Abstract:
A surgical device ( 1 ) for bone surgery including a body ( 2 ) able to be gripped by the user and a tip ( 3 ) mounted at the head of the body and set in vibration at a modulated ultrasonic frequency to operate on bone tissue, the surgical device ( 1 ) being particularly suitable for oral surgical procedures such as bone sampling, excision of cysts, third molar extraction, preparation of alveolar sites, creation of an opening into the maxillary sinus (Caldwell Luc), elevation of the maxillary sinus by the crestal route and orthopedic and neurosurgical procedures such as osteoplasty, ostectomy and osteotomy.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 10/716,437 filed on Nov. 20, 2003 (now abandoned); which is a divisional of U.S. patent application Ser. No. 09/740,937 filed on Dec. 21, 2000 (now U.S. Pat. No. 6,695,847); which claims priority to European Patent Application Serial No. 99830784.7 filed on Dec. 21, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present invention refers to a surgical device and method for bone surgery. The device is particularly suitable, for example, for orthopedic surgical procedures such as osteotomy, ostectomy, osteoplasty etc. and for oral surgical procedures such as excision of cysts, third molar extraction, preparation of implant sites, creation of an opening into the maxillary sinus and elevation of the endosteum. 
     BACKGROUND 
     Bone surgery operations that involve cutting of the bony tissue (osteotomy) and/or modeling thereof (osteoplasty) have hitherto been performed with manual and/or rotary instruments. Manual instruments consist of scalpels and/or chisels operated by hand or with a mallet. Rotary instruments consist of motor-driven milling cutters or disks. 
     These methods both have serious limitations if they have to be used in difficult situations such as restricted surgical access, anatomically difficult bone conditions and particularly when it is necessary to operate in the vicinity of soft tissue. 
     The cutting characteristics of the techniques currently in use are unsatisfactory for the following reasons:
         the cutting depth is poorly controlled;   the mechanical force is often excessive, therefore cutting directionality is lost and/or accidental fractures are caused; and   cutting is not selective and can therefore damage the soft tissue (for example the vascular nerve bundles).       

     SUMMARY 
     The object of the invention is to eliminate these drawbacks by providing a surgical device for bone surgery that makes it possible to perform surgical procedures with the utmost precision and therefore with less risk. 
     Another object of the present invention is to provide such a surgical device for bone surgery that is practical and versatile. 
     Another object of the present invention is to provide such a device for bone surgery that is capable of cutting the mineralized bone tissue without causing cuts and lesions in the soft tissue, and particularly in the neurovascular structures. 
     Another object of the present invention is to provide a surgical method for bone surgery that is most accurate, efficient and with less risk for the patient. 
     Preferred embodiments of the invention will be apparent from the claims. 
     The surgical device for bone surgery according to the invention provides a handpiece comprising a tip capable of operating on bone tissue. For this purpose, according to requirements, various tips such as chisels, compressors, osteotomes, periosteal or endosteal elevators etc. can be mounted on the handpiece. 
     The handpiece comprises a transducer, which can be piezoceramic, for example, and serves to generate sound waves that set the tip in vibration. The tip is made to vibrate at a frequency within the sonic and ultrasonic range so that when it comes into contact with the mineralized bone tissue an extremely fine and precise cut is made in said tissue. Compression, compaction and displacement of said tissue is also possible according to surgical requirements. 
     The surgical device according to the invention can be equipped with a console which provides for the electrical and hydraulic supply to the handpiece. The console has a keyboard that can be operated by the operator to control the control electronics of the handpiece. 
     The control electronics allow the handpiece to be operated with sonic and/or ultrasonic vibrations, modulated or not at low frequency or with low frequency bursts. In this manner the user can modulate the ultrasound pulses to be transmitted to the tip of the handpiece according to the requirements of the surgical procedure. 
     The surgical device for bone surgery according to the invention has various advantages. 
     With the surgical device for bone surgery according to the invention, the cutting action on the bone tissue is produced by variable modulation ultrasonic vibrations that are activated only on the cutting end of the tip that comes into contact with the mineralized tissue to be cut. Consequently, the bone tissue surface affected by the action is extremely small. This allows the surgeon to draw the ideal type of procedure that he intends to carry out on the bone tissue with extreme precision. Thus, for example, the actual cut made by the tip will differ minimally from the ideal cut planned beforehand by the surgeon. 
     Another advantage of the surgical device according to the invention is provided by the fact that, since the cut is extremely fine, the trauma suffered by the bone tissue due to the friction of the cutting instrument and the resulting heat loss will be minimal. 
     Furthermore, when the vibrating tip encounters soft tissue, such as a neurovascular structure, it loses its cutting capacity. In fact the soft tissue absorbs the vibrations of the tip without being resected and the energy caused by the vibrations of the tip is dissipated in the form of a slight heat. This can be further reduced by the surgeon&#39;s promptness in withdrawing the instrument as soon as he feels that it does not vibrate any more. The transmission of heat into soft tissue, such as neurovascular structures, therefore causes no irreparable damage, as might be that caused by injury or cutting of such structures. 
     Consequently, if during an operation the surgeon touches a neurovascular structure with the tip, he has plenty of time to withdraw the tip without the problem of causing irreparable damage. Thus use of the surgical device according to the invention makes it possible to solve more severe clinical cases of bone surgery in which it is necessary to operate in the vicinity of neurovascular structures. 
     For example, the device according to the invention can be used in oral surgery for the following types of operations:
         bone sampling in anatomically difficult areas, whether for access or because they are near the nerve endings or where there is extremely little bone tissue;   excision of cysts and/or of inflammatory or phlogistic tissue of the third branch of the trigeminal nerve;   extraction of impacted third molars in the vicinity of the dental alveolus;   preparation of an implant site in the vicinity of nerve endings;   creation of an opening into the maxillary sinus (Caldwell-Luc) without damaging the sinusal membrane; and   elevation of the maxillary sinus by the ethmoidal crest route.       

     The device according to the invention can also be used in orthopedic and neurological surgery, in operations such as:
         osteoplasty;   ostectomy; and   osteotomy in the vicinity of neurovascular structures as is the case, for example, in vertebral surgery.       

     Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non limiting embodiment thereof, illustrated in the appended drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an axonometric view of a surgical device for bone surgery according to the invention, complete with equipment for operation thereof; 
         FIG. 2  is a block diagram illustrating operation of the surgical device according to the invention; 
         FIG. 3  is an axial section of the surgical device in  FIG. 1 , with a connector element and a tip exploded; 
         FIG. 4  is a plan view showing five types of osteotomy tips; 
         FIGS. 5   a ,  5   b  and  5   c  show respectively three different types of chisel insert and each figure shows a side view, a plan view and a view from the other side; 
         FIG. 6  shows respectively a side view, a plan view and a view from the other side of a compressor tip; 
         FIGS. 7   a  and  7   b  show two different types of universal tip and each figure shows a plan view and a view from the right side, respectively; 
         FIG. 8  shows respectively a side view, a plan view and a view from the other side, of a periosteal elevator; 
         FIGS. 9   a  and  9   b  show two different types of endosteal elevator and each figure respectively shows a view from one side, a plan view and a view from the other side; 
         FIGS. 10   a - 10   f  show the various stages of a surgical procedure carried out with the surgical device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     A surgical device for bone surgery according to the invention, indicated as a whole with reference numeral  1 , is described with the aid of the figures. As shown in  FIG. 1 , the surgical device  1  is a handpiece comprising a body  2 , substantially cylindrical in shape so that it can be easily gripped by a surgeon. On the head of the body  2  is mounted a tip  3  having a suitable shape for the various types of bone surgery operations for which the handpiece is intended, as will be described below. 
     The body  2  of the handpiece is connected to an external connector element  4 . The external connector  4  carries two electrical supply cables  5  and  6  and a first hydraulic supply tube  7  which are wrapped inside a sheath  8 . The connector  4  also carries a second hydraulic supply tube  9 . 
     The electrical supply cables  5  and  6  are connected to a console  10  that takes its electrical supply from the supply mains or has an independent supply system. The first hydraulic supply tube  7  is connected to a hydraulic supply system, which can be provided in the console  10  or in a separate hydraulic system. The second hydraulic supply tube  9  is connected to a peristaltic pump  11  provided on the console  10 . 
     The peristaltic pump  11  comprises a rotor  12  with a controlled speed of rotation so as to be able to vary the flow rate of the fluid sent, by means of the second tube  9 , to the handpiece  1 . 
     The console  10  provides a housing  13  in which the handpiece  1  is positioned and a supporting rod  14  that supports a container  15 , which can be a bottle or a bag, for example, which contains a sterile fluid that must be used during the surgical procedure to bathe the surgically treated area. The tube  9  passes inside the peristaltic pump  11  and is inserted in the container  15  through an outlet  80 . The sterile fluid from the container  15  is sent through the tube  9  to the peristaltic pump  11  which in turn feeds the sterile fluid toward the handpiece  1 . The tube  9  and the outlet  80  of the container  15  can be supplied in sterile disposable packages. 
     On the console  10  a control keyboard  17  that can be operated by the operator to control the microprocessor control unit  10  provided inside the console  10 . With reference to  FIG. 2 , the electrical supply taken from the electrical supply mains  21  is sent to a power supply  22  provided inside the consol  10 . The power supply  22  provides electrical power to the microprocessor unit  20 , to a power stage  23  and to a control unit  24  of the peristaltic pump  11 . 
     The power stage  23  is able to generate an adequate output current and voltage signal to supply the handpiece  1 . The control unit  24  of the peristaltic pump  11  gives out a control signal to operate the rotor  12  of the peristaltic pump  11  so as to feed the sterile fluid from the container  15  toward the handpiece  1 . 
     The keyboard  17  generates control signals S 1  toward the input of the microprocessor unit  20 . The microprocessor unit  20 , on the basis of the control signals S 1  received, sends out output control signals S 2  and S 3  respectively toward the power stage  23  and the control unit  24  of the peristaltic pump  11 . 
     The power stage  23 , on the basis of the control signal S 2  received, sends the electrical supply to the handpiece  1 . The control unit  24  of the peristaltic pump  11 , on the basis of the control signal S 3  received, regulates the speed of the rotor  12  of the peristaltic pump  11 . 
     With reference to  FIG. 3 , the external connector element  4  provides two electrical contacts  30  and  31  connected to respective wires  5  and  6  of the electrical power supply. Furthermore the connector element  4  provides a hydraulic duct  32  connected to the hydraulic supply tube  7 . The tube  9  can be clipped to the sheath  8  by means of a band  33 . The external connector element  4  is destined to be inserted into a complementary connecting element  40  provided in the rear part of the handpiece  1 . 
     The connector  40  provides two electrical contacts  41  and  42  destined to come into contact with the contacts  30  and  31  of the connector  4 . The connector  40  also provides two ducts  43  and  44  for the hydraulic supply of the handpiece that couple respectively with the duct  32  of the connector  4  and the tube  9 . The duct  43  is stopped and serves to confine any fluid coming from duct  32  of the connector. The handpiece is supplied by the fluid through the tube  9  which is inserted into the connector of the duct  44 . 
     The electrical contacts  41  and  42  are connected respectively to electrical wires  45  and  46  which carry the electrical supply to a transducer  47 . The transducer  47  is a piezoceramic resonator which must be supplied with alternating voltage and current. The transducer  47  is preferably supplied with a sinusoidal voltage of about 160 V r.m.s. at a frequency ranging between 25 and 30 kHz. 
     To obtain this type of electrical supply, the console  10  has the power supply  22  and the power stage  23  which act as an electrical transformer, transforming the line voltage from supply mains into a sinusoidal voltage of about 160 r.m.s. at a frequency ranging between 24 kHz and 30 kHz. 
     The transducer  37 , when it is supplied electrically, acts as a sound wave concentrator and sets a tang  48  provided in the head of the handpiece  1  in vibration at an ultrasonic frequency. The tang  48  has a threaded attachment  39  for engagement in a threaded seat  50  of the tip  3 . Thus the ultrasonic vibrations are transmitted from the tang  48  to the tip  3 . 
     The microprocessor unit  20  of the console  10 , through the control signal S 2  controls the power stage  23  so as to allow different operating modes for supplying the transducer  47 . In this manner the tip  3  can be set in vibration with ultrasound alone, with ultrasound modulated at low frequency (6-40 Hz), or with a series of low frequency bursts. 
     This method, which adopts modulation of the vibration of the tip  3 , allows the heat that develops on the soft tissue to be minimized because of the dissipation of energy due to the vibration of the tip. 
     The method that provides for use of modulated ultrasound in low frequency bursts with a variable duty cycle, makes it possible to have a hammering effect of the tip, combined with the ultrasonic vibration efficiency which produces a clean, precise cut in mineralized tissue. 
     The microprocessor unit  20  is able to perform various functions:
         control of the power stage  23 ;   automatic tuning of the ultrasound that acts on the particular tip  3  used;   setting of the modulation, that is of the duration and frequency of the bursts; and   operation with bursts of increasing or decreasing amplitude.       

     For these purposes the microprocessor unit  20  has a series of pre-set software programs for use with particular types of tips and in particular clinical setting. These software programs can be updated or other software programs can be stored in the console  10  to make possible applications tested at a later date. Furthermore the user can set operating parameters of his own choice through the control keyboard  17  and store them in the console  10  for subsequent applications. 
     The hydraulic duct  44  of the connector  40  communicates with a chamber  52  in turn communicating with a duct  53  provided inside the body of the handpiece. The duct  53  is connected to a tube  54  that carries the fluid toward a duct (not shown) inside the tang  48 . From the duct inside the tang  48  the fluid spreads into the seat  50  of the tip  3  and through a duct  55  made in the tip  3  it flows toward the outside. In this manner the fluid can irrigate the tissue on which the tip is working, minimizing the operating temperatures due to friction between the tip and the tissue. 
     In  FIGS. 4-9  various types of tips that can be used in the handpiece according to the invention are shown. In these figures the same reference numerals indicate the same or equivalent parts. Each tip provides a seat  50  able to engage with the threaded attachment  49  provided in the handpiece  1 . The seat  50  is connected to a stem  60  having an axis substantially parallel to the axis of the handpiece  1 . The stem  60  ends in an elbow part  61  connected to the head  62  of the handpiece. 
       FIG. 4  shows five osteotome tips denoted by the abbreviations OST 1 , OST 2 , OST 3 , OST 4 , and OST 5 . These tips show a head  62  with a very wide blade  63  used for bone resection. The blade  63  must in fact cause a fracture, breaking the continuity of the skeletal segment without causing removal of bone tissue. 
       FIGS. 5   a - 5   c  show three chisel-type tips denoted by the initials T 1 , T 2  and T 3 . The chisel tips have a thinner blade  64  that the blade  63  of the osteotomes. In fact the chisel tip is intended for operations in which a very fine, precise cut in the bone tissue is required. For this purpose the blade  64  of the chisel-type tip can have a diamond surface for greater cutting efficiency. 
       FIG. 6  shows a compressor-type tip is denoted by the initials CP 1 . This tip has a flattened part  65  in the head to compress the bone tissue. 
       FIGS. 7   a  and  7   b  show two universal tips denoted by the initials U 1  and U 2  which can be used for various types of operation. 
     In  FIG. 8  SP 1  denotes a periosteal elevator tip. This tip has a spoon-shaped head  66  to detach the bone from the membrane (periosteum) surrounding it. 
       FIGS. 9   a  and  9   b  show two endosteal elevators denoted by the initials SE 1  and SE 2 . These tips have a spoon-shaped head  67  smaller in size than the spoon-shaped head  66  of the periosteal elevator. In fact the endosteal elevator must remove the connective tissue (endosteum) that lines the bone cavities. 
     A surgical technique using the surgical device  1  according to the invention is described with the aid of  FIGS. 10   a - 10   f . By way of example a surgical procedure for implantation on an edentulous ridge is described. 
     In  FIG. 10   a  an edentulous ridge  100  is shown at the beginning of the surgical procedure. The thickness of the edentulous ridge  100 , measured with a periodontal probe  101 , ranges from 2.2 to 2.8 mm. For edentulous ridges with such a small thickness an operation with the instruments of the prior art such as cutters or chisels is impossible or extremely difficult. 
       FIG. 10   b  shows a side view of the edentulous ridge  100  of  FIG. 1 . This Figure was taken during the surgical operation and shows the type of mucous flap of mixed thickness of the edentulous ridge  100 .  FIG. 10   b  shows a type T 2  chisel-type tip driven by means of the ultrasound handpiece  1  according to the invention. 
       FIG. 10   c  shows the edentulous ridge  100  after the T 2  chisel tip has drawn a horizontal crestal incision  103  with two releasing incisions, one mesial and the other distal. In this figure it can be seen that the cut made by the T 2  tip is extremely precise and fine. 
       FIG. 10   d  shows the edentulous ridge  100  after passage of a second type of chisel tip, V 2 , again mounted on the handpiece  1  according to the invention and operated by ultrasound. The V 2  tip has a widened point to separate the vestibular cortical bone wall from the palatal one, according to the bone flap surgical technique. 
       FIG. 10   e  shows edentulous ridge  100  after two implant sites  104  with a diameter of 2 mm have been created on the bottom of the horizontal crestal incision  103 . It has been possible to create implant sites  104  with such a small diameter, using an osteotome tip of the OST 1  type described with reference to  FIG. 4 . The OST 1  tip has been mounted on the handpiece  1  and operated by ultrasound. 
       FIG. 10   f  shows the edentulous ridge  100  three months after the implant. Two implants  105  are visible which have been placed in the respective implant sites  104 , in the position for grafting bone material between the cortical walls. The perfectly mineralized bone ridge is visible and, after measurement with the probe  101 , it has been possible to detect an increase in the thickness of the bone ridge which has grown from about 2.5 to 5 mm. 
     The surgical device according to the invention can be used for maxillo-facial and otorhino-laryngol surgical procedures. 
     The surgical device according to the invention can be used for vertebral laminectomy treatments. 
     The surgical device according to the invention can be used for hand and foot bone surgery.