Patent Publication Number: US-2020275950-A1

Title: Perforating trocar

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/434,157, filed Apr. 8, 2015 and titled PERFORATING TROCAR, which is a National Phase Application of PCT/FR2014/051346, filed on Jun. 5, 2014 and titled Trocart Perforant, which claims priority to French Patent Application No. 1356391, filed Jul. 1, 2013 and titled Trocart Perforant, each of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a device that can be used in surgery and in interventional radiology, and more particularly to a perforating trocar that can be used especially in the field of percutaneous procedures for bone or marrow biopsy, vertebroplasty, cementoplasty of the skeletal areas, and more generally the treatment of bone damage. 
     DESCRIPTION OF RELATED ART 
     Various types of perforating trocars are known, which are surgical instruments used to drill bone in order to reach a zone where a bone biopsy is to be performed. These trocars are composed of a hollow outer tube, of which the end is more or less sharp, and of a rod, of which the end is ground in order to perforate the bone and which slides in the tube. 
     Thus, the patent application WO 2006/061514 describes a trocar intended for bone biopsy and comprising an outer tube, of which the distal end is divided into two segments with a helical cutting edge, in which a ground rod slides. This type of instrument is used manually by way of a handle. 
     The U.S. Pat. No. 7,850,620 describes a trocar intended for bone marrow biopsy and composed of an outer tube, of which the distal end has a traditional grinding for this type of instrument, combined with a ground rod. This instrument is used by coupling it to a drill. 
     The patent applications US 2003/225411 A1 and US 2009/0204024 A1 concern trocars intended for bone marrow biopsy. These trocars each have a rod with a notch permitting the removal of pieces of bone and of tissue. The U.S. Pat. No. 6,575,919 B1 describes a trocar with an inner opening permitting the passage of a needle. 
     The known perforating trocars are able to drill bone but cannot be guided on a pin at the same time. This shortcoming has two major disadvantages: the lack of precision at the moment of reaching the bone, and the risk of accidents. Percutaneous procedures are mainly performed with imaging and therefore based on images. The point of entry and the trajectory can thus be visualized and defined in advance. The importance of the precision of the point of entry is self-evident in the case of small bone lesions, since these have diameters of sometimes less than a millimetre; matters are of course more difficult when targeting a lesion located within a deep bone. Therefore, in obese patients, it is not uncommon to have to pass through 150 mm to 200 mm of soft tissue before reaching the cortical bone. Under such conditions, it is particularly difficult to keep the trajectory of the trocar, of which the diameter is approximately 2 mm, to within a millimetre. Moreover, there are risks associated with direction introduction of a perforating trocar when this bone is situated in a dense zone comprising organs, veins and nerves. Confronted by such situations, the practitioner will accept the need to perform more manoeuvres and will first of all manually insert a thin and minimally invasive rigid pin, which will serve as a guide for the various coaxial trocars and instruments in the course of the surgical procedure. 
     Perforated drill-bits are also known which are used in orthopaedics and which can drill the bone while being guided on a pin. However, these drill-bits are not used, or not often used, in a percutaneous procedure, even less so when the latter is performed manually. The use of these drill-bits requires that a pin first be inserted into the bone by means of a drill. This is because these drill-bits do not have a distal tip, since they are perforated all the way through so as to slide on the pin. Therefore, in the absence of an inserted pin, they risk sliding on the bone and deviating from the point of entry defined by the practitioner. 
     Objects and Summary 
     The present invention relates to a device, in particular for surgery and interventional radiology, which efficiently provides good perforation while at the same time being entirely suitable to be guided on a rigid pin until contact with the bone. The invention also relates to a device with which the practitioner can choose to commence a surgical procedure manually and complete it using an automatic rotational drive means, such as a drill, if the hardness of the bone so demands, and this without losing the point of entry to the bone. 
     The device according to the present invention, in the form of a perforating trocar, comprises an outer sleeve having a rigid tube, and a mandrel having a rod. The rod is suitable for sliding in the outer sleeve and has, at its distal end, a perforating tip. The rod additionally has a longitudinal groove arranged on the surface of the rod, and extending from the distal end to the proximal end of the rod, in order to allow the device to slide on a guide pin. 
     According to an embodiment of the invention, the groove is V-shaped. 
     Preferably, the perforating tip is formed by bevelled grinding or sharpening of the distal end of the rod. According to a preferred variant, the distal end of the rod comprises three bevels, of which one is less inclined than the two others with respect to the axis of the rod, and a perforating tip centred with respect to the axis of the rod. 
     Advantageously, the distal end of the rod comprises at least one cutting ridge extending from the perforating tip to the edges of the rod. According to one embodiment, this cutting ridge is situated on one of the faces of the groove. Preferably, this cutting ridge is more inclined than another cutting ridge with respect to the axis of the rod. 
     The bevelled pyramidal grinding, with the cutting ridge whose angle is greatest with respect to the axis of the rod situated on one of the faces of the longitudinal groove, permits better penetration into the bone. Indeed, tests carried out on the bone marrow of cattle have shown that the tip thus formed penetrates up to 5 times more deeply than a traditional triangular tip. 
     According to a feature of the invention, the distal end of the tube comprises at least two segments with a helically shaped cutting edge. 
     Advantageously, the outer sleeve additionally comprises a connector piece at the proximal end of the tube, and the mandrel additionally comprises a stopper at the proximal end of the rod. The stopper is suitable for receiving the connector piece in order to form an integral assembly. The connector piece is perforated in order to permit the sliding of the rod, and the stopper is perforated in order to permit the sliding of the guide pin. 
     According to some embodiments, the assembly formed by the outer sleeve and the mandrel is mounted in a handle or in an automatic rotational drive means. For example, the automatic rotational drive means can be a drill having an endpiece in which the assembly is mounted. 
     Advantageously, the automatic drive means can be provided with a protective envelope. The protective envelope can, for example, be attached to the endpiece of a drill by means of a connector piece which is at the same time adapted to receive the outer sleeve of the perforating trocar. 
     For example, in the case of a bone lesion located in a dense cortical area, the practitioner, after providing local anaesthesia by conventional techniques, introduces the guide pin parallel to or through the anaesthetic needle in place until contact is made with the bone. The anaesthetic needle is then removed while leaving the guide pin in place. The device according to the invention, equipped with a removable handle, is introduced through the tissues, until in contact with the bone, by being guided on the pin. The pin is removed once the surface of the cortical bone is reached, then the practitioner drills the bone by turning the trocar manually, without losing the point of entry. In 80% to 90% of cases, the drilling will be performed manually, but if the wall of the bone is very hard, the practitioner may remove the removable handle and connect the trocar to a drill in order to complete the surgical procedure. 
     The simplicity of the structure of the device according to the invention means that, depending on the depth or location of the lesion, the user can be provided with a single instrument which permits a choice between a direct route and one guided on the pin, and of which the drilling can be manual or done using the drill, or else can be commenced manually and completed using the drill. The combination of drilling by hand and drilling with a drill permits a high level of precision of the surgical manoeuvre and also considerable power regardless of the hardness of the bone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become clear from the following description of a preferred embodiment and by reference to the attached drawings, in which: 
         FIG. 1  shows a perspective view of a device according to the invention mounted in a handle; 
         FIGS. 2 to 3  show perspective views of a tube of the device according to the invention mounted in a connector piece, forming an outer sleeve; 
         FIGS. 4 to 5  show perspective views of a grooved rod of the device according to the invention mounted in a stopper, forming a mandrel; 
         FIGS. 6 to 9  show views of an example of the distal end of the grooved rod; 
         FIGS. 10 and 11  show views of an example of the distal end of the rod provided with a hole; 
         FIG. 12  shows a perspective view of a handle for receiving the assembly formed by the sleeve and the mandrel of the device according to the invention; and 
         FIG. 13  shows a perspective view of a drill for receiving the assembly formed by the sleeve and the mandrel of the device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The trocar  1 , shown in  FIG. 1 , is composed of an outer sleeve  5 , in which is mounted a mandrel (of which only the distal end of the rod  18  is visible in  FIG. 1 ), and of a handle  2 , in which the sleeve/mandrel assembly is inserted. 
     The outer sleeve  5 , shown in  FIGS. 2 and 3 , has a connector piece  7  in which the bevelled tube  8  is accommodated. The tube  8  has a distal end  9  divided into two segments with a helical cutting edge as described in the application WO 2006/061514. The connector piece  7  has a hexagonal shape cooperating with hexagonal cavities  12  of the handle  2  and hexagonal cavities  13  of the endpiece  3  of a drill  4  (see also  FIGS. 12 and 13 ). The connector piece  7  has a bore  10 , in which the tube  8  is accommodated, and two flexible parts  11  that latch into recesses  14  of the handle  2  or into recesses  15  of the endpiece  3  of the drill  4 . 
     The mandrel  6 , shown in  FIGS. 4  et  5 , comprises a grooved rod  18  accommodated in a stopper  17 . The grooved rod  18  has a V-shaped longitudinal groove  20  and a distal end of pyramidal shape. The stopper  17  has a hexagonal shape cooperating with the hexagonal cavities  12  of the handle  2  and the hexagonal cavities  13  of the endpiece  3  of the drill  4 . The stopper  17  has a bore  45  in which the grooved rod  18  is accommodated, and a bore  41  permitting the passage of the guide pin. 
     The connector piece  7  of the outer sleeve  5  is completely perforated  43  in such a way as to permit the sliding of the rod  18 . The end  16  of the outer sleeve  5  is in the form of a Luer connector permitting the screwing of the stopper  17 . The stopper  17  has a thread  46  cooperating with the thread  16  of the connector piece  7 , allowing it to be screwed in order to assemble the outer sleeve  5  and the mandrel  6 . 
       FIGS. 6 to 9  shows views of an example of the distal end of the rod  18 . The distal end of the rod  18  comprises a tip  21  having a pyramidal grinding with three bevels. Two of the bevels  22 ,  23  have the same inclination (β 3 ), preferably β 3 =30°, with respect to the axis of the rod  18  and extend through approximately 120° of the cross section of the rod  18 , generating a cutting ridge  24 . The third bevel  25 , inclined preferably by β 1  and at 40° with respect to the axis of the rod  18 , generates a second cutting ridge  26 . The second cutting ridge  26  is situated on one of the faces of the groove  20  and has an inclination β 1  greater than the inclination β 2  of the ridge  24  with respect to the axis of the rod  18 . This permits better cutting of the bone since the second cutting ridge  26  has a greater angle of attack, generated by one of the faces of the groove  20 . The inclination β 1  of the cutting ridge  26  is greater than the inclination β 2  of the cutting ridge  24  and than the inclination  134  of the other cutting ridge  28  situated on the other face of the longitudinal groove. The intersection of the three bevels generates the tip  21  allowing the mandrel  6  not to slide on the bone. 
     The views in  FIGS. 10 and 11  show a distal end of the rod  18  according to a variant. The rod  18  has, centred on its axis, a hole  34  allowing it to be guided on a pin. The distal end of the rod  18  has a pyramidal grinding with three bevels of the same inclination, of which one bevel  31  is greater than the other two bevels  32 , in such a way as to generate a tip  33  situated on the edge of the hole  34 . 
     The perspective view in  FIG. 12  shows the handle  2  with a hexagonal cavity  12  in which is mounted the outer sleeve  5  equipped with the mandrel  6 . The flexible parts  11  of the connector piece  7  latch into the recesses  14  provided for this purpose. 
     The perspective view in  FIG. 13  shows a drill  4  on which is mounted the endpiece  3  having a hexagonal cavity  13 , for the assembly of the outer sleeve  5  equipped with the mandrel  6 , and recesses  15  in which the flexible parts  11  of the connector piece  7  latch. 
     Referring to  FIGS. 2, 3, 12 and 13 , the chamfer  35  of the connector piece  7  of the outer sleeve  5  cooperates with the chamfers  36  of the handle  2  and the chamfers  37  of the endpiece  3  of the drill  4  in such a way as to reduce play during the drilling of the bone.