September 2, 2008

BONE REPAIR (OSTEOGENESIS) WITH ELECTRICAL STIMULATION^©

Lyn Paul Taylor, A.A., B.A., M.A., R.P.T.

(Editing Assistant and Computer Consultant: Joanna Soon, B.S.)

Clinical research and experience have confirmed that low intensity, low frequency electrical stimulation may facilitate the healing processes of damaged bone, increasing the quality and rate of repair.  Electrical stimulation has been shown to be remarkably effective for precipitating the healing of long-term nonunion fractures.

Many types of electrical instrumentation provide current forms with the requisite amplitudes (0 to 100 milliamperes or up to 90 volts), frequencies (1 to 10 hertz), and pulse width duration (100 to 200 milliseconds) necessary to facilitate bone healing.  Of all the current forms, the pulsed square wave has been shown to be the most effective and safest.

To promote osteogenesis with electrical stimulation, go through the following steps:

• Surface electrodes should be placed above and below the fracture site, so that the current flow is parallel with the long axis of the bone.  If the electrical stimulation unit is monophasic, the negative electrode(s) should be placed as close to the fracture site as is possible, even over the site, since osteogenesis is promoted right under it.

• The electrical stimulation unit should be preset at zero amplitude, at a minimum frequency of 28 hertz, and at the longest pulse width possible (from 100 to 200 milliseconds).

• The electrical stimulation unit should be turned on and the intensity slowly increased until the patient “feels” the stimulation, usually occurring at the 20 milliampere level or slightly less.  Higher currents are not thought to be advisable, and no involuntary muscle contraction or increased muscle tonus should be produced.

• Stimulation should last for 20 to 60 minutes.

• Ideally, this treatment should be applied three or four times a day, at equally spaced intervals.  Successful treatment has been noted to occur if stimulation is provided once a day.

• Following treatment, the surface electrodes should be removed and the skin under the electrodes thoroughly cleansed.

Precautions:

As mentioned above, the selection of the electrode site and electrode polarity may be critical to the healing process it facilitates.  Osteogenesis is facilitated by the presence of the negative electrode and inhibited by the presence of the positive electrode.  Additionally, research has demonstrated that if the electrodes are placed in opposition to one another across the fracture site, perpendicular to the long axis of the bone, it will cause osteogenesis to occur in a manner that creates bone cells at right angles to the long axis of the bone.  This will produce a relatively weak union and a weakened bone.  A stronger union is produced if the electrodes are placed in opposition across the fracture site, parallel to the long axis of the bone; this facilitates osteogenesis of bone cells parallel with the long axis of the bone more closely imitating original bone formation.

If osteogenesis (calcific deposit) is not desired, the positive electrode should be placed over the treatment site and the negative electrode placed in a relatively distant site, and the protocol described above for osteogenesis should be followed in all other particulars.  This technique may be useful in discouraging calcium deposit in joints, muscles or along tendons.

References:

H. Aro, J. Aho, K. Vaatoranta and T. Ekfors, "Asymmetric Biphasic Voltage Stimulation of the Osteotomized Rabbit Bone," Acta Orthop. Scand., vol. 51, 1980. Pp. 711-718

D.B. Harrington and R. Meyer, "Effects of Small Amounts of Electric Current at the Cellular Level," Annals of the N.Y. Academy of Science, vol. 238, October 11, 1974. Pp. 300-305

J. Kahn, "Transcutaneous Electrical Nerve Stimulation for Nonunited Fractures," Physical Therapy, 62:6, June 1982. Pp. 840-844

K. Piekarski, O. Demetriades and A. Mackensie, "Osteogenetic Stimulation by Externally Applied DC Current," Acta Orthop. Scand., vol. 49, 1978. Pp. 113-120

I. Yasuda, "Mechanical and Electrical Callus," Annuls of the N.Y. Academy of Science, vol. 238, October 11, 1974. Pp. 457-465

L.P. Taylor, T. Hui, The Taylor Technique of Soft Tissue Management, Inflammation: Evaluation & Treatment, 2002.  p. 76

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