had a history of infection, and an average of 2.4 prior operations had failed to produce bone union. Thirty-eight patients who were initially treated with grafts and pulsed electromagnetic fields for ununited fractures with wide gaps, synovial pseudarthrosis, and malalignment achieved a rate of successful healing of 87 per cent. Forty-five patients who had initially been treated unsuccessfully with pulsing electromagnetic fields alone had bone-grafting and were re-treated with pulsing electromagnetic fields. Ninety-three per cent of these fractures healed. The residual failure rate after two therapeutic attempts, one of which was operative, was 1.5 per cent. The median time to union for both groups of patients was four months.

The use of pulsing electromagnetic fields to achieve arthrodesis of the knee following failed total knee arthroplasty. A preliminary report.

Treatment with pulsing electromagnetic fields was used as an adjunct in twenty patients who had had a knee arthrodesis after failure of a total joint arthroplasty. Eighteen had had an infected arthroplasty; one, mechanical loosening; and one, recurrent dislocation. Arthrodesis had been attempted twenty-five times in these twenty patients prior to application of the coils. These procedures included the use of twenty-two external fixation frames, one compression plate, one intramedullary rod, and one cylinder cast. Two groups of patients were identified: those with non-union and those with delayed union. Fourteen patients began treatment six months or more after arthrodesis and were considered to have a non-union. The other six patients started treatment less than six months after attempted arthrodesis because there was no evidence of progression toward union. They were considered to have delayed union. In seventeen (85 per cent) of the twenty patients a clinically solid arthrodesis with roentgenographic evidence of bone-bridging was achieved. The average time to union after coil therapy was started was 5.8 months, with a range of three to twelve months. The patients who started coil treatment earlier after arthrodesis showed a tendency to heal faster. The three patients who had failures were the only ones who did not adhere to the protocol, and all three were in the non-union group. All patients with a solid arthrodesis were free of pain and able to walk at the time of follow-up, nine to thirty-one months after the completion of treatment. The use of pulsing electromagnetic fields appears to be a valuable non-invasive adjunct when performing arthrodesis of the knee after failed total joint arthroplasty.

Treatment of ununited tibial diaphyseal fractures with pulsing electromagnetic fields.

One hundred and twenty-five patients with one hundred and twenty-seven ununited fractures of the tibial diaphysis were treated exclusively with pulsing electromagnetic fields. The over-all success rate in healing of the fracture with this surgically non-invasive out-patient method was 87 per cent. The success rate was not materially affected by the age or sex of the patient, the length of prior disability, the number of previous failed operations, or the presence of infection or metal fixation.

The effect of postoperative electromagnetic pulsing on canine posterior spinal fusions.

An experimental canine study was devised to evaluate the efficacy of a noninvasive adjunct to improve the rate and quality of the posterior fusion mass over the standard surgical technique. Ten large adult mongrel dogs underwent a three-level lumbar spinal fusion. Bone excised from the spinous processes was packed in removed facet joints and over the decorticated laminae. To insure rigid internal fixation, custom-made distraction instrumentation was placed bilaterally under the laminae of the vertebrae above and below the three fused vertebrae. Five dogs underwent electromagnetic pulsing, and five dogs acted as controls. Two dogs were sacrificed at 4, 6, 9, 12, and 15 weeks to assess the radiographic and histologic status of the fusion mass. Preoperative and preautopsy hematologic studies as well as gross and histologic autopsy specimens revealed no abnormalities attributable to the electromagnetic pulsing. High-resolution radiography and histologic studies showed earlier incorporation of the graft, improved new bone formation, and better organization of the fusion mass in the 4-, 6-, and 9-week stimulated specimens. However, by 12 and 15 weeks there did not appear to be any histologic or radiographic differences between the stimulated and control dogs. Although electromagnetic pulsing appears to produce an early accelerated osteogenic response, it does not appear to improve the overall results of primary canine spinal fusions.

Development of the iron-cored electromagnet for the treatment of non-union and delayed union.

The development of the iron-cored electromagnet as a stimulator of bony union is described. In a clinical trial extending over eight years, 80 patients were treated for various forms of failed union. Their results are presented, as well as tentative conclusions regarding the indications and efficiency of the method. The latest, fully-portable apparatus is described.

Effects of high-peak pulsed electromagnetic field on the degeneration and regeneration of the common peroneal nerve in rats.

Apart from preliminary notices of present work, previous reports of experimental and clinical trials of the effects of a high-peak pulsed electromagnetic field (PEMF) on degeneration and regeneration of peripheral nerves lacked statistical analysis. Therefore, we designed experiments with standardised operative, histological, cytological and morphometric techniques to assess the effect of PEMF on lesions of the common peroneal nerves in paired male rats matched for age, environmental conditions and level and type of lesion. One of two types of lesion was induced in the left common peroneal nerve: in 12 pairs of rats the nerve was crushed just above the knee and in the remaining 12 pairs the nerve was cut and immediately sutured at the same level. The right common peroneal nerve of each rat served as a control. Animals received 15 minutes of PEMF produced by a Diapulse machine or sham treatment daily for periods ranging from three and a half days to eight weeks after injury. Healthy nerves were unaffected, but after damage there were statistically significant differences between PEMF treated and sham treated rats. PEMF accelerated the recovery of injured limbs and the degeneration, regeneration and maturation of myelinated axons; epineural, perineural and intraneural fibrosis was reduced; and the luminal cross-sectional area of intraneural vessels increased after both types of lesion. Findings are discussed and the need for clinical trials is stressed.

The development and application of pulsed electromagnetic fields (PEMFs) for ununited fractures and arthrodeses.

This article deals with the rational and practical use of surgically noninvasive pulsed electromagnetic fields (PEMFs) in treating ununited fractures, failed arthrodeses, and congenital pseudarthroses (infantile nonunions). The method is highly effective (more than 90 per cent success) in adult patients when used in conjunction with good management techniques that are founded on biomechanical principles. When union fails to occur with PEMFs alone after approximately four months, their proper use in conjunction with fresh bone grafts insures a maximum failure rate of 1 to 1.5 per cent. Union occurs because the weak electric currents induced in tissues by the time-varying fields effect calcification of the fibrocartilage in the fracture gap, thereby setting the stage for the final phases of fracture healing by endochondral ossification. The efficacy, safety, and simplicity of the method has prompted its use by the majority of orthopedic surgeons in this country. In patients with delayed union three to four months postfracture, PEMFs appear to be more successful and healing, generally, is more rapid than in patients managed by other conservative methods. For more challenging problems such as actively infected nonunions, multiple surgical failures, long-standing (for example, more than two years postfracture) atrophic lesions, failed knee arthrodeses after removal of infected prostheses, and congenital pseudarthroses, success can be expected in a large majority of patients in whom PEMFs are used. Finally, as laboratory studies have expanded knowledge of the mechanisms of PEMF action, it is clear that different pulses affect different biologic processes in different ways. Selection of the proper pulse for a given pathologic entity has begun to be governed by rational processes similar, in certain respects, to those applied to pharmacologic agents.

Magnet extraction of frontal sinus foreign body.

We report a metallic foreign body that entered through the anterior table of the frontal sinus, and rolled down to lodge in the nasofrontal duct. An electromagnet was used to remove the foreign body through a trephination.

Selective resolution of plaques and treatment of atherosclerosis by biophysical alteration of "cellular" and "intracellular" properties.

Presenting a totally new approach to the effective treatment of Atherosclerosis through the alteration of biophysical properties both "intracellularly" and "extracellularly." The experimental data is preliminary but the results obtained indicate that by allowing the atherosclerotic lesions to take up the magnetically excitable submicron particles and then applying an external alternating electromagnetic field, the atherosclerotic lesions may be selectively resolved without damaging normal blood vessels. This concept suggests many areas of investigation since there are a variety of means of biophysically altering the atherosclerotic plaques, and many substances may be utilized to enhance the process. This new technology and this initial experimentation introduces a "new era" in the effective treatment of Atherosclerosis.

Intracellular hyperthermia. A biophysical approach to cancer treatment via intracellular temperature and biophysical alterations.

This paper introduces a new multi-disciplinary "intracellular" biophysical treatment of cancer. The basic concept uses locally induced heat energy after tumor phagocytosis of submicron particles whose composition permits magnetic excitation. The key to this process is the utilization of the cancer cell membrane to contain the energy within the cancer cell. Any magnetic or electric dipole contained within or introduced into the cell, or that is capable of being produced by an external field, can be used. Submicron particles are colloidally suspended, injected intravenously and are phagocytized by cancer cells. Application of an external high frequency or pulsed electromagnetic field then raises the particles' temperature thus generating intracellular heat in precise increments. This results in selective thermal destruction of cancer cells with little effect on normal cells. Experimental evidence is presented showing tumor cell destruction in spontaneous mammary tumors in Sprague Dawley rats. In addition, we suggest that certain biophysical properties are altered within the cancer cells and could be used to enhance this effect. Specific radioisotopes or tumor specific antibodies bound to particles or chemotherapeutic microspheres increase cancer cell sensitivity and affinity for these particles. This "intracellular" treatment of cancer has a wide potential range of applications.

The cause of cancer: biochemical defects in the cancer cell demonstrated by the effects of electromagnetic radiation, glucose and oxygen.

The responses of a person carrying a cancer to 434 MHz electromagnetic radiation are such that they demonstrate that each human cell contains at least two separate respiratory pathways which can convert glucose to energy. The first pathway produces energy by an anaerobic mechanism and it can be demonstrated that this energy is used for the purpose of cell replication. The second pathway(s) produces energy from glucose by aerobic oxidative processes which can be shown to energise other cellular functions. One of these functions is that of controlling its own cell division. Other demonstrable functions of this aerobic energy producing mechanism are concerned with individual cellular repair processes, multicellular organisation and repair and the preservation of gross anatomical perfection. Release of the first or anaerobic system from supervisory control by the second or aerobic sytem(s) permits the unlimited cell division which is the phenomenon known as cancer. The available circumstantial evidence suggests that this is not the result of nuclear or chromosomal defects or mutations but is due to direct irreversible sublethal damage to the cellular aerobic glucose metabolic system whilst the anaerobic system remains intact.

Pulsing electromagnetic field therapy in nerve regeneration: an experimental study in the cat.

A multidisciplinary approach to the study of peripheral nerve regeneration in the cat has been presented. The purpose of this work has been to determine if pulsing electromagnetic field (PEMF) therapy can enhance peripheral nerve regeneration after injury. In equal groups of animals, two types of pulsing electromagnetic field treatment were compared with untreated controls. All animals underwent quantitative electrophysiologic and morphologic assessment at the area of injury. In addition, muscle fiber sizing in the periphery and retrograde labeling of anterior horn motoneurons with horseradish peroxidase were studied. Results have shown no statistical differences between the groups in electrophysiologic or morphologic parameters. However, in animals treated with a pulse-burst electromagnetic field there was a statistically significant improvement in the labeling and localization of anterior horn cells in the central nervous system. These results indicate that pulse-burst electromagnetic radiation can increase the numbers of motor neurons that reestablish appropriate connections to the periphery after nerve injury. It remains to be seen if this improved spinal cord organization can translate to improved peripheral functional return.

Properties of electromagnetic field focusing probe.

The electromagnetic field focusing (EFF) apparatus consists of a radio frequency generator, solenoidal coil, and a hand-held or catheter probe. Applications such as aneurysm treatment, angioplasty, and neurosurgery in various models have been reported. The probe is operated in the near field (within one wavelength of an electromagnetic field source) of a coil inducing eddy currents in biological tissues, producing maximal convergence of the induced current at the probe tip. The probe produces very high temperatures depending on the wattage selected for the given radio frequency of output power. The high temperature can be used in cutting, cauterizing, or vaporizing. The EFF probe is comparable to different types of lasers and to bipolar and monopolar cautery. The EFF probe can be used with catheters or endoscopes. Objectives of this study were to determine what the thermal properties of the EFF probe are and how instrument parameters can be varied to obtain different temperatures in the tissue near the probe tip. In this study an F2 catheter was used as an insulated sheath and the tip of the guide wire was used as the probe tip. Different powers, wave forms, coil-to-probe distances, and probe-tip lengths were tested on a phantom that simulates tissue electrical properties. Some of the experiments were conducted under normal saline to simulate treatment of tissue with body fluids such as blood vessels or brain tissue under normal physiologic conditions. It is concluded that the EFF probe has the advantages of easy manipulation, relative safety, cost effectiveness, and a high degree of spatial control.(ABSTRACT TRUNCATED AT 250 WORDS)