LLLT - laser therapy -
|This page includes|
|Preoperative Low Level Laser application to reduce post-operative pain in patients receiving winograd type of partial matrixectomy surgery of hallux.|
|PHYSICAL MECHANISMS OF BIOLOGICAL EFFECT OF COHERENT AND NONCOHERENT LIGHT.|
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Les Jonsson B H Sc (Podiatry). Dip. Podiatry, Dip Podiatric Surgery, Dip. Soc. Sc. (Psychology). Cert. L.L.T. email email@example.com
Mary Needham, R.G.O.N., Cert., L.L.T.
Low level laser was introduced as a part of our surgical regime to assist with post operative healing following digital surgery. It was observed that fewer patients returned for post-operative redressings complaining of post operative pain. A pilot study has been undertaken to report the level of pain experienced by patients who received a Winograd type partial matrixectomy of the hallux. To reduce the number of extraneous variables the surgery was undertaken in the same setting with the same surgeon and staff with the same operative instructions provided. Laser Therapy was used within 30minutes of surgery.
Each patient was placed on the operating table in the supine position. The laser probe was placed against the epidermis and applied at 1.8J/cm 2 ,5.7Hz, with wavelength 830 nm and output power 40mW. from a "Maestro", laser manufactured by Medicom, Praha , Czech Republic . The probe was applied at 2 points at each surgical site and at one point at each of the two sites for undertaking the digital anaesthetic block at the proximal aspect of the great toe. A mixture 5cc of 50/50 2% plain xylocaine and 0.5% Marcaine was injected dorsal to plantar into the proximal aspect of the great toe. The feet were prepped and draped in the normal sterile manner. A partial nail plate avulsion was achieved with removing 2-3mm of the fibular and/or tibia nail borders. A Betadine scrub was then undertaken. This was followed with an incision proximal to the proximal end of the matrix along the course of the new nail edge to the distal end of the nail. A second incision was made in a semi elliptical fashion from the proximal end of the first incision along the course of the original nail border joining with the distal end of the first incision. Both incisions were made down to bone and all tissue was removed. Matrix within the cavity was removed. Saline irrigation was applied to the cavity. The cavity was closed with Proline sutures at proximal and distal ends with steristrips across the nail section. The tourniquet was released and blood flow was observed to return to the area. A dressing of Betadine and Bactagras was applied with 4 x 4 sterile gauze, followed by gauze bandage and Coban.
Each patient was given oral and written instruction and an appointment for redressing in 5 to 7 days. Instructions included the suggestion that the patient take Panadol. Each patient appeared tolerated the procedure well and left the surgery ambulated.
One returning to the surgery after five to seven days for redressings, each patient scored on a 10cm Visual Analogue Scale, the level that best illustrated the highest level of pain that they experienced following the operation.
Those in the Laser group (N=12) scored an average of 2.1 whereas those in the Non laser group scored an average 7.2 (N=3).
The level of self medication for pain relief was not monitored and no breakdown of ethnicity, age or sex was recorded for any patients. The authors note the small number of subjects in this study, in particularly the “No Laser” group. Given the low pain scores of the laser group reporting low pain scores, it is expected that these authors will afford all future eligible patients the opportunity of pre-operative laser therapy for this and other types of surgery. Other practitioners who do not use laser, who use like surgical techniques are encouraged to conduct a similar study on their patients, to make a comparison with the current study and to report their findings.
MECHANISMS OF BIOLOGICAL EFFECT OF COHERENT AND NONCOHERENT LIGHT.
biological action of low intensity laser radiation is well known and
widely used in laser therapy. In spite of a great success in this field
the primary mechanism of laser stimulating effect remains disputable.
The main question to be answered is: whether the observed effects are
caused by absorption of light by some photoreceptors, the excitation
of which starts some chains of biochemical events, or we encounter here
with some other mechanism of interaction of light with biological matter.
If the first is true, i.e. primary interaction of light with biological
object is of pure photochemical nature, then we must find those receptors,
study their properties and look for the light source, which emission
is best overlapped with the absorption band of the receptors. In this
case coherence and polarization of light can not be of importance.
we may make the first conclusion: noncoherent light may influence ensemble
of particles (biological system) through light induced dipole-dipole
comparison with the dipole-dipole interaction the optical Kerr effect
is less probable at interaction of low intensity light with biological
objects. Because of low intensity of light, required by biological safety,
considerable torque may appear only for particles of micron scale size.
Such large particles contain large number of electrons whose oscillations
are summarized producing the light induced dipole moment of the whole
particle. If the particle is not a crystal but a biological cell or
an organelle then it is difficult to expect essential anisotropy over
the whole volume of a particle.
It is formed only at illumination
of an object with coherent light. The higher degree of the coherence
the higher degree of the intensity modulation in a speckle structure
is observed. At illumination of the same object with noncoherent light
from lamps, photodiodes or so like the speckle structure disappears
and the object appears illuminated uniformly.
Fig. 5 illustrates action of gradient forces on 6 ? plastic particles in water illuminated by the interference field of He-Ne laser. One can see that under the action of gradient laser field all particles are gathered at the maximums of laser intensity. So the laser field here causes change of local concentration of particles.
Captions to figures
Fig.1. Interaction of dipole
moments induced by light in neighboring particles.
Fig.2. Rotation of the particle characterized by anisotropic polarizability under action of linearly polarized light. a) – the torque acts on a particle because the light induced dipole moment P does not coincide with the direction of the electrical vector E of the light field. b) – particle is aligned with its dipole moment P along the electrical vector E under action of the torque.
Fig.3. Interaction of reflected and scattered micro-beams in an inhomogeneous medium, which causes appearance of speckles of a laser field in the medium.
Fig.4. Polarization of a dielectric particle under action of uniform (a) and not uniform (b, c) electric field; b) and c) show that at change of the electric field sign the direction of the gradient force does not change.
Fig.5. Trapping of 6 ? plastic particles in water under action of gradient forces in the interference field of a He-Ne laser; a) – random distribution of particles at illumination by a single laser beam. b) – distribution of the particles in the fringes of the two beam interference laser field.
Fig.6. Aligning of erythrocytes under action of gradient forces in the interference fringes of Ar laser; a) – the first moment after the interference field has been switched on; b) – several minutes later – both erythrocytes have oriented themselves along the interference fringes.
Fig.7. Splitting of the erythrocyte
rouleau under the action of gradient forces of the Ar-laser interference
field; a) an erythrocyte rouleau illuminated by a single laser beam;
b) – splitting of the rouleau into separate erythrocytes at switching
on the interference field.
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