Patent Publication Number: US-2020289146-A1

Title: Rotating scalpet including overmolded gears, and method for manufacturing and using same

Description:
PRIORITY CLAIM 
     The present application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/816,650, filed on Mar. 11, 2019, the entirety of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to a scalpet with an overmolded gear and a method of manufacturing same, and more specifically to a rotatable scalpet with the gear molded into the outer surface of the scalpet. 
     BACKGROUND 
     Rotational fractional resection (“RFR”) is a procedure which may be used to achieve focal aesthetic contouring by removing lax skin and excess fat tissue from a patient. Skin may be removed by the use of a rotating scalpet, which is a hollow, sharpened tube which excises full thickness dermal resections. Due to the presence of longitudinal and/or rotational forces, however, the scalpet may fail if not properly formed. 
     SUMMARY 
     The present disclosure provides an improved scalpet that can withstand increased longitudinal and/or rotational forces, and a method of forming same. In a general example embodiment, a rotatable scalpet includes a hollow tube extending along a longitudinal axis and including an inner surface and an outer surface, the inner surface forming a passageway between a first end and a second end of the hollow tube, a cutting edge located at the first end of the hollow tube, the cutting edge configured to cut a patient&#39;s tissue when the hollow tube is rotated around the longitudinal axis, and a gear molding feature formed into the outer surface of the hollow tube, the gear molding feature enabling a gear to be molded around at least a portion of the hollow tube. 
     In another embodiment, the gear molding feature includes at least one aperture extending through the outer surface of the hollow tube to the passageway. 
     In another embodiment, the gear molding feature includes at least one indentation extending into the outer surface of the hollow tube, wherein a depth of the at least one indentation is less than a thickness of the outer tube. 
     In another embodiment, the gear molding feature includes a plurality of apertures. 
     In another embodiment, the plurality of apertures are aligned in a row along the longitudinal axis of the hollow tube. 
     In another embodiment, the plurality of apertures are aligned at a same height along the longitudinal axis of the hollow tube. 
     In another embodiment, the gear molding feature includes at least one slot. 
     In another embodiment, the at least one slot extends parallel to the longitudinal axis. 
     In another embodiment, the at least one slot includes a radial indentation extending perpendicular to the longitudinal axis around a diameter of the outer surface. 
     In another embodiment, the gear molding feature includes a plurality of slots aligned at a same height along the longitudinal axis of the hollow tube. 
     In another embodiment, the gear molding feature includes at least one radial indentation creating a knurled surface on a portion of the outer surface of the hollow tube. 
     In another embodiment, the rotatable scalpet includes the gear molded into the gear molding feature. 
     In another general example embodiment, a rotatable scalpet includes a hollow tube extending along a longitudinal axis and including an inner surface and an outer surface, the inner surface forming a passageway between a first end and a second end of the hollow tube, a cutting edge located at the first end of the hollow tube, the cutting edge configured to cut a patient&#39;s tissue when the hollow tube is rotated around the longitudinal axis, and a gear configured to rotate the scalpet, the gear molded into the outer surface of the hollow tube. 
     In another embodiment, the gear is molded into at least one aperture extending through the outer surface of the hollow tube. 
     In another embodiment, the gear is molded into an indentation into the outer surface of the hollow tube, wherein a depth of the at least one indentation is less than a thickness of the outer tube. 
     In another embodiment, a rotational fractional resection device includes the rotating scalpet. 
     In another general example embodiment, a method of manufacturing a rotatable scalpet includes providing a hollow tube extending along a longitudinal axis and including an inner surface and an outer surface, the inner surface forming a passageway between a first end and a second end of the hollow tube, forming a gear molding feature into the outer surface of a hollow tube, and molding a gear over the gear molding feature by dispensing at least a portion of a material used to form the gear into the gear molding feature. 
     In another embodiment, molding the gear includes dispensing the material used to form the gear into an aperture of the gear molding feature. 
     In another embodiment, molding the gear includes dispensing the material used to form the gear into an indentation of the gear molding feature. 
     In another embodiment, the method includes curing the molded gear to harden the molded gear within the gear molding feature. 
     In another embodiment, the entire scalpet with the gear is an injection molded part. 
     In another embodiment, the entire scalpet with the gear is a 3D printed part. 
     In another embodiment, the entire scalpet with the gear is a molten metal 3D printed part. 
     The advantages discussed herein may be found in one, or some, and perhaps not all of the embodiments disclosed herein. Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a perspective view of an example embodiment of a rotatable scalpet in accordance with the present disclosure. 
         FIG. 2  shows a side view of an example embodiment of a hollow tub which may be used to form the scalpet of  FIG. 1 . 
         FIG. 3  shows a cross-sectional view taken vertically through the center of the hollow tube of  FIG. 2 , with a gear molded to the outer surface of the hollow tube. 
         FIGS. 4A to 4C  show cross-sectional views which may be taken horizontally through the hollow tube of  FIG. 2  at the locations of the apertures therein. 
         FIG. 5  shows a side view of an example embodiment of a hollow tub which may be used to form the scalpet of  FIG. 1 . 
         FIG. 6  shows a cross-sectional view taken vertically through the center of a the hollow tube of  FIG. 5 , with a gear molded to the outer surface of the hollow tube. 
         FIGS. 7A to 7C  show cross-sectional views which may be taken horizontally through the hollow tube of  FIG. 8  at the locations of the slots therein. 
         FIG. 8  shows a side view of an example embodiment of a hollow tub which may be used to form the scalpet of  FIG. 1 . 
         FIG. 9  shows a cross-sectional view taken vertically through the center of the hollow tube of  FIG. 8 , with a gear molded to the outer surface of the hollow tube. 
         FIG. 10  shows an example embodiment of a method of manufacturing the scalpet of  FIG. 1 . 
         FIG. 11  shows an example embodiment of a device using a plurality of the scalpets of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Before the disclosure is described, it is to be understood that this disclosure is not limited to the particular apparatuses and methods described. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only to the appended claims. 
     As used in this disclosure and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. The methods and apparatuses disclosed herein may lack any element that is not specifically disclosed herein. Thus, “comprising,” as used herein, includes “consisting essentially of” and “consisting of.” 
     The present disclosure is directed to a scalpet that may be used, for example, by a rotational rotational fractional resection (“RFR”) device, either alone or in combination with other scalpets having similar or the same features.  FIG. 1  illustrates an example embodiment of a scalpet  10  according to the present disclosure. In the illustrated embodiment, scalpet  10  includes a hollow tube  12  and a gear  14  encircling the hollow tube  12 . In use, the gear  14  may be used to rotate the hollow tube  12  and/or to cause another scalpet to rotate using the motion of the hollow tube  12 . 
     Hollow tube  12  includes an inner surface  16  and an outer surface  18  extending between a first end  20  and a second end  22 . Inner surface  16  forms a passageway  24  through the hollow tube  12 , along the longitudinal axis  13  between the first end  20  and the second end  22 , placing the opening at the first end  20  in communication with the opening at the second end  22 . Outer surface  18  includes a gear molding feature  28  (shown in  FIG. 2 ), which enables the gear  14  to be molded thereto, as explained in more detail below. 
     At the first end  20  of the hollow tube  12 , the scalpet  10  includes a beveled cutting edge  26  which is configured to cut into a patient&#39;s tissue when the scalpet  10  is rotated, for example, via the gear  14 . At a second end  22  of the hollow tube  12 , a vacuum may be applied for collecting incised tissue. By rotating the cutting edge  26  into a patient&#39;s tissue using the gear  14 , and then applying a vacuum at second end  22 , the patient&#39;s tissue that is cut by the cutting edge  26  may be removed from the patient via passageway  24 . The scalpet  10  may be configured to provide a tissue resection density between 10% and 25%. 
     In an embodiment, the hollow tube  12  may be formed of metal, for example, SAE  304  stainless steel, SAE  316  stainless steel, or the like. In the illustrated embodiment, the hollow tube  12  is about 29.5 mm in length along the longitudinal axis  13 , the passageway  24  is 1.5 mm in diameter, and the hollow tube  12  is about 1.83 mm thick, but those of ordinary skill in the art will recognize that other dimensions may be used. For example, the hollow tube  12  may have a diameter between 0.8 mm and 1.2 mm. 
     In the illustrated embodiment, the gear  14  is molded to the hollow tube  12  so as to encircle the hollow tube  12  at a location between the first end  20  and the second end  22  along the longitudinal axis  13 . In the illustrated embodiment, the gear  14  is located closer to the second end  22  than to the first end  20 , but those of ordinary skill in the art will recognize that other configurations are possible. In the illustrated embodiment, toothed gear portion  30  is located about 7 mm from the second end  22 , which has been determined to be effective for desired cutting depths into the patient for this design, but those of ordinary skill in the art will recognize that other configurations are possible. 
     In the illustrated embodiment, the gear  14  includes the toothed gear portion  30  and a smooth portion  32 . The toothed gear portion  30  may be used, for example, to communicate with other gears to cause rotation of the scalpet  10  and/or additional scalpets or other elements. The smooth portion  32  adds strength to the securement of the gear  14  to the outer surface  18  by adding to the overall length of the gear  14  while minimizing the size of the teeth extending therefrom. The smooth portion  32  is also advantageous because it serves as a location for tooling to inject the plastic material for the gear  14  without distorting the teeth of the toothed gear portion  30  during manufacturing. Those of ordinary skill in the art will recognize that the sizes of the toothed gear portion  30  and the smooth portion  32  may be altered, or smooth portion may be eliminated and toothed portion may extend the entire length of the gear  14 . 
     In an embodiment, the gear  14  is molded with plastic, but those of ordinary skill in the art will recognize that other materials may be used. 
       FIGS. 2 to 9  illustrate example embodiments of the gear molding features  28  which may be used to attach the gear  14  to the hollow tube  12 , for example, by the molding gear  14  into the outer surface  18  of the hollow tube  12 . As explained in more detail below, one or more gear molding features  28  may enable more material of the gear  14  to adhere to the outer surface  18  and more securely attach to the hollow tube  12  in comparison with alternative designs, enabling more torque to be applied to the gear  14  without causing the scalpet  10  to break or fail. In other words, the gear molding features  28  enables the gear  14  to be attached with additional strength to keep the gear  14  on or otherwise attached to the hollow tube  12  in the presence of longitudinal and/or rotational forces. It has been found, for example, that longitudinal strength in particular is improved with this design. 
       FIGS. 2 to 4  show a first embodiment of a gear molding feature  28 . In  FIGS. 2 to 4 , the gear molding feature  28  includes at least one aperture  40  extending through the outer surface  18  to the inner surface  16  and the passageway  24 . More specifically, the at least one aperture  40  includes a plurality of apertures  40  comprising a plurality of first apertures  42  at a first longitudinal location along the longitudinal axis  13 , a plurality of second apertures  44  at a second longitudinal location along the longitudinal axis  13 m a plurality of third apertures  46  at a third longitudinal location along the longitudinal axis  13 , and/or a plurality of fourth apertures  48  at a fourth longitudinal location along the longitudinal axis  13 . As illustrated, the first, second and third longitudinal locations are spaced at equal distances, whereas the gap between the third and fourth longitudinal locations is greater than the gap between the first and second longitudinal locations or the second and third longitudinal locations. In the illustrated embodiment, the top three apertures are evenly spaced to provide uniform adherence directly under the toothed gear portion  30 , while the fourth aperture is located underneath the smooth portion  32  which carries less load and requires less adherence. In the illustrated embodiment, a plurality of apertures  40  are aligned in a row along the longitudinal axis  13  at multiple locations around the hollow tube  12 , but it should be understood that the apertures may also be offset along the longitudinal axis  13 . Those of ordinary skill in the art will recognize alternative configurations which may be used. 
     In the illustrated embodiment, the plurality of apertures  40  are between about 0.4 mm and 0.6 mm in diameter, and are spaced apart by about 0.8 mm to about 1.2 mm parallel to the longitudinal axis  13 . Those of ordinary skill in the art will recognize that other dimensions may be used. 
       FIGS. 4A to 4C  show a cross section of the hollow tube  12 , demonstrating example embodiments of how any of the apertures  40  may be positioned around the hollow tube  12 . In  FIG. 4A , two apertures  40  are placed on opposing sides of the hollow tube  12 . In  FIG. 4B , four apertures  40  are equally spaced in quarter sections around the hollow tube  12 . In  FIG. 4C , six apertures  40  are equally spaced in sixth sections around the hollow tube  12 . Those of ordinary skill in the art will understand that different configurations may be used, and that the more apertures  40  used, the stronger the attachment between the gear  14  and the hollow tube  12 , particularly when torque is applied to rotate the scalpet  10 . In  FIGS. 2 and 3 , the first apertures  42 , second apertures  44  and third apertures  46  are positioned as shown in  FIG. 4B , while the fourth apertures  48  are positioned as shown in  FIG. 4A . 
     As illustrated in  FIG. 3 , the gear  14  is molded into the plurality of apertures  40  of the gear molding feature  28 . The gear  14  may be molded to the hollow tube  12 , for example, by surrounding the hollow tube  12  with a mold having the appropriate shape of the gear  14 , and then injecting liquid plastic or another material for the gear  14  into the mold. As liquid material is injected into the mold, the material migrates into the plurality of apertures  40 , causing the plurality of apertures  40  to fill with the same material used to mold the gear  14 , increasing the adherence strength of the gear  14  once the liquid material hardens. A pin may be inserted into the hollow tube  12  to prevent the liquid plastic from flowing into the hollow tube  12 . If plastic forms inside the passageway  24 , it may prevent effective removal of tissue that is pulled through passageway  24  with a vacuum. 
       FIGS. 5 to 7  show a second embodiment of a gear molding feature  28 . In  FIGS. 5 to 7 , the gear molding feature  28  includes at least one longitudinal slot  50  extending through the outer surface  18  to the inner surface  16 . More specifically, the at least one longitudinal slot  50  includes a plurality of longitudinal slots  50  extending parallel to the longitudinal axis  13 . In the illustrated embodiment, each slot  50  is between about 0.4 mm and 0.6 mm in width perpendicular to the longitudinal axis  13 , and is between about 0.8 mm to about 1.2 mm in length parallel to the longitudinal axis  13 . Those of ordinary skill in the art will recognize that other dimensions may be used. 
       FIGS. 7A to 7C  show a cross section of the hollow tube  12 , demonstrating example embodiments of how any of the longitudinal slots  50  may be positioned around the hollow tube  12 . In  FIG. 7A , two slots  50  are placed on opposing sides of the hollow tube  12 . In  FIG. 7B , four longitudinal slots  50  are equally spaced in quarter sections around the hollow tube  12 . In  FIG. 7C , six longitudinal slots  50  are equally spaced in sixth sections around the hollow tube  12 . In  FIGS. 5 and 6 , the longitudinal slots  50  are positioned as shown in  FIG. 7A . 
     As illustrated in  FIG. 6 , the gear  14  is molded into slots  50  of gear molding feature  28 . The gear  14  may be molded to the hollow tube  12 , for example, by surrounding the hollow tube  12  with a mold having the appropriate shape of the gear  14 , and then injecting liquid plastic or another material for the gear  14  into the mold. As liquid material is injected into the mold, it migrates into the slots  50 , causing the slots  50  to fill with the same material used to mold the gear  14 , increasing the adherence strength of the gear  14  once the liquid material hardens. A pin may be inserted into the hollow tube  12  to prevent the liquid plastic from flowing into the hollow tube  12 . If plastic forms inside the passageway  24 , it may prevent effective removal of tissue that is pulled through the passageway  24  with vacuum. 
       FIGS. 8 and 9  show a third embodiment of a gear molding feature  28 . In  FIGS. 8 and 9 , the gear molding feature  28  includes a knurled surface  61  created by at least one radial indention  60  extending into the outer surface  18 , wherein the depth of the at least one radial indentation  60  is less than the thickness of the hollow tube  12  between the inner surface  16  and the outer surface  18 , with the at least one radial indentation  60  not passing through the entire thickness of the hollow tube  12  to the passageway  24 . In an embodiment, the at least one radial indentation extends into the outer surface  18  about 50% or less of the entire thickness of the hollow tube  12  between the inner surface  16  and the outer surface  18 . In the illustrated embodiment, five radial indentations  60  are shown, but those of ordinary skill in the art will recognize that more or less may be used. Additionally, the illustrated embodiment shows each radial indentation  60  encircling the entirety of the hollow tube  12 , but those of ordinary skill in the art will recognize that the radial indentions may instead only partially encircle the hollow tube  12 , for example, by extending about 25%, 50% and/or 75% around the outer surface of the hollow tube  12 . 
     In the illustrated embodiment, the radial indentations  60  are each between 0.4 mm and 0.6 mm in width parallel to longitudinal axis  13 , and are spaced apart by 0.8 mm to 1.2 mm parallel to longitudinal axis  13 . In the illustrated embodiment, the radial indentations are equidistant from each other, but they may also be spaced at varying distances. Those of ordinary skill in the art will recognize alternative configurations which may be used. 
     As illustrated in  FIG. 9 , the gear  14  is molded into the radial indentations  60  of the knurled surface  61  of the gear molding feature  28 . The gear  14  may be molded to the hollow tube  12 , for example, by surrounding the hollow tube  12  with a mold having the appropriate shape of the gear  14 , and then injecting liquid plastic or another material for the gear  14  into the mold. As liquid material is injected into the mold, it migrates into the radial indentations  60  of the knurled surface  61 , causing the radial indentations  60  to fill with the same material used to mold the gear  14 , thereby increasing the adherence strength of the gear  14  once the liquid material hardens. A pin may be inserted into the hollow tube  12  to prevent the liquid plastic from flowing into the hollow tube  12 . If plastic forms inside the passageway  24 , it may prevent effective removal of tissue that is pulled through the passageway  24  with vacuum. 
       FIG. 10  illustrates a method  100  of manufacturing a scalpet  10  as illustrated in  FIGS. 1 to 9 . Those of ordinary skill in the art will recognize that additional steps may be added, or the illustrated steps may be omitted in some circumstances. 
     At step  102 , a hollow tube  12  is obtained. The hollow tube  12  may be machined to create a passageway  24  and/or the cutting edge  26 , or these elements may already be provided with the hollow tube  12 . The hollow tube  12  may be formed of metal, for example, SAE  304  stainless steel tubing, which may be formed, for example, by extruding the metal through a die or by welding a flat piece of metal into a tube. In an embodiment, the hollow tube  12  may be formed to be about 29.5 mm along its longitudinal axis  13 , and may be formed with a passageway  24  of about 1.5 mm in diameter and a hollow tube  12  thickness of about 1.83 mm, but those of ordinary skill in the art will recognize that other dimensions may be used. In an embodiment, the hollow tube  12  may be provided without additional machining necessary to complete step  102 . In an embodiment, hollow tube  12  may be an injection molded part. In an embodiment, the hollow tube  12  may be 3D printed, for example, using plastic or metal, for example, molten metal. 
     At step  104 , at least one gear molding feature  28  is machined into hollow tube  12 . The gear molding feature  28  may include, for example, an aperture  40 , slot  50  and/or indentation  60  discussed above. The gear molding feature  28  may be machined into hollow tube  12 , for example, by drilling partially or fully into the outer surface  18  of hollow tube, for example, at an angle perpendicular to the longitudinal axis  13 . 
     At step  106 , gear  14  is molded to hollow tube  12  at gear molding feature  28 . Gear  14  may be molded to hollow tube  12 , for example, by surrounding hollow tube  12  with a mold having the appropriate shape of gear  14 , and then injecting liquid plastic or another material for gear  14  into the mold. As liquid material is injected into the mold, it migrates into the gear molding feature  28 , causing the gear molding feature  28  to fill with the same material used to mold the gear  14 , increasing the adherence strength of the gear  14  under longitudinal and/or rotational forces. A pin may be inserted into the hollow tube  12  during injection to prevent liquid plastic from adhering to the inner surface of the tube. 
     At step  108 , the plastic to form the gear  14  hardens. In an embodiment, the plastic for the gear  14  may be injected at high pressure and temperature so that it cools in an ambient environment to form gear  14 . In an alternative embodiment, the liquid material for gear  14  may be cured, for example, by applying heat or light to the material. Upon curing, the liquid material may harden, creating portions of gear  14  which project into outer surface  18  of hollow tube  12 , which strengthen the bond between hollow tube  12  and gear  14 , increasing the resistance of gear  14  to longitudinal and/or rotational forces. 
     In an alternative embodiment, the entire scalpet  10  may be an injection molded part. In an alternative embodiment, the entire scalpet  10  may be 3D printed, for example, using plastic or metal, for example, molten metal. 
       FIG. 11  illustrates an example embodiment of a device including plurality of scalpets  10  arranged with interacting gears  14  which cause the scalpets  10  to rotate simultaneously. In the illustrated embodiment, a central rod or tube  70  rotates a plurality of scalpets  10 . In another embodiment, a gearing mechanism may rotate one or more scalpet  10 , which may simultaneously cause additional scalpets  10  or other elements to rotate. In an embodiment, the device shown in  FIG. 11  may be used in a rotational fractional resection (“RFR”) device. Those of ordinary skill in the art will recognize additional methods to utilize the present disclosure. 
     It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.