- THIS MATERIAL IS PUBLISHED AND PROTECTED BY U.S. COPYRIGHT LAW - REPRODUCTION PROHIBITED UNLESS FOR PERSONAL USE, EXCEPTING AUTHOR PERMISSION - Peter F. Kelly, D.P.M., F.A.C.F.A.S. Diplomate, American Board of Podiatric Surgery Fellow, American College of Foot and Ankle Surgeons APPLICATIONS OF THE Nd:YAG LASER TO PODIATRIC SURGERY An article in three parts: PART I: THE LIGHT SCALPEL - Nd:YAG LASER CONTACT TIP PART II: THE Nd:YAG LASER FOR THE PODIATRIC SURGEON PART III: QUANTITATIVE STUDIES - THE Nd:YAG VS. CONVENTIONAL SURGERY PART I: THE LIGHT SCALPEL - Nd:YAG LASER CONTACT TIP The author presents a new technology useful in soft tissue and reconstructive surgery of the foot and ankle. This series of three articles will present practical insight on the function of the Nd:YAG laser for invasive Podiatric surgical procedures, as well as the application of the Nd:YAG laser for the hands-on utilization for the Podiatrist. The third section will present data quantifying post-operative pain, edema, and tissue remodeling when comparing this new method to conventional surgery involving identical surgical procedures. It is anticipated that this new application will advance applications of state-of-the-art surgical instrumentation currently available. A review of the literature to date has not revealed any information presented in the Podiatric profession for applications of the Nd:YAG laser. Occasional reports have been seen in the Orthopaedic literature for Nd:YAG applications to carpal tunnel release, and the soft tissue component of joint replacement procedures. This instrument has been widely received in multidisciplinary medical specialties. It is applied to the endoscopic destruction of esophageal and tracheal tumors. Q- switched YAG lasers have been applied to stenose occular vascular aberations. Recently, general surgery has popularized a variety of techniques such as laparoscopic cholecystectomy, coronary angioplasty, and transluminal bladder tumor surgery. Over the past three years, the author has developed the use of the Nd:YAG contact laser for a large number of soft-tissue applications in Podiatric foot and ankle soft tissue and reconstructive surgery. The lasers used in this study discussed in part three are the Scientific Laser Technology CL-60 and LaserSonics 8000 Nd:YAG in the contact-tip mode. The Nd:YAG laser is a mid-infrared laser operating in a continuous wave mode at 1064 nm. Because of light characteristics at this frequency, it is convenietly transmitted through a multistranded quartz fiberoptic cable. Other characteristics of this frequency allow minimal absorption by water and tissue chromophores of melanin, protein, and hemoglobin. This is responsible for the extensive destructive power of this laser, when compared to lasers of other frequencies more superficially absorbed, ie: the CO2, Argon, or Ho:YAG. This wavelength thus transmits easily through human tissue when used in the free beam mode. Therefore, until the advent of the laser scalpel, the Nd:YAG held little use for general surgery. The Nd:YAG laser can be applied in either the free beam mode with a bare fiber, or focused with a sapphire or quartz light scalpel for precise dissection at a powerful localized energy concentration. The former application is useful at high power levels for general destruction of large tumors requiring deep penetration for their eradication. The latter, using the contact-tip, is generally the most applicable for Podiatric surgery and general dissection. The sapphire contact-tip has on its distal end a polished lense allowing a precise concentration of energy which limits tissue penetration to within 50 to 200 microns. This is quite useful for incisional work and dissection. This compares with its bare-fiber application, where the water transmission window effect of the 1064 nm frequency allows deep transmission into tissue to penetrate over 6 mm. The author has found this nonincisional mode only occasionally useful to treat dissecting vascular tumors that have required extensive diffusion of thermal energy through the tissue for their destruction. Laser scalpels are sized according to lense diameters from 0.2 mm to 1.2 mm and graduated in 0.2 mm increments. As the power density (P.D.) varies according to the inverse square law, extreme variations in P.D. to tissue may be accomplished by the surgeon's selection of the contact-tip diameter. A linear, thus more graduated variation, in tissue P.D. may be achieved by varying the change in wattage in direct laser output. The author has found the power density selections most appropriate to Podiatric surgery are in the range from 11,500 to 45,000 watts per cm2. For particularly delicate procedures (ie: dorsal nerve decompressions and complex ganglion excision) the P.D. is not recommended to exceed 6,000 W/cm2. For the study presented in this series, a P.D. setting of 33,000 watts per cm2 uniformly used with a 0.4 mm frosted sapphire scalpel. By convention, the standard of care in laser surgery has now required power density calculations on operative report for the purpose of documentation and reproducibility by other surgeons. The P.D. is simply calculated by dividing watts by square centimeter of tissue upon which the laser is focused. This may also be specified in joules for total tissue irradiation when this function is multiplied by time. Two types of light scalpels are utilized, frosted and nonfrosted. The frosted scalpel transmits laser energy from its distal 5 mm margin as well as its distal lense, and is appropriate for higher power applications where significant micro-coagulation is desired for dissection. Non-frosted tips are used for more precise thermal laser dissection where energy is focused at the scalpel apex and absolute hemostasis would not be a consideration. In the author's practice there is little question that the Neodynium-YAG Contact-Tip Laser has achieved a significant impact to improving the quality of surgical services delivered. In the next article, details of Podiatric dissection using the Nd:YAG contact-tip will be discussed. The importance in these basic techniques when using the Nd:YAG laser should be emphasized because of the steep learning curve of the instrument. Appropriate use of the instrument results in significant decreases in postoperative patient pain, edema, and decreased tissue remodeling time resulting in less patient disability. Although the author is optimistic when seeing the clinical results, as his patients are seen on a daily basis, the laser scalpel is not an instrument that is rapidly learned by the casual surgeon. Basic laser surgical techniques require considerable retraining and experience, which the experienced surgeon may find initially intimidating. The author advocates that the Nd:YAG laser is not a substitute for a good foundation in surgical training and principles. With appropriate application, however, significant improvements in surgical results can be achieved. REFERENCES: 1. Absten, Gregory T., and Joffe, Stephen N., "Overview of Clinical Applications, Orthopaedics", _Lasers In Medicine: An Introductory Guide_, Chapman and Hall, Ltd., 1989, Pg.46, 171-173. 2. Joffe, Stephen N., and Schroder, Tom, "Lasers in General Surgery", _Advances in Surgery_, 20:125-154, 1987, Yearbook Medical Publishers, Inc. 3. Carlson, Bruce A., and Pyrcz, Robert A., "Lasers in Podiatry and Orthopaedics", _Nursing Clinics of North America_, v. 25, No. 3, September 1990, Pg. 719-723. 4. Schultz, Robert J., "The Neodynium-YAG Laser in Arthroscopic Surgery: Indications for Use", Laser Medicine in Surgery News and Advances, August 1988, Pg. 36. 5. "A Series on Current Trends and Techniques in Contact Laser Surgery and Endoscopy", ASLT Data Source, October 1987, Pg. 2-14, Surgical Laser Technologies, Cincinnatti, OH. 6. Carlson, Bruce A., and Nicholson, Ronald A., "Laser Matrixectomy Subject of Podiatric Controversy", Clinical Laser Monthly, v.9, No. 3, March, 1991, Pg. 45-6 7. Joffe, Stephen N., and Schroder, Tom, Editorial from Annales Chirurgiae et Gynaecologae, 75:3-4, 1986. 8. Kelly, Peter F., "Nd:YAG Contact-tip Treatment Reduces Pain From Foot Surgery", Clinical Laser Monthly, Laser Practice Report, v.10, No. 1, January, 1992, Pg. 7-8. 9. Kelly, Peter F., _Nd:YAG Contact-Tip Vs. Cold Steel Applications in Podiatric Foot and Ankle Surgery_, Paper accepted by American Society for Laser Medicine and Surgery, Twelfth Annual Meeting, May 1992.