- 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 II: THE Nd:YAG LASER FOR THE PODIATRIC SURGEON The previous article reviewed briefly the technical aspects of the Nd:YAG laser. A thorough understanding of laser physics and tissue interaction is fundamental for correct application. The hands-on application of techniques will be discussed here to familiarize the Podiatric surgeon with laser contact-tip dissection methods. Podiatry has the most to gain from this new laser method. The dependent lower extremity is subject to increased hydrostatic pressure causing peripheral edema. Reconstructive procedures are performed on this weightbearing structure which, being farthest from the heart, is the most poorly perfused and thus complicated by delayed healing as compared to other extremities and end organs. Axonal conduction for repair of damaged nerves in the foot occurs at a very slow rate due to the distance nutrients traverse from nuclear nerve origins. These are a few of the reasons as to why many diseases first present in the foot. These are the same indications for methods that can reduce intraoperative tissue necrosis, postoperative edema, minimize fibroblastic stimulation and scarring, and optimize tissue remodeling. Conventional anesthesia is utilized. A tourniquet is not mandatory, and is left to the surgeon's preference. The surgery is initiated with a superficial epidermal inscription using a steel blade. This is carried to the level of the dermis only. The white dermis encountered determines the depth of the cold steel incision. Bleeding should never be encountered. The remainder of the tissue dissection including layer delaminations is performed with the laser scalpel. This is the optimal incision method, and was derived from a variety of incisional techniques. The author has found this technique optimizes the cosmetic result, minimizing fibroblastic stimulation and cell necrosis. While using the frosted contact-tip, perfect hemostasis should be observed. Only a minimal charring or tissue carbonization should be encountered. Delicate neural and vascular structures paralleling the incision will be observed to remain patent, even if separated by a thin membrane of tissue adjacent by only a few microns. Vessels smaller than 1.0 mm can be photocoagulated. The author finds it expedient to ligate larger vessels conventionally. An important principle of technique is that tissue dissection responds from laser light intensity, not by customary mechanical pressure. The tactile feedback of mechanical pressure of the blade is an acquired reflex of the experienced surgeon. This is the most frequent problem with laser scalpel that surgeons encounter. The tactile feedback from contact-tip is reduced and cuts comparatively like a hot knife through butter. Dissection with the laser scalpel should be continued in linear strokes from proximal to distal margins through the incision. Local tissue temperatures rapidly exceed 100 degrees centigrade so the tip must be kept moving. Tissue carbonization will be minimal and thus smoke evacuation requirements in the operating room are greatly reduced, but still necessary. Minimal smoke plume is produced as compared with the CO2 laser. Thermal hydrolysis of adipose tissue produces water which must be sponged frequently. Water rapidly disseminates the 1064 nm laser frequency and impedes effecient dissection. Because Podiatric incisions are rarely more than several centimeters, the fascial layer integrity is easily maintained and neurovascular structures are readily identified to avoid untoward neural thermal effects. This is important because of the reduced tactile feedback of the more powerful laser ability in dissection. With general bone cases, dissection is continued through to the joint capsule. This capsular incision is carried down through the periosteum with a slight reflection from the bone. Periosteum is to be preserved for future revascularization of the cortex, and any additional dissection off of the bone should be performed with cold steel only. Intense local thermal effects of the laser avascularize small periosteal arteries. Areas where rapid periosteal revascularization would be most appreciated are metaphyseal osteotomy. For nonosseous cases the author routinely allows soft tissues to undergo periods of thermal relaxation by withdrawl of the laser scalpel. This is a good technique to apply when dissecting adjacent to bone so as to minimize adjacent thermally induced periostitis to osseous structures. Closure and dressings for all cases are customary. Sutures remain for an additional several days due to the decreased fibroblastic activity following Nd:YAG interaction with dermal tissue. Margins of laser dissected tissue require a longer period of healing, but there is less scarring. Although reduction in pain, recovery time, and edema will be observed even in initial cases, potential complications exist. These include thermal periostitis, resulting from excessive time exposure form the laser in the proximity of bone capsule and periosteum. Also neural shutdown when infrared energy is radiated into a peripheral nerve causing a reversible protein denaturation affecting conduction velocity, resulting in paresthesia distal to the affected site. It can be expected that the first several laser cases will proceed more slowly and with somewhat more frustration to the surgeon. Sensitizing the surgeon to the decreased tactile feedback of the light scalpel will take only a short time and soon the laser technique will expedite the procedures more rapidly, and personal preferences will develop. The Nd:YAG laser will rapidly become a highly personalized instrument to most surgeons. The next article will review the results of the extensive database research of clinical results by the author. This study was originally designed arising from skepticism of Nd:YAG laser utilization, as the author has been previously satisfied with the results from his conventional surgery. The author required that specific parameters of his laser surgery cases be quantifiable to be compared with identical parameters of conventional surgery to justify laser utilization. Further, an improvement of a significant margin was required by the author previous to making a decision on the appropriateness of the Nd:YAG laser to his practice.