Abstract:
The acromioclavicular joint prosthesis of the present invention provides a mechanism for securing the distal or outer end of the clavicle to the acromion of the scapula. The present prosthetic device includes an acromion attachment component, an opposite clavicle attachment component, and an articulated joint between the two components. The intermediate joint may include a “breakaway” component, allowing the joint to be temporarily misaligned in the event that a severe force is applied to the shoulder, rather than damaging the joint or shoulder structure. The breakaway joint may be quickly and easily realigned by a medical professional. The joint may also include a spring loaded shock absorption component as well, to avoid damage to the joint due to excessive tensile forces. Tools and a method for surgically installing and locking the present prosthesis securely to the respective bones of the skeletal structure, are also disclosed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to the medical and surgical fields, and more specifically to an internal prosthesis (endoprosthesis) for the shoulder joint between the acromion extension of the scapula and the outward end of the clavicle. The acromioclavicular joint prosthesis of the present invention serves to reconnect the two bones of this joint, while providing the freedom of movement and shock absorption required.  
         [0003]     2. Description of the Related Art  
         [0004]     Shoulder injuries occur relatively frequently, and may comprise injury to any of a number of different joints and tissues. While a relatively simple dislocation of the ball of the upper arm bone (humerus) from its glenoid seat in the scapula is perhaps the most common shoulder injury, there are a large number of other injuries which can occur, from breakage of bones in the shoulder area to the tearing of ligaments and other tissues, damage to the joints due to arthritis or other osteal deterioration, etc. In many cases, the shoulder joint is damaged to the extent that it is no longer capable of functioning to anywhere near a normal extent.  
         [0005]     As a result, a number of artificial shoulder joints have been developed in the past, as evidenced by the number of earlier patents for such devices. However, none of those devices provide for the repair of a separation between the distal (outward) end of the clavicle and the acromion, which extends outwardly from the scapula. This joint serves to hold the shoulder up in its normal position, among other purposes. When this joint separates, the scapula and its attached humerus tend to drop downwardly and outwardly, as there is no other bone joint connecting the scapula to the remainder of the skeletal structure. At least some form of external support is required for even limited function of the affected joint and limb, with surgical repair being desired.  
         [0006]     However, surgical repair does not always prove effective. In many instances, the repaired joint separates again, reverting to the same problem as before the surgery was done. Yet, to the knowledge of the present inventor, no one has developed any form of artificial or prosthetic joint that may be substituted for the damaged acromioclavicular joint for forming a durable repair.  
         [0007]     Accordingly, the present invention provides a solution to this problem in the form of an acromioclavicular joint prosthesis which may be used to provide a secure and durable repair to a damaged acromioclavicular shoulder joint. The present prosthesis essentially comprises an acromion attachment component and a clavicle attachment component, with appropriate connection elements therebetween to provide the required freedom of movement for the joint. Means for securing the two attachment components to their respective bones, is also provided.  
         [0008]     A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.  
         [0009]     U.S. Pat. No. 3,869,730 issued on Mar 11, 1975 to Barry A. Skobel, titled “Surgically Implantable Joint Prosthesis,” describes an artificial joint for replacing the shoulder attachment ball of the humerus and its scapular glenoid socket. The prosthetic joint includes a gimbal to provide the necessary degrees of freedom for the joint, as well as perforations to provide for bone ingrowth for more secure attachment as the repair heals. However, the Skobel prosthetic device does nothing to provide for the reattachment of a separated acromioclavicular joint and does not provide a prosthetic joint structure for this joint, as provided by the present invention.  
         [0010]     U.S. Pat. No. 3,979,778 issued on Sep. 14, 1976 to Jerome H. Stroot, titled “Shoulder Prosthesis,” describes another artificial replacement for the humerus and scapula glenoid joint. Again, no disclosure is made of any form of prosthetic joint for the acromion and clavicle, as addressed by the present invention.  
         [0011]     U.S. Pat. No. 4,550,450 issued on Nov. 5, 1985 to James G. Kinnett, titled “Total Shoulder Prosthesis System,” describes both a humerus—scapula joint prosthesis and a prosthesis secured to the acromion, with the artificial ball of the humerus bearing against the acromion prosthetic component. However, the acromion component is a relatively simple plain bearing pad against which the upper portion of the joint ball of the humerus bears. Kinnett appears to indicate that the distal or outer end of the clavicle would be immovably affixed to the acromion by means of his acromion prosthesis, which would greatly limit certain motions of the shoulder. Kinnett does not disclose any form of articulated joint between the clavicle and acromion extension of the scapula, as provided by the present acromioclavicular joint prosthesis.  
         [0012]     U.S. Pat. No. 5,944,757 issued on Aug. 31, 1999 to Paul M. Grammont, titled “Total Trochitero-Acromial Shoulder Prosthesis,” describes a shoulder joint prosthesis comprising an artificial ball for attachment to the shoulder joint end of the humerus and a plain bearing for attachment to the lower surface of the acromion, against which the ball of the humerus bears. However, Grammont fails to provide any form of attachment between the acromion and the clavicle. The present acromioclavicular joint prosthesis provides for an articulated connection between these two skeletal components.  
         [0013]     U.S. Pat. No. 6,132,467 issued on Oct. 17, 2000 to Arnold Keller, titled “Endoprosthesis, In Particular For The Sternoclavicular Joint,” describes a prosthetic joint configured for installation in a joint where the two bones cannot be easily distracted (separated) from one another. One such joint is the inner end of the clavicle and its connection to the sternum, which is the opposite end of the clavicle from the end to which the present acromioclavicular prosthesis is secured. While Keller does provide a ball joint, he does not disclose the means for positively attaching the two bones together, particularly the acromion and scapula, as provided by the present invention.  
         [0014]     U.S. Pat. No. 6,193,758 issued on Feb. 27, 2001 to Randall J. Huebner, titled “Shoulder Prosthesis,” describes a replacement for the shoulder contact ball of the humerus. The Huebner prosthesis includes an extension which is driven into the medullar (marrow) canal of the humerus, to secure the joint ball in place. However, Huebner does not disclose any form of joint prosthesis for connecting the acromion and clavicle together, as provided by the present invention.  
         [0015]     U.S. Pat. No. 6,620,197 issued on Sep. 16, 2003 to Brian J. Maroney et al., titled “Method And Apparatus For Performing A Shoulder Replacement Procedure In The Treatment Of Cuff Tear Arthropathy,” describes a prosthetic humerus ball joint, similar to the Huebner device discussed immediately above. The major difference between the Huebner and Maroney et al. prostheses is that Maroney et al. provide a spherical ball surface of more than 180 degrees of spherical arc. However, no prosthetic acromioclavicular joint is disclosed by Maroney et al.  
         [0016]     U.S. patent Publication No. 2002/99,381 published on Jul. 25, 2002, titled “Method And Apparatus For Resecting A Greater Tubercule From A Humerus Of A Patient During Performance Of A Shoulder Replacement Procedure,” describes a tool and method for removing the protuberance of bone from the humerus which is adjacent the ball end thereof. This tool and method would be used during the operation for installing the prosthetic ball described in the &#39;197 U.S. patent to Maroney et al., described immediately above. No acromioclavicular joint prosthesis is disclosed in the &#39;381 patent Publication.  
         [0017]     U.S. patent Publication No. 2002/99,445 published on Jul. 25, 2002, titled “Method And Apparatus For Performing A Shoulder Replacement Procedure In The Treatment Of Cuff Tear Arthropathy,” is the earlier publication of the U.S. patent application which resulted in the issuance of the &#39;197 U.S. patent to Maroney et al. on Sep. 16, 2003, discussed further above. The same points of difference between the device of the Maroney et al. &#39;197 U.S. patent and the present invention noted in that discussion, are seen to apply here as well.  
         [0018]     U.S. patent Publication No. 2003/144,738 published on Jul. 31, 2003, titled “Acromial-Humeral Prosthesis And Method Of Implantation,” describes a two piece bearing which is affixed to the underside of the acromion extension of the scapula, and which serves as a plain bearing surface for the upper portion of the ball of the humerus. However, the &#39;738 publication does not disclose any form of connection between the acromion and the clavicle, which connection is addressed by the present prosthetic joint invention.  
         [0019]     U.S. Design Pat. No. 285,969 issued on Sep. 30, 1986 to James G. Kinnett, titled “Acromial Prosthesis Component For Total Shoulder Prosthesis System,” illustrates a design for the acromion attachment bearing described in the &#39;450 U.S. Utility patent to the same inventor, discussed further above. As in the case of his &#39;450 U.S. Utility patent, no acromioclavicular prosthetic joint is disclosed by Kinnett in his &#39;969 U.S. Design patent.  
         [0020]     French Patent Publication No. 2,541,890 published on Sep. 7, 1984, titled “Total Shoulder Prosthesis,” describes (according to the drawings and English abstract) a prosthetic humerus ball joint replacement and a prosthetic replacement for the glenoid socket of the scapula. The glenoid replacement also attaches beneath the acromion, but no acromioclavicular joint prosthesis is disclosed in the &#39;890 French Patent Publication. While the inventor named in the &#39;890 French patent is also the inventor of record in the &#39;757 U.S. patent discussed above, it should be noted that the inventions described in the &#39;757 U.S. patent and the &#39;890 French Patent Publication are different from one another.  
         [0021]     Finally, PCT Patent Publication No. WO 93/09733 published on May 27, 1993, titled “Modular Prosthesis,” describes a series of components for a modular humerus ball joint prosthesis. The assembly is quite similar to that disclosed in the Huebner &#39;758 and Maroney et al. &#39;197 U.S. patents and the Maroney et al. &#39;445 U.S. patent Publication. The same points of difference noted further above in the discussion of the &#39;758 Huebner and &#39;197 Maroney et al. U.S. patents and the Maroney et al. &#39;445 U.S. patent Publication are seen to apply here as well, i.e. no acromioclavicular joint prosthesis is disclosed in those patents and patent publication.  
         [0022]     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus an acromioclavicular joint prosthesis solving the aforementioned problems is desired.  
       SUMMARY OF THE INVENTION  
       [0023]     The present acromioclavicular joint prosthesis provides a device for replacing the joint between the acromion extension of the scapula and the distal or outward end of the clavicle. This joint can become separated due to excessive force being applied thereto and resultant tearing of the ligaments or tendons securing the two bones together. Alternatively, the joint may deteriorate due to arthritis or other disease. Regardless of the underlying reason, a damaged or separated acromioclavicular joint requires repair or replacement.  
         [0024]     The present invention serves as a durable and flexible prosthetic replacement for the acromioclavicular joint in the human skeletal structure. The present prosthesis includes an acromion attachment component and a clavicle attachment component, with the two bone attachment components being linked by a spring loaded spherical joint, or other joint providing two degrees of freedom of motion. A “breakaway” joint connection may be provided between the two components, with the “breakaway” connection allowing the prosthesis to temporarily “break” linearly when excessive force is applied thereto. Such a joint may be realigned fairly quickly and easily by a medical professional, if misalignment occurs.  
         [0025]     Each bone attachment component of the present invention also includes an extension providing positive attachment to the respective bone structures. Passages and other components are provided for new bone growth to develop therethrough and therearound, thereby further strengthening the prosthetic installation. The present invention further includes tools providing for the installation of the present acromioclavicular prosthesis, and a method of surgically installing the prosthesis for replacement of the acromioclavicular joint.  
         [0026]     Accordingly, it is a principal object of the invention to provide an acromioclavicular joint prosthesis for prosthetic replacement of a natural acromioclavicular joint in the human skeletal structure.  
         [0027]     It is another object of the invention to provide a prosthesis having an acromion attachment component and a clavicle attachment component, with the two components being connected by an articulated joint.  
         [0028]     It is a further object of the invention to provide an acromioclavicular joint prosthesis having extensions of both the acromion and clavicle attachment components, with the extensions providing additional security for the attachment by means of bone growth and adhesion thereto.  
         [0029]     Still another object of the invention is to provide tools for the installation of the present acromioclavicular joint prosthesis, as well as a method for installing the prosthesis.  
         [0030]     It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.  
         [0031]     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]      FIG. 1  is a perspective view of a first embodiment of a left side acromioclavicular joint prosthesis of the present invention as seen from the front and top, showing various features thereof.  
         [0033]      FIG. 2  is a perspective view of an alternative embodiment of the acromioclavicular joint prosthesis of the present invention as seen from the front and top, showing an alternative connection assembly.  
         [0034]      FIG. 3  is a detailed, exploded perspective view of the alternative breakaway connection between the acromion and clavicle components, showing various details of the connection.  
         [0035]      FIG. 4  is a front elevation view of the alternative embodiment breakaway connection, showing its operation.  
         [0036]      FIG. 5  is a top plan view in partial section of an alternative embodiment shock absorption component of the present prosthetic device, showing details thereof.  
         [0037]      FIG. 6  is an exploded perspective view as seen from the front and top showing the initial steps in installing the present acromioclavicular joint prosthesis to the acromion of the scapula.  
         [0038]      FIG. 7  is a perspective view as seen from the front and top showing subsequent steps in securing the present acromioclavicular joint prosthesis in the acromion, and an exemplary installation tool.  
         [0039]      FIG. 8  is a perspective view of an alternative embodiment securing means as seen from the front and top, using the tool of  FIG. 7  and a generally circumferential locking band around the acromion.  
         [0040]      FIG. 9  is an exploded perspective view as seen from the front and top showing the initial steps in installing the present acromioclavicular joint prosthesis to the distal end of the clavicle.  
         [0041]      FIG. 10  is a perspective view as seen from the front and top showing a subsequent step in the installation of the present prosthesis to the clavicle, and an exemplary installation tool.  
         [0042]      FIG. 11  is a perspective view as seen from the front and top showing the completed installation of the present acromioclavicular joint prosthesis between the distal end of the clavicle and acromion. 
     
    
       [0043]     Similar reference characters denote corresponding features consistently throughout the attached drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]     The present invention comprises a series of embodiments of an acromioclavicular joint prosthesis, serving to reconnect a separated or damaged joint between the acromion of the scapula and the clavicle.  FIG. 1  of the drawings provides a front and top perspective view of a first embodiment of the present prosthesis, designated by the reference numeral  10 . The prosthesis  10  of  FIG. 1  is relatively simple in comparison to other embodiments of the present invention, having only a single pivot point or hinge between the two attachment components to permit only one degree of freedom of motion between the two components. It will be seen that additional motion may be provided by including additional pivotal axes and/or telescoping mechanisms, as may be required or desired.  
         [0045]     The acromioclavicular prosthesis  10  of  FIG. 1  essentially comprises an acromion attachment component  12 , a clavicle attachment component  14 , and an articulated linkage  16  therebetween to connect the two components  12  and  14  to one another. The prosthesis  10  is shown diagrammatically attached to the left shoulder in  FIG. 1 , the clavicle being designated at C, the acromion process at A, the coracoid process at CP, the glenoid cavity at GC, the scapular notch at SN, and the remainder of the scapula S being fragmented. The acromion process A is reshaped as required to fit the acromion attachment component  12  closely and to provide a solid attachment for the component  12 . The clavicle C is also reshaped as required to provide a good fit for its clavicle attachment component  14 .  
         [0046]     The acromion attachment component  12  includes a pair of opposed short flanges  18  and  20  which straddle the edge of the acromion A, with the flanges  18  and  20  sandwiching a rounded seat  22  therebetween (the equivalent seat is more clearly shown in the alternate embodiment device illustrated in subsequent drawings). A single thin, flat, elongate acromion attachment and locking band  24  extends axially from the seat  22 , opposite the linkage  16 . The band  24  includes a series of tool gripping slots  26  formed through its free distal end  28  and one or more apertures  30  therethrough which provide for bone growth therethrough during the healing process to anchor the component  12  more solidly to the acromion A. The attachment and locking band  24  is used to pull the acromion attachment component  12  tightly against the reshaped acromion A, using a tool and method described in detail further below. The acromion attachment component  12  also includes a series of small anchoring spikes which extend from the seat  22 , with the spikes more clearly shown in alternate embodiments in subsequent drawings.  
         [0047]     The clavicle attachment component  14  of  FIG. 1  comprises a generally cylindrical or conical body portion  32  having a pair of opposed, generally parallel clavicle attachment arms  34  and  36  extending therefrom, opposite the articulated link  16  joining the two bone attachment components  12  and  14 . The first clavicle arm  34  includes a countersunk hole  38  therethrough, and the opposite clavicle arm  36  includes a threaded passage  40  therethrough for the installation of a screw  42  which passes through a passage which is drilled through the clavicle C during the installation operation. A clavicle insertion and locking band  44  extends axially from the clavicle attachment body  32 , between the two attachment arms  34  and  36 . The clavicle band  44  inserts in an axial slot which is formed in the attachment end of the clavicle C, with the band  44  also including one or more bone growth apertures  46  therein to provide more solid attachment for the clavicle component  14  once the installation has healed.  
         [0048]     The articulated link  16  joining the acromion and clavicle components  12  and  14  of the prosthesis  10  of  FIG. 1  comprises a simple hinged joint, with an optional leaf spring providing for articulation normal to the hinge axis. The acromion component  12  includes a bifurcated pair of joint attachment arms  48  and  50  extending therefrom, with a transverse hinge pin  52  extending across the two arms  48  and  50 . The attached clavicle component  14  includes an attachment fitting  54  having a lateral passage therethrough, through which the hinge pin  52  passes to pivotally link the two components  12  and  14  together. A leaf spring  55  may extend between the attachment fitting  54  and the clavicle attachment body  32 , with its thinnest dimension normal to the axis of the pivot pin  52  in order to provide joint articulation in two mutually normal planes. Other means of linking the components  12  and  14  may be provided, as exemplified in other embodiments illustrated in subsequent drawings and discussed below.  
         [0049]      FIG. 2  of the drawings provides an illustration of an alternative acromioclavicular joint prosthesis, designated by the reference numeral  100 . The prosthesis  100  includes an acromion attachment component  102 , opposite clavicle attachment component  104 , and a joint structure  106  between the two components  102  and  104 , essentially as in the prosthesis  10  of  FIG. 1 . However, the joint assembly  106  of the prosthesis  100  is somewhat more complex than the simple hinged or pivoting joint  16  of the prosthesis  10  of  FIG. 1  and provides additional degrees of freedom of motion, which may be desirable in some patients receiving the present acromioclavicular prosthesis.  
         [0050]     While most of the various components of the two attachment components  102  and  104  are identical to the corresponding components of the prosthesis  10  of  FIG. 1 , e.g. the acromion attachment and locking band  24 , the opposite clavicle attachment and locking band  44 , the clavicle attachment arms  34  and  36 , etc., it will be seen that the joint structure between the two attachment components  102  and  104  is quite different from the simple hinged joint  16  of the prosthesis  10  of  FIG. 1 . The prosthesis  100  of  FIG. 2  includes a spherical joint  106 , formed by a spherical socket  108  in the acromion attachment component and a mating ball  110  extending from the clavicle attachment component  104 , thereby providing three degrees of angular freedom of motion. It will be seen that the ball and socket relationship may be reversed if so desired, with the ball extending from the acromion attachment component and the socket formed in the extended end of the clavicle attachment component, if so desired.  
         [0051]     An additional angularly displaceable, locking “breakaway” joint component  112  may be provided between the spherical joint  106 , if so desired.  FIGS. 3 and 4  respectively provide exploded perspective and front elevation views of this “breakaway” joint  112 . The joint  112  includes a pair of arms  114  and  116  extending from the ball fitting  110  which is secured to the acromion attachment component  102 , with the two arms  114  and  116  forming a bifurcated fork with a slot  118  between the two arms  114  and  116 . The opposite joint component extending from the clavicle attachment shock absorber body  120  includes a tongue  122 , which fits within the slot  118  between the two attachment arms  114  and  116  of the opposite joint member. A pin  124  is permanently installed and passes laterally through the attachment arms  114  and  116 , and through a passage  126  through the tongue  122  to allow the tongue to pivot relative to the fork arms  114  and  116 .  
         [0052]     Spring-loaded retaining balls  128  protrude resiliently from the mutually facing inner surfaces of the two arms  114  and  116 , and engage corresponding dimples or depressions  130  formed in the opposite surfaces of the tongue  122 . The retaining balls  128  protrude into the dimples  130  to hold the arms  114 ,  116  and tongue  122  in linear alignment with one another, unless a high force is encountered which causes the assembly to dislodge or break away from its locked linear arrangement and pivot about the pin  124 . This dislocation of the angularly displaceable “breakaway” joint assembly  112  acts to prevent damage to other components of the prosthesis, and may be reset by a medical professional without undue difficulty.  
         [0053]      FIG. 5  provides a detailed top plan view in partial section of another resilient joint component for incorporation with the present acromioclavicular joint prosthesis, if so desired. A person having the present acromioclavicular prosthesis may occasionally encounter a sharp compressive blow to the shoulder, which could result in damage to the prosthesis. Accordingly, a linearly displaceable, spring-loaded fitting may be provided in the acromion attachment shock absorber body  120  of the prosthesis embodiment  100 , if so desired. The component  120  acts somewhat as a shock absorber, as the name implies. A washer  132  or the like is immovably affixed to the shaft extension  134  which carries the tongue  122  of the breakaway fitting  112 . Compression and extension springs  136  and  138  are assembled within the housing or body  120  on opposite sides of the washer  132 .  
         [0054]     A compression of the prosthetic joint  100  will cause the compression spring  136  to compress between the washer  132  and the opposite attachment end  140  of the shock absorber body  120  of the clavicle attachment component  104 , with the compression spring  136  rebounding to return the clavicle attachment component  104  to its original position relative to the acromion component  102 , once the compressive force is removed. A tensile force applied to the joint results in the compression of the extension spring  138  between the washer  132  and the distal end  142  of the shock absorber body  120 . Again, the assembly returns to a neutral point once the tensile force is removed. The various joint assemblies illustrated in the prosthesis embodiment  100  may be used separately or in combination with one another, as desired.  
         [0055]      FIGS. 6 through 10  illustrate the installation of the present acromioclavicular prosthesis between the acromion and clavicle, with  FIG. 8  illustrating yet another alternative embodiment and  FIG. 11  illustrating the completed installation. The embodiment illustrated in  FIGS. 6, 7 , and  9  through  11  is the prosthesis  100  shown in  FIG. 2 , with details thereof being illustrated in  FIGS. 3 through 5 . The embodiment of  FIG. 8  differs in its means of anchoring or locking to the acromion, and is discussed in detail further below.  
         [0056]      FIG. 6  illustrates the initial steps in the method of attaching the acromioclavicular prosthesis  100  to the acromion A. Initially, the acromion A must be reshaped in order to accommodate the acromion attachment component  102 . This is accomplished by forming a series of cuts, depressions, slots, and/or receptacles in the acromion A using conventional surgical tools and methods. While a certain order is described below, it will be recognized that the specific order of forming the cuts and receptacles in the acromion A will depend upon many factors, such as the tools used, the specific joint structure of the patient, and perhaps other factors as well. The specific order described below is not a required condition for the installation of any of the embodiments of the acromioclavicular joint prosthesis of the present invention. It will also be appreciated that while the embodiment  100  of the present acromioclavicular prosthesis is illustrated in  FIGS. 6, 7 , and  9  through  11 , the installation method described herein is generally applicable to any of the embodiments of the present invention.  
         [0057]     Initially, the surgeon may cut away the site where ligaments originally attached the clavicle to the acromion A to form an acromion attachment component seat D. Additional reshaping of the acromion attachment component seat is carried out by forming a pair of shallow opposed recesses E and F to each side of the acromion A in order to seat the two opposed flanges  18  and  20  of the acromion attachment component  102  (or  12 , etc.). The acromion attachment component  102  may obviously be manufactured in a wide range of sizes and thickness, in order for the thickness of the device to closely match the thickness of the acromion so that the outer flanges  18  and  20  lie essentially flush with the surface of the acromion A when the prosthesis  100  is completely installed.  
         [0058]     The surgeon may next form a generally rectangular recess G in the opposite, outboard or distal edge of the acromion A, to accommodate the distal end  28  of the locking band  24  and the operation of an attachment tool, as illustrated in  FIGS. 7 and 8  and discussed further below. A passage H is then formed through the acromion A, connecting the acromion attachment component seat D and the opposite locking band and tool recess G. The passage H may have a relatively low and wide cross section, just sufficient to accept the width and thickness of the acromion attachment and locking band  24  therethrough. Finally, a transverse passage I is formed through the acromion A, intersecting the locking band passage H. This passage I provides for the installation of a locking clip  142  across the locking band passage H, with the clip  142  passing through one of the tool grip slots  26  in the band  24  to prevent the band  24  from slipping out of the passage H.  
         [0059]     At this point, the attachment end of the clavicle C may be reshaped as required. The clavicle attachment component  104  (or  14 , etc.) includes a generally conical socket defined by the shape of the clavicle attachment component. The attachment end of the clavicle C is reshaped accordingly by removing bone material to form a congruent shape J for the end of the clavicle C, generally as shown in  FIG. 9 . A relatively wide and shallow slot K is then formed axially in the attachment end of the clavicle C, to accept the clavicle insertion and locking band  44 . Finally, a hole or passage L is formed transversely through the clavicle C, for the clavicle attachment screw  42  which passes through the two clavicle attachment component arms  34  and  36  to secure them to the end of the clavicle C.  
         [0060]     Once the acromion A has been reshaped as required, the acromion attachment component  102  (or  12 , etc.) may be secured to the acromion A by inserting the acromion component attachment and locking band  24  through the acromion slot H until the acromion attachment component seat  22  is seated within the mating recess D previously formed in the acromion A. A tensioning tool  144  (essentially similar to conventional tools used to tension packaging bands and straps, but formed of surgical grade materials) is applied to the distal end  28  of the locking band  24  and used to pull the band  24  in order to draw the acromion attachment component  102  tightly against the acromion A, generally as shown in  FIG. 7  of the drawings. A resilient pad or cushion  146  may be applied between the acromion bone A and the nose of the tool  144  in order to avoid chipping the acromion during this process.  
         [0061]     It will be noted that the acromion attachment component  102  includes a series of small spikes  148  extending from the seat  22  thereof. These spikes  148  are shown most clearly in  FIGS. 3, 4 ,  9 , and  10  of the drawings. As the acromion attachment component  102  is drawn tightly against the seat D previously cut into the acromion bone A, the spikes  148  imbed themselves in the acromion bone A, thereby further securing the attachment component  102  to the acromion A. A conventional bone adhesive or cement may be used to further enhance the attachment of the acromion attachment component  102  (or other embodiment) to the acromion bone A, as desired or required by the surgery. The locking clip  142  is inserted through its transverse passage I in the acromion A and through one of the slots  26  in the attachment and locking band  24 , to preclude withdrawal of the locking band  24  from its passage H through the acromion A.  
         [0062]     When the above described attachment of the acromion attachment component  102  (or other) has been completed, any excessive material of the locking band  24  may be trimmed off to leave only a short stub extending from the tool recess G previously formed in the acromion A, generally as shown in the completed installation shown in  FIG. 11 . As the surgery heals, the acromion bone material will regrow around the end of the locking band  24  and through the bone growth passages  30  in the locking band  24 , thereby further anchoring the acromion attachment component  102  (or other) solidly, permanently, and immovably to the acromion bone A.  
         [0063]      FIG. 8  of the drawings illustrates a further embodiment of the present acromioclavicular prosthesis, designated by the reference numeral  150 . In this embodiment, the acromion attachment component  152  does not have the acromion attachment and locking band extending axially therefrom, as do the other embodiments of  FIGS. 1 through 7  and  9  through  11 . The acromioclavicular joint prosthesis  150  of  FIG. 8  instead has an attachment and locking band which surrounds the acromion A when installed. The clavicle attachment component  154  and the connecting linkage assembly  156  of the prosthesis  150  remain essentially the same as in the embodiments illustrated in  FIGS. 2 through 7  and  9  through  11 , with the simplified alternative linkage illustrated for the prosthesis embodiment of  FIG. 1  also being adaptable to the prosthesis  150  of  FIG. 8 , if so desired.  
         [0064]     In the prosthesis  150  of  FIG. 8 , the acromion attachment and locking band  158  comprises an elongate band which has its central portion  160  passing through a transverse slot  162  formed through the acromion attachment component  152 . The two extended portions  164  and  166  pass to each side of the acromion A and meet at the distal portion of the acromion A opposite the acromion attachment component  152 , thereby surrounding the acromion A. The two ends  168  and  170  of the band  158  are gripped by a banding tool  144 , similar to the tool  144  illustrated in  FIG. 7 , and pulled taut around the acromion A and secured by a conventional banding clip to hold the prosthesis  150  in place on the acromion A. This installation method eliminates the need for forming the passages H and I through the acromion A, thereby simplifying the process.  
         [0065]     The reshaping of the clavicle C has been described further above, and once the clavicle reshaping has been accomplished, the clavicle attachment component  104  (or other embodiment) may be installed on the clavicle C. This installation is illustrated in  FIGS. 9 and 10  of the drawings. Initially, the clavicle attachment component  104  is placed over the reshaped end of the clavicle C, with the two clavicle attachment arms  34  and  36  straddling the end of the clavicle C and the axially extending clavicle insertion and locking band  44  inserted into the corresponding axial passage K previously formed in the clavicle C. A conventional bone adhesive or cement may be applied to provide a more secure attachment, if so desired.  
         [0066]     At this point, the clavicle attachment component  104  must be pulled tightly up against the end of the clavicle C in order to assure a secure installation. The present invention may include a specialized tool  172  which may be temporarily clamped to the clavicle C, and used to pull the clavicle attachment component  104  tightly against the end of the clavicle C. Padding, not shown, is preferably placed between the clavicle C and the tool jaws to avoid bone damage. The clavicle attachment tool  172  may generally be in the form of a pair of Vise-Grip® pliers, or other suitable hands-free clamp which may be temporarily secured to the clavicle C. However, the tool  172  further includes a pair of levers  174  extending laterally therefrom, with the levers  174  having hand grip ends  176  adjacent the hand grip end  178  of the attachment tool  172  and opposite tensile force application ends  180  adjacent the jaws  182  of the gripping tool  172 .  
         [0067]     A tension rod  184  extends from the tensile force application end  180  of each of the levers  174 ; only a single one of the tension rods  184  is shown in  FIG. 10 , due to the perspective of the drawing. The tension rods  184  each have a tool attachment end  186  which is pivotally attached to the tensile force application end  180  of a respective one of the levers  174 , and an opposite clavicle attachment arm end  188  which temporarily secures into a respective tension rod attachment hole or passage  190  formed in the ends of each of the clavicle attachment arms  34  and  36 ; the tension rod attachment holes  190  are specifically indicated in  FIGS. 1, 2 ,  6 , and  10  and are visible in other drawings.  
         [0068]     The clavicle attachment tool  172  and tension rods  184  are used generally as shown in  FIG. 10 . The clavicle attachment portion  104  of the prosthesis  100  (or other embodiment) is initially placed reasonably securely against the previously reshaped end of the clavicle C. The clavicle attachment arm ends  188  of the tension rods  184  are then temporarily and removably secured to their respective passages  190  in the ends of the two clavicle attachment arms  34  and  36 . This defines the location along the clavicle C for the temporary placement of the clavicle attachment tool  172 , which is then clamped removably to the clavicle C, generally as shown in  FIG. 10 . The two levers  176  (which may have only a single hand grip  176 , if so desired) are then manipulated by squeezing toward the hand grip  178  of the clamping tool  172 , which results in the tension rods  184  pulling the clavicle attachment component  104  tightly against the end of the clavicle C and locking the locking band  44  securely therein.  
         [0069]     Once the clavicle attachment portion  104  of the prosthesis  100  has been pulled tightly against the end of the clavicle C, it may be permanently secured in place. Careful measurement has previously permitted the lateral screw passage L (shown in  FIG. 9  of the drawings) to be drilled or otherwise formed at the proper location through the clavicle C, as described further above. The clavicle attachment screw  42  may then be installed through its countersunk hole  38  in the first clavicle attachment arm  34 , and threaded into the opposite threaded hole or passage  40  (indicated in  FIG. 1 , and shown in other FIGS.) in the opposite second arm  36 . The screw  42  includes a locking head, e.g. conventional teeth or the like formed in the underside of the head to engage the mating face of the countersunk hole  38 , or other locking means as desired.  
         [0070]     Once the screw  42  has been tightened, the clamping tool  172  may be released from the clavicle C and the clavicle arm attachment ends  188  of the two tension rods  184  removed from the clavicle attachment component arms  36  and  38  to complete the installation. The completed installation of the acromioclavicular joint prosthesis  100  of the present invention is illustrated in  FIG. 10  of the drawings. Other embodiments, e.g. the embodiment  10  of  FIG. 1 , will be seen to install in a similar manner as that described for the prosthesis  100 . The result is a durable and reliable prosthetic joint serving to secure the distal or outboard end of the clavicle to the acromion process of the scapula, to repair or replace that joint which has been previously damaged due to injury or disease.  
         [0071]     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.