Abstract:
Improved fixation devices for treating, for example, a radius fracture include a first member adapted to engage a distal portion of a radius fracture and a second member operably coupled to the first member adapted to engage a proximal portion of a radius fracture, wherein the first member is shiftable relative to the second member. Due to the adjustability of the first member relative to the second member, the linear distance, between the portion of bone proximal to the fracture and the portion of bone distal to the fracture can be fixed at a desired distance, which can promote suitable healing of the fracture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The current application claims the benefit of priority from U.S. provisional patent application filed on Feb. 13, 2004, entitled “Distal Radius Fracture Device” having Ser. No. 60/544,624, which is hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to treatment and surgical repair of bone fractures. More specifically, the invention relates to surgical repair of long bones such as distal radius fractures that do not involve the articular surfaces of the radius and are minimally comminuted.  
       BACKGROUND  
       [0003]     Distal radius fractures are the most common fractures presenting to emergency rooms. In 1998, radius fractures were responsible for 2.9 million visits to physicians and accounted for 0.7% of all emergency room visits.  
         [0004]     The majority of distal radius fractures occur with the wrist in extension. Commonly, an individual who falls will extend their hands out in from of them to break the fall. Sometimes this causes damage to the bones of the wrist and forearm. The result is that the volar (palm) side of the radius fails in tension while the dorsal (back) side of the radius fails in compression. This results in a simple fracture line of the volar side of the radius and a comminuted fracture pattern on the dorsal side of the radius. The crushed or splintered bone in the comminuted portion of the fractured radius lacks structural integrity so that attempts to realign the fracture portion of the radius to promote healing often fail. The fractured portion of the bone tends to return to its position immediately after the injury occurred due to lack of support. This creates a deformity of the radius that may have several deleterious effects. First, there is visual deformity. Second, there is decreased function due to loss of motion. Third, this deformity increases the stress on certain parts of the articular cartilage, which tends to result in the development of degenerative arthritis in the wrist.  
         [0005]     Currently there are several approaches used to repair distal radius fractures. They include closed reduction and casting, the use of percutaneous pins, the application of external fixation and open reduction with internal fixation. While all of these techniques may be appropriate in some circumstances, none is appropriate for every type of fracture or for every patient. Each of the above-mentioned treatment methods must be tailored to the meet the needs of the individual patient. The physician must weigh the risks and benefits of the treatment option to devise a treatment plan that is best suited for each patient.  
         [0006]     Closed reduction and casting includes aligning the broken bone ends by external manipulation and applying a cast to the affected limb to immobilize it. The presence of soft tissues between the cast and the fracture allows for some movement of the fractured bone ends relative to each other which is particularly problematic in comminuted fractures where the crushed fracture margins do not meet neatly. Thus, the reduction will often tend toward its post-fracture position. Prolonged immobilization of the wrist joint which can result in stiffness of the wrist after the cast is removed.  
         [0007]     Percutaneous pins are passed through the skin and help to bridge the compressed portion of a comminuted fracture. The pins are passed through bone on one side of the break, across the gap and into the bone on the other side of the break. The insertion of percutaneous pins provides some additional support for the break but percutaneous pins also allow some relative movement between the broken bone portions. Percutaneous pins, if buried, must be surgically removed at some later date after healing is complete and if left protruding through the skin must be kept dry and create a risk of infection while present.  
         [0008]     External fixators support the fractured bone in proper alignment via external rings and struts that are connected to the bone by rods that pass through the skin and soft tissues generally perpendicular to the bone&#39;s long axis. External fixation devices also require that exposed portions of the appliance pass through the skin with attendant concerns of infection. The probes associated with external fixation provide a potential portal for infective agents to pass through the skin. In addition, external fixation may also result in significant joint stiffness after healing.  
         [0009]     Internal fixation devices are generally plates that are secured to bone on either side of the fractured area, commonly by screws. The internal fixation device bridge the gap in a comminuted fracture to support the fractured bone ends while healing takes place. Open reduction and internal fixation require a full surgical procedure with the attendant risks and potential for complications. In addition, internal fixation hardware may also require removal at a later date. Removal of the internal fixation device requires a separate surgical procedure, again, with attendant possibility of infection and complication.  
         [0010]     It would be beneficial to the orthopedic surgical arts to have another means to stabilizing comminuted fractures of the long bones that is minimally invasive and provides an additional surgical option for those fractures that require more stabilization than a close reduction supplies and yet do not need open reduction with internal fixation.  
       SUMMARY OF THE INVENTION  
       [0011]     The fixation device of the present invention solves many of the above described problems. The fracture fixation device of the present invention can support many comminuted fractures that need more than closed reduction but do not need open reduction and internal fixation with use of a plate or rod.  
         [0012]     The invention disclosed here will be described in the context of reduction (setting) of a comminuted fracture of the distal radius. However, it is to be understood that the present invention can be used to stabilize fractures in other bones at other locations and that the invention is not necessarily limited to used in the distal radius.  
         [0013]     An improved fixation device for treating, for example, a radius fracture includes a first member adapted to engage bone distal to a radius fracture and a second member operably coupled to the first member adapted to engage bone proximal to a radius fracture, wherein the first member is axially adjustable relative to the second member. Due to the adjustability of the first member relative to the second member the linear distance between the bone proximal to the comminuted fracture and the bone distal to the fracture can be adjusted to a desired distance, which can promote suitable healing of the fracture and prevent deformity. For example, controlling the linear distance between the distal portion and the proximal portion of the fracture can promote desired healing of fractures having crushed or splintered bone fragments, since the bone ends remain fixed relative to each other throughout the healing process. In some embodiments, the adjustability of the first member relative to the second member can be provided by a ratcheting and/or screw expander operably connected to the first member and the second member. In other embodiments, the first member can include a plurality of openings that facilitate securing the second member to the first member at desired locations.  
         [0014]     The fixation devices of the present invention address the needs of patients who suffer from distal radius fractures and solve many of the problems noted above. The fixation devices of the present disclosure can be relatively small, and thus can be positioned within a patient via a small surgical incision. In addition, the fixation devices can provide support of the dorsal aspect of the distal radius where a comminuted fracture has occurred, and therefore can reduce any tendency for the comminuted area to collapse and prevent limb deformity. Moreover, the fixation devices can function like a jack or spacer to keep the area of the fracture open and the distal portion of the fracture properly aligned during the healing process.  
         [0015]     In some embodiments, a portion, or all, of the fixation device can be formed from one or more bioresorbable polymers, which can eliminate the need for a second surgery to remove the implanted device.  
         [0016]     The fixation devices also provide an additional surgical option that bridges the gap for those fractures that fall between fractures that need nothing more than a close reduction and those fractures that need open reduction with internal fixation in order to achieve the best results for an individual patient  
         [0017]     In one embodiment, the invention is a fixation device having a first member, a second member and an expander operably coupled to the first member and the second member. In these embodiments, the first member and the second member can be clip-like support devises that grasp the distal and proximal bone portions at the fracture site, and the expander can be a ratcheting and/or screw mechanism that facilitates adjusting the distance between the first member and the second member.  
         [0018]     The expander can comprise a screw mechanism that can be turned by the operating surgeon in order to force the distal clevis and the proximal clevis apart from one another. In another embodiment, the expander can be a ratchet mechanism that can be rotated within an aperture in one or both of the distal and proximal devises in order to allow the distal and proximal devises to be brought closer to one another to facilitate the insertion of the distal and proximal devises within the fractured area of the distal radius.  
         [0019]     In yet another embodiment of the invention, the expander may be fixed to either the distal clevis or the proximal clevis with a screw mechanism and fixed to the other clevis by a ratchet mechanism that then can be used to force the distal and proximal devises apart in order to provide stabilization for the comminuted fracture.  
         [0020]     In another embodiment, the invention relates to a fixation device having a first member that extends to the subchondral bone at the end of the medullary canal of the distal radius. In these embodiments, the fixation device can further include a second member that is adapted to engage the proximal portion of radius fracture and can slidably engage the first member such that the second member can move or slide along the major axis of the first member. In these embodiments, the first member can include a plurality of openings positioned along the major axis of the first member, which facilitates coupling the second member to the first member at a desired position using a positioning pin.  
         [0021]     In another embodiment, the invention relates to an implantable fixation device including a first member adapted to engage with a distal portion of a fracture, and a second member operably coupled to the first member adapted to engage with a proximal portion of a fracture. In these embodiments, the fixation device can be formed from one or more bioresorbable polymers.  
         [0022]     In a further embodiment, the invention relates to a method of treating a comminuted fracture, wherein the radius fracture comprises a distal portion and a proximal portion, the method including the step of adjusting a first member relative to a second member such that a desired distance between the distal portion of the fracture and the proximal portion of the fracture is achieved, wherein the first member is engaged with the distal portion of the fracture and the second member is engaged with proximal portion of the fracture, and wherein the first member is operably coupled to the second member.  
         [0023]     Another embodiment includes a proximal clevis and an expander. In this embodiment the expander is extended into the distal medullary canal to make contact with the distal subchondral bone to provide support to the fractured radius.  
         [0024]     Another embodiment includes a notched rod and a clamp to adjustably fix the expander to the proximal or distal clevis. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIG. 1  is a side sectional view of an embodiment of the present invention in situ in a fractured distal radius;  
         [0026]      FIG. 2  is a perspective view of proximal and distal devises in accordance with the present invention;  
         [0027]      FIG. 3  is a top plan view of the embodiment of  FIG. 1  in situ in a distal radius;  
         [0028]      FIG. 4  is a side sectional view of a second embodiment of the present invention in situ in a fractured distal radius;  
         [0029]      FIG. 5  is a top plan view of the embodiment of  FIG. 4 ;  
         [0030]      FIG. 6  is a top plan view of a third embodiment of the present invention;  
         [0031]      FIG. 7  is a side sectional view of the third embodiment in situ in a fractured distal radius;  
         [0032]      FIG. 8  is a plan view of a notched rod and a clamp in accordance with the third embodiment of the present invention;  
         [0033]      FIG. 9  is a perspective view of another embodiment the present invention having a first member, a second member and a positioning pin;  
         [0034]      FIG. 10  is a perspective view of the embodiment of  FIG. 9  depicting the second member engaged with first member;  
         [0035]      FIG. 11  is a back perspective view of the second member of the embodiment of  FIG. 9 ;  
         [0036]      FIG. 12  is a front perspective view of the second member of  FIG. 11 ;  
         [0037]      FIG. 13   a  is a side view of the embodiment of  FIG. 9  depicting the second member engaged with a proximal portion of the fracture and the first member inserted into second member;  
         [0038]      FIG. 13   b  is a side view of the embodiment of  13   a  where the second member has been extended to engage the distal portion of the fracture;  
         [0039]      FIG. 14  is a perspective view of an embodiment of a fixation device having a first member with a mushroom shaped end portion. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0040]     The invention is described herein in the context of devices and methods for repairing comminuted fractures of the distal radius. This should not be considered limiting. The invention can be used to reduce fractures of other long bones such as, for example, the ulna, humerus, tibia, fibula and the femur.  
         [0041]     Referring to  FIGS. 1 and 2 , in one embodiment, fixation device  10  generally includes first member  12 , second member  14  and expander  16 . As depicted in  FIGS. 1 and 2 , first member  12  may be a clip-like distal clevis  13  having outer fork  18  and inner fork  20 . Outer fork  18  desirably has two legs  22  that terminate in a beveled tip  24 . Distal clevis  13  can also includes inner fork legs  26 . Outer fork legs  22  are separated from inner fork legs  26  by space  28 . Space  28  is sufficient to accommodate the thickness of the cortical bone supported, which, in this example, is the cortical bone of the distal radius. Typically, the cortical bone of the distal radius is about two millimeters thick, thus the space between outer fork legs  22  and inner fork legs  26  is typically about two to about four millimeters. However, the space between the outer fork legs  22  and the inner fork legs  26  can be from about one to about ten millimeters. The size of the space between the inner fork legs and the outer forks legs can be guided by the thickness of the bone that a particular fixation device is designed to engage.  
         [0042]     Inner fork legs  26  can have an extended length relative to outer fork legs  22  and may terminate in a blunt end  30 . The extended length of inner fork legs  26  is sufficient to extend well beyond the expected distance from a comminuted fracture from the distal end of the medullary canal in a distal radius or other bone to be repaired. This allows for inner fork legs  26  to be trimmed to an appropriate length to abut the distal end of the medullary canal in a fractured distal radius or other bone.  
         [0043]     As depicted in  FIGS. 1 and 2 , second member  14  may include a clip-like proximal clevis  15  having outer fork  32  and inner fork  34 . In some embodiments, outer fork  32  and inner fork  34  are desirably substantially mirror images of one another. Inner fork  34  may have two inner legs  36  of substantially similar length and construction. Outer fork  32  desirably includes two outer legs  38  which are substantially of similar construction. Both inner legs  36  and outer legs  38  desirably end in beveled tip  40 . Referring to  FIGS. 4 and 5 , in some embodiments, the proximal clevis can further include struts  48 . In one embodiment, struts  48  extend distally, downwardly and outwardly from the proximal clevis so as to reach into and across the medullary cavity when fixation device  10  is in situ. Thus, in this embodiment, fixation device  10  provides additional stabilization of the distal radius by supporting the internal volar side of the distal radius via struts  48 .  
         [0044]     Referring to  FIGS. 6, 7  and  8 , in some embodiments, fixation device  10  can include a proximal clevis  50  having an L-shaped structure  52 . Proximal clevis  50  generally includes outer fork  54  and flange  56 . Flange  56  is oriented at a generally right angle to outer fork  54 . In this embodiment expander  58  interfaces directly with flange  56  and extends within the medullary canal proximal to the fracture to engage the distal radius cortex between the proximal portion  60  of the expander  58  so that the bone cortex is held between the proximal portion  60  and outer fork  54 . As depicted in  FIG. 7 , distal portion  62  of the expander  58  extends distally through the medullary canal until the distal end  64  of the expander  58  comes into contact with subchondral bone at the end of the medullary canal.  
         [0045]     As described above, fixation device  10  can include an expander  16  interposed between the first member  12  and the second member  14 , to facilitate moving first member  12  and second member  14  apart, to support the two halves of the comminuted fractured portion of the distal radius and prevent the fractured portions of the bone from returning to their post fracture alignment.  
         [0046]     In one embodiment, expander  16  may include a ratchet  42 . In this example, expander  16  will be referred to as being secured to second member  14  and to be slidably fixable relative to first member  12 . However it is to be understood that expander  16  may be fixed to either first member  12  or second member  14  and may be slidingly engagable to either first member  12  or second member  14 .  
         [0047]     In other embodiments, expander  16  may be threaded so that one end has a right hand thread and the other end has a left end thread. Thus, the expander may be threadably engaged to first member  12  at a first end  44  and to second member  14  at a second end  46 . In these embodiments, expander  16  may be turned so as to force first member  12  away from second member  14  in an operation similar to the operation of a turnbuckle.  
         [0048]     Referring to  FIG. 8 , expander  58  may take the form of a notched rod  66 . Notched rod  66  may be secured relative to proximal clevis  50  by clamp  68 . In addition, in another embodiment, proximal clevis  50  may engage with two notched rods  66 . Thus, in situ, the bone cortex is gripped between two prongs  70  of outer fork  54  and two notched rods  66 . Additional expander mechanisms are contemplated and are within the scope of the present disclosure.  
         [0049]     Referring to  FIGS. 9 and 10 , another embodiment of a fixation device  100  is depicted including first member  102 , second member  104  and positioning pin  106 . First member  102  can be adapted to slideably engage second member  104 , which facilitates coupling the first member to the second member at desired locations. As depicted in  FIGS. 9 and 10 , first member  102  can have an elongate major axis relative to a minor axis, and can include a plurality of openings  108  positioned along the major axis.  
         [0050]     Generally, second member  104  can include first opening  110 , which is adapted to receive first member  102  and facilitates slidably engaging first member  102  and second member  104 . In some embodiments, first opening  110  can have a rectangular cross-section, while in other embodiments first opening  110  can have an circular cross-section, an oval cross-section or other cross sectional shapes.  
         [0051]     Second member  104  can also include second opening  112 , which is adapted to receive positioning pin  106 . As depicted in  FIG. 10 , positioning pin  106  can be inserted into second opening  112  and extend into one of the plurality of openings in first member  102  to coupled second member  104  to first member  102 .  
         [0052]     As depicted in FIGS.  9 - 10 , first member  102  may include a rod having an elongated major axis relative to a minor axis. In some embodiments, first member  102  can have a rectangular cross-section, a circular cross-section, an oval cross-section or other cross sectional shape. The size and cross-sectional shape of first member  102  can be guided by the corresponding size and shape of first opening  110  on second member  104 . As depicted in  FIGS. 13   a  and  13   b , in some embodiments, end portion  114  of first member  102  can be tapered to facilitate engagement with the medullary canal  116  of the distal radius. As depicted in  FIG. 14 , end portion  114  can present a mushroom shape, a dome shape or the like to facilitate engagement with the medullary canal  116  of the distal radius.  
         [0053]     As described above, second member  104  is designed to engage the proximal portion of a radius fracture. Referring to  FIGS. 11 and 12 , in some embodiments, second member  104  can be a L-shaped bracket having a first leg  118  connected to a second leg  120 . First leg  118  includes first opening  110  adapted to receive first member  102 , while second leg  120  includes second opening  112  adapted to receive positioning pin  106 . As depicted in  FIG. 12 , a support plate  118  can be positioned adjacent to opening  110 , which can help support the L-shaped bracket when the bracket is under a load. Additionally, support plate  122  can be positioned into a notch cut into the proximal portion of the radius, or other bones, to prevent second member  104  from moving out of a desired location during healing of the fracture.  FIG. 13  depicts support plate  122  positioned within a notch in the proximal portion of a radius fracture to prevent second member  104  from shifting during healing of the fracture. In some embodiments, support plate  122  can have a length that is coextensive with a length of second leg  120 , while in other embodiments, as depicted in  FIG. 12 , second leg  120  can extend beyond support plate  122 .  
         [0054]     In operation, fracture stabilizer  10  is applied to a comminuted fracture, for example, of the distal radius. Once the surgeon has surgically accessed the fractured area of the radius, second member  14  is inserted so that the cortex of the proximal portion of the fractured radius is inserted between outer fork  32  and inner fork  34 . Similarly, first member  12  is inserted into the portion of the fractured radius distal to the break, so that outer fork  18  and inner fork  20  surround the cortex of the distal fractured radius. First member  12  and second member  14  are then aligned so that expander  16  may be interposed between the two. Expander  16  is then adjusted to force first member  12  away from second member  14  until the fractured radius is aligned as desired to allow for proper healing of the fractured bone.  
         [0055]     To employ fixation device  100 , a small incision is made on, for example, the dorsal wrist adjacent the fracture. A small notch, or cut, is then made in the proximal portion of the bone where second member  104  is to be positioned.  
         [0056]     First member  102  can then be inserted into first opening  110  of second member to make fixation device  100  more compact. Fixation device  100  can then be placed in the gap of a comminuted fracture such that support plate  122  of second member  104  slips into the notch into the proximal portion of the bone. Once second member  104  is engaged with the proximal portion of the fracture, first member  102  can be extended and extended through the marrow to the distal end of the intramedullary canal to abut the subchondral bone.  
         [0057]     Positioning pin  106  is then inserted into second opening  112  and extended into an opening  108  located on first member to secure second member  104  to first member  102 .  
         [0058]     The fixation devices of the present disclosure can be formed from any biocompatible material suitable for orthopedic implants including metals, metal alloys, polymers, bioresorbable polymers and combinations thereof. Suitable metals include, for example, consisting of stainless steel, titanium, alloys of iron, cobalt, nickel, tantalum, zirconium, silver, gold, alloys of copper, platinum, palladium and alloys and combinations thereof.  
         [0059]     Suitable polymers may include, for example, polyesters, polyanhydrides, polycarbonates, polyurethanes, polyphosphazenes, polyamino acids, polycyanocrylates, polyphosphazenes, and blends and combinations thereof.  
         [0060]     The fixation devices may be constructed from one or more bioresorbable polymers, which can eliminate the need for removal. For the purposes of this application the term bioresorbable is considered to include materials that are incorporated into the living tissue as well as materials that are broken down and excreted by the body. Bioresorbable polymers are well known the medical arts. Suitable bioresorbable polymers include, for example, poly(glycolic acid) (PGA), poly(d,1-lactic-co-glycolic acid), poly(caprolactone), poly(propylene fumarate), poly[1,6-bis(carboxyphenoxy) hexane], tyrosine-derived polycarbonate, polyurethane based on LDI and poly (glycolide-co-γ-caprolactone), ethylglycinate polyphosphazene, poly(dioxanone) (PDS), poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(1-lactic acid) (PLLA), poly(d,1-lactic acid) (PDLA) and combinations thereof.  
         [0061]     The embodiments above are intended to be illustrative and not limiting. Additional embodiments may be found within the claims. Although the present invention has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.