Abstract:
A fixation device, such as a bone screw, includes a bioresorbable proximal shaft portion and a non-bioresorbable distal threaded portion. In one aspect, the shaft portion is provided with a longitudinal throughbore which is aligned with a corresponding longitudinal bore in the proximal region of the threaded portion. A driver mechanism is employed to impart a rotary force so as to enable the device to be inserted into bone tissue. Afterwards, the driver mechanism is withdrawn from the respective bores. In another aspect, the non-bioresorbable distal portion is a substantially elongated solid member and includes a threaded distal region and a shaft-like proximal region. The comparatively smaller bioresorbable proximal region can mate with the distal portion either after or before the distal portion has been inserted into the bone tissue.

Description:
BACKGROUND 
     The present invention relates generally to bioresorbable devices, and more particularly, to new and improved bone screws having bioresorbable shaft portions and non-resorbable threaded portions, wherein specially adapted driver mechanisms are capable of delivering a torque force about the non-resorbable threaded portion during insertion of the bone screw into bone tissue, thus eliminating, or at least lessening, the torque stresses at the bioresorbable shaft portion/non-resorbable threaded portion junction. Additionally, different sizes of bioresorbable shaft portions, non-resorbable threaded portions, and driver mechanisms may be incorporated into a kit system. 
     Bone screws are generally defined as a threaded device which is inserted into bone tissue. The intended function of bone screws is to immobilize bones or bone fragments or to affix other orthopedic devices, such as metal bone plates or bone rods, to, or within, bones. Although bone screws are typically comprised of metallic materials (e.g., stainless steel, titanium, cobalt-chrome alloys, and the like), they may also be comprised of other materials, such as bioresorbable materials (e.g., hydroxyapatite, poly-lactic acid, poly-glycolic acid, and the like). The terms “bioresorbable,” “biodegradable,” “absorbable,” and “bioabsorbable” are used interchangeably herein. 
     The use of bioresorbable bone screws in connection with the treatment of various bone defects, such as fractures, and the like, is fairly well known in the art. These bioresorbable bone screws have enabled the medical community to achieve excellent surgical results, even under difficult clinical conditions. 
     The main benefit of using bioresorbable devices is that the devices resorb into the body over a generally predictable time period once a sufficient level of healing has occurred, for example, at the junction of a bone fracture, thus negating the need for subsequent removal of the device. By having the device resorb, the likelihood of osteolysis, stress fractures, and inflammatory immune system responses are greatly reduced. For example, a protruding head portion of a metallic bone screw may occasionally cause irritation of the surrounding skeletal tissues at the insertion site. 
     One resorbable material of particular interest is marketed by Biomet, Inc. (Warsaw, Indiana) under the tradename LACTOSORB®. LACTOSORB® is an absorbable co-polymer synthesized from all-natural ingredients: 82% L-lactic acid and 18% glycolic acid, unlike the homopolymers in common use such as 100% poly-L-lactic acid (PLLA) or 100% poly-glycolic acid (PGA), LACTOSORB® copolymer is substantially amorphous (i.e., without crystallinity), meaning that its degradation is uniform, precluding the crystalline release associated with degrading copolymers that have been associated with late inflammatory reactions. Furthermore, the LACTOSORB® copolymer ratio permits the polymer to retain most of it&#39;s strength for six to eight weeks, which is appropriate for healing, but not so long as to raise concerns about long-term stress shielding of bone. 
     Examples of surgical devices comprised of bioresorbable materials can be found with reference to the following U.S. Patents: 
     U.S. Pat. No. 5,695,497 to Stahelin discloses a screw made of biodegradable material for bone surgery purposes, wherein the outer surface of the screw body is provided with a coaxial external thread. A coaxial channel of saw-toothed star-shaped transverse cross-sectional profile is provided in the screw body, which channel is open at the proximal end in order to receive the complementary shaft of a screwdriver, and extends into the area of the distal end. 
     U.S. Pat. No. 6,096,060 to Fitts et al. disclose a bioabsorbable soft tissue anchor system comprising a cannulated soft tissue anchor for being turned through soft tissue, and a driver for driving the anchor and method for attaching soft tissue at a selected site of implantation. The soft tissue anchor is an elongated unitary body having a threaded distal section, a non-threaded proximal section, a transverse proximal head and a non-circular axial throughbore. The anchor is used with a driver having a driving shaft with a pointed tip and a cross-section adapted to engage the anchor&#39;s axial throughbore. The driving shaft is longer than the anchor so that the anchor may be placed on the shaft leaving the tip exposed to permit tissue to be pierced and placed adjacent a pre-formed hole at the site of implantation. Simultaneous pushing and turning of the driver will advance the anchor through the tissue and into the pre-formed hole. 
     Recently, there has been increased interest in employing bone screws, and other surgical devices, that are comprised of both metallic and bioresorbable portions, in order to take advantage of the respective merits of each type of material. 
     U.S. Pat. No. 5,522,817 to Sander et al. disclose a self-inserting absorbable orthopedic fixation device having a bioabsorbable fastening body portion for fastening body tissue, and having bone penetrating elements such as hard, pointed tips for penetrating bone or hard tissue fixed thereto. The pointed tips may be fabricated from metals or ceramics. The fixation device may be in the form of staples, pins, screws, and the like. The two components may be provided with mating surfaces (e.g., threaded external surface and threaded internal surface, lip and groove, and the like) that allow the two components to be simultaneously driven into tissue. 
     The main disadvantage of the this type of fixation device is that application of a rotary force (e.g., during insertion into bone tissue) produces a significant amount of torque at the bioresorbable portion/non-bioresorbable portion junction or interface. This torque force can potentially lead to failure of the fixation device, especially at the bioresorbable portion/non-bioresorbable portion junction or interface. The surgeon would then be required to retrieve the various pieces of the fixation device from the patient&#39;s body, if possible, and attempt another fixation procedure. 
     Therefore, there exists a need for a fixation device, such as a bone screw, wherein the device can be provided with a proximal bioresorbable shaft portion and a distal non-bioresorbable threaded portion, wherein a driver mechanism is capable of delivering a torque force about the non-resorbable threaded portion during insertion of the bone screw into bone tissue, thus eliminating, or at least lessening, the torque stresses at the bioresorbable shaft portion/non-resorbable threaded portion junction. There also exists a need for a kit having different sizes of bioresorbable shaft portions, non-resorbable threaded portions, and driver mechanisms. 
     SUMMARY OF THE INVENTION 
     In accordance with a first embodiment of the present invention, an orthopedic fixation system is provided, comprising a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The second member is substantially elongated with respect to the first member. The distal region of the second member is provided with an external threaded surface thereon. 
     In accordance with a second embodiment of the present invention, an orthopedic fixation system kit is provided, comprising a receptacle. The receptacle contains a plurality of first members comprised of a bioresorbable material and each having a different size, each of the first members having a distal and proximal region and a plurality of second members comprised of a non-resorbable material and each having a different size, each of the second members having a distal and proximal region. The distal region of each first member is adapted to selectively mate with the proximal region of each second member that has a corresponding size. The second member is substantially elongated with respect to the first member. The distal region of the second member is provided with an external threaded surface thereon. 
     In accordance with a third embodiment of the present invention, a method of affixing an orthopedic device to bone tissue is provided, comprising providing a fixation device, including a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The second member is substantially elongated with respect to the first member. The distal region of the second member is provided with an external threaded surface thereon. Also provided is a driver member adapted to be engaged by either the first member or the second member. A rotary force is applied to the driver member so as to cause either the first member or the second member to be inserted into the bone tissue such that either the first member or the second member is brought into abutting engagement with the bone tissue. 
     In accordance with a fourth embodiment of the present invention, a method of joining two bone fragments is provided, comprising providing a fixation device, including a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The second member is substantially elongated with respect to the first member. The distal region of the second member is provided with an external threaded surface thereon. Also provided is a driver member adapted to engage either the first member or the second member. A rotary force is applied to the driver member so as to cause either the first member or the second member to be inserted into at least one of the bone fragments so as bring both of the bone fragments together into abutting engagement. 
     In accordance with a fifth embodiment of the present invention, an orthopedic fixation system is provided, comprising a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The first member is provided with a throughbore extending along a longitudinal axis thereof. The second member is provided with a bore extending from the proximal region towards the distal region thereof. The second member is provided with an external threaded surface thereon. 
     In accordance with a sixth embodiment of the present invention, an orthopedic fixation system is provided, comprising a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The first member is provided with a throughbore extending along a longitudinal axis thereof. The second member is provided with a bore extending from the proximal region towards the distal region thereof. The second member is provided with an external threaded surface thereon. A driver member is adapted to be received simultaneously within the throughbore of the first member and the bore of the second member. 
     In accordance with a seventh embodiment of the present invention, an orthopedic fixation system kit is provided, comprising a receptacle. The receptacle contains a plurality of first members comprised of a bioresorbable material and each having a different size, each of the first members having a distal and proximal region, and a plurality of second members comprised of a non-resorbable material and each having a different size, each of the second members having a distal and proximal region. The distal region of each first member is adapted to selectively mate with the proximal region of each second member that has a corresponding size. Each first member is provided with a throughbore extending along a longitudinal axis thereof. Each second member is provided with a bore extending from the proximal region towards the distal region thereof. Each second member is provided with an external threaded surface thereon. The kit also contains at least one driver member adapted to be received simultaneously within the throughbore of each first member and the bore of each second member. 
     In accordance with an eighth embodiment of the present invention, a method of affixing an orthopedic device to bone tissue is provided, comprising providing a fixation device. The fixation device includes a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The first member is provided with a throughbore extending along a longitudinal axis thereof. The second member is provided with a bore extending from the proximal region towards the distal region thereof. The second member is provided with an external threaded surface thereon. Also provided is a driver member adapted to be received simultaneously within the throughbore of the first member and the bore of the second member. A rotary force is applied to the driver member so as to cause the fixation device to be inserted into the bone tissue such that the orthopedic device is brought into abutting engagement with the bone tissue. 
     In accordance with a ninth embodiment of the present invention, a method of joining two bone fragments is provided, comprising providing a fixation device. The fixation device includes a first member comprised of a bioresorbable material, the first member having a distal and proximal region, and a second member comprised of a non-resorbable material, the second member having a distal and proximal region. The distal region of the first member is adapted to selectively mate with the proximal region of the second member. The first member is provided with a throughbore extending along a longitudinal axis thereof. The second member is provided with a bore extending from the proximal region towards the distal region thereof. The second member is provided with an external threaded surface thereon. Also provided is a driver member adapted to be received simultaneously within the throughbore of the first member and the bore of the second member. A rotary force is applied to the driver member so as to cause the fixation device to be inserted into both of bone fragments so as bring both of the bone fragments together into abutting engagement. 
     A more complete appreciation of the present invention and its scope can be obtained from the following detailed description of the invention and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 illustrates an exploded view of an orthopedic fixation system, in accordance with one embodiment of the present invention; 
     FIG. 2 illustrates a top plan view of the proximal portion of the orthopedic fixation system depicted in FIG. 1, in accordance with one embodiment of the present invention; 
     FIG. 3 illustrates a bottom plan view of the proximal portion of the orthopedic fixation system depicted in FIG. 1, in accordance with one embodiment of the present invention; 
     FIG. 4 illustrates an elevational view of the proximal portion of the orthopedic fixation system depicted in FIG. 1, in accordance with one embodiment of the present invention; 
     FIG. 5 illustrates a top plan view of the distal portion of the orthopedic fixation system depicted in FIG. 1, in accordance with one embodiment of the present invention; 
     FIG. 6 illustrates a bottom plan view of the distal portion of the orthopedic fixation system depicted in FIG. 1, in accordance with one embodiment of the present invention; 
     FIG. 7 illustrates an elevational view of the proximal and distal portions of the orthopedic fixation system depicted in FIG. 1 in abutting engagement, in accordance with one embodiment of the present invention; 
     FIG. 8 illustrates a partial sectional view of a distal portion of an orthopedic fixation system about to be inserted into a fracture site of a femur head, in accordance with one embodiment of the present invention; 
     FIG. 8A illustrates a perspective view of a driver member, in accordance with one embodiment of the present invention; 
     FIG. 9 illustrates a partial sectional view of a distal portion of an orthopedic fixation system partially inserted into a fracture site of a femur head, in accordance with one embodiment of the present invention; 
     FIG. 10 illustrates a partial sectional view of a distal portion of an orthopedic fixation system fully inserted into a fracture site of a femur head, in accordance with one embodiment of the present invention; 
     FIG. 11 illustrates a partial sectional view of a proximal portion of an orthopedic fixation system being inserted onto the distal portion of the orthopedic fixation system, in accordance with one embodiment of the present invention; 
     FIG. 12 illustrates a partial sectional view of a fully inserted orthopedic fixation system, in accordance with one embodiment of the present invention; 
     FIG. 13 illustrates a perspective view of a kit containing various sizes of the components of the orthopedic fixation system as well as the driver member, in accordance with one embodiment of the present invention. 
     FIG. 14 illustrates an exploded view of an orthopedic fixation system, in accordance with an alternative embodiment of the present invention; 
     FIG. 15 illustrates a top plan view of the proximal portion of the orthopedic fixation system depicted in FIG. 14, in accordance with an alternative embodiment of the present invention; 
     FIG. 16 illustrates an elevational view of the proximal portion of the orthopedic fixation system depicted in FIG. 14, in accordance with an alternative embodiment of the present invention; 
     FIG. 17 illustrates a top plan view of the distal portion of the orthopedic fixation system depicted in FIG. 14, in accordance with an alternative embodiment of the present invention; 
     FIG. 18 illustrates an elevational view of the distal portion of the orthopedic fixation system depicted in FIG. 14, in accordance with an alternative embodiment of the present invention; 
     FIG. 19 illustrates an elevational view of the proximal and distal portions of the orthopedic fixation system depicted in FIG. 14 in abutting engagement, in accordance with an alternative embodiment of the present invention; 
     FIG. 20 illustrates a perspective view of an insertion member, in accordance with an alternative embodiment of the present invention; 
     FIG. 21 illustrates an elevational view of the insertion member depicted in FIG. 20, in accordance with an alternative embodiment of the present invention; 
     FIG. 22 illustrates an elevational view of the proximal and distal portions of the orthopedic fixation system depicted in FIG. 1, and the driver member depicted in FIGS. 20-21, in abutting engagement, in accordance with an alternative embodiment of the present invention; 
     FIG. 23 illustrates a partial sectional view of an orthopedic fixation system about to be inserted into a fracture site of a femur head, in accordance with an alternative embodiment of the present invention; 
     FIG. 24 illustrates a partial sectional view of an orthopedic fixation system partially inserted into a fracture site of a femur head, in accordance with an alternative embodiment of the present invention; 
     FIG. 25 illustrates a partial sectional view of an orthopedic fixation system fully inserted into a fracture site of a femur head, in accordance with an alternative embodiment of the present invention; 
     FIG. 26 illustrates a partial sectional view of a driver member being removed from a fully inserted orthopedic fixation system, in accordance with an alternative embodiment of the present invention; 
     FIG. 27 illustrates a partial sectional view of a fully inserted orthopedic fixation system wherein the optional insertion facilitation member has been removed, in accordance with an alternative embodiment of the present invention; and 
     FIG. 28 illustrates a perspective view of a kit containing various sizes of the components of the orthopedic fixation system as well as the driver member, in accordance with an alternative embodiment of the present invention. 
     The same reference numerals refer to the same parts throughout the various Figures. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1-7, there is generally shown an orthopedic fixation system  10 , in accordance with one embodiment of the present invention. Although a surgical or bone screw is shown for illustrative purposes, it should be appreciated that any number of different types of surgical devices, such as surgical fasteners, may be practiced with the present invention, including, but not limited to plates, rods, pins, staples. 
     The system  10  primarily includes a proximal portion  12  comprised of a bioresorbable material  14  and a distal portion  16  comprised of a non-resorbable material  18 . Distal portion  16  is substantially elongated as compared to proximal portion  12 . Bioresorbable material  14  is preferably comprised of materials selected from the group consisting of hydroxyapatite, polylactic acid, polyglycolic acid, and combinations thereof. Non- resorbable material  18  is preferably comprised of materials selected from the group consisting of stainless steel, titanium, cobalt-chrome alloys, and combinations thereof. 
     Proximal portion  12  includes a proximal region  20  and a spaced and opposed distal region  22 . Proximal region  20  includes a shaft-like portion  24  extending from distal region  22  towards proximal region  20 . As shaft portion  24  nears proximal region  20 , an adjacent and contiguous head portion  26  is provided. Disposed on the proximal surface of head portion  26  is a recess  28  which is intended to receive a driver member, as will be explained later. Alternatively, instead of employing a recess, an optional raised member, such as a hex-shaped member  29 , shown in phantom in FIG. 4, may used to engage a driver member. Disposed on the distal surface of shaft portion  24  is another recess  30 , which preferably has a threaded surface  32  thereon, the purpose of which will be explained later. 
     Distal portion  16  also includes a proximal region  34  and a spaced and opposed distal region  36 . An external threaded surface  38  is provided on the distal region  36  of distal portion  16 , and is intended to function as a cutting surface for permitting insertion into tissue, such as, but not limited to bone tissue. Proximal region  34  preferably includes a mating member  40  which is intended to selectively mate with recess  30  of proximal portion  12 . Preferably, mating member  40  is provided with a threaded surface  42  thereon which corresponds to threaded surface  32  of recess  30 . Accordingly, the respective configurations of recess  32  and mating member  40  should be complementary towards one another. Although mating member  40  and recess  32  are shown as being circular and threaded, other configurations are envisioned, as well. Furthermore, a snap-fit appendage (not shown) may be provided on mating member  40  that snaps into a further recess (not shown) on the surface wall of recess  32 . 
     System  10  is unique in that proximal portion  12  and distal portion  16  need not be joined together (as shown in FIG. 7) in order to initiate the insertion of system  10  into tissue, such as bone tissue, in order to join two bone fragments together, to attach an orthopedic appliance (e.g., bone plate) to and/or into a bone surface, or to accomplish any other suitable orthopedic procedure. That is, distal portion  16  may first be inserted, either partially or substantially completely, and then proximal portion  12  may then be joined to distal portion  16 , whereupon system  10  is then fully and completely inserted. In this manner, the torque forces encountered during initial insertion of system  10  into hard bone tissue are not acting upon resorbable proximal portion  12 , thus lessening the chances of catastrophic failure of system  10  at resorbable proximal portion  12 /non-resorbable distal portion  16  interface. 
     A non-limiting example of a method of using orthopedic fixation system  10  in conjunction will be described with reference to FIGS. 8-12. In order to facilitate the insertion of the distal portion  16 , a rotation facilitation and release facilitation system  34   a  is preferably provided on the proximal surface of proximal region  34 . By way of a non-limiting example, rotation facilitation and release facilitation system  34   a  preferably includes at least one, preferably at least two, and still more preferably, at least three areas defining recesses  34   b  located in the proximal surface of the proximal region  34 . By way of a non-limiting example, these recesses  34   b  can mate with a three-pronged driver member  104  having three matching prongs  104   a  which can then rotate and insert distal portion  16  and then can be easily removed from recesses  34   b  by simply pulling outwardly away therefrom. In this manner, there is no need to engage threaded mating member  40 . This is significant, in that if driver member  104  is used to mate with threaded mating member  40  (e.g., via an internal threaded surface), there would not be a simple way of disengaging driver member  104  from threaded mating member  40  once distal member  16  had been inserted into the bone tissue. To overcome this problem, mating member  40  may be configured as a hex-shaped member, or other suitable configuration, that is capable of disengaging from a corresponding driver member without causing distal member  16  to rotate once inserted into the bone tissue. 
     In FIG. 8, there is shown a fractured femur head  100  having a pilot hole  102  pre-drilled for receiving the orthopedic fixation system  10 . In this view, only distal portion  16  is shown as it will be driven first into pilot hole  102 . A suitable driver  104  is shown which preferably mates with recesses  34   b , or alternatively, mating member  40 . 
     In FIG. 9, driver member  104  is rotated in direction R (e.g., clockwise) so as to cause distal portion  16  to be driven into pilot hole  102 . The torque generated by the rotation acts exclusively on distal portion  16  as it cuts through the bone tissue adjacent to pilot hole  102 . Additionally, driver member  104  can be fitted which a device to create a countersink in the surface of the bone tissue. 
     In FIG. 10, distal portion  16  has been substantially fully inserted into pilot hole  102 . Note that distal portion  16  extends across both portions of the fracture site, providing outstanding physical support for the fracture site in which proper healing can take place. 
     In FIG. 11, proximal portion  12  is mated to distal portion  16  and another driver member  106  is used to rotate proximal portion  12  in direction RR so as to cause both proximal portion  12  and distal portion  16  to be inserted slightly more into pilot hole  102  until system  10  can no longer be inserted any further into the bone tissue. 
     In FIG. 12, system  10  is shown in its fully inserted position, with head portion  26  of proximal portion  12  being substantially co-planar with the surface of the bone tissue, thus eliminating any tissue irritation concerns previously discussed. Proximal portion  12  will eventually be resorbed by the body over time. New bone tissue will eventually grow into the portion of pilot hole  102  occupied by proximal portion  102 , as it gradually resorbs. It should be noted that head portion  26  need not be completely countersunk into the bone tissue, as shown. Occasionally, head portion  26  may protrude slightly above the surface of the bone tissue. Generally, this is not an undesirable condition, as head portion  26  will eventually be resorbed. However, the surgeon may optionally either remove the protruding portion (e.g., with a heat loop or a cutting tool such as a burr) or alternatively, melt the protruding portion so that it assumes a lower profile against the surface of the bone tissue. 
     It should also be appreciated that the present invention can also be used to affix or fasten orthopedic appliances, such as bone plates and the like, to and/or into bone surfaces. In that case, the orthopedic fixation system of the present invention would be simply driven through the orthopedic appliance (or a provided hole therein), by rotating the various driver members of the present invention, and into the respective bone surface. The orthopedic fixation system of the present invention can be used with resorbable, as well as non-resorbable, orthopedic appliances. 
     In order to provide the greatest versatility and flexibility to the orthopedic surgeon, the present invention provides various sizes of the aforementioned components of the orthopedic fixation system  10 , as well as various driver members  104  and  106 , in a surgical kit form, as shown in FIG.  13 . Kit  200  includes a receptacle  202  which can neatly, and preferably sterilely, store any number of different size component/driver so that the orthopedic surgeon can have his/her choice as to which size component/driver is appropriate to use. For example, the repair of a fracture of a relatively small bone (e.g., a metatarsal) may require a relatively small orthopedic fixation system  10 , whereas the repair of a large bone (e.g., a femur or tibia) may require a relatively large orthopedic fixation system  10 . Alternatively, a fracture site might be difficult to reach with one size driver member  104  or  106 , but is easily reached with a relatively larger driver member  104  or  106 . Kit  200  provides the surgeon with any number of choices as how to approach the orthopedic procedure presented to him/her. 
     Referring to FIGS. 14-19, there is generally shown an alternative orthopedic fixation system  110 , in accordance with an alternative embodiment of the present invention. Although a surgical or bone screw is shown for illustrative purposes, it should be appreciated that any number of different types of surgical devices, such as surgical fasteners, may be practiced with the present invention, including, but not limited to plates, rods, pins, staples. 
     System  110  primarily includes a proximal portion  112  comprised of a bioresorbable material  114  and a distal portion  116  comprised of a non-resorbable material  118 . Bioresorbable material  114  is preferably comprised of materials selected from the group consisting of hydroxyapatite, polylactic acid, polyglycolic acid, and combinations thereof. Non-resorbable material  118  is preferably comprised of materials selected from the group consisting of stainless steel, titanium, cobalt-chrome alloys, and combinations thereof. 
     Proximal portion  112  includes a proximal region  120  and a spaced and opposed distal region  122 . Proximal region  120  includes a shaft-like portion  124  extending from distal region  122  towards proximal region  120 . As shaft portion  124  nears proximal region  120 , an adjacent and contiguous head portion  126  is provided. Extending above head portion  126  is an optional insertion facilitation member  128 , the purpose of which will be explained later. 
     Extending along the longitudinal axis of proximal portion  112  is a throughbore  130 . At the distal surface  132  of proximal member  112  is a recess  134 , the purpose of which will be explained later. 
     Distal portion  116  also includes a proximal region  136  and a spaced and opposed distal region  138 . An external threaded surface  140  is provided on substantially the entire external surface of distal portion  116 , and is intended to function as a cutting surface for permitting insertion into tissue, such as, but not limited to bone tissue. Proximal region  136  includes a mating member  142  which is intended to selectively mate with recess  134  of proximal portion  112 . Accordingly, the respective configurations of recess  134  and mating member  142  should be complementary towards one another. Although mating member  142  and recess  134  are shown as being rectangular, other configurations are envisioned, as well. Furthermore, a snap-fit appendage (not shown) may be provided on mating member  142  that snaps into a further recess (not shown) on the surface wall of recess  134 . 
     Extending along the longitudinal axis of distal portion  116  is a bore  144 , which originated on the top surface of mating member  142  and extends approximately halfway along the length of distal portion  116 . When proximal portion  112  and distal portion  116  are placed in abutting engagement, throughbore  130  preferably aligns with bore  144 , as specifically shown in FIG.  19 . 
     Once proximal portion  112  and distal portion  116  are joined together (as shown in FIG. 19) it is then possible to insert system  110  into tissue, such as bone tissue, in order to join two bone fragments together, to attach an orthopedic appliance (e.g., bone plate) to and/or into a bone surface, or to accomplish any other suitable orthopedic procedure. 
     However, as opposed to previous hybrid fixation systems where substantial amounts of stress are imparted onto the bioresorbable portion of the fixation system, the present invention endeavors to substantially reduce the amount of stress, especially torque stresses and forces, imparted onto the bioresorbable portion of the fixation system. In this manner, the present invention greatly reduces the incidences of catastrophic failure of the bioresorbable portion of the fixation system. 
     In order to accomplish this goal, the present invention provides a specialized driver member that imparts the greatest stresses and torque forces on the portion of the fixation system that is best suited to absorb these forces and stresses, i.e., the non-resorbable distal portion. 
     Referring to FIGS. 20-22, a driver member  146  includes a cap portion  148  and an elongated appendage portion  150  extending from an internal surface  152  of cap portion  148 . 
     The purpose of elongated appendage portion  150  is to engage an internal surface of bore  144  of distal portion  116 . Optionally, elongated appendage portion  150  can also engage an internal surface of throughbore  130  of proximal portion  112 . In order for elongated appendage portion  150  to be able to engage an internal surface of bore  144  of distal portion  116 , it must first be inserted into throughbore  130  of proximal portion  112  and then preferably fully inserted into bore  144  of distal portion  116 . 
     In order to generate the proper amount of torque necessary to insert fixation system  110  into bone tissue, bore  144  is preferably provided with an anti-rotation device  154 , such as, but not limited to a rectangular or hex-shaped internal surface, as opposed to a circular internal surface. Preferably, elongated appendage portion  150  is provided with a complementary external surface that corresponds to the internal surface of bore  144 . For example, if bore  144  is hex-shaped, elongated appendage portion  150  should be hex-shaped, if bore  144  is rectangularly-shaped, elongated appendage portion  150  should be rectangularly-shaped, and so forth. 
     As previously mentioned, throughbore  130  may also be adapted to engage elongated appendage portion  150 , as well. For example, if bore  144  and elongated appendage portion  150  are hex-shaped then throughbore  130  should be hex-shaped, if bore  144  and elongated appendage portion  150  are rectangularly-shaped then throughbore  130  should be rectangularly-shaped, and so forth. However, in order to avoid any substantial stresses and forces acting upon throughbore  130 , it may optionally be provided with a slightly larger diameter than the diameter of elongated appendage portion  150  so as to avoid any contact therewith. In this manner, as driver member  146  is rotated, the torque generated will substantially be acting on distal portion  116 , as opposed to proximal portion  112 . Therefore, the probability that a catastrophic failure of proximal portion  112  will occur at the interface between proximal portion  112  and distal portion  116  is greatly reduced. 
     Internal surface  152  of cap portion  148  is substantially hollow, with the exception of elongated appendage portion  150  emanating therefrom. Because it is hollow, it is able to snuggly fit over optional insertion facilitation member  128 , although not so snuggly that driver member  146  can not be easily removed. In this manner, as driver member  146  is rotated, the torque generated will substantially be acting on optional insertion facilitation member  128  and to a much greater degree upon distal portion  116 , as opposed to proximal portion  112 . Even if throughbore  130  is optionally provided with a slightly larger diameter than the diameter of elongated appendage portion  150  as previously described, driver member  146  will not wobble, because it is held snuggly by bore  144  of distal portion  116  and internal surface  152  of cap  148  is held snuggly against optional insertion facilitation member  128 . Therefore, the probability that a catastrophic failure of proximal portion  112  will occur at the interface between proximal portion  112  and distal portion  116  is greatly reduced. 
     A non-limiting example of a method of using the orthopedic fixation system  110  in conjunction with driver member  146  will be described with reference to FIGS. 23-27. 
     In FIG. 23, there is shown a fractured femur head  200  having a pilot hole  202  pre-drilled for receiving the orthopedic fixation system  110 . In this view, proximal portion  112  and distal portion  116  are joined together with driver member  146  associated therewith. 
     In FIG. 24, driver member  146  is rotated in direction R (e.g., clockwise) so as to cause orthopedic fixation system  110  to be driven into pilot hole  202 . The torque generated by the rotation acts primarily on distal portion  116  as it cuts through the bone tissue adjacent to pilot hole  202 . 
     In FIG. 25, driver member  146  can no longer be rotated anymore, indicating that orthopedic fixation system  110  has been fully inserted into pilot hole  202 . 
     In FIG. 26, driver member  146  is removed from orthopedic fixation system  110  by applying a gentle pulling force in direction P, exposing elongated appendage portion  150 . 
     In FIG. 27, optional insertion facilitation member  128  may optionally be removed (e.g., with a heat loop), if the clinical setting requires so. Otherwise, optional insertion facilitation member  128 , as well as proximal portion  112 , will eventually be resorbed by the body over time. New bone tissue will eventually grow into the portion of pilot hole  202  occupied by proximal portion  112 , as it gradually resorbs. 
     It should also be appreciated that the present invention can also be used to affix or fasten orthopedic appliances, such as bioresorbable bone plates and the like, to and/or into bone surfaces. In that case, the orthopedic fixation system of the present invention would be simply driven through the resorbable orthopedic appliance (or a provided hole therein), by rotating the driver member of the present invention, and into the respective bone surface. After insertion is complete, the driver member of the present invention would be removed from the orthopedic fixation system of the present invention. As the resorbable orthopedic appliance resorbs, the resorbable portion of the orthopedic fixation system of the present invention would also resorb, although perhaps at a slower rate to prevent premature detachment of the resorbable orthopedic appliance from the bone surface. 
     In order to provide the greatest versatility and flexibility to the orthopedic surgeon, the present invention provides various sizes of the aforementioned components of orthopedic fixation system  110 , as well as driver member  146 , in a surgical kit form, as shown in FIG.  28 . Kit  300  includes a receptacle  302  which can neatly, and preferably sterilely, store any number of different size component/driver so that the orthopedic surgeon can have his/her choice as to which size component/driver is appropriate to use. For example, the repair of a fracture of a relatively small bone (e.g., a metatarsal) may require a relatively small orthopedic fixation system  110 , whereas the repair of a large bone (e.g., a femur or tibia) may require a relatively large orthopedic fixation system  110 . Alternatively, a fracture site might be difficult to reach with one size driver member  146 , but is easily reached with a relatively larger driver member  146 . Kit  300  provides the surgeon with any number of choices as how to approach the orthopedic procedure presented to him/her. 
     The foregoing description is considered illustrative only of the principles of the invention. Furthermore, because numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and process shown as described above. Accordingly, all suitable modifications and equivalents that may be resorted to that fall within the scope of the invention as defined by the claims that follow.