Patent Application
20080208194
The present invention is directed to surgical cutting instruments used in arthroscopic and endoscopic surgery.
Surgical cutting instruments in which an inner member is rotated within an elongate tubular outer member are known in surgical procedures where access to the surgical site is via a narrow portal or passage. Typically, the tubular outer member has a distal end with an opening defining a cutting port or window. The inner member has a distal end with a cutting tip for engaging bodily tissue via the opening. Proximal ends of the inner and outer members commonly include hubs which attach to a handpiece having a motor for rotating the inner member relative to the outer member. The distal end of the inner member can have various configurations dependent upon the surgical procedure to be performed. Often the inner member is tubular so that the loose tissue resulting from a cutting, resecting or abrading procedure can be aspirated through the lumen of the inner member.
The cutting port or window of the tubular outer member is typically provided with teeth having angled configurations and being fabricated by a two-step process. First, the profile of the teeth is formed in the conventional through-cut manner. Subsequently, the teeth are “sharpened” by removing material by Electrical Discharge Machining (EDM), to form a beveled surface on the portion of a tooth in contact with the tube inner lumen. The resulting teeth are effective for penetrating tissue and preventing ejection of tissue from the cutting window as the inner and outer cutting edges approach each other. However, this two-step approach has several drawbacks. Although EDM is used to remove the material to form the beveled surface (as conventional machining processes are unable to produce the required geometry under production conditions), the EDM process has nevertheless high consumable tooling costs as the electrode is eroded during use. In addition, because EDM removes material by melting and vaporization, it is difficult to produce a sharp point on the teeth. The surfaces produced by EDM are also generally rough and present a high resistance to tissue sliding over the surface, inhibiting penetration of teeth into tissue.
Accordingly, there is a need to provide an improved cutting instrument used in arthroscopic surgery, that has a sharper cutting edge and that is produced with more control over the angle of the teeth during manufacturing. A surgical cutting instrument that has sharper cutting edges with cutting teeth at varying angles is also needed. A method of fabricating cutting edges for cutting instruments, such as shaver blades, with high resection efficiency due to advanced cutting edge tooth geometry is also needed.
The present invention provides a surgical cutting instrument with high resection efficiency due to advanced cutting edge tooth geometry. The cutting instrument comprises a tubular member with at least two cutting windows, preferably two cutting windows, provided at the distal end of the tubular member. The two cutting windows have one most distal common region, preferably provided about perpendicular to the longitudinal axis of the tubular member. At least one of the two cutting windows may be provided with teeth. The two cutting windows may be symmetrically or asymmetrically disposed relative to the tube axis when viewed in a plan view, independent of the teeth orientation. The teeth of the cutting instrument are advantageously formed with a laser, rather than EDM, resulting in very sharp teeth.
These and other features and advantages of the invention will be more apparent from the following detailed description that is provided in connection with the accompanying drawings and illustrated exemplary embodiments of the invention.
The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventors of carrying out their invention. Various modifications, however, will remain readily apparent to those skilled in the art.
The present invention provides a surgical cutting instrument with high resection efficiency due to advanced cutting edge tooth geometry. The cutting instrument comprises a tubular member with at least two cutting windows, preferably two cutting windows, provided at the distal end of the tubular member. Each of the cutting windows has a plurality of teeth positioned along lateral cutting edges, the teeth being configured for easy penetration into tissue to prevent ejection of tissue from the cutting windows during closure. At least one of the cutting edges is formed by laser cutting technology. Preferably, both cutting edges are formed by laser cutting technology.
The two cutting windows have one most distal common region, preferably provided about perpendicular to the longitudinal axis of the tubular member. In one embodiment, the teeth of each window are symmetrically disposed relative to the tube axis when viewed in a plan view. In another embodiment, the teeth are asymmetrically disposed. The two cutting windows may be symmetrically or asymmetrically disposed relative to the tube axis when viewed in a plan view, independent of the teeth orientation.
As shown in the drawings, tubular member 100 comprises a distal end portion 10 that includes cutting means including at least two cutting windows 50, 60 having a plurality of teeth 55, 65 positioned along lateral cutting edges 51, 61, the teeth being configured for easy penetration into tissue to prevent ejection of tissue from the cutting windows during closure. At least one of the cutting edges 51, 61 is formed by laser cutting technology. Preferably, both cutting edges 51, 61 are formed by laser cutting technology.
As also shown in
In one embodiment, the teeth of each window may be symmetrically disposed relative to the tube axis 11 when viewed in a plan view. In another embodiment, the teeth may be asymmetrically disposed. In other embodiments, the two cutting windows 50, 60 may be symmetrically disposed relative to the tube axis 11 when viewed in a plan view. Alternatively, the two cutting windows 50, 60 may be asymmetrically disposed relative to the tube axis 11 when viewed in a plan view.
According to embodiments of the present invention, the step of cutting the teeth 55, 65 with laser is conducted by cutting from top down (i.e., from top to bottom), and not from the side profile (as in conventional wire EDM technology). The top-down orientation affords a “sharper” cutting edge, since the teeth are not cut straight across but rather from the top, making the beveled edge much sharper. Another advantage of the laser cutting technology is that there is more control over the laser angles as compared to the wire EDM, affording more control during manufacturing. Wire EDM does not allow any varying of the angle of the teeth during cutting. In contrast, by employing the laser technology to form the teeth, the angle can be changed to obtain a sharper cutting edge on the teeth.
Tubular member 100 of the present invention may be an inner member or an outer member of a cutting instrument, for example, an arthroscopic shaver, and may be disposed coaxially or concentrically within a corresponding outer or inner tube. Tubular member 100 may be formed from a medically acceptable material such as stainless steel. In a preferred embodiment, tubular member 100 has a hollow cylindrical configuration.
The tubular member with double cutting windows of the present invention described above may be part of an arthroscopic shaver employed in various surgical medical procedures such as conventional open surgeries or in other, less invasive, techniques that use cannulas or various port access devices. The present invention has applications in surgical procedures where the target tissue is ablated or shaped, and may be employed in cutting various body parts such as the knee, shoulder, hip, ankle, elbow, hand or foot. For example, the tubular member 100 of the present invention may be part of an arthroscopic shaver employed in arthroscopic surgery of a knee joint structure.
Although the present invention has been described in connection with preferred embodiments, many modifications and variations will become apparent to those skilled in the art. While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Accordingly, it is not intended that the present invention be limited to the illustrated embodiments, but only by the appended claims.
This application claims the benefit of U.S. Provisional Application Serial No. 60/900,991 filed on Feb. 13, 2007, the entire disclosure of which is incorporated by reference in its entirety herein.
| Number | Date | Country | |
|---|---|---|---|
| 60900991 | Feb 2007 | US |
