Patent Application
20230371972
Surgical tissue shavers are devices that remove tissue from a patient's body. A typical tissue shaver has a cutting head formed by concentric inner and outer tubes or shafts. The concentric shafts are positioned next to tissue to be removed, and moved relative to each other to generate a cutting action to remove the tissue.
A conventional tissue shaver cutter head assembly 10 is shown in
Referring for example to the illustrations of the outer cutter head 20, each tooth 28 as a proximal surface 28a and a distal surface 28b, which join at a tooth point 28c. The proximal surface 28a and distal surface 28b also form a tooth edge 28d, that extends from the tooth point 28c in a direction away from the respective opening edge 26.
The cutter opening 22, edges 26 and teeth 28 typically are formed by using a cutting tool to remove a portion of the tubular wall of the cutter head 20. The cutting tool may be a cutting wheel, a grinder, a laser cutter, or the like. The cutting tool operates along a cutting path 14 that extends perpendicular to the longitudinal axis 12, and so the proximal surface 28a, distal surface 28b, and tooth edge 28d all extend parallel to the cutting path 14, and perpendicular to the longitudinal axis 12. When the cutter head 20 has a cylindrical shape (i.e., a circular profile extending along the longitudinal axis 12), as typically is the case, the cutting path 14 defines a chord of the circular profile of the cutter head 20. Thus, in this case, the proximal surface 28a and distal surface 20b are defined by a continuous series of chord lines, and the tooth edge 28d forms a single chord line.
The teeth 38, edges 36 and opening 32 of the inner cutter head 30 typically are made like those of the outer cutter head 20—i.e., using a cutting tool that moves along a cutting path 14 that is perpendicular to the longitudinal axis 12. Thus, the proximal and distal surfaces and tooth edge of each tooth 38 also extend parallel to the cutting path 14 and perpendicular to the longitudinal direction 12.
The foregoing construction is known to be beneficial because it allows simple and cost-effective fabrication using machine tools, such as a cutting wheel or grinder. This is particularly important in the context of shaver cutting heads, which can be very small (e.g., 3 mm or smaller in diameter, and having a wall thickness of well below 0.5 mm) and difficult to using complex machining motions. For example, a cutter head as described above can be fully formed from a tube by moving a grinding wheel back and forth along the cutting path, while indexing the tube along the longitudinal axis after each cutting tool pass (or indexing the cutting tool while holding the tube still). Each pass of the cutting tool forms a root of a tooth on each side of the opening, as well as the portion of the opening between those teeth. The shape of the grinding wheel defines the shapes of the teeth, and a full opening with all of the teeth can be formed in, for example, just four passes.
The foregoing construction is also known to be beneficial because it allows simple and cost-effective fabrication using laser cutting tools. For example, a laser cutter can be oriented to project along a cutting path that is perpendicular to the longitudinal axis, and, while maintaining a perpendicular relationship with the longitudinal axis, the laser cutter is moved along the cutter head along as shown by arrows 16 in
With this conventional understanding in place, the concept of modifying the particular shape of the cutter head teeth has not been developed, and its benefits have remained undiscovered.
In a first exemplary embodiment, there is provided a surgical tissue shaver comprising: a shaft extending from a proximal shaft end to a distal shaft end, the shaft comprising a tubular body defining a cannula extending from the proximal shaft end to the distal shaft end; and a cutter head at the distal shaft end and extending along a longitudinal axis, the cutter head having a cutter opening in fluid communication with the cannula, wherein at least a portion of the cutter opening extending along the longitudinal axis is defined between a first row of teeth and a second row of teeth opposite the first row of teeth with respect to the longitudinal axis. At least one tooth of the first row of teeth is defined by a respective proximal tooth surface and a respective distal tooth surface that intersect at a respective tooth edge, and wherein the respective tooth edge is oriented at a respective angle of less than 90° relative to the longitudinal axis.
In another exemplary embodiment, there is provided a method for manufacturing a tissue shaver cutter head, the method comprising: providing a cutter head blank comprising a hollow tube extending along a longitudinal axis; orienting a cutting tool along a first cutting path, wherein the first cutting path extends at a first angle less than 90° relative to the longitudinal axis and intersects the cutter head blank; and activating the cutting tool to cut along the first cutting path to cut a first tooth defined by a respective proximal tooth surface and a respective distal tooth surface that intersect at a respective tooth edge, wherein the respective tooth edge is oriented parallel to the first cutting path.
The following is a description of exemplary and non-limiting embodiments of a surgical tissue shaver, and parts thereof. Surgical tissue shavers are devices that might be used during arthroscopic surgical procedures to collect body tissue (bone, ligament, muscle, lesions, etc.), but the embodiments are not necessarily limited to such uses.
Referring now to
The outer shaft 200 and inner shaft 300 may include or be securable to features, such as a handle 400, a syringe 402, a drive motor 404, or the like, as known in the art.
One or both of the outer shaft 200 and the inner shaft 300 may comprise respective rigid tubular structures made of surgical steel or other materials suitable for the application. The outer shaft 200 and/or inner shaft 300 also may be constructed with a flexible region 208, 308. For example, the outer shaft 200 and inner shaft 300 may have coterminous flexible regions 208, 308, such as schematically illustrated in
As shown in
When assembled together for use, the outer cutter head opening 212 and inner cutter head opening 312 are aligned along the longitudinal axis 102, such that relative rotation of the shafts 200, 300 causes the cutter head openings 212, 312 to attain different states of alignment. In the position shown in
The cutter opening 612 is defined, in a direction transverse to the longitudinal axis 102, between a first row of teeth 614 and a second row of teeth 616. The remainder of the cutter opening 612 may be defined, along the longitudinal axis direction, between a proximal edge 618 and a distal edge 620, but a distal edge 620 is not strictly required (i.e., the cutter head 610 may be open at the distal end).
The two rows of teeth 614, 616 are located opposite each other with respect to the longitudinal axis 102. One or more teeth 614, 616 of each row may be aligned along a line parallel to the longitudinal axis 102, but this is not required. For example, in the shown embodiment, the proximal two teeth 614, 616 of each row are arranged in parallel along the longitudinal axis 312, while the distal tooth 614, 616 of each row is not aligned with the others. The first and second rows of teeth 614, 616 may extend the full length of the cutter opening 612 (length being measured in the longitudinal axis 102), but this is not required in all cases. In the shown examples, each row has three teeth, but more or fewer teeth may be present. The number of teeth in one row also may be different from the other row.
Referring specifically to the left row of teeth 614, each tooth 614 is defined by a proximal tooth surface 614a and a distal tooth surface 614b. The proximal and distal surfaces 614a, 614b intersect each other at a tooth edge 614c. The tooth edge 614c terminates, at the inner surface of the cannula 616, at a tooth point 614d.
As will be appreciated from
The angle A in the embodiment of
The angled tooth 614′ is expected to generate various benefits. First, the angled tooth, and especially the proximal surface 614a and/or distal surface 614b, can generate a longitudinal force along the longitudinal axis 102, which can help move tissue longitudinally. Without being bound to any theory of operation, it is believed that the proximal surface 614a tends to push tissue away from the longitudinal axis 102 because the proximal surface 614a is oriented to face generally away from the longitudinal axis 102, and the distal surface 614b tends to push tissue towards the longitudinal axis 102 because the distal surface 614b is oriented to face generally towards the longitudinal axis 102. In this case, the net result is that the severed tissue is generally driven in the distal direction D, which can help mix the severed tissue and move severed tissue back into the path of the cutting edges to be cut into smaller pieces. This can help provide a more homogenous mixture of severed tissue, and reduce large pieces that might otherwise lead to clogging problems or the like.
Another expected benefit of the angled tooth 614′ is that the side edges of the tooth engage the corresponding tooth edges of the other cutter head to generate a greater shearing component to the cutting force, which can potentially decrease the force necessary to cut the tissue, and provide a cleaner cut.
Other benefits may become apparent with practice of embodiments.
Still referring to
Such an embodiment may be useful to adjust the magnitude of force generated along the longitudinal axis 102.
As will appreciated from the foregoing, it is anticipated that various combinations of using all angled teeth, and combinations of angled and non-angled teeth can provide various benefits. Such variations include having rows of teeth that are mirror images of each other (i.e., symmetrical about a plane parallel to the longitudinal axis 102 and intersecting the center of the cutter opening), or not. Similarly, it will be understood that angled teeth in some locations may have angles A of different magnitudes. For example, the distal angled tooth 814′ may be oriented at an angle A of 80 degrees, while the proximal angled tooth 814′ may be oriented at an angle A of 70 degrees. The number of teeth can also be changed to potentially gain further benefits. Other alternatives and embodiments will be apparent to persons of ordinary skill in the art in view of the present disclosure.
It will also be appreciated that the foregoing embodiments of angled teeth may be used with an inner cutter head 200, an outer cutter head 300, or both. When use only in one cutter head 200, 300, the remaining cutter head can have a conventional construction. In addition, one cutter head may have different types of angled teeth than the other. For example, an outer cutter head 200 may be provided with teeth having angles A opening distally, as shown in
Embodiments of tissue shaver cutter heads with angled teeth may be manufactured using various methods.
In this example, a laser cutter 1540 is provided to cut the cutter head opening 1512. The laser cutter 1540 is oriented along a cutting path 1542 that extends at an angle of less than 90° relative to the longitudinal axis and intersects the blank at the edge of the intended cutter head opening location. As shown in
Once oriented, the laser cutter 1540 is activated to direct the cutting beam 1546 along the cutting path 1542. The laser cutter 1540, shaft 1500, or both, may be moved to guide the cutting beam 1546 to form the cutter head opening 1512. The cutting angle 1542, as well as the angular orientation and radial distance R of the plane 1544, may vary as the laser cutter 1540 and/or shaft 1500 moves to create the cutter head opening 1512.
As the cutting beam 1546 contacts the shaft 1500, it cuts away material to form the proximal tooth surface and the distal tooth surface of each tooth 1516. When complete, the proximal tooth surface and distal tooth surface intersect to form a tooth edge lying along the cutting direction 1542. The laser cutter 1540 can thus be used to cut the entire cutter head opening 1512, at which time the remaining waste of the tubular blank will be removed.
In the embodiment of
In other embodiments, the cutter head opening 1512 may be created using an abrasive grinder or other mechanical cutting device, or a combination of devices (e.g., an abrasive grinding wheel to cut the proximal and distal edges of the opening, and a laser cutter to cut the rows of teeth). Other alternatives and embodiments will be apparent to persons of ordinary skill in the art in view of the present disclosure.
It is noted that the angled cutting path Ac can add a difficulty not present in conventional cutting operations. Specifically, advancing the cutting tool along an angled cutting path Ac across the entire blank will result in asymmetrical cuts on each side of the cutter head opening 1512. This is in contrast to conventional cutting methods, in which the cutting tool is traversed across the full width of the blank along a cutting path that is perpendicular to the longitudinal axis 102, in which the cuts on both sides of the cutter head opening 1512 are identical and symmetrical.
It has been found that such undesirable asymmetrical cutting can be avoided when using a laser cutter 1540, by reducing the output and/or increasing the cutting movement speed to limit the cutting laser to penetrate the hollow blank at only a single location at any given time. This method result in some internal scarring of the cannula where the cutting laser impinges upon penetrating the opposite side of the blank, but it has been found that such scarring is not detrimental to the function of the device. In methods using mechanical cutters, undesirable asymmetrical cutting can be avoided by operating the cutter head at different angular orientations, or by rotating the blank between cuts or during cutting. Other alternatives and embodiments will be apparent to persons of ordinary skill in the art in view of the present disclosure.
The present disclosure provides a number of exemplary embodiments of the invention defined by the appended claims. The description of such embodiments is not intended to limit the scope of the claims beyond what is defined in the claims. It will also be understood that, while embodiments may provide particular advantages in certain cases, the scope of the claims is not limited to embodiments providing any particular advantage or functionality. It will further be appreciated that other embodiments encompassed by the claims may diverge from those described herein in both appearance and functionality, and the various features of particular described herein may be used with other embodiments without departing from the scope of the claims.
