Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-07-23
2003-09-23
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S022000
Reexamination Certificate
active
06623454
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of electrosurgery and, more particularly, to surgical devices and methods which employ high frequency voltage to contract soft tissue structures, such as collagen connective tissue.
Collagen connective tissue can be found in many places in the human body, such as the soft tissue surrounding joints, the tissue of the cornea, the epidermal and dermal layers of the skin and the like. Collagen fibers shrink or contract when subjected to elevated temperatures, causing the caliber of the collagen fibers to increase without substantially changing the structural integrity of the connective tissue. This molecular response to temperature elevation has made contraction of collagen tissue important in many applications, such as the shrinkage of collagen tissue in the shoulder capsule or knee joint, or the collagen soft tissue in the skin in wrinkle removal procedures.
Collagen tissue is particularly important in the stability of peripheral joints, such as the shoulder, knee, hip, or the like. Peripheral joints generally comprise a covering of hyaline cartilage surrounded by a soft tissue joint capsule that maintains the constant contact of the cartilage surfaces on the ends of bones. This joint capsule also maintains the synovial fluid that provides nutrition and lubrication of the joint surfaces. Instability of peripheral joints is a significant cause of disability and functional limitation in active patients. When a joint becomes unstable, for example, its soft tissue allows for excessive motion of the joint surfaces relative to each other, and in directions not normally permitted by the ligaments or capsule. Typically, the more motion a joint demonstrates, the more inherently loose the soft tissue is surrounding the joint. If the instability is severe and recurrent, functional incapacity and arthritis may result.
Recent surgical attempts to treat joint instability have focused on tightening the soft tissue restraints that have become loose in the joints. These procedures are typically performed through open surgical approaches that often require hospitalization and prolonged rehabilitation programs. Endoscopic techniques generally cause less blood loss, have a lower risk of infection, and faster postoperative recovery times. However, arthroscopic procedures are more technically demanding than open surgical procedures because it is often difficult to access the loose tissue within the joints with endoscopic instruments.
Laser energy has been employed to effect tissue heating for contracting collagen fibers in soft tissue. For example, infrared laser energy has been used on the cornea to induce collagen shrinkage for shape modification of the cornea (laser thermokeratoplasty). In these techniques, the collagen is typically irradiated with laser coherent energy in a wavelength range of about 1.8 to about 2.55 microns to elevate the collagen temperature to about 23° C. above normal body temperature to achieve collagen shrinkage.
Electrosurgery techniques have also been used to contract the collagen fibers in soft tissue. These techniques typically involve the application of radiofrequency (RF) energy to soft collagen tissue to contract and restrict the tissue elasticity. U.S. Pat. No. 5,458,596 to Lax, for example, describes a monopolar electrosurgical device for contracting soft tissue in which RF voltage is applied to an electrode terminal positioned near the target tissue. The electric current is caused to flow through the tissue to induce contraction of the collagen fibers. The transfer of the RF current can be through direct contact between the active electrode and the tissue, or through a thin layer of electrically conducting fluid, such as saline or gel.
Current electrosurgical devices and procedures such as the one described in Lax, however, suffer from a number of disadvantages. For example, monopolar devices generally direct electric current along a defined path from the exposed or active electrode through the patient's body to the return electrode, which is externally attached to a suitable location on the patient. This creates the potential danger that the electric current will flow through undefined paths in the patient's body, thereby increasing the risk of unwanted electrical stimulation to portions of the patient's body. In addition, the direct transfer of RF current through the target tissue tends to increase the thermal damage caused to the target tissue, and it may induce thermal damage or necrosis of body structures underlying and/or surrounding the target tissue.
For these and other reasons, improved systems and methods are desired for the electrosurgical contraction of collagen tissue.
SUMMARY OF THE INVENTION
The present invention provides systems and methods for selectively applying electrical energy to structures within or on the surface of a patient's body. The systems and methods allow the surgical team to perform electrosurgical interventions, such as selectively contracting soft collagen tissue and other body structures, while limiting thermal damage or molecular dissociation of such tissue and limiting the thermal damage to tissue adjacent to and underlying the treatment site. The systems and methods of the present invention are particularly useful for surgical procedures in electrically conducting environments, such as arthroscopic procedures in the joints, e.g., shoulder, knee, hip, hand, foot, elbow or the like. The present invention is also useful in relatively dry environments, such as treating and shaping the cornea, and dermatological procedures involving surface tissue contraction of tissue underlying the surface of the skin for tissue rejuvenation, wrinkle removal and the like.
In one aspect of the present invention, a method for contracting soft collagen tissue involves heating an electrically conducting fluid in the region of the target site, and directing the heated electrically conducting fluid onto the target tissue to induce contraction or shrinkage of the collagen fibers in the target tissue. The electrically conducting fluid is heated to a temperature sufficient to substantially irreversibly contract the collagen fibers, which generally requires a tissue temperature in the range of about 45° C. to 90° C., usually about 60° C. to 70° C. The fluid is heated by applying high frequency electrical energy to an electrode terminal in contact with the electrically conducting fluid. The current emanating from the electrode terminal heats the fluid and generates a jet or plume of heated fluid, which is directed towards the target tissue. The heated fluid elevates the temperature of the collagen sufficiently to cause hydrothermal shrinkage of the collagen fibers.
The electrode terminal may comprise an array of electrode terminals or a single electrode at the distal end of the electrosurgical probe. In a specific embodiment, a return electrode is positioned in contact with the electrically conducting fluid to provide a current flow path from the electrode terminal(s), through the electrically conducting fluid, to the return electrode. The return electrode draws the electric current away from the tissue site to limit the depth of penetration of the current into the tissue, thereby inhibiting molecular dissociation and breakdown of the collagen tissue and minimizing or completely avoiding damage to surrounding and underlying tissue structures beyond the target tissue site. In an exemplary embodiment, the electrode terminal(s) are held away from the tissue a sufficient distance such that the RF current does not pass into the tissue at all, but rather passes through the electrically conducting fluid back to the return electrode. In this embodiment, the primary mechanism for imparting energy to the tissue is the heated fluid, rather than the electric current.
In another aspect of the invention, the electrode terminal(s) are brought into contact with, or close proximity to, the target tissue so that the electric current passes directly into the tissue to a sele
Eggers Philip E.
Thapliyal Hira V.
ArthroCare Corp.
Batt Richard R.
Casler Brian L.
Raffle John T.
Thompson Michael M
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